Last Wednesday, Northwest Ohio Storm Prediction Center released a long range forecast, explaining that the ensembles were predicting a more transient and "potentially" stormier long range pattern. As you can see, this past week, we saw a major West Coast storm move into the Midwest, and slam the Upper Midwest with as much as four feet of snow, high winds throughout the Central Plains, and heavy rains to a widespread area. Not only that, but it brought along with it the first true Arctic blast of the season, with the lake effect snow affecting a large area of Michigan.
Global models are now expecting that this pattern be disrupted until Thanksgiving Week (next week). The disruption will occur as a major Gulf of Alaskan low becomes prevalent. It will cause the jet stream to "split", indicating that the pattern will be rather dry and inactive, with no major storms expected to hit any part of the United States until late next week. NOW, Global models as well as the ensembles are forecasting a potential pattern change at the end of Thanksgiving week (that could potentially screw up my entire winter forecast). In fact, the ensembles are forecasting that the Aleutian/Gulf of Alaskan low will begin to "dig" into the West Coast. In response, a strong elongated jet streak will begin to form across the Northern Plains, which will allow the PV (Polar Vortex) to begin shifting southward again. At the same time, ridging (North Atlantic blocking) will build into Greenland, forcing a trough to form in the East, with a flat ridge developing over the West. In fact, this could be the beginning of more widespread arctic air into the United States.
The storm that could bring these changes could either be a Midwest storm system, a Northeast coastal low, or both. In fact, both of these possibilities have been suggested by the global models. In my opinion, here is what will happen. A large storm will drop southeastward in the Midwest, drawing an Arctic air mass into the East. On the edge of the cold front, a secondary low could develop and move along the East Coast. Currently, there are too many differences to in fact make an accurate forecast of what will happen. In any case, this change will occur on Thanksgiving Day or the few days afterward.
Global models are now expecting that this pattern be disrupted until Thanksgiving Week (next week). The disruption will occur as a major Gulf of Alaskan low becomes prevalent. It will cause the jet stream to "split", indicating that the pattern will be rather dry and inactive, with no major storms expected to hit any part of the United States until late next week. NOW, Global models as well as the ensembles are forecasting a potential pattern change at the end of Thanksgiving week (that could potentially screw up my entire winter forecast). In fact, the ensembles are forecasting that the Aleutian/Gulf of Alaskan low will begin to "dig" into the West Coast. In response, a strong elongated jet streak will begin to form across the Northern Plains, which will allow the PV (Polar Vortex) to begin shifting southward again. At the same time, ridging (North Atlantic blocking) will build into Greenland, forcing a trough to form in the East, with a flat ridge developing over the West. In fact, this could be the beginning of more widespread arctic air into the United States.
The storm that could bring these changes could either be a Midwest storm system, a Northeast coastal low, or both. In fact, both of these possibilities have been suggested by the global models. In my opinion, here is what will happen. A large storm will drop southeastward in the Midwest, drawing an Arctic air mass into the East. On the edge of the cold front, a secondary low could develop and move along the East Coast. Currently, there are too many differences to in fact make an accurate forecast of what will happen. In any case, this change will occur on Thanksgiving Day or the few days afterward.
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