The first wave of run is this line of heavy rain and wind that's just now exiting Baltimore, lifting northeast. It should be into Philadelphia between 9:30 and 10 PM given its current trajectory and pace of movement. Showers continue across Pennsylvania at this hour, lifting northeast out ahead of the main shield of precipitation with the storm system.
With this squall line, damage was reported earlier tonight in Virginia around the Virginia Tech campus and the cells have had a history of producing wind gusts to 60 mph. The biggest threat with these cells is wind -- there's very little thunder with them. Heavy rain is also likely...but wind is the player to be dealt with. This line should push largely along I-95 and perhaps just north of that over the next couple of hours.
The first shield of rain is starting to approach the city from the west. The first band is pushing east but the front is still way back in Western PA, still a number of hours away from Philadelphia. The first push might get in a bit earlier and could produce a heavy burst of rain of wind...winds have gusted to 30-40 mph with the initial burst that's worked through Central Pennsylvania earlier this afternoon. The first burst may pass through Philadelphia over the next 90 minutes to two hours but it looks like the majority of stuff will pass through later than 7 PM.
Looking downstream towards DC and Baltimore, some of the mesoscale modeling is indicating that this shield of rain will lift northeast, so it bears watching downstream with the squall line working through Baltimore and near DC over the next few hours with trajectory. It wouldn't surprise me if there's a bit of a push northward with this moisture as the low level jet, the wind machine for later tonight, gets cranking and brings that surge of 80-90 mph winds aloft towards the region.
The main brunt of rain pushes all the way back into Ohio and West Virginia -- we have several hours to go with this main push of moisture tonight. The "squall" down across SW Virginia is something to keep an eye on locally this evening and tonight as modeling does try to push this northeast
So, what to expect this evening....
- Winds will continue to increase, strongest towards Midnight.
- This first shot of rain pushes in, with the main surge continues later tonight.
- Worst of the storm expected 11 PM - 4 AM from west to east. Front crosses generally 1 AM - 4 AM.
- Winds could exceed 60 mph in gusts at the Shore, 45 mph NW of city, 50 along I-95 and in suburban South Jersey.
- Around an inch of rain for most, higher amounts north/west of the city where two inches of rain are possible.
- A few rumbles of thunder possible but odds favor less thunder and a general windswept rain tonight across the region.
We'll have another update later on this evening.