Thursday, May 03, 2012

Slight Risk of Severe Weather Tomorrow

Tomorrow will not only bring summer back to the region en masse but an approaching cool front from the NW will also bring with it the trigger for thunderstorm development in the afternoon and evening hours.  The Storm Prediction Center has a slight risk for severe out for the region for tomorrow afternoon and evening.

Timing on when thunderstorms will fire up tomorrow, as well as the best chances for where thunderstorms fire up, varies slightly by each respective computer model -- the GFS and Euro place the best thunder threat farther north and limit how much thunderstorm activity moves through the region (they generally keep thunderstorms to the north of I-80 until later at night), while the NAM is a bit more southern in the extent of thunderstorm development and places the potential into our region into the early evening hours.  That said, even the NAM places the best chances of thunderstorms to our north towards the Poconos and north of there.


This is one of the higher resolution versions of the NAM -- showing its thinking for 8 PM tomorrow.  Most of the threat is scattered around to our west, with a stronger line of thunderstorms to our north over the Poconos and across Central Pennsylvania.  That northern line on the NAM slips southeast through the region, with the thunderstorms to the west moving east until they fuse in with the line later in the evening.

I do think some thunderstorms may fire up earlier in the afternoon across the Poconos or Central PA than what the models are hinting -- and it's possible we see thunder try to move into the region more towards the dinner hour than towards 9/10 PM.  It will be a pretty warm day around here, with increasing instability.  The front's approach should be enough of a trigger to get thunderstorms going in parts of the region in the afternoon, with the bulk of the activity in the early evening.   Any strong thunderstorm that develops could bring strong winds and heavy rainfall.