Advertisements

Worsening Weather to Feed Monstrous Thomas Fire Through Sunday

It shouldn’t be happening in typically wetter, cooler December. But, due to human-forced climate change, it is.

The Thomas Fire, at 242,000 acres, is now the fourth largest fire in California history. Alone, it has destroyed 900 structures — a decent town’s worth gone up in smoke. And today it threatens pretty much all of Santa Barbara’s 62,000 buildings. For future days promise conditions that could expand the monstrous blaze into the largest fire ever seen for the state.

(Persistent western ridge formation is an expected upshot of sea ice retreat in the Arctic. A feature that will result in a drier, warmer, more fire prone California if the trend toward sea ice melt and global warming continues.)

Firefighters battling the blaze have faced insane odds to manage a herculean feat — achieving 35 percent containment as blowtorch like Santa Ana winds consistently billowed through the region over the past two weeks. These winds have been both abnormally strong and persistent. And they’re run over dry lands through a season that is typically known for its more prevalent rainfall — not the expanding drought we see today.

Given these presently very abnormal conditions, fire officials don’t expect to achieve full 100 percent containment for three more weeks. And that’s with over 8,144 firefighters on the ground assisted by 1,004 fire engines and 27 helicopters.

(The 2012 to 2017 California drought was slaked by rains last winter. However, it appears to have returned in force with southern portions of the state again facing an extended dry period.)

Present weather conditions for California are extraordinary. A persistent ridge of high pressure has hovered over the region. And this high has helped to spike local temperatures, speed a re-emergence of drought, and drive very powerful Santa Ana winds through the region. The high formed as sea ice advance in the Chukchi and Bering Seas far to the north lagged. Open water that is usually ice covered at this time of year radiated more heat into the local atmosphere — providing a slot of warmer air that assisted this drought, heat, and wind-promoting high pressure ridge in forming.

The intensity of these highs, influenced by climate change, out west has consistently risen into the 1040+ hPa range. Highs that have been juxtapposed by a strong low further south near Mexico. And a steep pressure gradient between these two persistent weather systems has helped to drive the very strong, fire-fanning, Santa Ana winds through the region. As the Thomas Fire blossomed last week, fire conditions achieved extremes never before seen in state history as those hot, dry winds roared over hills and through valleys.

(GFS model runs show the fire fanning Santa Ana winds strengthening through Sunday. Hat tip to Dan Leonard.)

Unfortunately, weather models for the next few days show this Santa Ana wind producing pressure gradient either persisting or strengthening. Today, this gradient is producing winds with gusts of up to 55 mph. By Sunday, the high over the Pacific is predicted to face off against a low over Northwestern Mexico. And the gradient between these two systems may further intensify these fire fanning winds. Wind speed and fire hazard are not expected to be as extreme as last week. But the re-intensifying winds will do firefighters no favors.

In addition, and perhaps more importantly to the long range picture, there is not even a hint of rain in the forecast through at least the next week. Dry, warmer than normal weather is expected to remain in place at least through that period. And hope for wetter, cooler weather has only begun to emerge in the longer range, less certain forecast.

Advertisements

Winter is Supposedly Coming; So Why is California Burning?

As forecasters expect a warming climate will make Santa Ana winds more frequent and faster, that Santa Ana blowtorch is likely to do a lot more damage to the developed parts of the state. — One of the conclusions of a recent climate study.

You can only imagine the impact this weather is having. — Los Angeles Fire Chief.

*****

The popular refrain these days is that ‘winter is coming.’ But for California and the North American West, this is clearly not the case.

(Four large wildfires burn across Los Angeles in this December 5 satellite shot. Image source: NASA Worldview.)

Conditions across the West have been drier lately. Hotter lately. A lot less winter-like during the winter season lately. Add in the fact that climate change is expected to increase the strength of the wildfire-sparking Santa Ana winds and this trend of ebbing winter is a rather serious factor.

The very reason why we use the words — fire season — is due to the fact that fire is more prevalent when it is hotter, when it is drier, and when the dry winds blow more strongly. For California, fire season happens twice a year — once in early summer and again in autumn as the dry Santa Ana winds begin to howl.

(Consistent unseasonal heat and the development of powerful high pressure ridges over the North American West amplify the Santa Ana winds and set the stage for more severe wildfires. This week, a strong ridge and related abnormal warmth and drought helped to fan a historic Los Angeles outbreak. Image source: Climate Reanalyzer.)

The Santa Ana season lasts from October through April. It notable due to the fact that it tends to threaten more heavily populated areas. Its primary mitigating factor — cooler winter weather — is receding. And, according to this research, the same factors that are warming the U.S. West are also making the Santa Ana winds blow stronger. So we have good reason to believe that the effects of human-caused climate change are making California’s fall and winter fire season considerably worse.

Today is December 6, just a little more than two weeks before the Winter Solstice. Seasonally, we are at the gates of winter. Winter should be coming. But, instead, we have drought in Southern California. Instead we have had consistently warmer than normal weather over the past 30 days. Instead we have 70 mile per hour Santa Ana winds raging over withering peaks and through the drying valleys. These are conditions consistent with a fire season amplified by climate change. Not with normal winter.

And today, in Los Angeles alone, we have four fires raging simultaneously.

The largest fire, the Ventura Fire, has now burned more than 65,000 acres. It threatens 12,000 buildings. And it is already estimated to have consumed at least 150 of these structures. The fire has cut off power to upwards of 250,000 people and has forced numerous closures and evacuations.

The Creek Fire, Rye Fire, and Skirball Fire have reportedly burned an additional 15,000 acres and forced more than 150,000 people to evacuate. The Skirball fire is threatening the Getty Museum even as it has forced the closure of a section of highway 405. This 150 acre fire is also encroaching upon a 28 million dollar home owned by right wing media mogul — Rupert Murdoch. Notably, Rupert has used his media empire to support the views of climate change deniers and has called rational concern over climate change related risks ‘nonsense.’ Today, one of his many homes may burn as a result of such ‘nonsense.’

(Present location and extent of Los Angeles wildfires. Image source: Google Maps.)

In total, more than 1,000 firefighters are presently battling these four fires around the Los Angeles region. And the risks to the city are now as high as they have ever been. For on Wednesday, weather forecasters are calling for Santa Ana winds to continue to gust as high as 70 miles per hour. With the strength of these powerful fire-inducing winds peaking on Thursday as gusts are predicted to hit as high as 80 miles per hour. The winds will loft sparks and burning material from the fires and drop it over the city — creating nightmare conditions for firefighters trying to contain the four blazes. Red flag warnings — indicating that conditions are ideal for fire combustion — are expected to remain in place over Southern California through Friday.

Advertisements
%d bloggers like this: