MESOSCALE DISCUSSION 1693
   NWS STORM PREDICTION CENTER NORMAN OK
   0459 PM CDT FRI JUL 22 2011
   
   AREAS AFFECTED...SRN/CNTRL WV...FAR SRN OH...ERN KY...WRN VA...FAR
   NWRN NC...FAR NERN TN
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 222159Z - 230000Z
   
   A FEW PULSE STORMS COULD POSE A THREAT FOR DMGG WIND GUSTS INTO THE
   LATE AFTERNOON AND EARLY EVENING HOURS. HOWEVER...THE DISORGANIZED
   NATURE OF THE CONVECTION WILL LIKELY KEEP THE SVR THREAT ISOLATED
   AND PRECLUDE THE ISSUANCE OF A WW.
   
   WITH THE COMBINATION OF PRECONVECTIVE SFC TEMPERATURES IN THE LOWER
   90S AND DEWPOINTS IN THE LOWER/MIDDLE 70S...A MODERATELY TO VERY
   UNSTABLE AIR MASS HAS DEVELOPED ACROSS PORTIONS OF THE CNTRL/SRN
   APPALACHIANS AND OH/TN VALLEY REGION. THE LACK OF MLCINH AND THE
   PRESENCE OF OROGRAPHIC FORCING HAVE FOSTERED THE DEVELOPMENT OF
   ISOLATED TO WIDELY SCATTERED CONVECTION ACROSS THE DISCUSSION AREA.
   THE DEGREE OF INSTABILITY WILL CONTINUE TO SUPPORT VIGOROUS UPDRAFTS
   INTO EARLY THIS EVENING. WET MICROBURSTS WILL BE A CONCERN AS STORMS
   COLLAPSE...WITH DOWNWARD BUOYANCY ENHANCED BY THE PRESENCE OF STEEP
   LOW-LEVEL LAPSE RATES AND WATER LOADING PROCESSES OWING TO PWAT
   VALUES OF 1.8 TO 2.2 INCHES PER GPS DATA. DMGG WIND GUSTS MAY OCCUR
   ON AN ISOLATED BASIS...THOUGH VWP DATA DEPICT WEAK VERTICAL WIND
   SHEAR WHICH WILL MITIGATE THE THREAT FOR ORGANIZED CONVECTION.
   LOCALIZED RAINFALL RATES IN EXCESS OF 1 INCH PER HOUR WILL ALSO BE A
   THREAT...ESPECIALLY IN AREAS WHERE CONVECTION BECOMES ANCHORED BY
   LOCAL TERRAIN EFFECTS. AFTER 00Z...STABILIZATION DUE TO NOCTURNAL
   COOLING WILL LIKELY BE ASSOCIATED WITH A WEAKENING TREND IN ONGOING
   CONVECTION.
   
   ..COHEN.. 07/22/2011
   
   
   ATTN...WFO...RNK...RLX...GSP...MRX...JKL...ILN...
   
   LAT...LON   36078189 36518349 37788395 38808293 39008140 38798041
               37997978 37287963 36358028 36078189