Friday, February 24, 2012

A Bit Wild, A Bit Wacky

If you're north of Philadelphia, hopefully you had a chance to enjoy yesterday...it may end up being your warmest day (or close to it compared to Wednesday) of the week.  We hinted last night about the warm front not getting enough lift to get through the region today, getting stuck somewhere near Philadelphia in terms of northward extent...and it looks like that will be the case today as gusty northeast and east winds are blowing through the region, drawing some cooler air off of the Atlantic.  Having the rains around the area don't help the cause as they add some extra cooling to the atmosphere...the result this morning is temperatures in the lower 40's in Philadelphia, 30's in the Lehigh Valley and higher elevations of the Philly suburbs.

Farther north, sleet was mixing in with early morning rain in the higher elevations of the Lehigh Valley, with snow falling in the Poconos.  Thunder snow was reported in a couple of spots up to the north -- there's some decent dynamics with this warm surge aloft.  The problem is for those who want warmth -- that surge is aloft and not at the surface.

North of the Turnpike, you might be blessed to see temperatures get above 50 degrees today.  Those east breezes this morning off of 40 degree Atlantic Ocean waters will not only keep you cool, but they will add a stable layer into the lower atmosphere that the warm front may not be able to budge through at the surface.   The question is how far north that warm front ultimately gets before a cold front out to the west pushes in -- right now the best guess is that it teases close to Philadelphia, perhaps reaches the Airport briefly, but doesn't clear the city.  This makes the temperature forecast for the city, Delco, and immediate South Jersey oh so fun...and oh so full of potential fail.

South of the city has its own issues...the warm front should clear most of you and temperatures will bounce into the 60's and low 70's this afternoon.  If you get enough sunshine, you have a shot at severe thunderstorms this afternoon as the atmosphere is unstable and there's enough wind dynamic aloft to allow a line of thunder to develop along and just east of the cold front.  Severe doesn't look likely where the warm front can't cross -- if you're in the 50's you might get some gusty thunder but severe chances look slim.  The Storm Prediction Center has a slight risk for severe weather out south of a Dover-Atlantic City line in our region.

After this morning's showers and light rain for the city and north, the afternoon cold front arrival should trigger more showers and thunderstorms.  Timing for those should generally occur after 3-4 PM from the west on east.  With the front passing through, winds veer around to the west and will increase to between 20 and 30 miles per hour sustained, gusting to over 40.

Summing everything up temperature wise -- 45 or so in Allentown, around 50 on the Turnpike, 50's (dinner time or early evening temperatures) in the city and just south of the city (city will be in the 40's into the afternoon), and 60's to low 70's south of a Long Beach Island-Wilmington line.  If the warm front does get enough traction and push north, we could see everything bump up a bit...but with higher resolution modeling continue to trend away from that it looks like we're going to struggle to see a third warm day in the city itself.