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The most powerful episode of poleward heat transport into the stratosphere on record has split the stratospheric polar vortex in two. The polar vortex forms in the winter in the stratosphere when there is no UV energy to heat the ozone in the upper stratosphere. A zone of high winds, called the polar night jet, normally spins high above the Arctic. Normally there is one cyclonic vortex centered near the pole. Right now, there is a weak, warm anticyclone above the pole and there are two cold cyclonic vortices spinning over north America and Eurasia. There is intense compressional heating above the Labrador sea and central Eurasia caused by this planetary wave number 2 of unprecedented power. The image above shows what northern hemisphere planetary wave no. 2 looks like — warm over the Arctic and oceans — cold over the continents. This wave pattern is intensified by the presence of warm water and the loss of sea ice on the Atlantic side of the Arctic.
Records are meant to be broken" new all time record set in poleward
#heat transport into the #polar stratosphere.Increasing trend was subject of my 2009 paper and still relevant today: http://web.mit.edu/jlcohen/www/papers/Cohenetal2009.pdf …
Judah Cohen discovered in his 2009 paper that the presence of warm water in the fall and winter in the seas on the Atlantic side of the Arctic, that used to be mostly ice covered, is destabilizing the polar vortex in late winter and changed fall and winter weather patterns across the northern hemisphere. The additional water vapor and heat tends to increase snow over Siberia in the fall, intensifying the jet stream over northeast Asia and into the western Pacific. Thus, increased Siberian snowfall in September and October alters the atmospheric circulation pattern of the whole northern hemisphere in the fall and winter. In north America, this shift is making fall warmer and longer, with a tendency for severe cold air outbreaks in late December through February. In the winter months, sea ice decline enhances the warm Arctic / cold continents pattern.
Record low Arctic (and global) sea ice extent for the month of January was recently reported by the National Snow and Ice Data Center (NSIDC). nsidc.org/...
The new year was heralded by a week of record low daily ice extents, with the January average beating out 2017 for a new record low. Ice grew through the month at near-average rates, and in the middle of the month daily extents were higher than for 2017. However, by the end of January, extent was again tracking below 2017. The monthly average extent of 13.06 million square kilometers (5.04 million square miles) was 1.36 million square kilometers (525,000 square miles) below the 1981 to 2010 average, and 110,000 square kilometers (42,500 square miles) below the previous record low monthly average in 2017.
The pattern seen in previous months continued, with below average extent in the Barents and Kara Seas, as well as within the Bering Sea.
Arctic sea ice extent is at a record low for today’s date after have suffered two days of major melting on the Atlantic side after being slammed by an intense warm storm that moved from the Atlantic into the Arctic ocean.
The possible impact of the polar vortex split on the weather is complicated, but there has been consistency between models and consistency withing models that cold air will be be displaced towards northern Eurasia for the next six weeks. Thus, northern and central Siberia, which are normally very cold this time of year will be even colder than normal. Western Europe may also be colder than normal because cold easterly flow off of the continent will be enhanced by strong Siberian high pressure. Most of the continental U.S. will likely be cooler than normal in March while Alaska will be likely be warmer than normal.
The CFSv2 model, run by NOAA and the U.S. Climate Data Center predicts warmer than normal temperatures in most of the northern hemisphere beginning in April, but the model has a warm bias. The spring months following La Niña winters, like this one have an increased probability of severe tornado outbreaks because warm water tends to build up in the Gulf of Mexico while cold air tends to flow into the plains from western Canada. Intensification of the east Pacific high subsequent to the polar vortex split could enhance this northwest flow of cold into the plains that will come in conflict with warm moist Gulf air. It’s a very difficult forecast but conditions may be developing for an active and very destructive tornado season.