Polar Vortex Collapse, Arctic Freeze ImminentA polar vortex collapse and subsequent Arctic Freeze is imminent across the nation in January. The stratospheric temperatures at the 70mb level, commonly known as one of the lowest levels in the stratosphere. Looking at the 2012 section, that recent stratospheric temperatures have taken an uptick to normal temperatures, expressed by the dashed green line. This uptick indicates that the stratosphere is now at average temperatures, and the polar vortex is now at average strength.
This is an animation of observed temperatures at the 50mb level (slightly higher up in the air than the 70mb level) over the past month. In late November, a large zone of red appear and propagate into the Arctic Circle. This was a significant stratospheric warming (SSW), meaning warm air from the lower atmosphere was pushed into the stratosphere. This was also shown in the 70mb chart by that spike in observed temperatures a month ago. the observation on November 25-27. The warm air entered east Asia before blowing up and moving into the Arctic. Looking at the most recent December image, there is another small red zone of warm air has emerged in central Asia. Judging by the last two or three images, this zone also looks to be entering East Asia, indicating another stratospheric warming if this warm air moves into the Arctic Circle.
This is the 8-10 day height anomalies at the 500mb level. The 500mb level is the best area to identify areas of low pressure (blues) and high pressure (reds). Stormy patterns and quiet patterns correspond to these colors, respectively. The image is of two model forecasts- the one on the left is the ECMWF model, and the one on the right is the GFS model. For those unfamiliar with the polar vortex, it is a permanent low pressure system stationed over the Arctic. When enhanced low pressure is over the Arctic, the polar vortex (PV) is stronger than normal, and high pressure weakens the polar vortex.
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