For Sunday, expect a cold, blustery day, with temperatures not making out of the 30s most places in Southwest Virginia as a shot of Arctic air is rotated in behind the departing storm off the Northeast coast. There may be a few more upslope-produced snow flurries and showers moving over from West Virginia overnight and early Sunday morning. I wouldn’t rule out a skiff in a few spots mostly west of Roanoke.
It hasn’t turned out entirely like almost anybody wants this past week in Southwest Virginia, but winter has certainly begun to show its hand, after three toasty weeks to start December. Frequent blog commenter Doppler Carol has allowed me to share several photos from Floyd County, where both the beauty and mayhem of winter weather has struck this week with Wednesday’s power-crippling ice storm (and a little more ice/snow on Saturday morning, too). The inset shot at left, shown larger here, displays the cold canvas of both a winter sky and landscape. There was lots of ice in Floyd County this week, where the Blue Ridge forms an elevated plateau for many miles, rather than the sharp, narrow ridgelines that surround the Roanoke Valley. Linked are a foggy shot of icy woods, sharp icicles on a clothesline post against a blue sky, and icicles adorning a bird house. But the ice also had a destructive side, as this image speaks, and to which the thousands who lost power for at least some period of time can attest. HokieTrax also shared an image from Blacksburg that seems appropriate for her nickname — bird tracks on Saturday morning’s light skiff of snow. It doesn’t take a blizzard to coax the beauty, or the beast, out of winter.
Summary: A pool of extremely cold air is developing over Hudson Bay during the next week that likely will lead to some bouts of colder temperatures in days and weeks to come. The coming week will be seasonably cold with two possible storm systems affecting Southwest Virginia. The first may produce rain, freezing rain, sleet, snow or a mixture of these, for New Year’s Eve and New Year’s Day. The second system is even more iffy, but there is some potential for a larger storm system forming near the Gulf Coast or Southeast and affecting the Eastern U.S. late in the week.
Discussion: There is a development taking shape in the next week that could have significant implications on the course of winter in January. The strongest polar vortex, or deep swirl of extremely cold air, is setting up shop in the Hudson Bay region of Canada over the next several days. The 12Z European model for next Saturday clearly depicts this, with bring pink and purple colors signalling where the coldest air in the world will be residing, likely for several days, perhaps some weeks. The polar vortex in Hudson Bay doesn’t mean that it will be cold in Southwest Virginia every single day of its presence, but it does mean that a huge source of cold air is available to be tapped with almost any storm system that makes its way through the East. And it is very possible that some of the more extreme Arctic air will ooze southward from this polar vortex at some point in January. The coming week looks to be seasonably cold to somewhat below normal, for the most part. (Climate normals for the first week of January are mid 40s highs, upper 20s lows at Roanoke; low 40s highs, low 20s lows at Blacksburg.) There are some other features that may make the next week intriguing for winter fans, including high pressure building across the West (the Pacific-North America positive pattern, or PNA+, that often leads to colder air and increased of storm systems in the East) and a subtropical flow undercutting that ridge of high pressure that will scoot some storm systems across the South. The first arrives New Year’s Eve/New Year’s Day, likely throwing some Gulf of Mexico moisture into cold air to the north. Early forecast models show us on the borderline, once again, of freezing temperatures and also on the northern edge of the moisture flow, but of course all this is subject to change. From this distance, rain, freezing rain, sleet or snow, or a mixture of these, are possible come time for 2012 to roll into 2013. A second disturbance late in the week (about Thursday) has some chance of developing a larger storm system over the Gulf Coast or Southeast, which could threaten a larger winter storm in parts of the East, IF it develops and doesn’t run quickly out to sea. So, after two wintry mix systems this past week, one that was a little colder than expected and one that was a little warmer than expected, we may be fighting the same battles with forecasts again in the week ahead.