An approaching cold front and a vigorous disturbance aloft will help lift some more of the moisture that has overspread our region on Monday for additional rain showers. Don’t expect copious downpours but a few more tenths of an inch, maybe locally 1/2 inch-plus, will be possible as temperatures hang mostly in the 50s. The cold front pushes through by late Monday or early Tuesday, a few snow showers in its wake mainly on mountain ridges along and west of the Virginia-West Virginia border and Interstate 77. After a couple of mild days, we are still on track for a rather strong surge of Arctic air by Friday and possibly a more widespread round of snow showers as cold northwest winds cross the Appalachians, with some strong wind gusts possible. There remain some questions about just how long that cold air will remain over us, and also on the evolution of what could be a robust storm system in the central or eastern United States in the days just after Christmas. My best guess, based on current forecast models and the developing weather pattern, is that seasonable or somewhat colder than normal temperatures hang on til Christmas Day or possibly the day after, and then the post-Christmas storm heads to our northwest, bringing in somewhat milder air and possibly substantial and needed rain. There is much time and many moving parts that could change this outlook to a colder or warmer (or drier or whiter) direction, so we’ll keep an eye on it. Flip-flopping long-range forecast models have already engendered much discussion on the blog Sunday.
Snow meter, 12/17-12/23
Chance of 1 inch of snow in next week:
Roanoke, 2 snowflakes out of 10 * *
Blacksburg, 4 snowflakes out of 10 * * * *
Outlook: After two easy weeks, a late-week situation has me scratching my head a bit about Blacksburg. An Arctic cold front will blow through late Thursday or early Friday. Blustery northwest winds crossing the Appalachians will likely spread snow showers into many parts of Southwest Virginia, as Great Lakes moisture is lifted up the slopes and condensed. Intermittent snow showers may continue into the weekend, depending on how fast a low pressure system crosses the Great Lakes and New England. I’m thinking both Blacksburg and Roanoke will see snowflakes flying in the breeze late this week. Blacksburg sometimes scratches out an inch from similar situations; Roanoke rarely does. I’m leaning against Blacksburg getting an inch out of the snow showers late this week, but will go as high as four flakes for the possibility.
Looking back: There were a few snow flurries in the New River Valley on Tuesday morning but little accumulation. (One commenter on my blog reported a skiff on the Appalachian Trail near Angel’s Rest in Giles County.) My zero flakes pick for Roanoke and one for Blacksburg was on target. Less than five flakes on the snow meter and not getting an inch of snow at either site means I get wins for the week. Current records: 2-0 for Roanoke, 2-0 for Blacksburg.