WASHINGTON (7News) — Saturday will start the weekend on a relatively quiet note, but attention quickly turns to Sunday, when the First Alert Weather Team will be on Weather Alert for the potential for strong to severe thunderstorms and heavy rain.
High pressure will keep much of Saturday dry with a mix of clouds and sun. Highs will reach the mid to upper 80s, with only a few showers or thunderstorms possible from the Potomac Highlands into the central Shenandoah Valley and toward I-64. Late Saturday night bears watching. Recent guidance has increased the possibility that remnants of a thunderstorm complex moving through the Ohio Valley could cross the Alleghenies.
Confidence remains low on how much of that activity survives, but it could have an impact on how Sunday develops.
Sunday is the main day to watch. Some showers or storms may already be around during the morning, with the severity of the afternoon threat depending on how quickly the atmosphere recovers. If enough heating takes place, conditions will become very warm, humid and unstable, with temperatures well into the 80s and heat index values climbing into the 90s.
There will also be enough wind shear to support organized thunderstorms. Damaging wind gusts are the primary severe weather concern, although other severe hazards could develop if storms remain more isolated.
Heavy rain will be another concern. Atmospheric moisture may become unusually high, allowing thunderstorms to produce torrential downpours. The greater flash-flood threat would come from storms repeatedly moving across the same locations. A Slight Risk for excessive rainfall extends from much of the Alleghenies eastward along and north of I-66 and U.S. 50. Storms could continue into Sunday night before the cold front finally moves through early Monday.
Behind the front, somewhat drier air arrives for Tuesday and Wednesday, bringing a break from the daily thunderstorm pattern. Another system may approach Thursday or Friday with another chance for stronger storms, but confidence remains low this far out…