A Visibly Extreme Jet Stream in Advance of Irma

On Tuesday, I wrote this blog about how Jet Stream behavior and related severe weather during summer of 2017 jibed with the findings of recent climate science. About how human-forced polar warming appears to be impacting extreme summer weather patterns by altering the upper level winds — with a particular focus on impacts to North America.

Yesterday, I looked at the upper level wind patterns running over North America in advance of Irma’s approach and saw this:

(Classic ridge-trough pattern like that identified by Dr Jennifer Francis and Dr Michael Mann. One that, according to their related research, increases the likelihood of certain kinds of extreme weather patterns and events. One that these scientists associate with polar warming set off by human-caused climate change. Image capture from 1500 UTC on September 6. Image source: Earth Nullschool.)

It’s a classic high amplitude wave form in the Jet Stream. One that shows an extremely deep trough digging all the way down to the Gulf Coast in the east and arching back up into a pointed ridge north of Alaska and into the Arctic Ocean in the west. This kind of high amplitude wave pattern is not typical. Or if such a pattern did appear in the past, it tended not to stick around for so long. But during this summer, such intense high amplitude ridges have been forming again and again over the west and such deep troughs have been forming again and again in the east.

New Precipitation and Temperature Extremes

The most apparent visible effect of this ridge-west — trough-east pattern has been to produce record heat, drought, and wildfires in the west and record rainfall in conjunction with an extremely stormy weather pattern in the south and east. You can plainly see this dipolar relationship in the precipitation and temperature anomaly maps provided by NOAA below:

These maps cover precipitation and temperature observations for the last 30 days compared to climatological averages. In the west we find that precipitation for large regions has been less than 10 percent of normal (less than 1/10th normal). Meanwhile temperatures in the west have ranged between 1 and 4 C above average. In the south and east, large regions have seen between 200 and 800 percent of typical precipitation amounts (2 to 8 times the norm). Temperatures, meanwhile have ranged between 1 and 3 C below average.

This is the very definition of heightened extremes. Looking at the prevalent upper level air pattern over the U.S. for the summer of 2017, it’s clear that south to north upper level winds pulling air up from the Equatorial zone toward the pole are facilitating one side of the extreme and that a countervailing upper level wind originating near the pole and running south toward the tropics is driving the opposite extreme.

Slowing Upper Level Winds in a North-South Orientation Weakens the Steering Currents

Unfortunately, prevalent and long lasting heat or heavy rainfall isn’t the only apparent impact of this new pattern. Another aspect of this extreme dipole is a weakening of the west to east steering currents that typically begin to pick up in a region between 25 and 30 degrees North Latitude and to intensify further beyond the 30 N line. This effect is due to the fact that upper level wind patterns are oriented more in a north-south (west) or south-north (east) direction and due to the fact that under such large Jet Stream meanders the upper level steering winds tend to slow down.

(It’s not just Harvey and Irma. Weak upper level steering currents are contributing to a long range potential that Jose might loop back to strike South Florida.)

For Hurricanes like Harvey and Irma, stronger west to east steering winds have had two protective effects for the United States. First, they have helped storms to keep moving — working to generally prevent the kind of long duration stall we saw that helped to produce such catastrophic flooding during Harvey. Second, they have tended to deflect storms away from the U.S. East Coast. And for Irma, what this means is that this storm is more likely to strike the U.S. East Coast if the upper level steering winds that would typically turn it to the east are weak.

This is a dynamic upstream aspect of human-forced polar warming. One that produces added extreme weather risks on top of those already generated by warming ocean waters — which increase peak potential storm intensity — and rising atmospheric water vapor — which helps to add latent heat, lift and related convective available potential energy that increases top limits for storm intensity and heavy rainfall.

And as we sit here hoping and praying that Irma will re-curve away from the U.S. east coast, we should consider how polar warming may be helping to make such a terrible strike more likely — increasing risks to so many people and to so much that we all hold dear.

RELATED STATEMENTS AND INFORMATION:

Links:

Dr Jennifer Francis

GFS Model Runs illustrated by Earth Nullschool

Extreme Weather Events Linked to Climate Change’s Impact on Jet Stream

This is the Pattern Climate Scientists Warned us About

NOAA

Hat tip to Scott

Hat tip to Wharf Rat

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A Halo of Storms and Heatwaves — New Study Confirms that Global Warming is Wrecking the Northern Hemisphere Jet Stream

“We came as close as one can to demonstrating a direct link between climate change and a large family of extreme recent weather events.”Michael Mann

*****

The Earth is warming, the weather is growing more extreme, and from the observational perspective, it appears that the Northern Hemisphere Jet Stream has undergone some seriously disturbing changes. Over the past five years, this subject has been one that’s spurred heated debate among scientists, meteorologists, and global climate and weather watchers. Now, a new model study finds that it’s likely that the Jet Stream is being significantly altered by human-forced climate change and that this alteration is helping to drive extreme weather events like the 2003 European heat wave, the 2010 Pakistan flood and Russian heat wave, the 2011 Texas heat wave and recent floods in Europe.

(More extreme variation in upper level wind speeds is an upshot of polar warming during boreal summer. The result is that risks of severe heatwaves, droughts, wildfires and floods increases as the Earth warms. Image source: Michael Mann, Penn State.)

From the study:

… our analysis of both historical model simulations and observational surface temperature data, strongly suggests that anthropogenic warming is impacting the zonal mean temperature profile in a manner conducive to wave resonance and a consequent increase in persistent weather extremes in the boreal summer.

What this means is that the new study provides still more evidence that the Jet Stream’s north to south variance is increasing during summer. As a result, it is enabling powerful heat domes to form in regions where winds run from south to north. In regions where the upper level winds run from north to south, it creates cooler zones in which powerful storms can flood large swaths of countryside. In other words, increasingly juxtapposed zones of extreme temperature anomalies and higher atmospheric instability and moisture loading tend to form more and more often. And this results in weather patterns that we have never really seen before.

(An Inconvenient Sequel is a call for action on climate change like we’ve never seen before. And the imperative to act on climate is now stronger than it ever was.)

The fact that the Mann study uses observational and model assessments to find that such changes are likely to very likely now being caused by human-forced warming and related polar amplification is a highly significant scientific finding. It adds one more attribution tie to the extreme weather events that we’ve been seeing with increasing frequency. A tie directly to global warming. And it does so through model studies that identify the underlying physical mechanisms at work. It’s a pivotal moment in the atmospheric sciences. And everyone needs to sit up and pay attention.

Credits: 

Hat tip to Colorado Bob

Hat tip to Cate

Scientific hat tip to Dr Michael Mann

(Please support publicly-funded, non-special interest based science that is now under assault by the climate change denying Trump Administration)

Warm Winds Take Aim at Chukchi as Arctic Sea Ice Volume Hits Record Lows

Temperatures over the Chukchi Sea are predicted to hit as high as 37 degrees Fahrenheit (2.9 C) on Wednesday and Thursday as a massive high pressure ridge building over Alaska pulls warm, moist Pacific air northward. These temperatures represent staggering warmth for this Arctic Ocean zone during March when temperatures are typically about 54 degrees F (30 degrees C) cooler.

Major Warm Wind Invasion for the Chukchi This Week

(Multi-day above freezing temperatures for the Chukchi sea predicted for later this week is not a normal event for early March. Unfortunately, warm wind invasions like this one have become more common as the globe has warmed up due to human fossil fuel emissions. Image source: Earth Nullschool.)

This recent warm wind invasion is one of many observed over the past five years in which enormous bulges in the Jet Stream have pierced deep into what was once a mostly impenetrable pall of winter chill hanging over the Arctic. It’s a new atmospheric condition associated with rampant fossil fuel burning. One that has produced considerable damage to the Arctic environment by reducing sea ice coverage, threatening key species, melting glaciers and thawing permafrost.

Such incursions of extreme warmth bear the obvious marks of a failing of Arctic cold brought on by human-forced climate change and have tended to generate significant spikes in overall Arctic surface temperatures during fall, winter, and spring. This week’s warm air invasion of the Chukchi is expected to help push readings for the entire region above the 66 degree north latitude line to 4.5 C (8 F) above average for this time of year. That’s a strong departure for this region during the month of March when the typically more uniform advance of warmth in the lower latitudes tends to strengthen the Jet Stream — locking in Polar winter conditions in the far north through about the middle of April.

(The warm wind invasion of the Chukchi Sea is expected to help push overall Arctic temperatures considerably higher. Image source: Climate Reanalyzer.)

Far above average Arctic surface temperatures extending from October of 2016 through March of 2017 have been triggered again and again by these floods of warm air rising up from the south. And the net effect on Arctic sea ice volume has been little short of devastating.

Arctic Sea Ice Volume Lowest Ever Recorded During Winter, Comparable to Summer Volumes of the Early 80s

Arctic sea ice volume for both January and February of 2017 are now far below past record low trend lines for this time of year. Present record low monthly values for this past February are around 17,000 cubic kilometers vs previous record lows for the month during 2013 at around 19,500 cubic kilometers. Last February’s sea ice volume average of 17,000 cubic kilometers is about the same sea ice volume measured at the end of melt season in September of 1981. In other words, sea ice volume in winter now is comparable to sea ice volumes during the summers of the early 1980s.

(Arctic sea ice volume has never been this low during winter time. Image source: PIOMAS.)

All the record warmth flooding into the Arctic during 2016 and 2017 has undoubtedly contributed to these new record lows for sea ice volume. And a cooling of the Arctic surface relative to recent record warmth during March and April could soften this worrying trend somewhat. To this point, it is worth noting that sea ice extent measures are now closer to past record low trend lines. So there has been some slightly more hopeful inching back to slightly less ridiculously abnormal measures. A more positive movement that will likely take a hit as Arctic temperatures are predicted to significantly warm again this week.

Weather is Variable, But the Underlying Trend Looks Pretty Bad

Weather, as we should note, can be quite variable and may bring a more pleasant surprise later in the month. However, despite this potential, sea ice states are looking as bad or worse than they ever have at the end of freeze season. And it is worth noting that less ice coverage and volume leaves more dark water open to absorb the sun’s springtime and summer rays and less ice to reflect it. Furthermore, post La Nina periods, as we are now experiencing, tend to flush more atmospheric and ocean heat into the Arctic. So, despite the variable nature of weather overall, we’re in a bit of a situation where the systemic trend odds of a noteworthy sea ice recovery toward more rational trend lines pre-summer 2017 aren’t looking very good.

Links:

NSIDC

Arctic Sea Ice Graphs

Earth Nullschool

Climate Reanalyzer

PIOMAS

Wipneus

Tropical Tidbits

Chukchi Sea

Arctic Heatwave Forecast to Crush Northern Hemisphere Snow Cover This Week

The Russian side of the Arctic is heating up.

A high amplitude ridge in the Jet Stream is forecast to develop atop the Yamal region of Russia, expand northward over the Kara and Laptev seas, inject a plume of anomalously warm air over the polar region, and then proceed on along the Arctic Ocean shores of Siberia. Beneath this ridge, temperatures over the Arctic Ocean will spike to +1 to +4 C above average while temperatures over land will hit extreme +20 C and higher anomalies.

Arctic Heatwave June 6

(Arctic heatwave invades Siberia in the GFS forecast for later this week as depicted by Climate Reanalyzer.)

Arctic Ocean zones are forecast to see temperatures climb above freezing for much of the 80 degree North Latitude zone. Over Siberia, land-based temperatures are predicted to range from the 40s and 50s along the Arctic Ocean boundary and climb to the 60s to 80s in regions just inland.

As temperatures tend to flatten out over Arctic Ocean waters and as permafrost zones in Siberia are used to far cooler readings during Northern Hemisphere Summer, the predicted heatwave is likely to have some rather strong impacts should it emerge. Most notably, snow cover over remaining land and sea ice is expected to see a rather extreme reduction over the next seven days. In other words, GFS forecast models show Northern Hemisphere snow cover basically getting crushed:

Current snow CoverPredicted Snow Cover

(Massive reduction in Northern Hemisphere [NH] snow cover predicted coincident with Siberian Heatwave later this week. Left frame shows current NH snow cover. Right frame shows predicted NH snow cover for Tuesday, June 9. Image source: Climate Reanalyzer.)

Sparse remaining snow cover in Northeast Siberia along the East Siberian Arctic Shelf coastal zone is expected to be pretty much wiped out. One foot average snow cover along the shores of the Laptev and Kara seas is also expected to melt. And a broad section of remaining snow upon the sea ice is predicted to retreat away from the North Polar region — receding back toward the final haven near Greenland.

Snow is important for spring and summer-time Arctic temperature moderation due to the fact that it provides insulation to sea ice and permafrost as well as serving as a reflective, high-albedo surface that bounces back some of the incoming heat from the 24-hour seasonal Arctic sun. Snow melt, on the other hand, serves to form albedo-reducing melt ponds over the Arctic Ocean sea ice during summer. A critical factor in late season melt forecasting in which more June melt ponds tend to mean lower sea ice totals by end season. In addition, snow melt fills permafrost zone rivers with above-freezing waters that then flow into the Arctic Ocean — providing yet another heat forcing to the sea ice.

Conditions in Context

This weekly trend and forecast is consistent with an ongoing tendency during 2015 for strong ridge formation and warm air slot development over both Alaska and the Yamal region of Russia. The high amplitude ridges also likely have teleconnections with larger weather patterns such as El Nino in the Pacific, the warm water pool (hot blob) in the Northeast Pacific, and record low sea ice extents continuing for most of Northern Hemisphere Spring. Observations that are also consistent with the predictions made by Dr. Jennifer Francis that are a direct upshot of polar amplification set off by human-caused warming of the global climate system.

image

(GFS model forecast as depicted by Earth Nullschool showing ridge Northwest Territory, trough Greenland and North Atlantic, ridge Kara and Laptev region of Siberia. A dynamic that may be the result of teleconnections set off by factors related to human-caused climate change. Image source: Earth Nullschool.)

It’s worth noting that many of these factors are self reinforcing. For example, more sea ice melt results in higher amplitude wave formation in the Jet Stream. Higher amplitude wave formation in the Jet Stream transports more warmth to the Arctic environment, resulting in more sea ice and snow melt which in turn weakens the Jet Stream further. A longer-term amplifying feedback of Arctic carbon release may also be in play (hinted at by an overburden of both CO2 and methane in the local Arctic atmosphere), which would also contribute to the conditions we now observe.

A final feedback, this one somewhat negative, occurs as a result of Greenland Ice Sheet (GIS) melt. Large cold, freshwater outflows from GIS into the North Atlantic result in localized cooling in that region. This feedback (also related to AMO weakening) enhances trough formation throughout the North Atlantic region adjacent to Greenland and the Canadian Archipelago. A final potential teleconnection to the ridges we see forming over both Yamal and the Alaska/Northwest Territory zone.

Links:

Climate Reanalyzer

Earth Nullschool

Heat Wave Forecast for Russia

Rapid Arctic Sea Ice Loss Linked to Extreme Weather

Tracking for Early Season Melt Pond Formation at The Arctic Ice Blog

Jet Stream So Weak Winds Are Running From Pacific to Atlantic Across the North Pole

image

(Winds flowing north from just west of Hawaii, through the Bering Strait, over the North Pole and on into the North Atlantic as seen by NOAA’s GFS model and imaged by Earth Nullschool.)

This is a very odd pattern for global surface winds.

In the central Pacific, along a band above 20 North Latitude and about 500 miles west of Hawaii, a broad stream of easterly winds yesterday took a turn toward the north. The wind field was then pulled into a long frontal boundary spinning out from a large low pressure system off Irkutsk, Russian and driven on toward the Western Aleutian Island Chain.

The winds continued their sprint northward through the Bering Strait before being again captured by a low, this time over the East Siberian Sea. Sped on by this second nudge, the winds, running at 15-25 mph, spilled over the North Pole and into a third low spinning just north of Svalbard. This system shoved the winds southward over the North Atlantic and finally into a cyclone just north of England where the winds finally turned eastward, returning to the prevailing west-east global flow.

This is an epic journey in defiance of typical and prevailing weather patterns spanning thousands of miles and three oceans. It is decidedly not normal.

A Ruptured Jet Stream and A Flood of Winds Across the Pole

Typically, cold air over the polar region will insulate the Arctic from these kinds of circumpolar flows. The cold air to the north, warm air to the south, drives winds faster around the pole, creating a kind of wind wall that keeps south-north flows out of the Arctic. It is a pattern that tends to isolate Arctic air from the rest of the global air circulation to the south.

Jet Stream 30 July 2014

(Mostly disassociated Jet Stream with large rupture running north through the Bering Strait and on over the polar zone. Image source: University of Maine.)

But, during recent years, temperatures in the far north have been rapidly rising by in some cases as much as 0.5 to 1.0 degrees Celsius per decade. This heating of the polar zone, together with land and sea ice loss, has resulted in a weakening of the circumpolar wind pattern called the Jet Stream. This weakening has collapsed the wall keeping southerly winds from rushing over the Arctic as we see today.

The current pattern involves an extreme weakness and high amplitude wave in the Jet Stream extending from the Central Pacific and into the Arctic, extending well above the 80 degree North Latitude line. What remains of the cold air pool has been split, with some of the cold air mass shoved toward Greenland and the Canadian Archipelago and the remainder shoved toward the Kara Sea. Driving through it all is a wedge of warmer air accompanied with the southerly winds, winds that originated in the tropics near Hawaii.

Links:

Earth Nullschool

NOAA/GFS

University of Maine

Song of Flood and Fire Refrain: Epic Canadian Floods Wreck 5.5 Million Acres of Cropland

For the Northwest Territory of Canada, the story this summer has been one of record-setting wildfires. Fires casting away smoke plumes the size of thunderstorms, fires that burn regions of tundra the size of small states. Fires that just burn and burn and burn for weeks on end.

But to the south and east in Saskatchewan and Manitoba, the story is drastically different. For over the past month, unprecedented flooding in this region has wrecked untold damage to Canada’s farmlands.

Canada floods

(Powerful storms over Manitoba and Saskatchewan on July 23rd, 2014. Image source: LANCE-MODIS)

This situation is the result of an odd and wreckage-inducing tangle in the Jet Stream. For hot air has been funneling up over the Northwest Territory for the better part of two months now, pushing temperatures in this Arctic region into an unprecedented range topping the 70s, 80s, and even 90s on some days. This high amplitude ridge in the Jet Stream has been reinforced and locked in place, a result some scientists attribute to the loss of Arctic sea ice during recent years, setting up a hot weather pattern favorable to wildfires.

As the massive Arctic wildfires ignited and burned, they cast off giant streams of smoke, burdening the down-wind atmosphere with aerosol particles — an abundance of condensation nuclei for cloud formation. These smoke streams fell into a trough flowing down over Manitoba and Saskatchewan. The deep trough, often extending far into the Central US formed a kind of trap for storms and, like the fixed ridge over the Northwest Territory, it has remained in place for months on end.

Given this mangled positioning of atmospheric heat and moisture flows, it was only a matter of time before massive rainstorms erupted in the wake of the large-scale Canadian fires. And the result was an unprecedented flooding. The offspring of an unprecedentedly powerful and persistent atmospheric pattern set off by human warming.

Major Floods Wreck Canadian Crops

For some local farmers, the past couple of days have seen 48 hour rain totals in excess of 10 inches. A 100 year rain event at a scale few farmers in the region have ever seen. And the recent floods are just the latest in a series of heavy rainfalls that have been ongoing ever since early July. Flood follows flood follows flood. A progression that has left most farms swimming in inches to feet of water and mud.

In total, farmland encompassing 3 million acres in Saskatchewan and 2.5 million acres in Manitoba are now under water and are unlikely to produce any crops this year. As a result, wheat plantings are expected to decline by 9.8 percent from last year, canola is expected to decline by 5.8 percent from the June forecast, and oat is expected to decline by 6 percent, according to estimates from Bloomberg.

July flooding in these regions has so far resulted in over 1 billion dollars in damages to farmers. As much as half of these losses may not be covered as insurers are still reeling from severe moisture damages during 2011, just two years ago. As a result of the ongoing parade of storm casualties, insurers have also raised deductibles, leaving farmers more vulnerable to the odd and powerful new weather coming down the pipe.

The Part Played By Climate Change and a Mangled Jet Stream

We often hear of the expanding droughts of human-caused climate change wrecking croplands. But the upshot of expanding drought in one region is record downpours in another. And downpours, if they are intense enough, can have a negative impact on crops as well.

The cause of this is as simple as warming’s enhanced ability to evaporate water. For it is estimated by climate scientists that each degree C in temperature increase amplifies the global hydrological cycle by 7-8 percent. That means that current warming of about 0.8 C since the 1880s has resulted in about a 6% increase in both evaporation and precipitation. At the level of weather, this translates into more intense droughts under dry, hot weather, and more intense rainfall events under wetter, cooler weather.

High Amplitude Rossy Wave Over North America July 2014

(High amplitude Jet Stream wave pattern fueling wildfires in the Northwest Territory and record floods in Manitoba and Saskatchewan. Note the extreme northward projection of the Jet over the Northwest Territory and the strong, deep, trough back-flowing from Hudson Bay into Manitoba, Saskatchewan and the northern tier of the Central US. Image source: University of Maine.)

One mechanism that has tended to amplify drought and rain events during recent years has been a weakening and intensifying waviness of the Northern Hemisphere Jet Stream. This weakening has been attributed by some scientists to a large-scale recession of Arctic snow cover and sea ice. For since 2007, not one day has seen an average sea ice extent and the range has typically fallen into a zone between 20-50 percent below levels seen during the 1970s and 1980s. New major record low years in 2007 and 2012 have also fueled speculation that sea ice may completely melt away during one summer between now and 2030, 2025, or even 2020 — 50-100 years ahead of model predictions.

As the sea ice serves as a haven for cold air masses, its loss is bound to impact the resiliency of these systems and since a solid pool of cold air to the north is a major driver of Northern Hemisphere upper air currents, the weakening of this cold pool has had dramatic impacts on climates.

Dipole hot-cold pattern associated with mangled jet stream

(Extreme dipole hot/cold pattern associated with Jet Stream mangled by climate change. Image is for July 14, a match to the above Jet Stream shot. Note the extreme heat in the ridge and the much cooler air in the trough. This is exactly the kind of pattern we would associate with sea ice retreat and Jet Stream weakening. Image source: University of Maine)

For this year, the ridge over Canada’s Northwest territory was a direct upshot in a northward retreat of the Jet Stream over Canada and, at times, into the Arctic Ocean. This set the stage for severe wildfires in the zone of warmth underneath this ridge pattern. To the east, a powerful downsloping trough pulled cooler air into Saskatchewan and Manitoba as well as over the Central and Eastern US. This set the pattern up for cooler than average conditions as well as for strong rainstorms.

The crop-shattering events of July were a direct result of this climate change induced ‘Song of Flood and Fire.’ A pattern we’ve seen repeat again and again over the past few years and one that may well intensify as both time and human-caused warming advance.

Links:

Canada’s Record Rains Cut Wheat Averages to Three Year Low

Is Global Warming Causing Extreme Weather via Jet Stream Waves?

Top Climate Scientists Explain How Global Warming Amps Up the Hydrological Cycle, Wrecks the Jet Stream to Cause Dangerous Weather

LANCE-MODIS

University of Maine

A Song of Flood and Fire

Hat-tip to Colorado Bob

 

 

World Food Security in the Cross Hairs of Human-Caused Climate Change: Mangled Jet Stream, Ocean Heat and Melting Sea Ice To Deliver 500 Year Drought to California? Brazil, Turkey, Australia and More to Follow?

California snow pack January 18 2013California snow pack January 18 2014

(California Snow Pack for January 18 2013 vs the California Snow Pack for January 18 2014. Note the near-zero snow cover for this drought-impacted region. Image source: NASA/Lance-Modis)

“We are on track for having the worst drought in 500 years.” — B. Lynn Ingram, professor of earth and planetary sciences at the University of California, Berkeley.

Remember the historic drought that swept the US in 2011-2013? It was the worse drought in 50 years for some areas. Thankfully, the blocking pattern, excess heat and evaporation that set off this drought and that almost ran the Mississippi River dry abated and lessened, shifting westward and, instead delivered wave after wave of wet and stormy weather to the Eastern US.

Not so with the American West. There the high amplitude Jet Stream pattern remained, keeping regions locked in warm, dry conditions throughout the winter of 2012-2013, on through the end of 2013 and into the early months of 2014.

Looking further back, it was not just these years that had delivered dry weather to the US West Coast. California, ground zero for the current climate change related emergency, has endured dry, hot weather ever since the Pacific Decadal Oscillation (PDO) went negative ten years ago suffering drought years with almost bi-annual frequency.

Now, as Dr. Ingram notes above, California is currently ramping up to its worst drought in 500 years.

A long emergency for California

We only have to scratch the surface for the symptoms of systemic climate crisis in California to crop up. California water authorities failed to honor contracts for the first time in 54 years. Sacramento, as of December was experiencing its worst drought in 130 years even as conditions continued to worsen through January and February.

According to the New York Times, as of February 1rst, 40,000 people were at risk of losing access to water within the next 60 to 120 days. And State officials warned that this number was likely to rapidly rise as The State Water Project announced on January 31rst that it did not have enough water to supplement the fading supplies of local providers to a total of 25 million customers. Meanwhile, State emergency planners were laying out contingencies that included shipping water over land by truck to parched communities.

The drought is also having a devastating impact on local farmers with about 1/3 of California’s farmland expected to lay fallow, at least 25,000 farm laborers expected to be laid off work, and agricultural businesses expecting losses to mount into the tens of millions of dollars. Already, livestock owners in both New Mexico and California, unable to support their animals, have been forced to sell, as fields that used to support four foot high grass are brown and cracked.

Tim Quinn, executive director of the Association of California Water Agencies noted:

“I have experienced a really long career in this area, and my worry meter has never been this high. We are talking historical drought conditions, no supplies of water in many parts of the state. My industry’s job is to try to make sure that these kind of things never happen. And they are happening.”

Climate change, climate change, and climate change

Far flung and dynamic changes to the Earth System appear to have resulted in a variety of factors that have amplified the California drought. First, increasing global temperatures have amped up the rate at which water evaporates into the atmosphere by about 6%, this increased rate of evaporation results in more extreme conditions when heat and dryness do occur. So a drought that may last a year is likely to be even more intense, due to enhanced evaporation, than a comparable drought that occurred 50 or 100 years ago.

In addition, loss of sea ice, snow, and permafrost plays a key roll in re-shaping the Jet Stream. According to Dr. Jennifer Francis and other polar researchers, receding sea ice cover is likely to result in more powerful and long-lasting Rossby Wave type blocking patterns. This happens as more heat becomes concentrated in the polar regions, causing the Jet Stream to meander in great swoops and whirls. These large waves can become fixed into blocking patterns for extended periods. In the up-slope of these waves, warmth and heat predominate. In the trough or down-slope, stormy, wet and cool conditions prevail.

And just such a blocking pattern has dominated the US West Coast for 11 months running. The result is extraordinarily intense dryness, even during the rainy season of November through March.

PNAS drought model US southwest

(Image source: PNAS)

Sadly, according to climate models, we can expect this kind of dryness to intensify over the US Southwest as human caused global warming grows more extreme. A report conducted by PNAS in 2010 and authored by Seager and Vecchi confirmed other model findings that the US Southwest would continue to dry as the climate warmed — the upshot being that the wet season for the West would eventually evaporate.

Above, the PNAS drought model shows evaporation beginning to increase during the first two decades of the 21rst Century. Then, by about decade 2, precipitation rates rapidly fall and evaporation rates gradually rise through to 2100. The red line shows the compounding effects of evaporation increase and precipitation decrease over 24 separate climate model essays.

Rossby wave over West Coast Weakens

(Rossby Wave over West Coast Weakens. Image source: University of Washington)

It is worth noting that on a positive, and slightly hopeful, note, the current blocking pattern over the US West Coast and related Pacific Ocean waters has weakened somewhat. This should allow some moisture to flow into the parched west over the coming days and weeks. And, in the forecast, we do see a proper storm or two emerging from this new pattern. Unfortunately, we’d typically expect about 20-30 storms of this kind during a typical winter season and with March bringing in the end to this year’s rainy season, along with the northward retreat of the moisture flow, it appears likely that California will have to endure at least another 6 months of dry conditions before seeing any hope of major storms returning next fall/winter. A remote potential to say the least given both long-term trends and current conditions.

‘Like a microwave on full blast drying the Earth:’ drought, drought, and more drought

Dr. Kevin Trenberth, one of the world’s premier climatologists, in an email to Joe Romm recently noted:

“The extra heat from the increase in heat trapping gases in the atmosphere over six months is equivalent to running a small microwave oven at full power for about half an hour over every square foot of the land under the drought. No wonder wild fires have increased! So climate change undoubtedly affects the intensity and duration of drought, and it has consequences.”

Under such conditions, we would expect both drought and wildfires to proliferate. And, in fact, this is exactly what we are seeing. As major wildfires impacted both California and Arctic Norway during winter time, Brazil, Turkey, China, Argentina and Australia were also all experiencing some of their worst or most intense droughts on record.

In Brazil, the least rain in two decades is spurring a cattle sell-off that would be very familiar to livestock farmers in California and New Mexico. The expected summer rains did not come and Brazil, a heavily meat-dependent nation was left with soaring food prices after the sell-off as stocks first surged, then plummeted. The epic drought for this region is also causing a number of other impact such as coffee shortages and a related reduction in hydro power as rivers run dry.

Nearby Argentina also saw severe drought-related shocks in recent months as a December drought inflicted serious harm upon Argentina’s corn crop. In a typical year, Argentina produces about 32 million tons of corn. But this year’s drought is estimated to have wiped out about between 7 and 14 million tons of the crop. Argentina is the third largest producer of corn and with the US revising estimates down for its 2013-2014 crop, supplies of the grain are being drawn ever-lower. Though very intense, the December drought had abated by mid-January, providing a respite for other crops such as soybeans.

In Turkey, Lake Sapanca, which provides water for hundreds of adjacent farms, was within a half meter of ‘dying’ as a combination of drought and water drilling had pushed the lake to its limits. Local farmers have, for decades, drilled the land to provide irrigation water for farms and livestock. Now, the drilling is sapping the lake bed. A period of drought had, as of late January, left the lake in such a state that local officials were claiming the lake would be dead after another half-meter fall. The lake which is nourished both by springs and ground water has been deprived of flows both by human climate change induced drought and by human drilling into the lake’s spring-bed.

In Australia, drought conditions are now worse for some locations than at any time since 2003, a tall order since the 2003 to 2009 drought was Australia’s worst in 1,000 years. For Sydney, that means the lowest rainfall totals in more than 70 years. This particular drought hit both hard and fast with Australia seeing normal conditions before Christmas, but after, very intense heat and dryness resulted in a rapid scorching of farmlands, crops, and grazing fields. The dire drought situation has resulted in government relief funds being released to affected farmers. NSW Minister for Primary Industries, Katrina Hodgkinson noted to the Sydney Morning Herald:

“Seasonal conditions are now deteriorating at a rapid rate across a large portion of NSW and both the severity and speed at which this drought is moving is astonishing. Primary producers in some parts of NSW have simply not had the opportunity to prepare for another severe downturn in seasonal conditions so quickly after the Millennium drought broke.”

Lake Poyang May 2014Lake Poyang Jan 2014

(A mostly full Lake Poyang as seen from Satellite on the left during May of 2012. A parched and almost completely dry lake Poyang as seen from Satellite during January of 2014. Image source: NASA/Lance-Modis.)

And, in China, the largest lake for that populous nation has now dried up. Poyang, a massive lake usually spanning 3,500 square miles has been turned into a sprawling field of earth parched and cracked by a combination of drought and water diversions resulting from the construction of the Three Gorges Dam. According to reports from The Guardian and Chinese News Sources, a drought stretching from 2012-2014 in the region of Poyang is now the worst in at least 60 years leaving lake refill almost non existent as upstream river flows to the lake were periodically cut off by water storage operations at the Three Gorges Dam. The result was an extreme lowering of lake levels and dry bed conditions that have driven farmers and fishermen in the region out of business.

Implications for world food security

Major droughts during 2011-2012 impacted many of the world’s primary agricultural basins, resulting in forward food supply dropping to as low as 72 days. Since that time, food supplies have slightly recovered but are well below previous levels last seen in the 1990s at 104 days. Food insecurity and failure to distribute food to the malnourished remains a priority at international agencies like the UN which has identified numerous countries including Cameroon, the Central African Republic, Somalia, Syria, Mali, Sudan and Nigeria, among others, as extreme risks for hunger and famine. Relief agencies have allocated billions of dollars to address this problem but the UN continues to identify climate change as a major threat to global food security with the potential to wipe out all previous progress moving forward.

The droughts in California, Turkey, Australia, China, Argentina and Brazil so far for 2014 put the world at risk for another bout of food insecurity later this year should major weather and climate related crop disruptions emerge in other primary food producers such as the bread baskets of the US, Russia, and Europe (The US, Brazil, China, Russia, and Europe are top food producers). It is worth noting that, in large part due to the ongoing southwestern drought, the US has revised a number of its crop projections downward for end 2014.

With polar amplification playing havoc with the Northern Hemisphere’s weather systems, with Australia sitting in a pool of expanding warm Pacific Ocean water that makes drought more likely there, and with the Eastern Pacific edging closer to La Nina, conditions warrant a continued monitoring of both weather and the state of world food supplies. The added global heat engine also impacts soils and crop growth in ways to which we are currently unaccustomed, resulting in more extreme instances of flash drought as well as flash flood. In this respect, the examples of Australia and Argentina are of particular concern.

Though global crisis has not yet returned, it lurks at the edges as drought, extreme weather and over-use of ground water supplies continues to threaten a wide swath of productive zones. So, at this point, the situation is one best described as tenuous with ongoing regional impacts over the Sahel region of Africa and in other sporadically vulnerable locales.

Links:

Historic Drought of 2011-2013

This is What Human-Caused Climate Change Looks Like: Arctic to Warm, West Coast to Bake, Polar Vortex to Collapse and Flood Eastern US With Arctic Air

Well, the forecast is in. And it appears we are about to receive yet another helping of winter weather extremes driven by human caused climate change.

ECMWF and NOAA models both show mid and upper level warmth increasing over the polar region. This warmth, over the next week, will invade toward the surface, collapsing the polar vortex and driving Arctic cold into both Siberia and North America. In the image below, you can see that mid level cold is cut in half by warmth flooding into the polar zone resulting in both the polar vortex collapse and ejection toward southern latitudes all while severely malforming the circumpolar Jet Stream.

ECMWF Jan 26

(ECMWF 850 hPa temperature and pressure gradient for the Northern Hemisphere. Image source ECMWF)

Note that mid level atmospheric temperatures are about the same over the Central Arctic as they are over Central Europe, a much lower latitude. Also note how the polar cold, typically centered over the Arctic is driven away and further south into two distinct zones — one over Siberia, the other over North America. Already, observations in the high Arctic show temperatures as much as 30 degrees F above average for this time of year and such anomalies are projected to expand as this second vortex collapse of the season progresses.

This new temperature flux will make the fixed Rossby wave ridge and trough pattern very intense, forming high velocity upper level wind flows over much of the US. To the north, the Jet will invade Alaska. To the south, it will dig deep into the Gulf of Mexico, bringing cold Arctic air into direct contact with moist, warm tropical air. The result may well be a spectacular and dangerous series of winter storms over the next two weeks for the Central and Eastern US.

So you may wish to stay abreast of local weather reports as this most recent collapse series could pack quite a punch while spawning a variety of very extreme weather conditions.

Jet Stream Flow January 22

(ECMWF upper level wind flow over the US for January 22. Note the deep low over southeastern Canada and the powerful associated Jet Stream flow riding along the U shaped trough in the current blocking pattern.)

The vortex disruption, collapse, and flushing of cold air out of the Arctic and further south is forecast to result in a strong cold snap for the Eastern and Central US. Negative anomalies are projected to reach as low as -47 degrees F below average in some locations near the Great Lakes. According to these forecasts the cold may be about as strong but last a bit longer than the previous cold snap spurred by the early January polar vortex collapse.

Meanwhile, strong positive temperature anomalies up to +26 F are expected to dominate the US southwest, a region already suffering some of its driest conditions in a century. Such record warmth is likely to further exacerbate what has come to be a freakish and anomalous period of winter wildfires in the most drought stricken zones along the US West Coast.

ECMWF Vortex Collapse and Cold Snap

(ECMWF temperature forecast for January 23, 2014. Note the vertical line of temperature anomalies almost perfectly bisecting the North American Continent.)

This kind of extreme weather pattern almost perfectly models predictions by prominent polar researchers like Dr. Jennifer Francis, who projected increasingly anomalous Jet Stream patterns, blocking patterns, meandering, and cut off flows due to the massive Arctic melt having occurred since 1979. The retreat of snow and ice, both on land and at sea, results in more warm air invasions into the high Arctic and can directly spur just the kind of weather disruption predicted in the forecast above.

In the trough zones, periodic and powerful cold snaps are far more likely as the polar vortex collapses and cold, Arctic air is flushed south. In these troughs, storms are more frequent and powerful, amped up by the extreme temperature differences and by higher atmospheric moisture content due to overall warming. In the ridge zones, anomalous warmth, drought, and fires are experienced as the over-riding warm, dry air floods up through these regions and into the Arctic.

This is exactly the kind of dynamic we would expect from a warming world. From a world experiencing a powerful amplification of warmth in the northern polar zone. Such a pattern will likely continue to intensify until it is disrupted by large melt outflows from Greenland and from Baffin Island.

Links:

ECMWF

Premiering Next Week: Revenge of the Polar Vortex

Cold Snap for the US? It’s the Collapsing Polar Vortex, Stupid

Sea Ice Loss Locks Jet Stream into Severe Winter Storm Pattern for Most of US

The Polar Vortex is Probably Coming Back

Arctic Ice Graphs

Mangled Jet Stream Sparks Drought, Winter Wildfires…

Winter 2013-2014: Sea Ice Loss Locks Jet Stream into Severe Winter Storm Pattern For Most of US

It happened to Europe last year. A persistent erosion of Arctic sea ice set off changes to the polar jet stream that locked in place a severe winter weather pattern that pummeled the central and western European countries for much of the winter. Storm after storm piled snow high in locations that typically saw only modest winter precipitation while other areas were simply buried. The US also took a glancing blow from this extreme storm configuration. But now, with a large trough in the polar Jet remaining locked in place for almost a year, the US from the Rockies eastward appears to be in the line of fire for some very severe winter weather.

In other regions from Alaska to Eastern Europe, record or near record warmth and dryness have settled in with a large swath of eastern Europe showing average temperatures more than 6 degrees Celsius above the seasonal average. Over the extreme northern Pacific, adjacent to Alaska and the Bering Sea, seasonal temperature range from 4-12 degrees Celsius above average. And it is this extreme northward invasion of warm air that is displacing polar and Arctic air masses toward the east and south, putting much of the US in the firing line for strange and severe winter weather.

Just this week, the tale was one of record ice storms throughout the central and eastern US with hundreds of flights cancelled, deadly traffic pile-ups, and holiday shopping disrupted. On the east coast, from Virginia to Maine, workers and shoppers alike were treated to three days straight of snow turning to sleet and freezing rain and then turning back again to snow. With storms like these hitting in early December and with the pattern in the Jet Stream taking on such an extreme configuration, it appears possible that the winter of 2013-2014 could be a very, very stormy one indeed.

A Tale of Jet Streams and Melting Sea Ice

To understand how human caused global warming can make winter storms more severe in some areas while other areas hardly experience winter at all, one should first take a look at two major governors of Northern Hemisphere weather: the circumpolar Jet Stream and Arctic sea ice.

An extreme difference between the temperatures at high northern latitudes and at more temperate latitudes has driven a very rapid flow of upper level air called the Jet Stream for almost all of human meteorological reckoning. This high temperature difference drove powerful upper level winds from west to east. These winds tended to modulate only slightly and when they did, powerful weather events tended to occur.

Locking a greater portion of this cold air in place was the northern hemisphere ice cap, most of which was composed of a large swath of sea ice covering much of the northern oceans. This high volume of cold, reflective ice kept temperatures up north very, very low and provided the massive temperature differences which kept the Jet Stream predominantly flat with only occasional and more moderate severe weather causing ripples and bulges.

But since 1979, massive volumes of sea ice have been lost due to an immense and ongoing human caused warming trend taking hold in the Arctic. As human greenhouse gas emissions sky-rocketed, Arctic temperatures rapidly increased far faster than the global average. By this year, human greenhouse gas emissions had driven CO2 levels to the highest seen in more than 3 million years while Arctic temperatures are now warmer than at any time in the past 150,000 years. Sea ice retreat has been equally unprecedented with average winter values now 15-20% below extent measures seen during 1979 and with end summer sea ice extent values now a stunning 35-50% below that of 1979. Sea ice volume, the measure of total ice including its thickness, has shown even more stunning losses since 1979 with seasonal winter values 30-35% lower than in 1979 and end summer values between 65 and 80% lower during recent years.

JAXA sea ice Dec 9 2013

(Sea ice extent measure composed by JAXA. The light gray dotted line on the top shows sea ice extent averages during the 1980s. The three record lowest years — 2007, 2011 and 2012 — are shown in green, blue, and orange. The most recent year, 2013, is shown in red. Note the persistent and rapid melt trend.)

The loss of hundreds of thousands of square kilometers of sea ice radically reduces the Arctic Ocean’s ability to keep the Arctic cold. To the contrary, we see larger areas of open water that, in turn, radiate ocean heat into the atmosphere throughout winter. As a result the temperature difference between the Arctic and temperate regions is less and this, in turn, slows down the Jet Stream.

When the Jet Stream slows, it tends to meander. And when it meanders it creates very deep troughs and very large ridges. In the ridges, we get unseasonably hot temperatures along with increased risk of drought. And in the troughs, Arctic air swoops down to collide with warmer, moist air in a series of powerful storms. During the summer time, the hot, dry zones can bring deadly heat waves, record droughts, and major wildfires while the cooler stormier zones can bring epic rainfall events or even link up with tropical cyclones to result in highly severe hybrid storms. During the winter time, the hot zones can almost completely obliterate the winter season, while the stormy cooler zones can result in snow storm after snow storm.

Don’t believe me? Then take a look at what weather experts Jeff Masters and Jennifer Francis have to say on the matter:

Polar Warmth and Rossby Wave Pattern Going into Winter 2013-2014

As noted above, a powerful and continuous ridge in the Jet Stream over the north eastern Pacific near Alaska has persistently provided an equally powerful down-sloping trough over much of the US over the past year. The December 10 Jet Stream configuration map shows this pattern remaining locked in place:

Northern Hemisphere Jet Stream 10 Dec 2013

(Image source: California Regional Weather Server)

Note the strong multi-channel ridge to the south of Alaska and to the west of Canada diving down into a deep trough with convergent upper level air flows over the central and eastern US.

On the map, we also see powerful ridges and correlating warmer regions over Europe, Central Asia, and the western Pacific. These large meanders are now typical to the highly weakened Jet Stream pattern we have seen in recent years due to loss of polar sea ice.

Global temperature maps also show anomalously warm temperature departures for much of the Arctic as well as for regions beneath these powerful jet stream ridges. Note that the only northern hemisphere region showing strong anomalously cool conditions is a large swath adjacent to the large trough over North America and southern Greenland.

Global Temperature Averages Dec 1-7 2013

(Global Temperature Averages and Anomalies vs 1981-2010 mean. Image source: NOAA)

Temperature averages in the Arctic region of Kamchatka, the Bering Sea, the Chukchi Sea and Alaska have ranged between 11- and 12 degrees Celsius above average for the first week of December with much of the Arctic showing 4-12 degrees Celsius above average readings. The US and southern Canada, conversely, have shown temperatures 4-10 degress Celsius below average. It is also worth noting the massive swath of 3-12 C above average temperatures stretching all the way from the Middle East to the west coast of Greenland.

Overall, the prevalence of high latitude warmth and a continued high amplitude Rossby wave pattern trough over much of the US is a very conducive pattern for severe winter weather over the coming weeks. Most likely, this pattern will continue to persist through at least early to mid winter. So for the US and especially from the Rockies to the east coast, a progression of strong storms is likely to continue as winter advances.

Links:

California Regional Weather Server

NOAA

PIOMAS

Supporting Research:

Evidence linking Arctic amplification to extreme weather in mid-latitudes

Impact of sea ice cover changes on Northern Hemisphere atmospheric winter circulation

Impact of declining sea ice on winter snowfall cover

Weather extremes provoked by trapping giant waves in the atmosphere

Quasi-resonant amplification of planetary waves and recent Northern Hemisphere weather extremes.

Drought, Burning Rings of Fire out West, Severe Flooding in the East: How Climate Change and a Mangled Jet Stream Wrecked US Weather

Earlier this summer, I had a weather conversation with my mother. She was excited about a new business venture my sister had undertaken (Adventure Kayaks) and for an upcoming trip to Yosemite in August to celebrate her and my father’s 45th wedding anniversary. She wondered about the weather, hoping it would be a good summer for both the new business and the trip. Without thinking too much, I said:

‘Rain, cooler weather, and storms in the east, drought, heat and fires in the west.’

Immediately after saying this, I felt reticent. Perhaps I shouldn’t have spoken? Maybe I would scare my mom. What good would it do to ruin her enjoyment or her looking forward to both the trip and to my sister’s potential success?

It’s worth noting that, thankfully, the storms and cooler weather that did emerge with fury and flood in the east did not ruin my sister’s kayaking venture (although it did result in numerous interruptions both during spring and throughout summer). Should a tropical storm or hurricane make landfall on the US east coast this August, September or October, however, the devastation could be vast, perhaps exceeding a 1 billion dollar disaster event (more on this below).

But as my mother boarded her plane to California and a potential date with Yosemite yesterday morning, these were the satellite images I was looking at:

Yosemite Fire NASA Earth Observatory

Yosemite Fire NASA Earth Observatory

Image source: Earth Observatory

The vast Rim fire that had grown to consume over 192,000 acres as of today was steadily devouring the western border of Yosemite. You can see it on the above infrared satellite picture provided by NASA as a ring of bright white steadily inching into the indicated yellow border of Yosemite.

Jennifer Francis, Stu Ostro and How I Knew

Earlier this summer, my mother chided me on my ‘attempts to predict the weather.’ In a phone conversation last night, she asked ‘how did you know?’

It’s fair to say that in the overall prediction of more storms and rains in the US east, with more risk of flooding, and more heat and dryness out west, with more risks of fire, that I wasn’t entirely certain. However, I’d recently read the work of climatologist Jennifer Francis and had been listening to and following the statements of Stu Ostro. During early spring and summer, I observed a Jet Stream pattern setting up over the US that appeared to be settling into a ‘stuck position’ that would result in the high likelihood of the conditions I communicated with my mother. It’s worth noting that in looking at these Jet Stream patterns it’s not difficult to make such predictions because the patterns change slowly, they lumber and tend to remain stuck for long periods. Once a pattern settles into place, it’s a good bet that it will stick around for at least a few months these days, a fact that the models nail but which meteorologists, in general, have failed to communicate. In short, this is a climate change driven change in the weather.

In fact, some meteorologists and climatologists seem entirely reticent to accept this new weather pattern, despite the fact that it is a powerful tool for weather prediction and will tend to result in less surprises. The big troughs equal record floods sticking around for a long time and the big ridges equal record heat, drought, and probably fires sticking around for long periods of time.

In an example of this reticence, a recent paper by a University of Colorado researcher concluded that Jennifer Francis did not have enough evidence to support her claims of an observed slowing in the Jet Stream. Unfortunately, the paper included, as a part of its findings, a cross section of the atmosphere in which the Jet Stream does not typically reside even while the paper included a sample during which changes were already occurring, which would have likely biased its results. Despite these biases and errors, where the paper actually did measure Jet Stream flows, it corroborated Francis, showing Jet Stream slowing during the periods measured. This is odd considering the fact that the concluding statement contradicts the papers own findings, a point which Dr. Francis, herself, provides.

It’s easy to understand why reticence still lives in the science. As I noted above, it’s understandable to feel reticent when being the bearer of bad news. No one wants to be the messenger that gets metaphorically ‘killed.’ But without making use of the clear understanding provided by Francis and Ostro, we will continue to be surprised by extreme floods, storms, fires, heatwaves and droughts that can be easily predicted by simply looking at how the Jet Stream sets up and where it gets stuck. Instead, ‘surprise’ after ‘surprise’ just keeps coming our way.

When Rossby Waves Get Stuck: Changing to a More Radical Jet Stream

Dr. Jennifer Francis has observed that loss of sea ice and snow cover in the Northern Hemisphere has resulted in a slowing of the Jet Stream in recent years. Sea ice volume, the measure of total ice in the Arctic Ocean, since 1979 had declined by as much as 80% when measured at its low during 2012 (this measure may rally back to around 75 to 78 percent lower than 1979 this year, but the overall trend remains a death spiral). Greenland melt is unprecedented at 500 gigatons per year and with Arctic heatwaves blasting the tundra both permafrost and snow cover are at record and near record lows. 80 to 90 degree temperatures now often advance to the shores of the Arctic Ocean, with the coldest air pushed back above the 80 degree north latitude line, confining it to a shrinking region that, increasingly, huddles closer to the remaining large ice sheets in Greenland. Overall rates of warming for much of the Arctic are about .5 degrees C temperature increase each decade, more than twice the global average.

A more quickly warming Arctic results in changes to the atmosphere’s heat balance. According to Francis, the height of the atmosphere over the Arctic is rising relative to atmospheric heights in the lower lattitudes, this loss of slope results in lower gradients from north to south and since temperature, atmospheric height and pressure gradient drive Jet Stream speed, the Jet Stream slows down. And as the Jet Stream slows, it tends to seek out the highest gradients it can find. The result is more northward invasions of the polar region of the Jet Stream ridges and more southward invasion of the Jet Stream troughs. This amplification creates a rather large and elongated sine wave called a Rossby wave pattern.

Jet Stream Pattern Change. Image source: NOAA.

Jet Stream Pattern Change. Image source: NOAA.

In the sequence above, we see the progression of a flat Jet Stream to a Rossby wave ridge/trough configuration to, eventually, cut off lows and highs. In the past, such waves tended to set up for briefer periods, extending for days or weeks before returning to the usual, more flattened motion of the Jet. In more recent years, large Rossby type waves have been the typical pattern, one that transitions to cut off lows before it returns to a configuration more similar to (b) in the diagram, before setting up as a Rossby-type wave again.

Perhaps more importantly, this b, c, d progression has tended to occur again and again and again over the same geographical region for months and months on end. And, looking back at Jet Stream maps over the past months, this is exactly what we find.

Below is a progression of images I’m providing from this blog’s archive. It includes either direct temperature measures that indicate Jet Stream patterns or a mapping of air flow speed indicating the Jet Stream’s path.

Clover leaf Jet Stream Pattern April, 2013.

Clover leaf Jet Stream Pattern April, 2013.

(Image source: ECMWF)

In ‘For Central US, Climate Change and a Mangled Jet Stream Means Drought Follows Flood Follows Drought’ I described how the Jet Stream pattern had consistently switched from large trough to large ridge configurations over the past few years bringing either heatwaves and droughts or storms and floods. But the left hand portion of the image provides a good record of the Jet Stream configuration as of mid April this year. Following the temperatures, on the west coast we see a large, hot ridge and in the central and eastern US we see a deep, cool and stormy trough.

Wednesday July 3, Rossby wave still in effect over US.

Wednesday July 3, Rossby wave still in effect over US.

(Image source: ECMWF)

Throughout May and into June, this ridge over west, trough over east, pattern continued. By late June, a massive, record-shattering heatwave had set up over the US southwest. I described this highly anomalous event in ‘Mangled Jet Stream and Global Warming to Shatter Earth’s Highest Recorded Temperature This Week?’

Looking at the ECMWF image above we again see the highly exaggerated ridge/trough dichotomy setting up over the US with very hot, dry conditions out west and cooler, wet and stormy conditions in the east.

At this point, I want to tap Stu Ostro’s own observations to add to the Jennifer Francis mix. What Stu has found is that large, powerful high pressure systems have tended to develop more and more often. These extraordinarily dense systems seem to be exploding to new heights in a thickening atmosphere. Primarily, these monsters are driven by heat and so they tend to live in the massive ridges provided by our new, exaggerated and slowed, Jet Stream pattern. That said, these beasts can spring up almost anywhere there is a massive abundance of heat to tap, as one did over a super-heated region of ocean near Shanghai this summer sparking its own monstrous heat wave.

These large heat domes have major and far reaching effects. To understand them, we must first step back to think about the broader effects of human caused warming before looking at how heat domes manifest in the atmosphere. Based on models of the Earth’s atmosphere, we know that for each 1 degree Celsius of Earth temperature increase we get a corresponding 8% amplification of the hydrological cycle. What this means is that evaporation happens 8% faster and condensation happens 8% faster — OVERALL.

Since 1998, we have observed temperatures that are, on average, .8 degrees Celsius above those seen during the 1880s. What this means is that the hydrological cycle has amplified by 6% over this same time period. Because of this dynamic, droughts are more intense, but rainfall events are also more intense. Yet since the atmosphere is uneven we can expect this 6% amplification to manifest in somewhat more extreme fashion at the locations where more extreme Jet Stream patterns set up.

Mangled Jet Stream Dumps Deluge on US Midwest

Mangled Jet Stream Dumps Deluge on US Midwest

(Image source: California Regional Weather Server)

What goes up must come down. And that massive heat dome over the western US and Canada had been baking moisture out of the soil at unprecedented rates over an extended period from April to August. The moisture injected into the heat dome rose and rose, The high pressure system suppressed cloud formation so the moisture had no where to go but up and out. Eventually, this moisture found the edge of the massive high and spilled over into the storms riding along the Jet Stream trough rushing down from the Arctic Ocean and into eastern Canada and the US (hat tip to Colorado Bob).

The result was multiple flood events starting with the Midwest floods of April, then the massive Canadian floods (Calgary) of June, then the Toronto floods, then the Midwest floods of early August, and lastly the east coast floods of mid to late August. The Calgary floods were the worst ever recorded in Canada, the Toronto floods were the worst recorded for that region, and in the Midwest floods of early August, four months worth of rain fell in just one week.

Monthly rainfall estimates August 2013.

Monthly rainfall estimates August 2013.

(Image source: The Weather Channel)

On 8 August, the time of the second barrage of major Midwest floods this year, we find the Jet Stream in the same elongated configuration with a large northward ridge extending all the way from the southwestern US to the Arctic Ocean and with a deep trough diving back down into the central and eastern United States. As noted above, the mangled Jet Stream delivered its overburden of moisture directly to the US Midwest, dumping four months worth of rain in just one week.

A second pulse of moisture rode far south along this Jet Stream flow to dump massive amounts of rain over the southeastern US about a week after pummeling Missouri. This flow combined with a compromised tropical system to saturate the southeast, with some regions receiving as much as 300 percent their annual rainfall totals by late August.

One of the hardest hit areas is Lake Okeechobee. Water levels there as of mid August hit 16 feet at the Hoover Dike, a level that requires weekly monitoring for cracks or ruptures. The dike stretches over 140 miles along the perimeter of lake Okeechobee and was intended to keep the lake in check during major storms and hurricanes after large outburst events in the early 20th Century resulted in thousands of lives lost. The dike is 25 to 30 feet high and is as wide as a football field. The US Army Corps of Engineers has been working feverishly to shore up the dike in a project that will take years to complete.

At 16.5 feet water level, the dike will require daily monitoring. For each inch of increase above that level, the pressure put on the dike would greatly increase risks of catastrophic failure. The causes of such high water, this year, were neither tropical storms nor hurricanes. Florida has been, thus far, spared the wrath of these strong storms. Deep Jet Stream troughs and a constant Atlantic moisture flow have, instead, resulted in day after day rain events for much of southern Florida, pushing August totals near Lake Okeechobee above 16 inches, filling the massive lake and putting the dikes at risk. Should a hurricane or tropical storm strike Florida during late August, September, or October, the dike could overtop or rupture, unleashing the massive lake on communities sitting beneath it. (Hat tip to Colorado Bob).

As the threat of massive floods continued to increase in the east, the west was erupting with wildfires. Fire containment efforts went into high gear both exhausting the Forest Service Fire budget and briefly pushing the national fire alert level to 5. The Rim Fire, so close to my parents’ vacation site, expanded to 192,723 acres today making it the 6th worst in California history.

Rim Fire on August 28th, 2013

s Rim Fire on August 28th, 2013

(Image source: Lance-Modis)

You can see this massive fire, now 23% contained, burning to the west of Yosemite in the Modis shot below. A more detailed report of this major wildfire is provided by WeatherUnderground here and here.

Mangled Jet Stream Temporarily Edges Eastward

My parents wanted to see Yosemite’s amazing waterfalls. A major source of my reticence in telling them the likely pattern for this summer was that the heat and drought out west would probably dry out many of those magnificent falls. And, sadly, this has happened. So even if they brave the smoke and fires to reach Yosemite, the one attraction my mom had been most excited to see will likely be somewhat less magnificent.

But a cloud has suddenly appeared in this wrinkle. For the Jet Stream had edged slightly east.

As of the middle of last week, reports of heatwave conditions had emerged throughout the US Midwest with North Dakota, South Dakota, Nebraska, Illinois, Wisconsin, Iowa, Minnesota and Missouri experiencing temperatures in the range of 20 degrees (Fahrenheit) above average. With heat index values hitting as high as 110 degrees, communities sweltered and school systems declared closings. In California, where temperatures had remained in the upper 90s to lower 100s for much of summer, the trough advanced, pushing temperatures back down to the 70s. An upper level low flirting with the west coast may even toss a few fog clouds and rain showers toward California. Such an event would be a welcome change for both my parents and for beleaguered fire fighters in the region.

In any case, the shift is expected to be short lived with ECMWF models showing the Jet Stream again backing up and reforming a hot and dry ridge pattern over the US west. So the Midwest can expect cooling and a return to more stormy, rainy conditions while the US west, after only a brief respite, continues to bake:

Mangled Jet Stream Early September

(Image source: ECMWF)

The September 7 ECMWF forecast again shows a large and powerful Rossby-type wave pattern with a very large and hot ridge setting up over the US and Canadian West with a deep trough digging down toward the US East Coast. It is the same pattern we’ve seen since at least April, a pattern that has delivered numerous rounds of heat and drought to the US west and an equally vicious and persistent pattern of storms and flooding from the central US to the east coast. The Jet Stream has, essentially, been stuck these past 5 months and there is no end in sight. For even if this configuration of the Jet were to move, it would likely simply re-distribute the locations of heatwaves and droughts and storms and floods.

If anything, this past summer has been yet one more validation in evidence of the work of Dr. Francis. And it is because of her work that I, a relatively untrained observer, can make the accurate prediction that a large region from the Mississippi west to California will continue to stay hot and dry and will continue to see risk for large fires, while the region to the east will remain cooler and stormier so long as the current Jet Stream configuration continues to persist. The western region will risk periods of record heat, continued drying of lands, rivers and aquifers, and fires of record size. The eastern region will continue to risk record floods and storm events. As summer proceeds to fall, shifts in these weather patterns have the potential to grow violent with the possibility of powerful nor-easters or hybrid storms developing near the US East Coast. Both the southeast and Florida remain very vulnerable to continued large rain events or tropical storms and hurricanes as time moves forward and in the event of pattern persistence. Meanwhile, long range model forecasts show this general pattern continuing to persist until at least early to mid September.

At this point, the current US Jet Stream pattern will have been in place for at least 6 months.

 

 

 

A Song of Flood and Fire: One Million Square Kilometers of Burning Siberia Doused by Immense Deluge

About a week and a half ago, I reported on a great burning event in which a massive region of Russian Siberia erupted in hundreds of wildfires blanketing it in a sea of smoke clearly visible in the NASA Aqua Satellite record. Today, reports from Interfax/Radio Russia describe an immense flood emergency in which over 1 million square kilometers of Russia’s Yakutia region have been submerged by a catastrophic rain event.

From the Interfax report:

“It is a unique situation in the sense that it has spread over more than 2,000 kilometers if one looks from west to east, while its depth or width is more than 500 kilometers,” Vladimir Stepanov, head of the National Crisis Management Center of the Emergency Ministry, told a news conference in Moscow.

According to the report, hundreds of villages in this, thankfully, sparsely populated region have been inundated by water putting hundreds of thousands of people in amongst a swirling flood. According to reports from Russian government, the region is now the site of a massive and major rescue operation. As of August 11, the operation composed an army of 20,000 personnel — a force that is likely to have greatly swelled as this major climate disaster expanded through today.

Floods turn Amur Region of Russia into a Sea on August 14.

Floods turn Amur Region of Russia into a Sea on August 14.

(Image source: Radio Free Europe)

A Song of Flood and Fire

As of late July, heavy rainfall had emerged in a dense band along eastern Russia and bordering north China. This band of dense and heavy moisture rose north over an ocean heat dome that was setting off very dangerous high temperatures over the region of Southeast China even as it was baking a large region of ocean, heating a vast expanse of the surface waters to above 30 degrees Celsius. The added moisture and heat content provided fuel for low pressure systems skirting the high.

By early August, major flooding had begun to occur in this eastern region as very heavy storms sprang up over this large area.

We can see the development of this massive storm system starting on August 4th in the image below:

Russia August 4 -- Heavy Rains to the East, Massive Fires to the West

Russia August 4 — Heavy Rains to the East, Massive Fires to the West

(Image source: NASA/Lance-Modis)

In the above image, we are looking down on the Earth from a shot taken above the North Pole. The region we are looking at is Siberian Russia and Yakutia which dominates the central section of the image. Toward the lower left are the Laptev and East Siberian sections of the Arctic Ocean. Toward the central and upper left is Eastern Russia (Kamchatka), Mongolia, and extreme north China. In the upper right corner is central Asia.

Note the very dense region of clouds and rain pulsing up from the Pacific Ocean and overlaying Kamchatka and southern Yakutia. The storm at this point is vast and its cloud coverage immense. But it is just getting started.

Russia August 7 -- Low Pressure Emerges From Central Asia

Russia August 7 — Low Pressure Emerges From Central Asia

(Image source: NASA/Lance-Modis)

By August 7, the storms had sagged toward the south, drifting slowly eastward along the monsoonal flow. Occasional pulses of moisture rose northward from the Pacific to refresh and intensify this storm and cloud flux. This action brought the Pacific and monsoonal storms in direct contact with a hungry low pressure system rising up out of Central Asia and moving from the southwest toward the northeast. By August 7 we can begin to see this storm system entraining the massive volume of moisture associated with the Pacific storm pulse and monsoonal flows.

The storm was emerging over a region of Yakutia that had experienced a massive and terrifying explosion of very energetic wildfires. The air was heavily laden with particles of dense smoke from a great burning that had intensified since late July. There the moisture erupted into a powerful deluge that by August 11th had broken flood records set as far back as 1896. By that time, more than 20,000 personnel had been mobilized to help deal with the floods as hundreds of homes and scores of roadways were inundated.

Russia August 11 -- Deluge Fully Formed Over Yakutia

Russia August 11 — Deluge Fully Formed Over Yakutia

(Image source: NASA/Lance-Modis)

As of August 11, we see a massive and fully formed storm complex directly over Yakutia. The storm has now fully entrained the dense smoke cover belched out by the hundreds of fires, some of which were still burning throughout the region. It was also still drawing in moisture from the Pacific storms and monsoonal flow over south Russia, Mongolia and northern China. A second arm of the storm stretched northward linking the storm with the Arctic. With a strong south and north linkage, the storm had accessed energy to maintain strength and intensity for an extended period.

The large storm system continued to churn through Yakutia and by today, August 14th, a massive region covering 1 million square kilometers was inundated by floodwater. What we see in the satellite shot for today are not one, not two, not three, but four rivers of moisture linking the major storm system that has inundated Yakutia.

Russia August 14 -- Rivers of Moisture Collide

Russia August 14 — Rivers of Moisture Collide

(Image source: NASA/Lance-Modis)

The first river of moisture is a continuation of the Pacific flow rising up along the southeast Russian coast, the second is the monsoonal flow moving from west to east to combine with this Pacific flow. A third flow feeds into the storm from Europe as it rides along parallel and to the north of the more southerly monsoonal flow. A final river of moisture rides up the from the storm, linking it to the Arctic and likely sharing energy and instability with that cold and dynamic region.

With a second low developing to the west of the first and moving along in its shadow and with moisture continuing to feed into these storm systems from the monsoonal flow to the south, it appears that rainy conditions will persist for the already inundated Yakutia region over the next few days at least. And if this pattern continues as predicted, it may well come to rival the great Pakistani floods of 2010.

Fires Still Burn Near the Flooded Lands

One, rather odd, feature of this major flood and fire event is that large areas of wildfires are shown to still be burning throughout Russia. Though the onrushing deluge clearly put out some of the major fires burning in north and central Yakutia, still other major fire complexes continue to burn — some of which remain very near to flooded regions.

In the below MODIS shot a major fire complex is still visible in a region of Russia to the west and south of areas most heavily affected by flooding:

Fires Burn in One Part of Russia as Another Part Floods.

Fires Burn in One Part of Russia as Another Part Floods.

(Image source: NASA/Lance-Modis)

These fires are burning directly in the shadow of the second storm system with their smoke trails feeding into the storm along its southerly inflow.

Conditions in Context

Earlier this year, drought and heatwaves blanketed Siberia and Yakutia. But late July, this region had begun to erupt in a series of extraordinary wildfires that blanketed almost all of northern and eastern Russia in very dense smoke. By early August what is perhaps the worst rainstorm in the history of this area of Russia had begun to form. As of the writing of this article, on August 14, major storms and flooding continued with no immediate end in sight.

Major heatwaves and droughts in extreme northerly regions of Siberia are an anomalous event linked to human caused climate change. Rapid sea ice and snow cover retreat combine with temperatures that are warming at a rate of .5 degrees C each decade over this region to increase the likelihood of such extreme events. Methane and organic carbon stores in the thawing tundra steadily release under this heat forcing and likely provide an amplifying feedback to summer heating events by locally providing more greenhouse gas emission and also providing another fuel store that is available to wildfires. In some of these wildfires, there are reports coming in that fires burn as far as 3 feet into the ground, taking out root systems and stumps along with the trees that burn above ground. Reports of burning ground have also been trickling in (Hat tip to Colorado Bob)

Such burn events are anomalous enough. But for a flood that covers a 1 million square kilometer area to immediately follow in the wake of such amazingly large and widespread fires is anything but normal. Atmospheric patterns that link major weather systems and increase their intensity can be attributed to the formation of powerful heat dome high pressure systems along with weakened and meandering Jet Stream waves. Rising atmospheric heat caused by human warming adds to the density and strength of heat domes (identified as becoming more intense by meteorologist Stu Ostro). Meanwhile erosion of the Jet Stream caused by reduced snow and sea ice cover (identified by Dr. Jennifer Francis) is implicated in a host of problems including more intense and persistent droughts and storm events along with the increased likelihood that weather systems will link up as north to south weather patterns deepen, back up, slow down, and elongate.

A massive ocean heat dome to the south over the Pacific adjacent to China and sea ice and snow cover remaining near record lows must be taken into account when looking at features that likely contributed to the extreme swings from drought, heatwave and fire to massive deluge and flood in Russia.

One last point to consider as a likely contributor is the fact that for each degree (Celsius) of human-caused temperature change, the hydrological cycle amplifies by about 8 percent. This means that rates of evaporation and rainfall are now about 6 percent more intense than they would be in the world of the 1880s. When combined with powerful new weather features like a mangled Jet Stream and immense heat dome high pressure systems, an amped up hydrological cycle further inflates an already extreme environmental condition.

UPDATE: LARGEST FLOOD IN RUSSIAN HISTORY

Reports from the Russian government indicate the region hardest hit stretches from lake Baikal to the Pacific Ocean with some towns in far eastern Russia along the Amur River under as much as 20 feet (6 meters) of water. Reports as recent as yesterday indicated that a total of 113 towns were experiencing major flooding and that an additional 100,000 residents may need to be evacuated.

As of today monsoonal flows and a large moisture pulse rising off of the Pacific Ocean along the back side of a powerful heat dome high pressure system continue to dump copious rains over the region.

Russian officials have stated that this event represents the largest flood in Russia’s history.

I’ve provided a MODIS shot of the hardest hit area under dense cloud cover on August 17:

Flooding Lake Baikal to Pacific Ocean

Russia and China Flooding: Lake Baikal to Pacific Ocean

(Image source: NASA/MODIS)

Lake Baikal is on the left border of the image, the Pacific Ocean on the far right.

Links and Credits:

Interfax

RIA Novosti

NASA/Lance-Modis

Hat Tip to Commenter Steve

Hat Tip to Colorado Bob

Russia Experiences Great Burning

Ocean Heat Dome Bakes China

How Global Warming Amps Up the Hydrological Cycle and Wrecks the Jet Stream to Cause Dangerous Weather

Arctic Heat Wave Re-Intensifies Over Central Siberia Setting off Rash of Tundra Fires

Siberian Fires July 23

Large fires break out over Siberia during renewed Arctic heat wave.

(Image source: NASA)

 

UPDATE: LARGE METHANE PULSE OCCURS IN CONJUNCTION WITH ARCTIC HEATWAVE

 

Over the past week, temperatures have been building throughout Central Siberia. A broad swath of heat pushed thermometers into the upper 70s to upper 80s (with isolated spots showing 90+ degree readings, Fahrenheit) in a broad region stretching from Siberia’s forests all the way to the Arctic Coast. These heatwave conditions set off more than a score of large fires that raged through both Arctic forest and across broad areas of tundra. The largest of these fires covered areas up to 1000 square miles and numerous smoke plumes were visible from satellite, some of which stretched more than 800 miles in length. A larger pall of smoke from this region covered areas of North-Central Russia, the Arctic Coast and sections of Europe more than 2,000 miles away.

You can view these fires and related smoke plumes in the NASA Aqua Satellite image provided by Lance-Modis above.

The scorching Arctic heat wave and massive burning has been set off, once again, by a high amplitude northward bulge in the polar Jet Stream and related ‘heat dome’ high pressure system resting just beneath the bulge. As you can see in the below image, provided by the California Regional Weather Service, this particular heat bulge extends past the 80 degree North Latitude line, nearly reaching the North Pole. This extraordinary upward sweep in the Jet has completely compromised the polar vortex, allowing hot air to build far north and pass deep into the Arctic Ocean environs.

jetstream_northern July 23

(Image source: California Regional Weather Service)

Arctic coastal temperatures usually average less than 50 degrees Fahrenheit at this time of year, but the region beneath this Arctic heat dome has averaged about 15-20 degrees hotter over the past week. Further south, where the tundra fields and arboreal forests of Siberia lay, temperatures have been even warmer with highs stretching into the middle and upper 80s and even lower 90s in some isolated locations. The added heat and the occasional thunderstorm that will typically form under such highly unusual Arctic conditions enhances the chance of wildfires. Now, after a week of such conditions, more than a score of large fires rage.

Siberian Heatwave July 23

Tuesday daytime temperatures for Siberia. Red indicates temperatures ranging from 77-86 degrees Fahrenheit. Note the broad swath of these temperatures riding up from Russia all the way to the Arctic coastline. These measures represent daytime temperatures at the point recorded and do not necessarily record daily maximum temperatures for a given location.

(Image source: Arctic Weather Maps)

Unfortunately, forecasts call for hot conditions to persist over this region of the Arctic at least until Saturday. Then, the heat dome and related Jet Stream bulge is predicted to slowly shift toward Europe, bringing heat, dryness and related risk of wildfires along with it.

This particular heat wave is the most recent of many to plague the Arctic during 2013. Large Arctic regions from Siberia, to Europe, to Canada to Alaska experienced periods of extreme heat where temperatures rose 10, 15, 20 degrees or more (Fahrenheit) above average. The added heat and evaporation in one region appeared to aid in the formation of record floods in another with both Europe and Canada experiencing some of their worst floods on record.

Strange changes to the Jet Stream and the water cycle driving these extreme events are directly related to human-caused global warming. In the first instance, human-caused warming has set off a series of events that have caused a major erosion of Northern Hemisphere sea ice. Since 1979, more about 50% of sea ice extent and 80% of sea ice volume has been lost. Since the 1900s, more than 60% of sea ice extent has melted away. The sea ice, which tends to lock cold air in the Arctic, is thus dramatically weakened. The result is that more warm air tends to pool in the Arctic. As this happens, the temperature difference between the North Pole and temperate regions lessens. This loss of differential causes the Jet Stream to slow down. As the Jet Stream slows, it tends to move more like a lazy river, creating big loops, large high amplitude waves and numerous cut off flows. The net result is that weather systems move more slowly, causing weather patterns to persist over longer periods.

The high amplitude waves that have tended to form in the Jet Stream also result in warmer air being transported toward the North Polar region. In the case of the current Siberian heatwave and wildfires, this is exactly what is happening. What we have seen, this summer, is a ring of very hot conditions developing in the higher Latitude regions from about 60 degrees North to about 80 degrees North. This is the zone where much of the extreme Arctic heating has emerged.

This second factor, added atmospheric heat, causes greater evaporation to occur, especially in regions where the heat is most intense. On average, the global hydrological cycle, which is the net rate at which water evaporates and then comes back to the Earth in some form of precipitation, increases its intensity by 8% for each degree Celsius of warming. Currently, average global temperatures are about .8 degrees Celsius hotter than the 1880s average. So the rate at which water evaporates and the rate at which it falls from the skies as rain and snow has increased by more than 6%. In the hot regions under the Jet Stream bulges and related heat dome high pressure systems this means far more intense soil drying and risk of wildfires. In the wet regions of cut off lows and down-slopes in the polar Jet Stream this means more intense rainfall events.

In essence, this is how human caused global warming is helping to drive extreme weather events now. And the current Siberian heatwave and related wildfires is just one case in point.

Links:

NASA

California Regional Weather Service

Arctic Weather Maps

The Arctic Heat Wave, Heat Domes, and a Mangled Jet Stream

Double Barrel Retrograde Low Sets Off Rain, Flooding From East Coast to Desert Southwest

Double Barrel Retrograde

(Image source: NOAA)

An upper level low that originated this  weekend west of the Appalachians has now transitioned all the way to the New Mexico, Arizona border. If it continues this motion, it will exit the continent somewhere near Baja or Southern California this weekend, having pushed over 3,000 miles against an extraordinarily week Jet Stream.

Yesterday, a second low developed in the wake of the first over the southeast, slowly drifting east to west behind the first.

Today, this double barrel retrograde system brought rains and localized flooding to a wide region including Florida, Georgia, the Carolinas, Texas, New Mexico and Arizona. Miami, which consistently suffers from flooding these days due to an antiquated water management system unable to cope with encroaching seas and more intense rains brought on by climate change, was blanketed by high waters. City offices handed out sandbags to residents who saw roadways, golf courses and yards disappear beneath the flooding rains.

In Atlanta, warnings were issued as a local river approached flood stage and waters continued to rapidly rise as  Houston experienced flooded roads and dangerous driving conditions. Less heavy downpours were reported throughout the Carolinas and into New Mexico and Arizona. The western rains may be welcome, as they help to alleviate drought conditions that have lasted for more than a year. In the east, rainfall has saturated many areas causing added concern for what is expected to be a busy hurricane season.

This rainy, backwards moving weather has been facilitated by an extraordinary weakness in the Jet Stream over the US. The pattern and weak upper level wind flow have resulted in retrograde weather affecting much of the US, now for five days running. You can view these dual weather systems moving backward over the US via the following NOAA animation:

http://www.ssd.noaa.gov/goes/east/eaus/flash-wv.html

The first retrograde low can be seen moving into Arizona, the second is centered over Georgia, and another system looping over Maine and into the backward upper level wind pattern will potentially recurve into the East Coast over the next 36 hours.

Dr. Jennifer Francis of Rutgers University has been presenting compelling research that shows that Arctic sea ice loss significantly affects the upper-level atmospheric circulation, slowing its winds and increasing its tendency to make contorted high-amplitude loops. Such high-amplitude loops in the upper level wind pattern (and associated jet stream) increase the probability of persistent (that is, longer-duration) weather patterns in the Northern Hemisphere, potentially leading to extreme weather due to longer-duration cold spells, snow events, heat waves, flooding events, and drought conditions.

Given the strange backward moving weather events of the past week, weather system motion retrograde to typical upper level flows may also be a likely result.

Links:

NOAA

Jet Stream so Weak, Weather is Moving Backwards

Dr. Jennifer Francis, Top Climatologists Explain How Global Warming Wrecks the Jet Stream and Amps Up Hydrological Cycle To Cause Dangerous Weather

(Video not showing? Click here to watch it directly.)

A new program, posted above and produced by Australian Broadcasting, provides in depth analysis of the cutting edge climate science that begins to reveal how human-caused climate change is causing increasingly dangerous weather.

The program explores past extreme events like the European and Russian heatwaves that together resulted in nearly 100,000 deaths, the devastating floods of Pakistan, and this year’s extreme Northern Hemisphere winter and shows how climate change was the driving factor in each. The program also explores issues I’ve been covering here — like how melting sea ice causes the Jet Stream to meander, resulting in more persistent weather patterns that drive extreme events. The chief pioneer in this research, Dr. Jennifer Francis, provides some well rendered and somewhat chilling explanations about this key feature of our new atmosphere.

Another aspect explored is how global warming greatly increases the hydrological cycle. New findings have shown that just 1 degree Celsius of global temperature rise increases the intensity of the global hydrological cycle by a whopping 7%. Evaporation increases by 7%, fueling more droughts and heatwaves, and rates of rainfall during storms also increases by 7%, further increasing the damage caused by the most extreme storms. Predicted rises in temperatures of 2, 4, 6 or more degrees Celsius would result in a catastrophic amplification of the hydrological cycle by 15, 30, 40 percent or greater. This basic underpinning of storm and drought formation shows how devastating to human systems such a massive change in major weather drivers would be.

Lastly, the program explores how even a .8 degree Celsius rise in temperatures has resulted in more deadly heatwaves. The great European, Russian, US and Australia heatwaves of the past decade are all explored in this particular expose.

Please watch to entire video. It is well worth your time.

Hat tip to Climate Crocks for the head’s up. As ever, my best wishes and admiration to Dr. Jennifer Francis for her astounding research.

Retrograde Low Makes Rush Against Feeble Jet Stream Toward Desert Southwest

Weather Still Moving Backwards

(Image source: NOAA)

I’ve honestly never seen anything like this before. An upper level low and associated frontal systems had stalled near Tennessee this weekend. Then, on Sunday, the low abruptly turned west, riding against the now-feeble tide of the Northern Hemisphere Jet, its center transitioning all the way to eastern Arkansas last night even as associated frontal systems extended all the way to Utah. Today, the low continued to churn westward, against prevailing winds and centuries of weather precedent, and is now located near the Texas panhandle. You can watch the most recent flash animation of this extraordinarily strange weather sequence here.

Models show the low continuing to shift into the Desert Southwest, embedding itself into a monsoonal flow from the Pacific even as it pulls moisture in from the Gulf of Mexico. Such a situation will likely increase the ferocity of typical monsoonal rainfall events for this region with the potential for sudden downpours, locally extreme rainfall accumulations, and a heightened chance of severe thunderstorms.

A very moist Atlantic flow is now also flooding in from the east behind this retrograde low. For the US East Coast, the new and strange pattern will cause weather systems to now come in off the Atlantic rather than from the continent. In the hot conditions expected over the next week, added moisture may result in the firing of locally powerful storms or even the influx of tropical wave-like weather to the East Coast region. Greatest impacts will be seen for Florida, the Central Atlantic Appalachian chain, and the Great Lakes region.

This odd combination of moisture flows and a retrograde low pressure system will combine to create conditions for 1 inch or greater rainfall over broad swaths of the US over the next week. Areas most affected include the Eastern US, the US Gulf Coast, much of Texas, and Arizona and New Mexico. Areas hardest hit by rainfall are predicted to be West Texas and the border between New Mexico and Arizona, where rainfall totals could exceed 4 inches this coming week.

Retrograde Rainfall

(Image source: NOAA)

A substantial erosion of the Northern Hemisphere Jet Stream has permitted this strange pattern of weather to emerge for the US. Usually, higher levels of summer sea ice and greater areas of summer snow cover in the far north would tend to increase the speed of the Jet, allowing it to push weather systems more rapidly along. But a massive erosion of this sea ice and related colder air has slowed down the Jet, setting up the conditions for the current retrograde to move backward against the prevailing weather flow for many days.

(Hat Tip to BugWump who requested this update in the comments section of a previous post).

UPDATE:

A chain of not one, but two retrograde lows appear to be moving against the prevailing weather pattern in the Northern Hemisphere. Doug, in a previous comment’s post, provided this chilling GOES sequence of the two lows — the first over the Central US and the second over the Pacific Ocean — moving together in retrograde.

Double Retrograde, Not Pretty.

(View sequence in full motion here)

Unprecedented Jet Stream Wave Sparks 120+ Degree Temps in the US Southwest and Tundra Fires in Extreme Northern Canada.

Canadian Tundra Fires June 29

(Tundra Fires Near Hudson Bay in Northern Canada on June 29, 2013. Image source: Lance-Modis)

Today, as temperatures rocketed to above 120 in the US Desert Southwest, temperatures hit 87 degrees on the shore of the frozen waters of the Canadian Archipelago. These were the south to north markers of a heatwave that spanned 3,000 miles from Death Valley, California to Cambridge Bay in extreme northern Canada.

Beneath the southern section of this vast and sprawling heat dome, US communities coped by setting up cooling centers and issuing heat warnings. But despite this agile preparedness, hospitals in the hardest hit areas were flooded with cases of heat injury.

In one instance, an outdoor concert in Las Vegas saw more than 200 persons treated for heat injuries while more than 36 were hospitalized. Sadly, an elderly man also passed away at one local hospital after suffering from heat stroke. Temperatures reached an extraordinarily hot 115 (Fahrenheit) in Sin City.

Elsewhere, across the region, Palm Springs hit 122, Death Valley hit 125, and Phoenix hit a scorching 119. Tomorrow is expected to bring another day of extreme record heat, so area cities and residents are still under the gun.

Further north, near 90 degree temperatures stretched all the way to the frozen shores of Cambridge Bay in extreme northern Canada. There, some locations on the ice choked waterway experienced 87 degree temperatures, which is nearly 40 degrees (Fahrenheit) above average for this time of year.

The extreme heat sparked numerous tundra fires across Northern Canada, some of which you can see in the NASA satellite image above. Note the smoke tails rising from two clusters of fires in the upper center portion of the image. That ice speckled area of blue to the right is the, usually frigid, Hudson Bay.

The heat also set off melt and fracturing of sea ice in Cambridge Bay, which you can see in the NASA shot below:

Ice melt Cambridge Bay June 29

(June 29 Ice Melt and Fracturing, Cambridge Bay. Image source: Lance-Modis)

Warming air temperatures typical for this region (high 40s to low 50s) usually result in a more gradual melt. But hot air temperatures at up to 55 degrees (Fahrenheit) above freezing tend to have a far more rapid effect. It is also worth noting the nearly complete lack of visible snow cover in this extreme northern region.

I’ve Never Seen A Rossby Wave Like This

The cause of this 3000 mile swath of heat is an extremely high amplitude wave in the Jet Stream that stretches from the Western US all the way up to the Arctic Ocean. This large bulge has allowed a powerful ‘heat dome’ high pressure system to build up beneath it, concentrating heat over the vast area affected.

Epic Rossby Wave June 30

(Image source: California Regional Weather Office)

Note the up-flow of Jet Stream winds rising up the coast of California, Oregon, Washington and British Columbia then lifting all the way up to the Arctic Ocean before diving back down through central Hudson Bay and into the US Midwest, before making another hairpin turn north again over the Appalachians.

Large Jet Stream waves of this kind are termed ‘Rossby Waves’ after the climate scientist who first identified them. They show extreme north-south and south-north elongation. In the time I’ve been tracking the extreme changes to the Northern Hemisphere Jet Stream brought about by human-caused warming, I’ve never seen a Rossby Wave quite so large as this. Nor have I seen one that is the result of so many large back and forth meanders. In fact, the entire Northern Hemisphere Jet is a mess of meanders, cut off upper level lows and blocking highs.

One of these upper level lows is expected to bring abnormally heavy rain with up to 3-5 inches for some parts of the US East Coast over the next couple of days. So as heat bakes a swath from Death Valley to the Arctic Ocean, the Eastern US braces for potential flooding. Similar Jet Stream loops and swirls spawned the European floods this June, a series of deadly floods that killed hundreds in India and Tibet, and multiple anomalous Arctic heatwaves occurring throughout the past month.

Extreme Jet Streams, like the one displayed above (for late Saturday, June 29), are far more likely to spawn extreme weather events than the usual, gently wavy Jet Stream that human civilization has been used to for much of the 20th Century and, probably, for most of the 10,000 year period since the last ice age. But a combination of eroding sea ice and record or near record low Northern Hemisphere snow cover contribute to both a slowing of the Jet Stream and in greater north-south and south-north flows. The result is large wave patterns in the Jet that tend to get stuck in the same configuration for long periods. Beneath the swells in the Jet, we get hotter temperatures, dryer conditions, and the risk of everything from extreme heatwaves to droughts and fires. In the dips, we get cooler temperatures and much, much stormier conditions resulting in a range of weather from extreme winters (Europe during winter/spring 2013), to floods (Europe summer 2013, India late June 2013), to record rainfall and powerful thunderstorms (US May-June 2013).

These are vivid examples of how human-caused climate change can result in extreme weather.

Heat Wave to Last For at Least a Week

The current record heat wave affecting both the US West and a large section of Canada is expected to last at least until the end of this week. Slow moderation, though, is expected for some regions after Sunday. However, the blocking pattern that spawned this particular heat wave shows little sign of changing position. So hotter, dryer conditions are expected to remain in place for the foreseeable future for much of the US South-West.

Meanwhile, Canada and regions along the Arctic coastline are still likely to see much warmer than usual conditions as periodic warm air invasions from the south are likely to continue.

Links:

Lance-Modis

California Regional Weather Office

Punishing Heat Hits Western US

 

 

 

Arctic Heatwave Sizzles Northeastern Europe With 92 Degree Temperatures, Mangled Jet Stream Hosts Record Canadian Floods, and the Persistent Arctic Cyclone is Coring Through the North Pole

It’s your typical abnormal summer day in the Arctic. The Arctic heatwave flares again, Canada tries to recover from violent record floods, and a Persistent Arctic Cyclone that began in late May is continuing to core a hole through the sea ice near the North Pole.

The Arctic Heatwave Moves to Eastern Europe

An Arctic heatwave that has skipped from Scandinavia to Alaska to Central Siberia, pushing temperatures in this polar region into the 80s and 90s (Fahrenheit), has now re-emerged to plague Eastern Europe. Temperatures in the middle 80s are once again emerging in Finland, an area that blazed with anomalous 80 degree temperatures in early June. But areas north of the Arctic Circle in nearby Russia are, this time, receiving the real baking. There, highs in the region of Archangel, near the Arctic Ocean, reached 92 degrees Fahrenheit. Out over the Kara Sea, just north of these record-hot conditions, an area still choked with sea ice experienced near 70 degree temperatures today.

Average temperatures for most of these regions range from the 40s to the 60s. So current conditions are about 20 to, in some cases, nearly 30 degrees above average.

Arctic Heatwave June 24

(Image source: Uni Koeln)

In the above weather map, provided by Uni Koeln, we can see today’s record high temperatures showing up in pink in the lower right-hand corner of the map. Note the instances of 32 and even 34 degree Celsius temperatures (which converts to 90 and 92 degrees Fahrenheit respectively).

We can also see that some of last week’s fires over Siberia, which I described here, have been put out by a massive rainstorm now dousing the region. The storm emerged as a trough surged down from the Arctic and over Siberia, setting off large storms.

Extreme Jet Stream Sets Off Floods in Canada, Forcing 100,000 to Evacuate

During the middle of last week, the convergence of two upper-level flows of the Jet Stream set off very unstable conditions over Alberta, Canada. A cut-off upper level low stalled, trapped beneath a long-period blocking pattern and dumped rain on Alberta and regions of Central Canada from Wednesday through Monday. Consistent moderate-to-heavy rainfall fell in some areas for up to 16 hours without stop. By the weekend, many places had set one day records as a swath of 2 to 7 inch rainfall blanketed a broad region. Many areas, including Calgary, received their highest rainfall totals ever recorded.

Contributing to the problem was hard, frozen ground and ongoing mountain melt filling up streams and rivers. This combination of impenetrable ground, snow melt, and ongoing, record rainfall resulted in massive floods that turned streams into torrents, roads into rapids, and stadiums into lakes. In total, more than 100,000 people were forced to abandon their homes.

This particular event is likely to see damages well in excess of 1 billion dollars and could rival the record 22 billion dollar floods that rocked Europe just last month. Jeff Masters, at WeatherUnderGround, speculates that the 2013 Canadian floods may be the most costly in that country’s history. Given the massive impact of this major flood, damage totals may exceed previous record flood impacts, at around 800 million, by well more than an order of magnitude.

Persistent Arctic Cyclone Cutting Through the Central Sea Ice

PAC 2013 June 24

(Image source: DMI)

Lastly, a Persistent Arctic Cyclone that began in late May, and has now composed numerous storms remaining in place over the Central Arctic for about a month, continues to cut a hole into the sea ice near the North Pole. The above image, provided by DMI, shows PAC composed of an old low near the Canadian Archipelago and a new, stronger low that just entered the Central Arctic.

Lowest pressures are now about 990 mb, which is somewhat stronger than the storm that lingered over the Arctic this weekend.

Impacts to central sea ice appear to be ongoing even as somewhat rapid edge melt continues. The latest model assessment and forecast from the US Navy shows a widening and thinning area of broken ice near the North Pole, one that displays much greater losses than those seen earlier in the month. A band of open or nearly open water has now emerged just on the Russian side of the 180 degree East line. As you can see, model forecasts show this area of open water continuing to widen over this coming week.

PAC2013modelforecastJul1

(Image source: US Navy)

Meanwhile, some of the thickest sea ice is also showing the corrosive impacts of these ongoing storms. In the image above, you can clearly see the invasion of ice thinner than 2 meters where 2.5, 3, and 3.5 meter ice previously dominated. In fact, in later sequences, it appears that a knife of much thinner ice begins to drive down through the relatively small pack of remaining thick ice.

The Central Arctic is extraordinarily cloudy today. So it is not possible to verify these Navy observations with visual shots. That said, the Navy projections have been both consistent and confirmed in the other monitors since early-to-mid June.

****

Any one of these extreme weather events — a heatwave in Arctic Europe, immense floods never before seen in Canada, and an anomalous storm coring through the thickest sea ice — would be evidence that human caused climate change has radically altered the weather. Instead, we have all three occurring over the span of as many days. It is a pace of extreme events that is both troubling and astounding. And each has been affected by the sea ice loss, ocean, ice sheet, and atmospheric warming, loss of summer snow cover, and extreme changes to the circum-polar Jet Stream brought about by human caused climate change.

We are in the age of extreme weather brought on by our fossil fuel use. If we are to have any hope of preventing the very worst impacts, we need to drastically begin reducing CO2 and related greenhouse gas emissions as soon as possible.

Links:

Calgary Flood May be Most Expensive In Canadian History

Uni Koeln

DMI

US Navy

Heatwave Sends Temperatures in Alaska to 94 Degrees. Large Pulse of Warmth Envelopes Beaufort, Chukchi, and East Siberian Seas.

Yesterday, temperatures in Prince William Sound hit upwards of 93 degrees. Communities there, including Valdez and Cordova, both set new record highs. Talkeetna hit 94 degrees, also an all-time record high for the date. Meanwhile, Seward hit a new record of 88 degrees Fahrenheit. Temperatures in the interior rose to between the mid 80s and lower 90s.

This pulse of heat was driven by a persistent bulge in the Jet Stream over the Pacific Ocean, the Western United States, and the Pacific Northwest that has been present since mid winter. The bulge has resulted in warmer than normal temperatures and drier conditions for much of the Western US while keeping temperatures warm for western Canada and Alaska. It is a blocking pattern implicated in the ongoing drought conditions in places from Colorado to Nevada and California. A pattern which sees 44% of the US still locked in drought.

Sunday and Monday, this blocking pattern enabled warm air to flood north into Alaska, setting off a record heatwave there. You may not think of 50 and 60 degree temperatures in Barrow, Alaska as a heatwave. But when average highs for June there are about 38 degrees, 50 and 60 degree weather is quite hot for this time of year.

Last Thursday saw temperatures in Barrow above 60 degrees. Today, so far, temperatures have risen to 52 degrees, though the high will probably not be reached for a few hours yet.

All this warmth is doing a number on sea ice in the region. As I posted yesterday, large, dark melt ponds and holes in the ice are now visible off Barrow. You can see them in the most recent Barrow Ice Cam shot below:

Barrow sea ice June 18

(Image source: Barrow Ice Cam)

Note the near-shore melt  as well as the large, dark holes forming and widening off-shore.

The pulse of warm air riding up into Alaska is common to a warmer air mass now pervading much of this region of the Arctic. As a result, above freezing temperatures have now invaded large sections of the Beaufort, Chukchi, and East Siberian Seas. This warmer air is causing melt ponds to form over the region leaving their tell-tale bluish tint in the satellite pictures.

Melt Ponds Beaufort, Chukchi, East Siberia

(Image source: Lance-Modis)

In the above image you can see this bluish tint covering about half of the Arctic Ocean area represented in the picture. Also note the large and rapidly expanding area of open water north of the Bering Strait and the large and expanding cracks over the East Siberian Arctic Shelf.

Ice of this color indicates a speckling of melt ponds and hints at the ongoing impacts of solar insolation on the sea ice. Warm conditions in this region have favored insolation for at least the past week. And persistent warmer, clearer weather is beginning to enable the sun to do some serious work on the sea ice.

Warmth is expected to continue for this area until at least next week. The latest long-range forecast from ECMWF shows above-freezing and even 50 degree temperatures plunging deep into this region of the Arctic all the way through late June.

Beaufort Warmth Late June

(Image source: ECMWF)

By June 28th we have 40 degree average temperatures extending far off-shore with above freezing temperatures covering much of this section of the Arctic. Melt in this region, therefore, is likely to be greatly enhanced as the sun is provided with an extended period during which to do its work.

Links:

Heatwave Sets Records Across Alaska

Barrow Ice Cam

Lance-Modis

ECMWF

Climate Change and Jet Stream Erosion Again: Epic European Floods Drive Thousands From Homes

According to news reports, a broad swath of central Europe is suffering severe impacts from major flooding.

In the Czech Republic, over 3,000 people have been forced to flee their homes as raging flood waters threatened both lives and property. Officials in Prague shut down the subway system and erected flood barriers to protect valuable historic districts from waters that were still rising as of Tuesday. In Germany, at least 10,000 were forced to evacuate as 1,700 soldiers were called up to manage major water rises. The German Chancellor noted that damage from this week’s floods appeared likely to exceed the devastation experienced in 2002, Germany’s worst flood in modern memory.  In Passau, where the Danube reached 12.2 meters above flood stage, the historic city center was under water higher than any level recorded since 1501, the year flood records began. Austria also suffered severe impacts as all three countries remain crippled with road, rail and river service suspended due to immense flooding.

The 2002 flood was called a ‘millennial flood’ because this kind of event is supposed to happen only once every thousand years. Yet flood levels have rivaled that of the 2002 flood at least on one occasion with the most recent flood already exceeding 2002 levels in a number of locations. Unfortunately, human-caused climate change has resulting in 1,000 year floods happening about twice a decade in Europe. And as greenhouse gas emissions continue to ramp up, the situation is likely to grow worse.

This year, extreme weather induced by just this kind of climate change has continued to persist. A major dip in the jet stream plunging down over Greenland and invading Britain and Europe resulted in severe weather throughout this winter and spring. Germany so far has received nearly double the amount of rain of a normal spring. Britain has suffered its wettest spring on record, while Italy saw its wettest conditions in 150 years. Since the early 2000s, four record floods have impacted Europe causing between $1 billion and $40 billion dollars in damages. The current event is likely to rival the most damaging of these floods.

Increasingly, scientists are showing that loss of Arctic sea ice caused by human warming is a primary contributor to these extreme weather events. Sea ice volume is down as much as 80% since 1979. This major erosion, scientists note, results in a slowing of the polar Jet Stream. This slowing, in turn, creates a higher frequency of blocking patterns that cause weather conditions to persist for long periods over a given area. In Europe, the northwest-southeast dip in the Jet Stream has resulted in cooler, stormier conditions to persist through southern and central regions since winter. It is a pattern that has been stuck in the same mode for months, bringing storm after storm to the region.

Back in April, the UK Met Office held an emergency meeting to discuss the impacts of climate change on the Jet Stream and attempted to plan for the severe weather now in store. Earlier this spring, the European Environmental Agency warned of the potential for record flooding. Now these predictions appear to be born out.

Links:

Record Floods Inundate Central Europe

Historic Flooding in Central Europe

Heat, Humidity, A Disrupted Jet Stream: How Climate Change Puts Mid-West Tornadoes on Steriods

oklahoma-tornado

(Image source: Basehunters)

On Earth, there is no other tornado breeding ground like the US Mid-West. To the south, the Gulf of Mexico provides heat and moisture, to the north, Arctic air masses regularly plunge down over the heating plains of spring and summer, and to the west, mountains provide both dry air and instability. These features combine annually to spawn hundreds of tornadoes over this region.

In the more stable climate of the 20th century, risk posed by these powerful storms was a regular part of Mid-Western life. But now, with humans inducing the world’s climate system to rapidly change, the world’s most violent tornadoes are being put on the extreme weather equivalent of steroids. This amping up the atmosphere to produce more violent storms occurs through three processes: added heat, added moisture, alterations to the jet stream.

Tornado Fuel: Added Heat, Moisture, Instability and a Mangled Jet Stream

Since the 1880s, world temperatures have risen by .8 degrees Celsius. This increase is roughly equivalent to 1/6th the difference between now and the last ice age, but on the side of hot. Moreover, more than half of this increase has occurred over the past three decades. Added heat goes to providing more energy instability in the atmosphere and instability is one of the key ingredients of the supercell thunderstorms that spawn tornadoes.

Another key ingredient to thunderstorm strength is moisture. As the oceans warm, more moisture ends up in the atmosphere. This added moisture held aloft goes to feed many of the thunderstorms that do spawn, making them, on average, larger and more powerful. Larger and more powerful storms, like the 60,000 foot tall and 100 mile wide behemoth that pummeled Oklahoma last Friday, tend to spawn more destructive tornadoes.

The final ingredient adding to the strength of storms over the US Mid-West are changes to the polar jet stream. Over the past decade, massive losses of sea ice in the Arctic have led to a slowing of the polar jet stream. This slowing has caused the jet to, more and more often, stretch out in elongated wave patterns. These high amplitude meridonal waves (Rossby waves) reach higher into the Arctic and dip lower into the tropics. The result is that warm and cold air masses meet more often. This confluence of air masses further adds to the instability already created by higher temperatures.

The image of the jet stream below provides an illustration of this kind of amplified wave in the jet stream. It is exactly the kind of dip that emerged during mid-to-late spring of 2013 and has persisted through early June. While serving as a conveyer belt for the storms plaguing the Mid-West throughout this spring, it was also a source of enhanced atmospheric instability. One that has aided in the spawning of numerous severe tornado outbreaks.

jet stream map

(Image source: Climate Sight)

A Clear Record of Increasing Damage

In total, added heat, added moisture, and added instability, all elements caused by human global warming, increase the power of thunderstorms and the intensity of tornadoes. According to Dr. Kevin Trenberth, these changes have resulted in storms being more severe, adding about 5-10% to their intensity. This, in turn has had a compounding effect on thunderstorm and tornado damage.

Trenberth notes:

Warmer and moister conditions are the key for unstable air.

The climate change effect is probably… a 5 to 10 percent effect in terms of the instability and the subsequent rainfall, but it translates into up to a 32% effect in terms of damage.

(It is highly nonlinear).

Trenberth’s observations are born out in Munich Re damage assessments from thunderstorms over the past few decades. In fact, Munich Re tracking shows that Dr. Trenberth’s estimates may well be conservative. What Munich Re has found is that damage from thunderstorms has more than tripled since 1980 :

MunichRe1

(Image source: Munich Re)

More intense and severe thunderstorms result in more intense and severe tornadoes. These numbers and assessments by some of the world’s top climate and hazard experts have now been born out in one of the worst episodes of tornado damage in the US. It follows numerous similar episodes that have happened with greater and greater frequency over the past decade. And these events, most certainly, have been made worse by a combination of factors caused by climate change.

What To Expect: Increasing Periods of Intense Storms Broken Primarily by Drought

The heating of the atmosphere, its added moisture content, and the alterations to the northern polar jet stream will result in a number of severe impacts for the US Mid-West. The first is that we can expect the weather to, increasingly, whip-saw between extended periods of hot and dry weather back to periods of increasingly severe weather.

Such whip-sawing will be brought about by the increasing prevalence of high amplitude Rossby-type waves forming over the central US. During periods when the wave pattern is south to north, hot and dry conditions will dominate, leading to more extreme droughts and heat-waves. During periods when the wave pattern is north to south, stormy conditions will dominate, leading to more extreme floods and tornadoes.

This period will likely intensify over the next two to four decades until large pulses of Greenland melt dump massive volumes of cold water into the North Atlantic. At this time, weather will, likely, again shift into an even more extreme pattern dominated by massive and powerful frontal storms scouring the Northern Hemisphere.

These extreme events can be moderated, and possibly prevented, by a rapid reduction and elimination of worldwide greenhouse gas emissions. But under business as usual ‘growth,’ they are almost certain to continue to worsen.

Links:

Tornadoes, Extreme Weather, and Climate Change

Climate Change and Jet Stream

Munich Re Natural Disasters

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