Keeping It Simple

Now that Isaac has decided to SLOWLY drift away from southern Louisiana and up the Mississippi River Valley, the question begs "what will happen with Isaac's remnants?".  Well....I'm glad you asked!  I'm going to keep it simple and illustrate what the GFS depicts as the movement of the deeper tropical moisture at the 700 mb level (10,000') and where the computer modeling suspects it will travel.  You might be wondering why I am showing you the 700 mb level.  Essentially, when the relative humidity is 100% or higher (different story/different day), precipitation is likely to occur in those saturated clouds and be observed on the surface of the earth.  I will show you the 12Z run (8am EDT) of the GFS for each 24 period starting with the initialization of the parameters for Thursday morning. 

Do you remember this morning?  A beautiful, almost full moon shining brightly in the pre-dawn sky with nary a cloud to be found!  In fact, as I type this on my humble patio watching the hummingbirds feast on the Mexican salvia, I can't find a cloud in the sky!  Hence, the air is dry including the 700 mb level.  If there was ample humidity at the 700 mb level, clouds would be quite prevalent across the sky.  That is not the case...the deep blue below indicates LOW humidity.  The yellows; 'bout half, greys=rain!

Thursday morning:

Friday morning:  Isaac northward of the Arklotex region...still sunny and HOT here in PA!

Saturday morning:  Some thin cirrus moving into PA thanks to the broad circulation around Isaac.  Still some very dry air being advected SE from the northern lakes over southern NY and northern PA...

Sunday morning:  With the church bells ringin', clouds will be increasin'!  In meteorology, we often talk about pressure and temperature gradients.  Well, that is one heck of a humidity gradient over PA running NW to SE!  While it's raining in Washington County, PA, nary a cloud will be found in Dauphin & Lebanon Counties!

Monday morning:  The wx deteriorates rapidly from west to east with rainfall likely across the entire state for Labor Day.

Tuesday morning:  WET!

Wednesday morning:  Front whisks Isaac's remnants out to the sea, with a refreshing NW flow replacing the damp air with much drier air once again!  Note Leslie out near Bermuda...she must be watched!

Gut feeling...about a 24-36 hour period of moderate to at times heavy rain for our region amounting to about 1-2" in tote.  Once things become more clear, I'll update on the Labor Day wx...but until then, enjoy your Football Friday and the kickoff of the 2012 High School Football Season!  Go Rams and Go Panthers!  Rams over the Streaks and the Panthers over the Greyhounds!  Gotta love it!

Hey...at the very least, I posted a slew of psychedelic maps in at which y'all can stare...they are pretty cool!  Enjoy your week's end...and remember, the whiter the shade of grey (in the models above), the more likely for rain...so I'll leave you with this...enjoy this old classic.

Smitty

AA:  Isaac's remnants to affect PA's wx later Sunday through Tuesday with a healthy amount of rain...enjoy your Labor Day weekend my friend!