There has been lots of interest for days in the timing of potential rainfall on Saturday, with the morning Blue Ridge Marathon in Roanoke and a host of related downtown activities (including evening bicycle races), the annual Blue Ridge Kite Festival at Green Hill Park outside Salem and the 4 p.m. Virginia Tech Hokies spring football game. It seems the third Saturday in April is often packed with popular activities like this – I certainly remember April 16 last year with the marathon, kite festival, motorcycle festival (which happened last week this year) and April 16 memorial activities at Tech — all hampered by morning downpours that gave way suddenly to mid/late afternoon dryness while eastern Virginia and the Carolinas suffered a tornado outbreak. This week’s packed April Saturday appears likely to have the reverse timing of a year ago — dry in the morning, giving way to rain and possibly storms by mid to late afternoon as a cold front pushes into what will be a rather warm and sticky day (highs mostly in the 70s, maybe a few low 80s, and dew points in the 50s). The National Weather Service provides a handy tool for hourly forecasts, linked here for Blacksburg and here for Roanoke. As of shortly after midnight on this Saturday morning, they’re showing a chance of showers picking up about 1 p.m. at Blacksburg and 2 p.m. at Roanoke. The latest simulated radar for 2 p.m. on the North American Model seems to agree with this timing. The most important thing to watch, though, will be actual National Weather Service-Blacksburg radar linked at the top of the page (and again, right here).
Saturday’s showers and storms begin about a 3-day period in which Eastern U.S. weather will make an interesting circuit, thanks to this powerhouse coastal low-pressure system that will be wrapping up on the coast. For our region, there is some threat of strong to severe storms Saturday afternoon as the cold front bumps into warm, moist air — not all the ingredients are there for a big severe outbreak, but some strong wind gusts or hail may occur in some storms, especially Roanoke and eastward. Then comes rain overnight Saturday into Sunday as the low develops and moves up the coast — projections of 1 to 1.75 inches common across Southwest Virginia. Then, as the low tightens off the coast and gets pulled inland by the jet stream trough digging far southward in the Eastern U.S., it will start pulling cold air from Canada southward through the Applachians by Sunday night and especially into Monday and Tuesday. Just to the west of the low, over parts of Pennsylvania and West Virginia, there may be some heavy, wet snow measuring several inches. In many of those areas, it could be similar to the late October storm that knocked out power and damaged leafed-out trees, in this case budding and greening early because of the excessively warm March that occurred. For Southwest Virginia, don’t rule out some snowflakes getting swirled in by strong northwest winds as early as Sunday night or perhaps early Monday or Monday night, especially in higher elevations west of Roanoke. Snow in April is not all that unusual at 3,000-plus elevations in the Appalachians — it’s a little odd to see it anywhere lower than that, but not unprecedented, as there appears to have been a snow shower event across the region, even into Roanoke, on May 7, 1989. (Heavy snows in the New River Valley on April 26-27, 1978, too — follow the last comments on the last thread to see the discussion about these). But it does appear this odd winter/spring season is about to throw us another curve ball, as we go from possibly 80 with strong storms Saturday afternoon to a few snowflakes in some areas within 48 hours.