Thursday, April 12, 2012

Next Week's Warmth

Cue up your favorite summer-based is another fling of late Spring or even early Summer on tap for the region for at least Sunday and Monday...perhaps even Tuesday.   High pressure that works through the Eastern US tomorrow will set up shop off of the Carolinas this weekend, bringing a warm southwest flow of air to the region as we push into Sunday.  80 is not out of the question on Sunday afternoon in the Delaware Valley as those warm winds of change, a dry ground, and a decent dose of sunshine contribute to our first 80 of April.

There is still a touch of a question of how warm we ultimately get on Monday and Tuesday.  The GFS still is trying to paint a stalled front nearby on Monday but it has been slowly trending the position of this frontal boundary farther and farther north...past runs of the model had the front clearing through Philadelphia before stalling it down near Cape May.  Last night's run and this morning's early run only bring the front down to about Trenton before stalling and then retreating it on Tuesday.   The Euro still has the frontal boundary farther to our north.  The combination of a stronger ridge on the Euro and warmer air aloft allows temperatures on Monday on its forecast to get into the middle 80's around Philadelphia, while the GFS "only" suggests upper 70's.   Still warm no matter how you slice it but given the trends through this morning that the front was stalling farther north, the Euro's forecast may end up being closer to reality.

The forecast temperatures aren't records by any stretch -- the record high on Monday is 90, on Tuesday it's 95 -- both of which were from the 2002 heat event that hit the region.  80's in April also aren't uncommon -- we last went through an April without hitting 80 degrees back in 2000.   Despite the common nature of getting at least one 80 degree day in April, the frequency of hitting 80 has increased.  While 7 of 10 years in the 90's featured a 80 degree day in April compared to 9 of 10 in the 2000's, the average number of 80's in the 1990's was just the 2000's it was 2.7.  In the last two years we averaged 5.5 80 degree days in April (5 in 2010, 6 in 2011).

We'll get to drop two or three on that tally...the question is if Tuesday can hit 80 before a cool front slides into the region.  Shower and thunder chances will reside along the front but it ultimately comes down to timing of the front reaching the region and how much oomph the Carolina high will still have over the region.  If the warmer Euro is right, we would hit 80 on Tuesday as well.