Winter didn’t get the cue to start when meteorologists declared the start of winter on Dec. 1. But the season seems to be listening better to astronomers. The first day of astronomical winter on Friday — the winter solstice — will bring a day truly worthy of the label “winter” in Southwest Virginia, with 20-35 mph sustained winds and 40-60 mph gusts (enough for some scattered tree damage and power outages) hauling in a chilling dose of Arctic air to awake us from our mild, meek December slumber. These winds lifting over the Appalachians will cause upslope snow squalls to develop in the mountains of West Virginia, where many counties are under a winter storm warning, and some high elevation areas will see blizzard conditions at times. Snow squalls will pick up during the afternoon and evening, as the winds turn from more of a westerly trajectory to northwesterly, blowing perpendicular to the southwest-to-northeast slant of the Appalachian ridges. There will also be some instability from daytime “heating” (using the term very loosely, as peekaboo sun may raise temperatures only as high as near 40 even around Roanoke) and a weak trough of low-pressure rotating around the big low to the north. The New River Valley will almost certainly see snow dancing through the air at times Friday and Friday evening, and the Roanoke Valley likely will, with some flurries possible in any part of Western, Central or Southside Virginia at times. Accumulations in Virginia will mainly occur in the counties near the Virginia-West Virginia border and west of Interstate 77 — and even there, moreso in elevations above 2,500 feet and on west-facing slopes, generally an inch or two. But these snow squalls can sometimes surprise folks farther east. It is possible just about anywhere from the Blue Ridge and Roanoke Valley westward could see a few minutes of surprisingly heavy snow with a random snow squall, even enough to briefly whiten the ground in a few spots. The strong wind gusts and intermittent snow showers will continue into Saturday, slowly diminishing, with calmer, drier and seasonably cold weather (40s highs, 20s lows, some teens) settling in for Sunday and Monday.
This has already been a major winter storm for a big part of the central and northern U.S., as many areas broke out of record snowless streaks in a big way with some amounts topping a foot. The blizzard conditions led to a fatal multi-car pileup in Iowa. There were also tornadoes late Wednesday in Arkansas and Alabama.
There has been — and will continue to be — much conjecture about a potentially high-impact central and/or eastern U.S. storm system for Christmas and 2 days afterward, especially now that forecast models have shifted the likely track of the storm significantly eastward. The Climate Prediction Center hazards map includes heavy snow and heavy rain areas to our west and southwest on Christmas and the following day, but does not yet continue them farther north or east. Yet the wording of the hazards discussion contains this: “THE OPERATIONAL 12Z GFS MODEL AND MANY OF ITS ENSEMBLE MEMBERS FROM DEC 20 INDICATE THE DEVELOPMENT OF A COASTAL LOW ALONG THE EAST COAST WITH THE THREAT FOR HEAVY SNOW AND SIGNIFICANT ICE ACCUMULATIONS ACROSS THE NORTHEAST AND MID-ATLANTIC LATER NEXT WEEK. SINCE THE EXACT TRACK OF THIS WINTER STORM AND ITS ASSOCIATED PRECIPITATION TYPE/AMOUNTS ARE EXPECTED TO CHANGE WITH FUTURE MODEL RUNS, RESIDENTS OF THE CENTRAL AND EASTERN U.S. ARE URGED TO MONITOR THE LATEST FORECASTS FOR A POTENTIAL HIGH IMPACT WINTER STORM NEXT WEEK.”
In the same discussion, there’s also this: “12Z GFS ENSEMBLE MEMBERS FROM DEC 20 INDICATE INCREASED CHANCES FOR ANOTHER MAJOR WINTER STORM TO AFFECT THE EAST-CENTRAL U.S. AT THE BEGINNING OF JANUARY.”
Friday may not be the end of the world, but it is the start of a brave new world for Winter 2012-13. Much to monitor in the days and weeks ahead, starting with high winds and some snow squalls/showers/flurries on this Friday.