MESOSCALE DISCUSSION 0762
   NWS STORM PREDICTION CENTER NORMAN OK
   0623 PM CDT TUE MAY 21 2013
   
   AREAS AFFECTED...WRN-MIDDLE TN / FAR NWRN AL / NRN MS / FAR SERN AR
   
   CONCERNING...TORNADO WATCH 207...
   
   VALID 212323Z - 220030Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 207 CONTINUES.
   
   SUMMARY...ISOLD POCKETS OF WIND DAMAGE APPEAR TO BE THE MAIN THREAT.
    TORNADO POTENTIAL WILL LIKELY REMAIN LIMITED BASED ON LINEAR
   CONVECTIVE MODE.
   
   DISCUSSION...RADAR MOSAIC SHOWS AN ORGANIZED QLCS FROM FAR SRN IL
   SWD TO E OF THE GREATER MEMPHIS METRO SWWD INTO SERN AR.  THE NRN
   PORTION OF THE QLCS FROM NEAR MEM NWD INTO WRN KY REMAINS LARGELY
   SUB-SEVERE AND SURFACE OBS OVER WRN TN SUPPORT THIS NOTION WITH ASOS
   GUSTS AT TIME OF QLCS PASSAGE REMAINING BELOW 30 KT.  SURFACE
   ANALYSIS SHOWS A LARGELY WEST-EAST ORIENTED OUTFLOW BOUNDARY
   EXTENDING FROM THE TRAILING PORTION OF THE SRN APPALACHIANS QLCS
   WESTWARD AND INTERSECTING THE QLCS 25 MI ESE MEM.  EARLIER IN THE
   DAY SUBSTANTIAL CONVECTIVE OVERTURNING OCCURRED N OF THIS BOUNDARY
   ACROSS WRN AND MIDDLE TN -- LIMITING THE MAGNITUDE OF
   DESTABILIZATION OCCURRING IN ITS WAKE.  CURRENT THINKING IS THE TN
   PORTION OF THE QLCS MAY ONLY POSE A LOW DAMAGING WIND THREAT.
   
   FARTHER S OVER NRN MS...A WARM/UNSTABLE AIRMASS AHEAD OF THIS
   CONVECTIVE LINE IS MORE FAVORABLE FOR ISOLD POCKETS OF WIND DAMAGE
   GIVEN THE STEEPER LOW LEVEL LAPSE RATES.  IT IS UNCERTAIN HOW FAR
   EAST THIS QLCS MAY POSE AN ISOLD DAMAGING WIND THREAT...ESPECIALLY
   SINCE THE BOUNDARY LAYER WILL BEGIN TO COOL BY THE TIME THE QLCS
   APPROACHES THE ERN EDGE OF THE WATCH NEAR THE NERN MS/NWRN AL
   BORDER.  ALTHOUGH A BRIEF TORNADO IS POSSIBLE NEAR THE OUTFLOW
   BOUNDARY-QLCS INTERSECTION...THIS THREAT WILL LIKELY REMAIN LIMITED
   BASED ON THE LINEAR CONVECTIVE MODE.
   
   ..SMITH.. 05/21/2013
   
   
   ATTN...WFO...OHX...BMX...HUN...MEG...JAN...LZK...
   
   LAT...LON   36478874 35098975 33489168 33019107 33018934 34268807
               35638754 36378760 36478874