A complicated but somewhat diffuse low-pressure system will sweep through the South and East over the next 36 hours, bringing periods of light rain with possibly some sleet and snow to Southwest Virginia. Without a solid feed of cold air in the lower layers of the atmosphere, the potential for wintry precipitation will not be maximized with this event for our region, though some periods of sleet and snow definitely cannot be ruled out, especially west of Interstate 81 and in elevations above 3,000 feet. Temperatures on this Tuesday night are in the 40s to low 50s after highs in the 50s to near 60s, and there do not appear to be strong mechanisms in place to trigger a large-scale temperature drop to near freezing throughout the atmosphere and across much of the region as we have seen in several recent wintry weather situations. But there may be just enough cold air to tap for some patchy sleet and wet snow to develop as rain moves in, especially near the front and back ends on Wednesday morning and again Wednesday evening. In any event, we are not talking about large amounts of precipitation, as evening balloon soundings show very dry air from 1 to 2 miles up over Blacksburg. As is often the case, our region may be caught between the stronger flow of Gulf of Mexico moisture to the south and the stronger system dynamics to the northwest. The Hydrometeorological Prediction Center is projecting only 0.10 to 0.25 inch of liquid for most of the region east of Interstate 77 over the next 24 hours. If it were all snow and it all stuck, that would only be 1 to 2.5 inches, presuming a 10:1 ratio … and it almost certainly will not be all snow, and even if it were, it definitely would not all stick, and it likely will be too warm aloft for a 10:1 ratio. So this looks to be more of a nuisance event rather than anything with high impact, but beware if traveling into higher elevations or west and northwest toward West Virginia, where the impact could be much greater with a few inches of snow possible. We will keep an eye out for surprises, even localized ones, as we’ve had a track record of these in small wintry precipitation situations dating back to late December.
Regarding the weekend … you may see lots of chitter-chatter out there in the virtual realm about the potential storm disappearing or re-appearing on the models. For Southwest Virginia interests, I think it’s very likely that we will NOT experience a major winter storm (widespread 8+ inches) and that any strong low that forms will develop too late, off shore or too far to the north. However, it is quite possible that a “shortwave” trough moving around the larger trough will trigger some level of precipitation — leaning to snow at this point — over the weekend. Often in this region, we experience light to moderate precipitation from a disturbance moving through on its way to blowing up a larger storm system farther east or north. This is what I think is far more likely than experiencing a major storm, and why I haven’t dropped off the weekend potential just yet. Neither has the HPC, showing at least light precipitation amounts widespread for the weekend.