MESOSCALE DISCUSSION 1680
   NWS STORM PREDICTION CENTER NORMAN OK
   0525 PM CDT THU JUL 21 2011
   
   AREAS AFFECTED...WRN TN...SWRN KY...FAR NRN MS
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 212225Z - 220030Z
   
   THE BROKEN SQUALL LINE OVER PORTIONS OF TN/KY COULD POSE A THREAT
   FOR STRONG WIND GUSTS INTO THIS EVENING AS IT APPROACHES THE MS
   RIVER. WHILE CONVECTIVE TRENDS WILL BE MONITORED...THE OVERALL LACK
   OF CONVECTIVE ORGANIZATION WILL LIKELY PRECLUDE THE NEED FOR A WW.
   
   A BROKEN CONVECTIVE LINE AND TRAILING STRATIFORM REGION ARE MOVING
   WWD ACROSS PORTIONS OF THE TN VALLEY AND LOWER OHIO VALLEY
   REGION...WITH MEAN STORM MOTIONS OF 15 TO 20 KT. SFC MESOANALYSIS
   DEPICTS A WELL-DEFINED COLD POOL OVER MIDDLE TN WITH AN ATTENDANT
   MESOHIGH AND SFC PRESSURE RISES AROUND 2 MB IN 2 HOURS. DOWNSTREAM
   OF ONGOING CONVECTION...THE MESOSCALE ENVIRONMENT IS CHARACTERIZED
   BY UNCAPPED MLCAPE VALUES OF 2000-2500 J/KG AND PWAT VALUES OF 2.0
   TO 2.3 INCHES. CONVERGENCE AT THE LEADING EDGE OF THE WWD-EXPANDING
   COLD POOL JUXTAPOSED WITH THE AFOREMENTIONED THERMODYNAMIC
   PARAMETERS WILL FOSTER CONTINUED WWD CONVECTIVE PROPAGATION INTO THE
   LATE AFTERNOON AND EARLY EVENING AS CONVECTION REGENERATES
   DOWNSTREAM. DCAPE VALUES IN EXCESS OF 1000 J/KG IN MANY AREAS WILL
   SUPPORT STRONG DOWNDRAFTS AND THE POTENTIAL FOR STRONG OR POSSIBLY
   DMGG SFC WINDS...WITH THE THREAT ENHANCED BY THE MESOSCALE
   CIRCULATION ATTENDANT TO THE CONVECTIVE SYSTEM. AFFIRMING THIS
   POTENTIAL...AN EARLIER GUST TO 64 KT WAS MEASURED AT BOWLING GREEN
   KY IN ASSOCIATION WITH MORE CELLULAR CONVECTION OVER THE NRN FLANK
   OF THE SYSTEM. HOWEVER...MEMPHIS VWP DATA INDICATE WEAK VERTICAL
   WIND SHEAR DOWNSTREAM OF ONGOING ACTIVITY...WHICH WILL LIKELY
   INHIBIT THE POTENTIAL FOR SUSTENANCE OF A MORE ORGANIZED CONVECTIVE
   SYSTEM AND ATTENDANT SVR THREAT. AFTER 01Z...STABILIZATION OWING TO
   NOCTURNAL COOLING WITHIN THE BOUNDARY LAYER WILL LIKELY RESULT IN A
   DECREASING TREND OF ANY ONGOING CONVECTION.
   
   ..COHEN.. 07/21/2011
   
   
   ATTN...WFO...OHX...PAH...MEG...
   
   LAT...LON   36408937 36898890 37058830 37108763 36808737 36338777
               35838804 35128821 34668853 34508952 34869013 35568987
               36408937