Tuesday, January 10, 2012

A Soaking For Most Tomorrow Night

Another round of rain from another southern system forthcoming tomorrow night. This storm system will bring rain to the vast majority of the Delaware Valley.  However, farther north could see a period of icy rain, sleet, or snow at the onset of the storm and for at least a portion.   Most computer guidance except the GFS model shows at least some frozen/freezing precipitation in the Poconos and the higher elevations of the Lehigh Valley tomorrow evening.  Precipitation moves into the Philadelphia region around 4 PM, with the Lehigh Valley in on the event around 6 PM or so.   The icy rain or sleet/snow combo should transition over to rain for everyone in the Poconos but the higher elevations up there might get a couple of inches of snow or some icy surfaces for a time before temperatures moderate above freezing aloft and at the surface.

For us here in Philly, rain will be steady to heavy at times from about 7 or 8 PM through Midnight and until 3 or 4 AM before tapering to showers before the morning commute on Thursday.  Rainfall could be heavy enough to cause some minor streams and the usual suspect streams to flood or approach the top of their banks later tomorrow night.   We've been pretty lucky as it's been relatively dry the last month outside of a couple of larger rainfall events so the region can handle a decent rainfall without much difficulty.  However, because of the amount of rain expected in a short timeframe there is some potential for minor flooding in spots.

Rainfall totals should exceed an inch in most spots, with the potential for a couple of inches in the heaviest locations (NAM suggests that, with the other models solidly in the one to one and a half inch department).

After this, we will transition to colder weather late Thursday night with a second cold front coming in from the west.  That front will bring more showers to the region, which may end as a shot of snow to the north/west of Philadelphia on Friday morning.  Accumulations would be minor if that changeover to snow does occur...and probably most likely on the highest hills and in the Poconos.