SPC AC 141227

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0627 AM CST SUN DEC 14 2014

   VALID 141300Z - 151200Z

   ...THERE IS A MRGL RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR
   PARTS OF THE CENTRAL/SRN PLAINS...

   ...SUMMARY...
   THUNDERSTORMS ARE EXPECTED TODAY ACROSS PARTS OF THE CENTRAL AND
   SOUTHERN PLAINS.  A FEW OF THESE STORMS COULD BE STRONG TO SEVERE
   PRIMARILY DURING THE AFTERNOON FROM WESTERN KANSAS AND CENTRAL
   OKLAHOMA INTO NORTH-CENTRAL TEXAS. ISOLATED LARGE HAIL...STRONG
   WINDS...AND PERHAPS A TORNADO ARE POSSIBLE.

   ...KS/OK/TX THROUGH THIS EVENING...
   A DEVELOPING CLOSED MIDLEVEL LOW OVER NM THIS MORNING WILL MOVE NEWD
   TO SW KS THIS AFTERNOON AND NE KS BY THE END OF THE PERIOD...ALONG
   WITH AN ASSOCIATED SURFACE CYCLONE.  STRONG FORCING FOR ASCENT IN
   ADVANCE OF THE WAVE IS ALREADY SUPPORTING THUNDERSTORM DEVELOPMENT
   ACROSS THE TX PANHANDLE...AND SOME FORM OF THIS ONGOING CONVECTION
   WILL PERSIST THROUGH THE DAY WHILE SPREADING BOTH NEWD ACROSS KS AND
   EWD INTO OK.

   LOW-LEVEL MOISTURE RETURN CONTINUES WITHIN THE WARM SECTOR ACROSS
   TX/OK/KS...WHERE BOUNDARY LAYER DEWPOINTS RANGE FROM THE LOW-MID 50S
   FROM NW TX INTO NW OK...TO THE LOW-MID 60S ALONG THE TX COAST. 
   GIVEN THE RELATIVELY WEAK N-S MOISTURE GRADIENT...ONLY GRADUAL
   MOISTURE INCREASES ARE EXPECTED TODAY FROM OK INTO KS. 
   MEANWHILE...MIDLEVEL LAPSE RATES WILL STEEPEN FROM W-E WITH THE
   APPROACH OF THE MIDLEVEL LOW AND COOLER MIDLEVEL TEMPERATURES.  THE
   EARLY CONVECTION WILL HELP REINFORCE A COOL BOUNDARY LAYER...THOUGH
   SOME SURFACE HEATING WILL BE POSSIBLE IN A NARROW CORRIDOR
   IMMEDIATELY BEHIND THE INITIAL CONVECTIVE BAND.  THE NET RESULT
   SHOULD BE MLCAPE OF 500-1000 J/KG RANGE BY MID-LATE AFTERNOON.  

   THE MARGINAL BUOYANCY WILL COINCIDE WITH DEEP-LAYER VERTICAL SHEAR
   SUFFICIENT FOR ORGANIZED SEVERE STORMS IN THE NARROW CORRIDOR E OF
   THE DRYLINE/PACIFIC COLD FRONT AND WITHIN THE MIDLEVEL DRY SLOT. 
   HOWEVER...BACKING WINDS WITH HEIGHT IN THE MID LEVELS WILL NOT BE
   IDEAL FOR SUPERCELLS FROM CENTRAL OK NWD INTO KS...AND THE
   COMBINATION OF WIND PROFILE AND BUOYANCY CONCERNS SUPPORT
   MAINTAINING LOW SEVERE PROBABILITIES IN THIS UPDATE.

   CLOSER TO THE SURFACE LOW...DEEP FORCING FOR ASCENT AND LARGE
   VERTICAL VORTICITY ON THE NOSE OF STEEPER LOW-LEVEL LAPSE RATES
   SUGGEST SOME POTENTIAL FOR LOW-TOPPED STORMS WITH A MARGINAL TORNADO
   RISK INTO SW AND W CENTRAL KS THIS AFTERNOON.  OTHERWISE...THE
   RICHEST LOW-LEVEL MOISTURE WILL BE CONFINED TO TX...GENERALLY S OF
   THE STRONGER HEIGHT FALLS AND FORCING FOR ASCENT.  MORE CLASSIC
   SUPERCELL HODOGRAPHS ARE EXPECTED NEAR AND S OF THE RED
   RIVER...COINCIDENT WITH THE SRN EXTENT OF THE CONVECTIVE BAND. 
   STILL...BUOYANCY WILL LIKELY REMAIN LIMITED BY A SOMEWHAT COOL/MOIST
   BOUNDARY LAYER AND LESSER MIDLEVEL LAPSE RATES COMPARED TO AREAS
   FARTHER N IN OK/KS.

   ..THOMPSON/PICCA.. 12/14/2014

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