SPC AC 171940
   
   DAY 1 CONVECTIVE OUTLOOK CORR 1
   NWS STORM PREDICTION CENTER NORMAN OK
   0240 PM CDT FRI MAY 17 2013
   
   VALID 172000Z - 181200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF TX...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN
   PLAINS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE CNTRL GULF
   STATES...
   
   CORRECTED FOR SIG HAIL LINE
   
   ...TX...
   
   HAVE OPTED TO INTRODUCE 10 PERCENT SIG HAIL THREAT TO PORTIONS OF TX
   AND EXPAND THE CATEGORICAL SLGT NORTH AND EAST TOWARD THE WRN PARTS
   OF NCNTRL TX.
   
   LATEST HIGH RES MODEL GUIDANCE HAS TRENDED TOWARD SCATTERED TSTM
   DEVELOPMENT ALONG THE DRYLINE FROM EAST OF SJT TO NW OF MWL OVER THE
   NEXT FEW HOURS.  LATEST VIS IMAGERY SUPPORTS THIS EVOLUTION WITH
   DEEPENING CU FIELD OVER MCCULLOCH COUNTY AND NEW CU OVER SHACKELFORD
   COUNTY NE OF ABI.  WITH SFC TEMPERATURES AROUND 103F AT BOTH ABI AND
   SJT...AND WITH DEW POINTS NEAR 70 EAST OF THE DRYLINE...IT APPEARS
   TSTMS WILL DEVELOP SHORTLY.  EXTREME SBCAPE...ON THE ORDER OF 4000
   J/KG...AND MODEST DEEP LAYER SHEAR SUGGEST VERY LARGE HAIL MAY
   ACCOMPANY THESE STORMS.  ADDITIONALLY...STRONG DOWNBURSTS COULD BE
   OBSERVED GIVEN THE TEMP/DEW POINT SPREADS.
   
   ...ELSEWHERE...
   
   EARLIER THOUGHTS REGARDING CONVECTION NEAR THE BLACK HILLS AND OVER
   THE CNTRL GULF STATES REMAIN.
   
   ..DARROW.. 05/17/2013
   
   .PREV DISCUSSION... /ISSUED 1145 AM CDT FRI MAY 17 2013/
   
   CORRECTED TORNADO POINTS PRODUCT
   
   ...NERN WY INTO WRN/CENTRAL SD...
   FULL-LATITUDE UPPER TROUGH HAS MOVED ONSHORE ALONG THE PACIFIC COAST
   AND IS FORECAST TO PROGRESS EWD THROUGH TONIGHT REACHING THE
   INTERMOUNTAIN REGION BY THE END OF THE PERIOD.  SOUTHERLY LOW LEVEL
   FLOW OVER THE PLAINS IS EXPECTED TO INCREASE IN RESPONSE TO THE
   APPROACHING UPPER TROUGH...WITH NWD MOISTURE TRANSPORT CONTINUING
   INTO THE NRN PLAINS.  AT THE SURFACE...A LOW CURRENTLY OVER SERN WY
   WILL MOVE SLOWLY NEWD TOWARD SWRN SD AS A WARM FRONT EXTENDING EWD
   ACROSS SRN SD EDGES NWD.  DEW POINTS ARE FORECAST TO REMAIN IN THE
   50S EAST OF A DRY LINE OVER THE HIGH PLAINS...WITH LOWER 60S
   POSSIBLE INTO PARTS OF SD...AND STRONG DIABATIC HEATING WILL RESULT
   IN DEVELOPMENT OF A DEEP WELL-MIXED BOUNDARY WITH CAPE REACHING
   1000-1500 J/KG.  
   
   ALTHOUGH DYNAMIC FORCING FOR LARGE SCALE ASCENT WILL BE
   MINIMAL...HEATING OVER ELEVATED TERRAIN COMBINED WITH OROGRAPHIC
   LIFT AND LOW LEVEL CONVERGENCE NEAR THE SURFACE LOW/WARM FRONT IS
   EXPECTED TO SUPPORT CONVECTION INITIATION FROM PARTS OF NERN WY INTO
   WRN SD DURING THE MID/LATE AFTERNOON HOURS.  DEEP LAYER SHEAR WILL
   BE ENHANCED AS STRONGER SWLY WINDS ALOFT /40-45 KT AT 500 MB/
   OVERSPREAD THE REGION.  THIS WILL SUPPORT POTENTIAL FOR HIGH-BASED
   SUPERCELLS TO DEVELOP AND SPREAD ENEWD DURING THE LATE AFTERNOON AND
   EVENING HOURS.  AS THE LOW LEVEL JET STRENGTHENS AFTER
   SUNSET...ACTIVITY MAY GROW UPSCALE INTO SEVERAL CLUSTERS/SMALL MCS/S
   AND CONTINUE EWD DURING THE OVERNIGHT HOURS.  A THREAT FOR PRIMARILY
   HAIL MAY ACCOMPANY THESE STORMS.
   
   ...MS/AL...
   UPPER LOW OVER THE MID-SOUTH IS EXPECTED TO CONTINUE SLOWLY
   WEAKENING AS IT MOVES EWD.  EXTENSIVE CLOUD COVER IS ASSOCIATED WITH
   THE LOW ACROSS MS AND NRN AL WHICH IS LIKELY TO INHIBIT HEATING THIS
   AFTERNOON.  FARTHER SOUTH...VISIBLE IMAGERY SUGGESTS PRESENCE OF
   SEVERAL LOW LEVEL BOUNDARIES EXTENDING FROM WEST-CENTRAL AL WSWWD
   ACROSS CENTRAL AND SRN MS WITH SOME BREAKS IN THE CLOUDS NOTED.  12Z
   RAOBS AT JAN AND LIX SUGGEST THAT DIABATIC HEATING MAY BE SUFFICIENT
   TO WEAKEN THE CAP AND PERMIT STORMS TO DEVELOP LATER THIS AFTERNOON
   AND EVENING WITHIN THE SRN SEMICIRCLE OF THE UPPER LOW.  ALTHOUGH
   THERE ARE SOME DIFFERENCES IN MODEL PRECIPITATION/CONVECTIVE STORM
   FORECASTS ACROSS THIS AREA...THERE IS POTENTIAL FOR STORMS TO
   DEVELOP AND FAVORABLE CAPE/SHEAR ENVIRONMENT SUGGEST POSSIBILITY OF
   A FEW SEVERE STORMS TO OCCUR.
   
   ...TX...
   THE SURFACE DRYLINE IS FORECAST TO EXTEND ACROSS WEST-CENTRAL TX
   LATER THIS AFTERNOON.  CONSENSUS OF MODEL GUIDANCE CONTINUES TO
   INDICATE ISOLATED CONVECTION INITIATION ALONG THE DRYLINE LATE THIS
   AFTERNOON AND EARLY EVENING.  FORECAST SOUNDINGS IN THIS AREA SHOW
   MLCAPE VALUES OF 2500-3500 J/KG WITH SUFFICIENT CAPPING TO LIMIT THE
   NUMBER OF STORMS THAT CAN FORM.  NEVERTHELESS...THERE WILL LIKELY BE
   A NARROW ZONE ALONG THE DRYLINE WHERE A COMBINATION OF STRONG
   HEATING AND DEEP MIXING CAN ELIMINATE THE CAP AND ALLOW A STORM OR
   TWO.  SUPERCELLS CAPABLE OF LARGE HAIL AND DAMAGING WINDS ARE THE
   MAIN THREATS.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z