MESOSCALE DISCUSSION 1732
   NWS STORM PREDICTION CENTER NORMAN OK
   1120 AM CDT FRI AUG 10 2012
   
   AREAS AFFECTED...PARTS OF CNTRL/ERN KY...MIDDLE/ERN TN...AND SRN
   WEST VIRGINIA... INTO THE CREST OF THE APPALACHIANS
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 101620Z - 101745Z
   
   PROBABILITY OF WATCH ISSUANCE...20 PERCENT
   
   SUMMARY...AN INCREASE IN THUNDERSTORM ACTIVITY IS EXPECTED ACROSS
   THE REGION THROUGH THE 18-20Z TIME FRAME.  THE SEVERE THREAT MAY NOT
   BE COMPLETELY NEGLIGIBLE...BUT THE ENVIRONMENT APPEARS TO SUPPORT
   ONLY LOW POTENTIAL FOR ORGANIZED SEVERE STORMS.  A WATCH IS NOT
   ANTICIPATED IN THE NEAR TERM...BUT TRENDS WILL CONTINUE TO BE
   MONITORED.
   
   DISCUSSION...BREAKS IN THE OVERCAST ARE ALLOWING INCREASING
   INSOLATION AND BOUNDARY LAYER DESTABILIZATION AHEAD OF THE SURFACE
   FRONT NOW ADVANCING SOUTHEASTWARD THROUGH THE LOWER OHIO VALLEY. 
   THIS IS MOSTLY TO THE SOUTH AND EAST OF THE MID-LEVEL COLD CORE OF
   THE GREAT LAKES UPPER LOW...AND FORECAST SOUNDINGS SUGGEST THAT A
   RELATIVELY WARM MID-LEVEL LAYER /AROUND 500 MB/ WILL LIMIT THE
   DEGREE OF DESTABILIZATION THROUGH THE AFTERNOON HOURS.  STILL...
   DEEPENING CONVECTIVE DEVELOPMENT IS ALREADY EVIDENT...AND SUFFICIENT
   INSTABILITY PROBABLY WILL DEVELOP THROUGH THE NEXT FEW HOURS TO
   SUPPORT INCREASING THUNDERSTORM ACTIVITY ACROSS PARTS OF THE
   TENNESSEE VALLEY AND CUMBERLAND PLATEAU INTO THE WESTERN SLOPES OF
   THE CENTRAL APPALACHIANS.  THIS COULD BE AIDED BY FORCING FOR UPWARD
   VERTICAL MOTION DOWNSTREAM OF A SHORT WAVE IMPULSE PIVOTING AROUND
   THE SOUTHERN PERIPHERY OF THE LOW...AND MODEST DEEP LAYER SHEAR
   BENEATH 30-40+ KT WESTERLY 500 MB FLOW.
   
   ALTHOUGH THE DEEP LAYER SHEAR IS SUPPORTIVE OF UPDRAFT ROTATION AND
   ORGANIZED CONVECTIVE DEVELOPMENT...THE RELATIVELY WARM MID-LEVEL
   TEMPERATURES AND RATHER MODEST CAPE AND LOW-LEVEL WIND FIELDS/SHEAR
   DO NOT APPEAR PARTICULARLY CONDUCIVE TO DAMAGING WIND POTENTIAL. 
   HOWEVER...GIVEN PRECIPITABLE WATER UP TO AROUND 1.75 INCHES...AND
   AMBIENT DEEP LAYER WESTERLY MEAN FLOW ON THE ORDER OF 20-30
   KT...LOCALIZED DOWNBURSTS AND POTENTIALLY DAMAGING WIND GUSTS MAY
   NOT BE COMPLETELY OUT OF THE QUESTION IN STRONGER STORMS.
   
   ..KERR/HART.. 08/10/2012
   
   
   ATTN...WFO...RNK...RLX...MRX...JKL...LMK...OHX...HUN...
   
   LAT...LON   36568563 37748407 38128238 37818069 36418199 35088514
               34978745 35288796 36568563