MESOSCALE DISCUSSION 0643
   NWS STORM PREDICTION CENTER NORMAN OK
   0259 PM CDT WED MAY 15 2013
   
   AREAS AFFECTED...MUCH OF NWRN TX
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 151959Z - 152130Z
   
   PROBABILITY OF WATCH ISSUANCE...80 PERCENT
   
   SUMMARY...ADDITIONAL STORMS EXPECTED TO FORM OVER NWRN TX...AND
   POSSIBLY EXTENDING SWD ALONG THE DRYLINE LATER THIS AFTERNOON. VERY
   LARGE HAIL IS LIKELY...WITH A DAMAGING WIND THREAT POSSIBLY
   MATERIALIZING LATE AFTERNOON/EVENING ACROSS N CNTRL TX.
   
   DISCUSSION...STORMS HAVE INCREASED IN INTENSITY AND COVERAGE JUST
   AHEAD OF THE UPPER LOW FROM SRN OK INTO FAR NRN TX...WHERE A MOIST
   AIR MASS EXISTS AND NO CAPPING. SOME OF THE INCREASE IN CORE
   INTENSITY CAN BE ATTRIBUTED TO STEEPER MIDLEVEL LAPSE RATES AS WELL
   AS AREAS OF HEATING UPSTREAM. THESE STORMS WILL CONTINUE TO HAVE A
   MARGINAL HAIL THREAT...AS DEEP SHEAR PROFILES ARE MARGINAL FOR
   SUPERCELLS WITH 25-30 KT.
   
   VISIBLE IMAGERY SHOWS CU FIELDS INCREASING ACROSS NWRN TX...AND
   EXTENDING SWD TO THE EDWARDS PLATEAU WHERE STRONG HEATING HAS
   STEEPENED LAPSE RATES BENEATH COOL MIDLEVEL AIR. HIGH BASED
   CONVECTION WAS NOTED OVER THE TX S PLAINS...INDICATIVE OF THE VERY
   STEEP MIDLEVEL LAPSE RATES. AS THIS ACTIVITY CONTINUES E...IT WILL
   INTERSECT THE STRONGER INSTABILITY AND MOISTURE. OTHER CELLS ARE
   ALSO EXPECTED TO FORM OVER NWRN TX AS HEATING PERSISTS. NWLY FLOW
   ALOFT ATOP SURFACE SELYS WILL PROVIDE AMPLE SHEAR FOR
   SUPERCELLS...WHILE LARGE UPDRAFT ACCELERATION AIDS IN THE
   DEVELOPMENT OF LARGE DAMAGING HAIL.
   
   CONGEALING OUTFLOWS WITH TIME SHOULD CAUSE STORMS TO MERGE INTO ONE
   OR MORE MCS/S...POSSIBLY FORWARD PROPAGATING INTO THE METROPLEX AREA
   LATER TODAY WITH BOTH HAIL AND DAMAGING WINDS. 
   
   ANY STORMS THAT FORM FARTHER E NEAR THE I-35 CORRIDOR MAY HAVE A
   BRIEF TORNADO THREAT...WHILE PROPENSITY FOR MERGING OUTFLOWS WITH
   HIGHER BASED ACTIVITY TO THE W WILL FAVOR WIND AND HAIL.
   
   ..JEWELL/CARBIN.. 05/15/2013
   
   
   ATTN...WFO...FWD...OUN...SJT...LUB...MAF...
   
   LAT...LON   31100043 31160073 31450103 31940076 32580046 33200030
               33870017 34339968 34399961 35039680 35049625 34819611
               34569612 32769663 32439669 31839727 31529789 31100043