Sometime during the day Sunday, the Arctic front arrives. But it won’t seem like that big of a deal. Downsloping winds may even help temperatures rise into the 50s east of Roanoke, with 40s most other places. It’s only the beginning, though. The core of the Arctic air that is pouring into the Dakotas tonight doesn’t arrive until late Monday into Tuesday. With lingering snowpack a significant factor especially west and southwest of Roanoke (plenty of snow left where I live just outside Roanoke, too) there may well be some single digits and even a few negative numbers around the region by Wednesday morning. It doesn’t look like we’ll calm the winds down long enough for that perfect radiational cooling night that could send temperatures plummeting regionwide. Northwesterly upslope flow over the mountains and a few disturbances squirting through may scatter some snow showers, though it looks like most of it will be weak and stay mostly in West Virginia.
Late week, a low-pressure system develops in the central U.S. and moves in some manner toward the Eastern U.S. Forecast models have come up with multiple scenarios already, but there is a significant chance moisture will get spread into lingering Arctic air for some kind of wintry precipitation for some period of time. That’s about as specific as it can get right now, so this will become our system of the week to monitor. The shot of Arctic air that follows it may be even colder than what we see in the middle of this week.
There are numerous indications on long-range guidance that Southwest Virginia is entering a period that may last 2-3 weeks or more when there will be occasional shots of Arctic air and a few winter storm threats. That doesn’t mean every day will be cold or that every “threat” will materialize into snow. But winter is upon us.