A loop (above) of 12Z GEFS 850 mb (~5000 feet) temperature anomaly forecast maps across North America shows quite well the plunge of the cold air mass next week from Alaska into the western US and then finally its expansion into the eastern US at then end of next week. The 7-day loop of 850 mb temperature anomaly forecast maps progresses from this Saturday, December 3rd to the following Saturday, December 10th with colder-than-normal conditions shown in blue and purple and the warmer-than-normal air in red and orange.
Following the passage of today’s frontal system, temperatures will cool down here on Thursday and then even colder air pushes in for the weekend with possible snow showers early next week. We will then likely warm up considerably once again in the eastern US during the middle and latter part of next week ahead of the cold blast which will initially dive into the western US. A major storm could actually form along the frontal boundary zone by the mid-to-late part of next week which would bring more rain here (at least initially) and perhaps significant accumulating snow to parts of the Upper Midwest. By the end of next week, the Arctic front separating the warm air to the south and east and cold air to the north and west is likely to plow through the Mid-Atlantic region ushering in the cold air mass all the way down into the Southeast US. Longer term, signs point to colder-than-normal conditions sticking around here as we progress through the month of December.
Meteorologist Paul Dorian