We have declared Thursday a WEATHER ACTION DAY for discrete supercells that could produce tornadoes during the afternoon and evening across Northern Virginia, Northeast Maryland, and northern portions of the Delmarva Peninsula.
Thunderstorms are expected to form along the Blue Ridge after 4:00 p.m. Thursday. The atmosphere ahead of these storms are prime for severe development. There is medium concern that discrete supercells will develop ahead of the main line of storms. These discrete cells have the highest potential of producing tornadoes.
By 6:00 PM Thursday, severe storms will approach the Interstate 95 Corridor, which could provide a messy rush hour. These storms will also contain damaging wind gusts over 60 mph and the potential for large hail. There is also the potential for these storms to produce very heavy rain, resulting in localized flash flooding across the region.
We’ll also have to watch the Roanoke Valley area as a few storms may develop by late afternoon or evening. While the tornado threat is lower towards the south, it should be noted that the threat is *not* zero and an isolated tornado is possible. The main concern with these storms will be gusty to damaging wind gusts that could bring down tree limbs or branches.
By early to mid-evening, the main line of thunderstorms will take over and turns into a straight-line damaging wind threat across the Virginia Northern Neck, Southern Maryland, and Upper Delmarva Peninsula region. A few storms will remain possible across Central and South Central Virginia, but the severe threat will likely diminish across those locations after 9:00 P.M.
Our Tornado Threat Index is up to a “5” (MEDIUM) across much of Northern Virginia, extending into Central and Southern Maryland. This number could go up depending on future radar trends as we are concerned about discrete supercells during the late afternoon and early evening, before this turns into a heavy rain and damaging straight-line wind threat. The chance for tornadoes is lower once you get to the Interstate 64 corridor and points south, however, it needs to be stressed that the threat is “lower” and *not* zero. Everyone in the highlighted area needs to remain weather aware during the afternoon and evening hours for all modes of severe weather..