The atmosphere has moistened up around here today with intensifying southerly winds just ahead of a powerful cold front that is now crossing the eastern Ohio Valley. There will be numerous light-to-moderate showers ahead of the front this afternoon, but the frontal system itself will be accompanied by heavy showers and scattered strong-to-severe thunderstorms late this afternoon and evening as it sweeps into the I-95 corridor. The most likely timetable for the wave of heavy showers and strong thunderstorms associated with the frontal system is 5-9PM in the DC metro region, 6-11PM in Philly, and 7-midnight across the NYC metro region. Steady rain will likely fall for awhile later tonight following that initial onslaught of showers and thunderstorms. All areas up and down I-95 could end up with an inch or more of rainfall by early Saturday morning at which time the front will exit off the east coast. Winds can gust up to 60 mph or so this evening in any strong-to-severe thunderstorm with the greatest chance of severe weather including isolated tornadoes from eastern Pennsylvania southwestward to the DC metro region. Skies will clear tomorrow behind the strong front and a chilly air mass will take hold in the Mid-Atlantic region. Temperatures will likely bottom out in the 30’s this weekend in many Mid-Atlantic suburban locations and frost is not out of the question in some of the normally coldest locations.
Two other notes – 1) the Lyrid meteor shower peaks late Sunday night/early Monday morning and viewing conditions should be quite favorable although it’ll be quite chilly for this time of year, and 2) the NASA Wallops Island, Virginia rocket launch is now set for 5PM on Saturday and conditions may very well work out for this scheduled launch time as high pressure builds into the Mid-Atlantic region. If indeed the 133-foot rocket is launched this weekend, it may be visible near the horizon in DC, Philly and NYC shortly after lift-off (in the southeastern sky in DC; southern sky in Philly and NYC).