MESOSCALE DISCUSSION 1604
   NWS STORM PREDICTION CENTER NORMAN OK
   0157 PM CDT WED JUL 13 2011
   
   AREAS AFFECTED...PORTIONS OF AR TO NORTHERN MS
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 131857Z - 132030Z
   
   AT LEAST ISOLATED SEVERE TSTMS CAPABLE OF WIND DAMAGE/PERHAPS
   MARGINALLY SEVERE HAIL AND LOCALLY HEAVY RAINFALL ARE EXPECTED TO
   INCREASE THIS AFTERNOON ACROSS CENTRAL/SOUTHERN AR...INTO NORTHERN
   MS. THE NEED FOR A SEVERE TSTM WATCH IS UNCERTAIN...BUT TRENDS WILL
   CONTINUE TO BE MONITORED.
   
   IMMEDIATELY AHEAD OF A SLOW-MOVING/WEAK MID-LEVEL IMPULSE AS PER
   SATELLITE IMAGERY...A FEW SURFACE BASED/STRONG TSTMS ARE NOTED ALONG
   THE OK/AR BORDER REGION NEAR-SOUTH OF I-40 AS OF 1845Z. TO THE
   EAST...TOWERING CU IS EVIDENT IN VICINITY OF A WNW-ESE ARCING
   OUTFLOW BOUNDARY WHERE THE AIRMASS CONTINUES TO AGGRESSIVELY
   DESTABILIZE WITH MLCAPE NOW ESTIMATED TO BE ON THE ORDER OF
   3000-3500 J/KG ACROSS CENTRAL/SOUTHERN AR INTO MS. VERTICAL SHEAR IS
   RELATIVELY WEAK /25 KT OR LESS/ AS PER REGIONAL DERIVED WINDS...BUT
   THE AFOREMENTIONED MID-LEVEL IMPULSE AND STRONG DESTABILIZATION AND
   WEAK CINH SHOULD YIELD AN INCREASE IN STRONG/SEVERE TSTMS CAPABLE OF
   DOWNBURSTS AS WELL AS LOCALLY HEAVY RAINFALL AND PERHAPS SOME HAIL
   THIS AFTERNOON.
   
   ..GUYER.. 07/13/2011
   
   
   ATTN...WFO...MEG...JAN...LZK...SHV...TSA...
   
   LAT...LON   33979401 35339450 35629369 35239264 34819120 34579052
               33239059 33099216 33979401