SPC AC 131248

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0748 AM CDT SUN APR 13 2014

   VALID 131300Z - 141200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS THROUGH TONIGHT FROM ERN KS/OK
   AND NE TX EWD TO THE MS VALLEY...

   ...ERN KS TO CENTRAL/ERN OK AND AR THIS AFTERNOON INTO TONIGHT...
   THE INITIAL SRN STREAM SHORTWAVE TROUGH OVER THE SRN HIGH PLAINS
   WILL EJECT ENEWD OVER N TX/OK/KS TODAY...REACHING MO/AR BY EARLY
   TONIGHT AS AN UPSTREAM WAVE DIGS SEWD TO THE FOUR CORNERS.  AT THE
   SURFACE...THE REMNANTS OF A LEE CYCLONE IN SW KS THIS MORNING WILL
   WEAKEN DURING THE DAY AND MOVE NEWD TO NW MO BY MID AFTERNOON...AND
   CONTINUE ACROSS NRN IL TO LOWER MI OVERNIGHT.  IN THE WAKE OF THE
   LOW...A COLD FRONT WILL ACCELERATE SEWD ACROSS KS INTO NRN AND WRN
   OK THROUGH THE AFTERNOON.  WIDESPREAD CLOUDS WILL DISRUPT SURFACE
   HEATING AND LAPSE RATES ALOFT...ASIDE FROM A NARROW CORRIDOR ALONG
   THE COLD FRONT BY EARLY-MID AFTERNOON.  BOUNDARY LAYER DEWPOINTS IN
   THE LOWER 60S ARE EXPECTED BENEATH LINGERING STEEP MIDLEVEL LAPSE
   RATES...WITH MLCAPE VALUES EXPECTED TO REACH 1500-2000 J/KG.  

   THE STRONGEST LOW-LEVEL ASCENT WILL BE ALONG THE COLD FRONT TO THE
   NE OF THE DRYLINE-COLD FRONT TRIPLE POINT...WHICH WILL COINCIDE WITH
   RATHER MODEST EFFECTIVE BULK SHEAR AND DEEP-LAYER FLOW/SHEAR VECTORS
   LARGELY PARALLEL TO THE FRONT.  THUS...ANY SUPERCELL STRUCTURES WILL
   TEND TO BE RATHER SHORT-LIVED WELL NE OF THE TRIPLE POINT
   /ESPECIALLY IN KS/ AND STORMS WILL LIKELY EVOLVE INTO A LINE ALONG
   THE COLD FRONT.  THE LINE OF STORMS WILL PERSIST INTO TONIGHT WITH A
   RISK FOR LARGE HAIL AND DAMAGING GUSTS AS CONVECTION SPREADS
   EWD/SEWD FROM SE KS/ERN OK TO AR.  MEANWHILE ...VERTICAL SHEAR WILL
   BE STRONGER IN PROXIMITY TO THE TRIPLE POINT...WHERE THE POTENTIAL
   EXISTS FOR AN ANCHOR SUPERCELL CAPABLE OF PRODUCING VERY LARGE HAIL
   AND A TORNADO OR TWO THIS AFTERNOON/EVENING.

   ...N CENTRAL TX THIS AFTERNOON/EVENING...
   THE LEAD SHORTWAVE TROUGH WILL PRODUCE WIDESPREAD MID-HIGH CLOUDS
   AND SOME LIGHT RAINFALL THE FIRST HALF OF THE DAY FROM CENTRAL/N TX
   INTO SE OK...WHICH WILL SLOW DAYTIME HEATING AND LEAVE POOR LAPSE
   RATES ALOFT WITHIN THE CLOUD BAND.  LAPSE RATES ALOFT WILL STEEPEN
   AND SURFACE HEATING WILL INCREASE IN THE WAKE OF THE MORNING-EARLY
   AFTERNOON CLOUDS...WITH MLCAPE STILL POTENTIALLY INCREASING TO 2000
   J/KG BY LATE AFTERNOON.  HOWEVER...THE LEAD SHORTWAVE TROUGH COULD
   PASS N TX BY MID AFTERNOON...LEAVING WEAK HEIGHT RISES IN ITS WAKE. 
   THUS...THUNDERSTORM DEVELOPMENT WILL DEPEND ON SOMEWHAT MARGINAL
   LOW-LEVEL CONVERGENCE ALONG THE QUASI-STATIONARY DRYLINE FROM
   21-00Z...AND SUFFICIENT RECOVERY FROM THE MORNING CLOUDS.  A
   CONDITIONAL RISK FOR VERY LARGE HAIL AND A TORNADO OR TWO PERSISTS
   GIVEN FAVORABLE FORECAST BUOYANCY AND WIND PROFILES...THOUGH STORM
   COVERAGE IS THE PRIMARY QUESTION S OF THE TRIPLE POINT AND NW OF THE
   EARLY CONVECTIVE BAND.

   ...NRN MO/SRN IA TO W CENTRAL IL THIS MORNING...
   ELEVATED CONVECTION WILL PERSIST THROUGH THE MORNING...ALONG THE
   SURFACE FRONT AND REMNANT CONVECTIVE OUTFLOWS.  RESIDUAL STEEP
   MIDLEVEL LAPSE RATES AND MUCAPE AOA 1500 J/KG /PER THE 12Z TOP
   SOUNDING/ WILL SUPPORT ISOLATED LARGE HAIL PRODUCTION FOR THE NEXT
   SEVERAL HOURS.  REFER TO MD 332 FOR ADDITIONAL INFORMATION.

   ...NE TX TO AR TODAY...
   MOST NUMERICAL GUIDANCE IS CONSISTENT IN DEVELOPING A BROKEN BAND OF
   INITIALLY ELEVATED CONVECTION IN THE WARM SECTOR...AS
   ASCENT/MOISTENING WEAKEN THE CAP WITHIN THE THICK BAND OF
   CLOUDS/SHOWERS PRECEDING THE EJECTING SRN STREAM SHORTWAVE TROUGH. 
   WIND PROFILES WILL BECOME FAVORABLE FOR SUPERCELLS...AND IF
   SUFFICIENT SURFACE WARMING AND MOISTENING OCCURS IMMEDIATELY IN
   ADVANCE OF THE BAND...EMBEDDED ROTATING STORMS WILL BE POSSIBLE.

   ...LOWER MS VALLEY OVERNIGHT...
   A SURGE OF RICHER MOISTURE/HIGHER PW FROM THE WRN GULF OF MEXICO
   WILL SPREAD INLAND TONIGHT OVER LA/MS.  CLUSTERS OF THUNDERSTORMS
   ARE EXPECTED TO FORM ON THE LEADING EDGE OF THE SURGE IN ASSOCIATION
   WITH LOW-LEVEL WAA ALONG THE SRN EXTENT OF A 40-50 KT SSWLY LLJ. 
   THE INCREASE IN MOISTURE WILL SUPPORT STORMS ROOTED VERY NEAR THE
   GROUND...IN AN ENVIRONMENT OF AT LEAST WEAK SURFACE-BASED BUOYANCY
   AND SUFFICIENT HODOGRAPH CURVATURE AND DEEP-LAYER SHEAR FOR EMBEDDED
   SUPERCELLS.  THESE FACTORS WILL RESULT IN A RISK FOR AT LEAST
   ISOLATED DAMAGING GUSTS AND A TORNADO OR TWO FROM CENTRAL/NE LA INTO
   CENTRAL MS...MAINLY 06-12Z.

   ..THOMPSON/DEAN.. 04/13/2014

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z