Friday AM snow: More south, less north, Roanoke on the bubble

Kevin Myatt 2 hrs ago

Weather patterns don't often easily align with county and state lines, but highways are sometimes a better reference marker. U.S. 460, the highway that connects Roanoke with Blacksburg, Christiansburg and Bluefield to the west and Bedford and Lynchburg to the east, is a fair divider for snow expectations early Friday.

Locations south of that highway have the best chance of seeing measurable snow on Friday, while locations along the highway -- about 15 miles either side, we'll say -- are a coin-flip to see white ground by midday Friday. North of the U.S. 460 corridor, there is less chance of snow accumulation, but it's not out of the question entirely, as these systems sometimes bump northward from expectations at the last minute.

A quick-moving low-pressure system, at the surface and aloft, will ride just south of our region early Friday, sweeping a limited but sufficient amount of moisture northward into just-cold-enough air over North Carolina and the southern part of Virginia to produce snowfall, starting near or just before sunrise Friday. The moisture will run into enough dry air to shut off at some vaguely defined point that appears likely to set up near the U.S. 460 corridor, but could vary somewhat north or south.

Surface temperatures will also be marginal, mostly in the 30-33 range, so snow will have to fall with some gusto to accumulate a lot on anything besides grass and exposed objects. That is more likely to occur to the south, where locations from about Pulaski to Floyd and Rocky Mount southward appear poised to see 1-3 inches, with locally heavier amounts especially near the North Carolina border and particularly the higher terrain of Grayson, Carroll and Patrick counties, which are under a winter storm warning for some possible 4+ amounts.

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Contact Kevin Myatt at kevin.myatt@roanoke.com. Follow him on Twitter @kevinmyattwx.