SPC AC 071251

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0751 AM CDT THU MAY 07 2015

   VALID 071300Z - 081200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
   TONIGHT FOR NW TX ACROSS MUCH OF OK TO CENTRAL KS AND SE CO...

   ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE UPPER MS VALLEY TO THE
   CENTRAL AND SRN PLAINS...

   ...SUMMARY...
   ISOLATED TO SCATTERED SEVERE STORMS ARE POSSIBLE FROM THE UPPER
   MISSISSIPPI VALLEY TO THE SOUTHERN GREAT PLAINS...MAINLY THIS
   AFTERNOON AND EVENING.  THE MAIN THREAT AREA FOR VERY LARGE HAIL AND
   A FEW TORNADOES WILL BE ACROSS NORTHWEST TEXAS AND SOUTHWEST
   OKLAHOMA.

   ...SYNOPSIS...
   A LARGE-SCALE TROUGH IS ESTABLISHED OVER THE WRN HALF OF THE
   CONUS...WITH A DOWNSTREAM RIDGE OVER THE OH VALLEY/APPALACHIANS. 
   WITHIN THIS FLOW REGIME...ONE CLOSED LOW WILL MOVE SLOWLY SWD OVER
   CENTRAL CA THROUGH TONIGHT...WHILE ANOTHER SHORTWAVE TROUGH
   PROGRESSES NEWD FROM NEB/DAKOTAS TO THE UPPER MS VALLEY WHILE
   WEAKENING.  A COLD FRONT ASSOCIATED WITH THE EJECTING MIDLEVEL
   TROUGH WILL SAG SEWD ACROSS KS...AND MOVE EWD INTO MN/IA BY TONIGHT.
   A WEAK LEE CYCLONE/TROUGH WILL BE MAINTAINED ACROSS THE SRN HIGH
   PLAINS IN THE SWLY FLOW REGIME ALOFT.  THE EFFECTS OF OVERNIGHT AND
   MORNING CONVECTION WILL PLAY A PRIMARY ROLE IN MODULATING THE SEVERE
   WEATHER THREATS TODAY ACROSS THE CENTRAL/SRN PLAINS.

   ...OK/TX THROUGH TONIGHT...
   AN OUTFLOW BOUNDARY IS LOCATED ACROSS N CENTRAL/NW TX THIS MORNING. 
   THE ONGOING CONVECTION OVER THE RED RIVER VALLEY WILL HELP MAINTAIN
   THE COLD POOL THIS MORNING...BUT IT IS LIKELY TO MODIFY AND RETREAT
   NWD LATER TODAY ACROSS NW TX/SW OK/SE TX PANHANDLE.  THE PROBABLE
   SCENARIO FOR TODAY IS TO SEE THE BOUNDARY RETREAT AND SOME
   ADDITIONAL CONVECTION FORM BY LATE MORNING-EARLY AFTERNOON TO THE
   W...WITH THE STORMS EXPECTED TO SPREAD EWD THROUGH THE
   AFTERNOON/EVENING ALONG THE RESIDUAL OUTFLOW BOUNDARY.  BOUNDARY
   LAYER DEWPOINTS IN THE MID-UPPER 60S IMMEDIATELY S OF THE
   OUTFLOW...COMBINED WITH DAYTIME HEATING AND A RE-ESTABLISHED
   ELEVATED MIXED LAYER PER 12Z MAF SOUNDING...WILL RESULT IN MLCAPE
   VALUES AOA 2500 J/KG.  DEEP-LAYER VERTICAL SHEAR AND BUOYANCY WILL
   AGAIN FAVOR SUPERCELLS CAPABLE OF PRODUCING ISOLATED VERY LARGE
   HAIL.  A FEW TORNADOES WILL ALSO BE POSSIBLE GIVEN THE SUFFICIENTLY
   MOIST BOUNDARY LAYER...AND SOME MODEST ENHANCEMENT TO LOW-LEVEL
   SHEAR BY THIS EVENING ACROSS N/NW TX AND SW OK WITH THE BELT OF
   STRONGER LOW-LEVEL FLOW...AND IN CONJUNCTION WITH ANY RESIDUAL
   BACKED LOW-LEVEL FLOW ALONG THE REMNANT OUTFLOW BOUNDARY.  STORMS
   MAY EVOLVE INTO ANOTHER MCS ACROSS CENTRAL/SRN OK THIS EVENING INTO
   EARLY TONIGHT. 

   ...KS/SE CO THIS AFTERNOON/EVENING...
   CONVECTIVE OVERTURNING AND RESIDUAL OUTFLOW FROM CONVECTION IN OK
   HAS REDUCED BOUNDARY LAYER MOISTURE CONTENT ACROSS MUCH OF KS
   COMPARED TO WEDNESDAY AFTERNOON.  STILL...DEWPOINTS IN THE 50S
   ACROSS WRN KS AND THE LOW 60S IN CENTRAL KS WILL COMBINE WITH
   DAYTIME HEATING TO SUPPORT SUFFICIENT BUOYANCY FOR STORMS WITH
   ISOLATED LARGE HAIL/DAMAGING WINDS ALONG THE SLOW-MOVING FRONT IN KS
   THIS AFTERNOON.  OTHER ISOLATED SEVERE STORMS MAY ALSO FORM ACROSS
   SE CO IN THE WEAK UPSLOPE FLOW REGIME IMMEDIATELY N OF THE FRONT.

   ..THOMPSON/ROGERS.. 05/07/2015

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