MESOSCALE DISCUSSION 0120
   NWS STORM PREDICTION CENTER NORMAN OK
   1114 AM CST WED FEB 18 2009
   
   AREAS AFFECTED...PORTIONS OF NERN AND CNTRL MS INTO NWRN AND W-CNTRL
   AL
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 181714Z - 181845Z
   
   THE POTENTIAL FOR SEVERE STORMS CAPABLE OF LARGE HAIL...DAMAGING
   WINDS AND PERHAPS A FEW TORNADOES IS EXPECTED TO INCREASE THIS
   AFTERNOON.  CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.
   
   LATEST TRENDS IN VISIBLE SATELLITE IMAGERY INDICATE DEEPENING
   CUMULUS BANDS ORIENTED WSW-ENE WITHIN PRE-FRONTAL WARM SECTOR FROM W
   OF THE I-65 CORRIDOR IN MIDDLE TN SWWD INTO CNTRL MS.  WHILE
   BOUNDARY LAYER IS NOT OVERLY MOIST /DEWPOINTS IN THE UPPER 50S TO
   LOWER 60S/...STRONG DAYTIME HEATING IS CONTRIBUTING TO THE
   DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES AND RESULTANT MLCAPE OF
   AROUND 500 J/KG.  OF CONCERN TO STORM INITIATION ARE: 1/ WEAK
   CONVERGENCE ALONG COLD FRONT...AND 2/ INFERRED MIDLEVEL SUBSIDENCE
   AND RESULTING POOR MIDLEVEL LAPSE RATES PER WATER VAPOR IMAGERY AND
   RUC OBJECTIVE FIELDS.  THUS...CONSIDERABLE UNCERTAINTY EXISTS WITH
   REGARD TO THE TIMING AND LOCATION OF ANY ADDITIONAL STORM
   DEVELOPMENT TO THE S OF ONGOING STORMS OVER S-CNTRL KY INTO MIDDLE
   TN.  
   
   ONCE STORMS DEVELOP AND BECOME SUSTAINED...THE PRESENCE OF 60-70 KT
   DEEP LAYER SHEAR AND LONG...STRAIGHT HODOGRAPHS WILL SUPPORT
   SUPERCELL DEVELOPMENT /SOME SPLITTING/ WITH THE THREAT FOR DAMAGING
   WINDS...LARGE HAIL AND PERHAPS A FEW TORNADOES.
   
   ..MEAD.. 02/18/2009
   
   
   ATTN...WFO...BMX...HUN...MEG...JAN...
   
   LAT...LON   33089017 34888846 34888765 34908725 34738701 33778701
               32488803 32398986 33089017