StormWatch: Winter Weather Advancing
There is little change in the forecast over the next several days as a large Arctic airmass develops over western Canada this weekend then spills southward over the Lower 48 next week. The good news is, as of this morning and yesterday afternoon, some of the forecasting data has backed off a bit on the overall intensity of the cold air. However, much colder air is still expected to move across the eastern half of the nation next week bringing well below normal temperatures to many areas — including many areas of the Deep South unaccustomed to such prolonged cold. High levels of uncertainty remain as the coldest air, as of this morning, is still transitioning from Siberia. Which areas will be the coldest and exactly how cold is “cold” are the specific details continuing to be addressed by StormWatch.
Once established over western Canada, the leading edge of the Arctic air is expected to make quick progress southward across the northern Rockies, Central and Northern Plains and Upper Mississippi River Valley on Sunday, January 9th then southward across the Southern Plains, western Gulf of Mexico and the remainder of the Mississippi Valley on Monday. The cold air will then slide eastward across the Atlantic Seaboard and Deep South on Tuesday as low pressure quickly intensifies off the North Carolina Coast. This low pressure has all the trappings of the second nor’easter in as many weeks and StormWatch will bring more details to YourWeatherBlog and the ImpactWeather YouTube channel as they become available. In addition, please note that strong offshore winds of 25 to 35 mph with higher gusts will be possible behind the cold front across the western and northern Gulf of Mexico southward to the Bay of Campeche late Monday through Wednesday.
Temperatures will likely drop well below normal behind this Arctic airmass through the remainder of the next week over most areas east of the Rockies, especially over the Great Plains and Mississippi Valley from the Dakotas and Minnesota southward to Texas and Louisiana. As mentioned above, the projected Arctic airmass does not look quite as cold as it did this time yesterday, but will still be capable of producing hard morning freezes across most inland parts of the Deep South from Tuesday, January 11 through Friday, January 14. Closer to the coast, a light early morning freeze (29-32) is still possible from the immediate Texas Coast to the Florida Panhandle. Even though we cannot completely rule out a hard freeze (<28) near the immediate coast, data today indicates the threat of this is much lower.
As for high temperatures next week, there has been a subtle change in the flow pattern and there is now a decreasing threat for freezing precipitation after the Arctic air arrives next week over the Deep South. As a result, fewer clouds are expected for the most part which should allow temperatures to recover into the 30s and 40s during the day over most parts of the same region.
In the Upper Midwest, a low pressure area will bring a threat of heavy lake-effect snow to portions of southwest Michigan this afternoon through tomorrow evening. Total snowfall amounts could range from 5-10 inches, isolated 15 inches. For Michigan’s U.P., the same low pressure area will bring a threat of heavy lake-effect snow to portions of the Upper Peninsula and extreme northern Wisconsin through Saturday morning. Total snowfall amounts could range from 6-12 inches, isolated 24 inches. In addition, northerly winds of 15-25 mph, gusts 35 mph, could produce some areas of blowing and drifting snow and hazardous travel conditions.