Thursday, June 06, 2013

Flash Flood Watch For Much Of Region

Flash flood watches are out for much of the region starting late tonight and continuing through Friday night as the combination of Andrea's remnants and an approaching cold front bring heavy rains to the Delaware Valley.  The only areas, as of now, that aren't under a flash flood watch are the Lehigh Valley, Berks, and the Poconos.  Even though you guys aren't under a flood watch up should be aware of the possibility that you could still see some flooding rains in susceptible spots -- the typical-to-flood streams that have issues will probably do so with this event.

Between one and three inches of rain is likely for the entire region with some spots getting more than that.  As of now, modeling is centering the heaviest rains along I-95 and just west of that with the incoming system.  We alluded to this possibility this morning...the combination of a frontal boundary nudging east, the Fall Line in place as a geographic boundary, and a remnant tropical system pushing up the coast typically yield rainy scenarios for the I-95 corridor and counties just west of that.  It would not shock me to see the heaviest rains (the more than three inches part) line up just west of the city tomorrow and tomorrow night.

The GFS and Euro are in pretty good alignment on the heavy rain potential -- the GFS a bit more aggressive than the Euro is but both show that potential for heavy rain.  The Euro has been more consistent on rainfall placement and amount than the GFS, which has waffled around on both from run to run.  That said, they are in agreement at this point.

Rain is the main threat with this system.  Wind will not be although it could be breezy at the Shore tomorrow and tomorrow evening -- gusts to 30 mph are doable, maybe a notch higher down there.  Inland, wind will not be a big factor at all but the rains will be.

Prime time for the rain tomorrow is from the morning hours through Friday night, with the bulk of the heaviest rains in the PM timeframe.  It will be raining pretty steadily, perhaps heavily in the morning but worst of worst  will align up to the city's west and northwest tonight into tomorrow morning before the prime time for the city kicks in.  With tonight's event, rains are already falling to the city's west and are pushing east and northeast.  Heavier rain will work in over the next few hours from West Virginia and Virginia, probably aligning itself along the Fall Line or just west late tonight and tomorrow morning.

As you can tell, between Andrea's landfall in Florida and the batch of rain approaching us, there's a lot of rain out there along the East Coast.

More:  Current Weather Page