Arctic Front To Pass Friday Early Morning

Just a very brief post to alert many of you that a very real shot of Arctic air will be invading PA on Friday!  With it, a relatively rare occurrence for us living here in the sub-tropics, will be an area of enhanced precip falling primarily in the for of snow, and doing so very quickly, possibly accompanied by thunder and lightning, followed by a Flash Freeze making for a real "fun" commute!

Now let me get through all of this.....first the precip Wednesday night into Thursday will be rain.  And we may see ~1.25" or slightly more when all is said and done by Thursday morning.  Take a look at the plumes from the Short Range Ensembles latest runs.  I block highlighted the 2 areas of precip...the one in red is Wed night; the purple is Friday early am.

Once the rain ends Thursday morning, clearing skies and mild temps will follow to make Thursday afternoon relatively benign.  Temps should reach the low 50s by Thursday at 3 pm.  But that sets the stage for a nasty cold frontal passage for overnight into early Friday morning where thunder-snows I believe a be a real possibility!  Here is the front as depicted by the modeled winds for 4 am Friday morning.

And as seen by the surface temps...note that overnight we are still way above freezing.  This is what will create the great instability with the rapid advancement of the Arctic air to the west.  A 30ºF difference will be seen over a 100 mile E-W distance!  The bright purple line is the freezing line.  When the front passes, it will likely start as rain, but QUICKLY change to snow and then FLASH FREEZE for the Friday am commute!  Be aware of this possibility!

Here is the larger scale global model GFS and its take on the synoptics for Friday morning...

If the closed 500 mb low passes just a bit further south, then we are looking at a 1-3" frontal passage snowfall Friday morning followed by a blustery and very cold Friday and Saturday!

OK....enough now....gotta go!  But it is something to talk about for the last few days of the PA Farm Show.  How could we get through this week without even a little winter wx!

Have a good Wednesday...

Smitty

AA::  Rainy Wed night into Thursday am, then a nice Thursday pm, arctic front passes pre-dawn Friday with some rain and mostly snow ~1" or so...and then very cold!