Saturday, December 31, 2011

12z ECMWF Strengthens Polar Vortex-Disrupting Ridge; GFS Introduces Deep Trough Pattern to Great Lakes

Both the ECMWF and GFS are portraying at least some sort of disruption in the polar vortex, as well as at least a slight indication of a cutoff low pattern in the Southwest judging by the 500mb height isobars. However, each model has a different scenario.
The ECMWF brings in a very strong ridge into the polar vortex. If this were to stay in place, essentially the polar vortex would break down, and all of the bitterly cold air would come rushing south, as the lack of motion by the deep low pressure systems would eventually take its toll. This would certainly be a very interesting development. But because not all models do good in the long range, we will have to take this as a 'heads up' item, rather than a sure fire assurance. Additionally, the ECMWF places a ridge in the Northeast.
The GFS introduces a lesser ridge into the polar vortex, but it's still enough to cause problems. A much bigger interest is how the GFS is showing a deep trough pattern in the Great Lakes, which appears to be stemming off of the low pressure systems in the polar vortex itself. It also shows a weak cutoff signal in the Southwest, judging by the isobars.
All in all, this will definitely be something to watch. I would get your snow removal equipment ready, because this is something i'm having a feeling may cause a snowstorm somewhere in the US.

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