MESOSCALE DISCUSSION 0171
   NWS STORM PREDICTION CENTER NORMAN OK
   0559 PM CST MON FEB 18 2013
   
   AREAS AFFECTED...NERN TX...CNTRL THROUGH SWRN AR AND NWRN LA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 36...
   
   VALID 182359Z - 190130Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 36
   CONTINUES.
   
   SUMMARY...GREATEST SEVERE THREAT THROUGH ABOUT 02Z WILL EXIST FROM
   NERN TX THROUGH NWRN LA INTO SWRN AND SCNTRL AR. ISOLATED LARGE HAIL
   AND DAMAGING WIND ARE THE PRIMARY THREATS IN THIS AREA...BUT A
   COUPLE TORNADOES ARE ALSO POSSIBLE. COUNTIES CAN CONTINUE TO BE
   ADDED ONTO THE SRN PORTIONS OF WW 36 AS NECESSARY AS RIGHT MOVING
   STORMS ADVANCE SEWD.
   
   DISCUSSION...DISCRETE STORM MODES PERSIST IN A RELATIVELY SMALL AREA
   FROM NERN TX...NWRN LA AND SWRN AR. THESE STORMS ALSO EXIST IN THE
   MOST FAVORABLE PARAMETER SPACE OF SHEAR AND INSTABILITY ALONG THE
   NRN END OF THE THETA-E AXIS. LOW LEVEL HODOGRAPHS AND STORM MOTION
   ARE SUPPORTING 200-250 M2/S2 0-1 KM STORM RELATIVE HELICITY IN THIS
   AREA. INSTABILITY REMAINS MARGINAL WITH MLCAPE AOB 800 J/KG AND HAS
   BEEN THE PRIMARY LIMITING FACTOR FOR A MORE ROBUST SEVERE THREAT.
   NEVERTHELESS...GIVEN FAVORABLE LOW LEVEL SHEAR AND DISCRETE STORM
   MODES...THREAT FOR A COUPLE TORNADOES REMAIN POSSIBLE THROUGH 02Z
   BEFORE ACTIVITY BEGINS TO MOVE INTO A MORE STABLE BOUNDARY LAYER AND
   BEFORE SIGNIFICANT NOCTURNAL COOLING OCCURS. OTHERWISE...STORMS WILL
   REMAIN CAPABLE OF PRODUCING LARGE HAIL AND ISOLATED DAMAGING WIND IN
   THE REMAINDER OF WW 36 NEXT COUPLE HOURS.
   
   ..DIAL.. 02/18/2013
   
   
   ATTN...WFO...LZK...SHV...
   
   LAT...LON   32949432 33399352 34439214 35609136 35129125 34109177
               33149220 31999266 31209396 31679514 32949432