MESOSCALE DISCUSSION 0430
   NWS STORM PREDICTION CENTER NORMAN OK
   0836 PM CDT THU APR 14 2011
   
   AREAS AFFECTED...ERN OK/FAR NERN TX
   
   CONCERNING...TORNADO WATCH 135...
   
   VALID 150136Z - 150300Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 135 CONTINUES.
   
   THE THREAT FOR SEVERE THUNDERSTORMS AND TORNADOES WILL LIKELY
   PERSIST BEYOND THE EXPIRATION TIME OF 03Z ACROSS SERN AND E-CNTRL OK
   AND FAR NERN TX. IN THESE AREAS...A NEW TORNADO WATCH WILL BE
   NEEDED.
   
   EARLY EVENING SFC ANALYSIS INDICATES THAT THE COLD FRONT HAD
   OVERTAKEN THE DRYLINE ACROSS NRN OK...AND EXTENDED FROM NRN OSAGE
   COUNTY TO THE INTERSECTION OF THE DRYLINE JUST SE OF THE OKC METRO
   AREA. THE DRYLINE EXTENDED FARTHER S-SW FROM THIS JUNCTURE TO THE
   RED RIVER NEAR INTERSTATE 35 AND INTO N-CNTRL TX. AS THE COLD FRONT
   CONTINUES TO ACCELERATE EWD ACROSS NERN OK...THE SEVERE THREAT WILL
   LIKELY HAVE SHIFTED INTO NWRN AR BY 03Z. HOWEVER...GIVEN THE NE-SW
   ORIENTATION OF THE OVERTAKING COLD FRONT...THE WARM/UNSTABLE SECTOR
   FEATURING MLCAPE VALUES OF 1500-2500 J/KG WILL PERSIST ACROSS
   SERN/E-CNTRL OK PAST 03Z. THIS AMOUNT OF INSTABILITY...JUXTAPOSED
   WITH EFFECTIVE STORM-RELATIVE HELICITY VALUES OF 200-400 M2/S2
   /NOTABLY INCREASING/...WILL SUPPORT PERSISTENCE OF THE DISCRETE AND
   SEMI-DISCRETE SUPERCELL MODE WITH AN ATTENDANT THREAT FOR
   TORNADOES...DAMAGING WINDS...AND LARGE HAIL. THE THREAT FOR STRONG
   TORNADOES WILL CONTINUE OVER THE NEXT FEW HOURS WITH THE MOST
   DISCRETE CONVECTION AND UNDISTURBED INFLOW -- I.E. ACROSS THE SRN
   TWO TIERS OF COUNTIES OF SERN OK AND ADJACENT COUNTIES OF FAR NERN
   TX.
   
   ..COHEN.. 04/15/2011
   
   
   ATTN...WFO...SHV...TSA...FWD...OUN...
   
   LAT...LON   33869728 33619513 34559449 36459472 36669580 33869728