MESOSCALE DISCUSSION 0426
   NWS STORM PREDICTION CENTER NORMAN OK
   0521 PM CDT THU APR 14 2011
   
   AREAS AFFECTED...ERN HALF OF OK / PARTS OF N-CNTRL AND NERN TX
   
   CONCERNING...TORNADO WATCH 135...
   
   VALID 142221Z - 142315Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 135 CONTINUES.
   
   A DRYLINE EXTENDS FROM THE KS/OK BORDER 20 NNE OF PNC TO 25 SE OF
   OKC TO THE RED RIVER 25 WSW OF ADM AND FARTHER S-SW INTO N-CNTRL TX.
   THE ARCING LINE OF SEMI-DISCRETE SUPERCELLS THAT INITIATED ALONG THE
   DRYLINE CONTINUES TO SHIFT EWD TOWARD ERN OK...AND WILL CONTINUE TO
   DO SO DURING THE NEXT FEW HOURS GIVEN EFFECTIVE BULK SHEAR VECTORS
   ORTHOGONAL TO THE DRYLINE WITH MAGNITUDES OF 45 TO 60 KT. THIS
   DEGREE OF DEEP-LAYER WIND SHEAR WILL MAINTAIN THE SUPERCELL THREAT
   AS STORMS APPROACH THE TULSA AND MCALESTER AREAS THROUGH 2330Z WHILE
   TRAVERSING MLCAPE VALUES OF 2000-2500 J/KG. EFFECTIVE SRH VALUES OF
   100-200 M2/S2 SUPPORT A TORNADO THREAT ANY SUSTAINED SUPERCELLS.
   THIS THREAT WILL FURTHER INCREASE INTO THE EVENING...ALONG WITH THE
   THREAT FOR STRONG TORNADOES...AS EFFECTIVE SRH VALUES INCREASE PER
   THE LATEST RUC GUIDANCE. THE GREATEST THREAT FOR STRONG TORNADOES
   WILL BE ACROSS SERN OK INTO FAR NERN TX THROUGH 00Z...WHERE SFC-3 KM
   CAPE VALUES FROM 100-150 J/KG WILL PROVIDE ENHANCED LOW-LEVEL
   BUOYANCY TO THE RELATIVELY MORE DISCRETE CONVECTION /COMPARED TO
   FARTHER NORTH/.
   
   FARTHER SOUTH ALONG THE DRYLINE...CONVECTION IS INITIATING ACROSS
   PORTIONS OF N-CNTRL TX TO THE NORTH OF THE DFW AREA. GIVEN THE
   DEGREE OF POTENTIAL INSTABILITY AND DEEP-LAYER WIND SHEAR...THESE
   STORMS COULD EVENTUALLY POSE A THREAT FOR LARGE HAIL. THERE WILL
   ALSO BE A THREAT FOR A TORNADO GIVEN THE VEERING WIND PROFILE
   EVIDENT IN THE SFC-2-KM LAYER PER THE NEARBY FORT WORTH VWP.
   THUS...THE TORNADO WATCH MAY NEED TO BE EXTENDED FARTHER SOUTH BY
   ONE TIER OF COUNTIES IN NERN TX IF STORMS FURTHER INTENSIFY.
   
   LATEST RUC GUIDANCE IS SUGGESTING THAT THE DRYLINE WILL REMAIN
   STATIONARY INTO EARLY EVENING ACROSS CNTRL/SRN OK...AND POTENTIALLY
   BE NUDGED WWD A BIT. THIS MAY SERVE TO FOCUS ANOTHER ATTEMPT AT
   CONVECTIVE INITIATION AFTER 00Z AS AN AREA OF DEEP-LAYER ASCENT
   APPROACHES. THIS IS SUPPORTED BY THE LATEST EXPERIMENTAL HRRR
   GUIDANCE...AND THESE TRENDS WILL CONTINUE TO BE MONITORED FOR A
   PERSISTENT SEVERE THREAT INTO THE EVENING ACROSS THE WRN PORTIONS OF
   THE WATCH.
   
   ..COHEN.. 04/14/2011
   
   
   ATTN...WFO...SHV...TSA...FWD...OUN...
   
   LAT...LON   33989751 34699722 36069688 36889678 36829513 36279469
               34199463 33239529 33059749 33989751