Say Farewell to the Beautiful Fall Wx

Just as difficult as it was to say goodbye to the Phillies 2011 season, it will be equally as difficult to say goodbye to this current spell of beautiful fall wx that has been nothing short of idyllic.  With daytime highs near 80 accompanied with low humidity and overnight lows near 50, fall weather just doesn't get much better than what we just experienced.  But all good things must come to an end and this is true of our current splendid wx.  The high thin cirrus of today is a precursor to this event.  The wx will begin to deteriorate late Tuesday and Wednesday will be a rainy and raw day with once again, I fear, some tropical downpours as the system that is about to affect us has its origins in the tropics!  But before we get to Wednesday's map, lets look at how the 500 mb has been anomalously warm in our area as shown by the ensembles.

However, things will change with the upper air pattern and Wednesday will be the transition day as we experience a wet transition from the storm that has been slamming Florida for the last couple of days.  Again, with the origins of this system from the tropical Atlantic, we should expect to see some heavy downpours along with longer periods of a more stratiform type rain.

The SREFs are showing a very high probability of rain for Wednesday.  It's not very often when the ensembles have a 100% POP at 2.5 days out into the future.  Here are both the NAM and the GFS showing their high likelihood for rainfall Wednesday. 

I expect the truth of the heaviest rain be somewhere in between the maps above.  However, look for ~1.5 inches of rainfall to fall over most of PA by Thursday morning, the bulk of it falling during the daylight hours of Wednesday.

Then a shot of rather brisk and downright chilly fall weather will invade for next weekend.  We should experience much atmospheric instability as some sub-freezing air at 1 mile up will invade PA by Saturday.  The blue line is the 0C line at 1 mile up.  Some lake effect rain and snow showers should materialize over the high ground of northern PA.  Take a look....

Here is the cold anomaly as shown by the GFS ensembles for this upcoming weekend!

Then, after a very brief moderation in temps (I'm not calling it a "warm-up"), another more serious shot of even colder weather will take aim at the Mid-Atlantic as shown by the longer range model here for next Thursday.  If this actual run would verify, the plateau of PA would be experiencing a widespread wet snowfall which is not too early for the north country of PA.  It would not be too surprising if a few snowflakes would be observed in the mountains just north of Harrisburg, which is a tad early!

And here are the ensembles' anomalies for 10 days out.  The further out into time, the more towards "normal" the ensembles trend.  Thus, when one sees an output that is a couple standard deviations from "normal" at this time frame, it sends a fairly clear signal that, in this specific case, cold air will be on the move.

So there are the next  couple of weeks in a nutshell.  A fairly quick synopsis of the pattern leading to a demise of our beautiful fall wx.  Not too dissimilar from the demise of the Eagles season as according to the Elias sports record keepers, the Eagles are one of only 2 teams in NFL history to gain over 1,000 yards offensively in back to back games AND LOSE THEM BOTH!!! That is what happens when you turn the ball over FIVE TIMES in the NFL!  There is no way to win these contests by gift wrapping the rock for the opponent; just doesn't happen at this or really any level of football.  Protect the ball and your likelihood to win dramatically increases.  The Eagles are in trouble, no doubt about that forecast!

Enjoy your week!

Smitty

AA:  Nice spell of wx ends with a rainy Wednesday...then more typical fall like weather, albeit colder than normal.  It could be unsettled with some very cold air aloft.  Looks like northern PA might even see a widespread ground whitening snowfall middle of next week after numerous snow flurries this weekend!