MESOSCALE DISCUSSION 0275
   NWS STORM PREDICTION CENTER NORMAN OK
   0740 AM CDT MON MAR 18 2013
   
   AREAS AFFECTED...WESTERN/MIDDLE TN AND SOUTHERN KY TO FAR NORTHERN
   MS/AL
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 181240Z - 181445Z
   
   PROBABILITY OF WATCH ISSUANCE...40 PERCENT
   
   SUMMARY...AT LEAST AN ISOLATED SEVERE POTENTIAL APPEARS TO BE
   INCREASING ACROSS WEST-CENTRAL TN THIS MORNING AND PERHAPS ADJACENT
   PORTIONS OF SOUTHERN KY AND/OR NORTHERN MS/AL. BOUTS OF DAMAGING
   WINDS/SOME HAIL WILL BE POSSIBLE. CONVECTIVE TRENDS ARE BEING
   MONITORED FOR A POSSIBLE WATCH.
   
   DISCUSSION...PERSISTENT /INITIALLY ELEVATED/ TSTMS HAVE SHOWN SIGNS
   OF INCREASING INTENSITY/LINEAR ORGANIZATION OVER THE PAST HALF HOUR
   /SINCE 12Z/ ACROSS WEST-CENTRAL TN. THESE TRENDS ARE COINCIDENT WITH
   THE APPARENT EVOLUTION/EXPANSION OF A SURFACE COLD POOL...WITH AN
   INFLUX OF LOW LEVEL MOISTURE /UPPER 50S F SURFACE DEWPOINTS/
   CONTINUING TO SPREAD NORTHEASTWARD INTO MIDDLE TN VIA A VERY STRONG
   SOUTH-SOUTHWESTERLY LOW LEVEL JET. ALTHOUGH AN INITIALLY WEAK
   BUOYANCY ENVIRONMENT /MLCAPE OF ONLY A FEW HUNDRED J PER KG/...THE
   12Z OBSERVED SOUNDING FROM NASHVILLE FEATURED A RELATIVELY STEEP
   LAPSE RATE PROFILE WITH STRONG VERTICAL SHEAR /40+ KT/...ACCENTUATED
   BY 50+ KT WINDS WITHIN THE LOWEST 1 KM. WHILE THE EXTENT OF THE
   SEVERE RISK IS A BIT UNCERTAIN IN THE SHORT TERM...SCENARIO MAY
   REMAIN CONDUCIVE FOR LINEAR ORGANIZATION/BOWING SEGMENTS WITH AT
   LEAST SOME DAMAGING WIND POTENTIAL ESPECIALLY AS THE BOUNDARY LAYER
   CONTINUES TO MOISTEN/WARM.
   
   ..GUYER/EDWARDS.. 03/18/2013
   
   
   ATTN...WFO...MRX...JKL...LMK...OHX...HUN...MEG...
   
   LAT...LON   34738932 35848839 36618701 37268491 36748462 34768661
               34738932