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 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.
(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 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.