MESOSCALE DISCUSSION 0179
   NWS STORM PREDICTION CENTER NORMAN OK
   1052 PM CST WED FEB 20 2013
   
   AREAS AFFECTED...PARTS OF WEST CENTRAL THROUGH NW TX AND SWRN OK
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 210452Z - 210645Z
   
   PROBABILITY OF WATCH ISSUANCE...40 PERCENT
   
   SUMMARY...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY
   THROUGH THE LATE EVENING INTO THE EARLY OVERNIGHT HOURS...INITIALLY
   ACROSS WEST CENTRAL TX...AND THEN DEVELOPING/SPREADING E/NEWD ACROSS
   NW TX TO SW-SRN OK. HAIL WILL BE THE GREATEST THREAT...GIVEN THAT
   THIS ACTIVITY WILL TEND TO REMAIN ELEVATED.
   
   DISCUSSION...TRENDS IN WIND PROFILER DATA AT JAYTON TX AND
   SURROUNDING WSR-88D VWP DATA ACROSS THE WRN HALF OF TX HAVE
   INDICATED AN INCREASE IN A SSELY LLJ /UP TO 50 KT/. THIS IS
   RESULTING IN INCREASING LOW LEVEL MOISTURE RETURN AND WAA NORTH OF A
   SURFACE WARM FRONT WHICH EXTENDED EWD FROM AN AREA OF LOW PRESSURE
   LOCATED ALONG THE BORDER OF SRN WARD/ERN REEVES COUNTIES TX THROUGH
   THE VICINITY OF KAUS TO KHOU. TWO PARALLEL NNE-SSW ORIENTED BANDS OF
   TSTMS IN WEST CENTRAL TX TO FAR SERN NM PER REGIONAL RADAR IMAGERY
   APPEAR TO BE DELINEATING THE LEADING EDGE OF DEEP LAYER FORCING...
   BEGINNING TO SPREAD INTO W/NW TX AHEAD OF THE POWERFUL SWRN STATES
   UPPER LEVEL LOW AND INTERCEPTING THE NWWD EXTENT OF THE MOISTURE
   RETURN. AT 04Z...OBJECTIVE ANALYSES SHOWED MUCAPE RANGING FROM
   500-1000 J/KG FROM N-S ALONG THE LEADING BAND OF CONVECTION. THE
   RECENT 00Z RUNS OF THE 4 KM WRF-NMM/NSSL WRF-ARW EACH SUGGEST THE
   ERN MOST BAND OF STORMS BECOMES THE PRIMARY ONE WITH A FAIRLY RAPID
   INCREASE IN NWD AND SWD DEVELOPMENT BETWEEN 06-09Z INTO PARTS OF
   CENTRAL AND NORTH CENTRAL TX TO CENTRAL OK. THIS MARKED INCREASE IN
   STORM COVERAGE IS LIKELY DUE TO THE GREATER ASCENT SPREADING ENEWD
   INTO THE SRN PLAINS AND AS LOW LEVEL WAA INCREASES ALONG A FURTHER
   STRENGTHENING SLY LLJ INTO NW-N CENTRAL TX TO CENTRAL OK. EFFECTIVE
   BULK SHEAR OF 40-70 KT IS ALREADY MORE THAN SUFFICIENT TO SUPPORT
   STORM ORGANIZATION/ROTATING UPDRAFTS.
   
   THE INITIAL MARGINAL ELEVATED INSTABILITY MAY TEND TO LIMIT THE
   COVERAGE OF STRONGER...SUSTAINED STORMS AND THUS RESULTS IN A LOWER
   PROBABILITY FOR WATCH ISSUANCE AT THIS TIME. GREATER CONCERN FOR AN
   INCREASED THREAT FOR LARGE HAIL MAY NOT OCCUR UNTIL AROUND 09Z. AT
   THAT TIME...STRONGER ASCENT...GREATER MIDLEVEL COOLING AND A FURTHER
   INCREASE IN LOW LEVEL MOISTURE/WARM AIR ADVECTION WILL BE UNDERWAY
   INTO NW-NORTH CENTRAL TX AND SRN OK SUGGESTING A WATCH COULD BE
   NEEDED DURING THE OVERNIGHT PERIOD.
   
   ..PETERS/MEAD.. 02/21/2013
   
   
   ATTN...WFO...FWD...OUN...SJT...LUB...AMA...MAF...
   
   LAT...LON   34160082 34800016 34869914 34559774 33419779 31879836
               31539998 32030168 32480146 34160082