Apr 24, 2011 1300 UTC Day 1 Convective Outlook
Updated: Sun Apr 24 12:49:04 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110424 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110424 1300 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
20110424 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
20110424 1300 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
   SPC AC 241245
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0745 AM CDT SUN APR 24 2011
   
   VALID 241300Z - 251200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THROUGH TONIGHT FROM CENTRAL/N
   TX AND SE OK ENEWD TO THE MID ATLANTIC...
   
   ...SYNOPSIS...
   NO MAJOR CHANGES TO PREVIOUS OUTLOOK.  A QUASI-STATIONARY FRONT WILL
   REMAIN THROUGH THE PERIOD FROM CENTRAL/N CENTRAL TX NEWD TO THE OH
   VALLEY.  ALOFT...A BELT OF MODERATE SWLY FLOW WILL BE MAINTAINED
   OVER THE FRONT FROM THE SRN PLAINS TO THE OH VALLEY AND NE
   STATES...DOWNSTREAM FROM A TROUGH THAT WILL MOVE EWD FROM UT/AZ THIS
   MORNING TO THE SRN HIGH PLAINS BY EARLY MONDAY.  THE FRONT HAS BEEN
   AUGMENTED BY MULTIPLE CONVECTIVE CLUSTERS DURING THE PAST 24
   HOURS...AND CONVECTIVE OUTFLOWS WILL KEEP THE EFFECTIVE FOCUS FOR
   NEW SURFACE-BASED CONVECTION A LITTLE S OF THE FORECAST POSITION OF
   THE SYNOPTIC FRONT ACROSS THE OH VALLEY REGION.
   
   ...AR/SE OK/N TX AREA THROUGH TONIGHT...
   WIDESPREAD ELEVATED THUNDERSTORMS NE OK THIS MORNING WILL LIKELY
   PERSIST THROUGH THE DAY AND SPREAD EWD/DEVELOP SWD AND REINFORCE THE
   FRONT FROM NRN AR INTO N TX.  ISOLATED LARGE HAIL WILL BE POSSIBLE
   WITH THE STRONGEST ELEVATED CONVECTION.  S OF THE FRONT...A FEED OF
   MID 60S TO LOW 70S BOUNDARY LAYER DEWPOINTS WILL CONTINUE ACROSS TX
   AND THE LOWER MS VALLEY.  SIMILAR TO THE PAST COUPLE OF DAYS...THE
   RELATIVELY SHALLOW NATURE OF THE MARINE BOUNDARY LAYER WILL ALLOW
   SOME INLAND MIXING OF MOISTURE DURING THE AFTERNOON...BUT AT LEAST
   MID 60S DEWPOINTS WILL HOLD IN THE ZONE OF LOW-LEVEL
   CONVERGENCE/ASCENT ALONG THE STALLED FRONT.  THIS MOISTURE WILL BE
   OVERSPREAD BY AN EML WITH MIDLEVEL LAPSE RATES AOA 7.5
   C/KM...ESPECIALLY OVER SW AR/SE OK/N TX PORTION OF THE OUTLOOK AREA.
   THE NET RESULT WILL BE ANOTHER DAY OF MLCAPE IN THE 2500-3500 J/KG
   RANGE ALONG AND IMMEDIATELY SE OF THE FRONT.
   
   THE MODERATE-STRONG INSTABILITY AND EFFECTIVE BULK SHEAR OF 40-50 KT
   WILL AGAIN SUPPORT SUPERCELLS IN BROKEN BANDS ALONG THE FRONT THIS
   AFTERNOON/EVENING...WITH CONVECTION AGAIN LIKELY TO TRAIN ALONG THE
   BOUNDARY.  THE DRYLINE WILL BE SUPPRESSED SWD INTO EDWARDS PLATEAU
   REGION OF TX.  AT LEAST ISOLATED THUNDERSTORM DEVELOPMENT WILL BE
   POSSIBLE ON THE DRYLINE...BUT THE MORE WIDESPREAD CONVECTION WILL
   AGAIN DEVELOP NEAR AND NE OF THE TRIPLE POINT ALONG THE STATIONARY
   FRONT.  LARGE HAIL WILL BE THE PRIMARY SEVERE THREAT...SOME OF WHICH
   COULD BE VERY LARGE...AND DAMAGING WINDS WILL ALSO BE POSSIBLE.  THE
   TORNADO THREAT APPEARS TO BE RELATIVELY GREATER ALONG THE AR/SE OK/N
   TX PORTION OF THE FRONT WHERE LOW-LEVEL MOISTURE AND SHEAR ARE
   EXPECTED TO BE MAXIMIZED /0-1 KM SRH OF 150-200 M2 PER S2/.
   
   ...OH VALLEY INTO THE MID ATLANTIC THROUGH TONIGHT...
   THE SYNOPTIC FRONT IS LOCATED N OF THE OH RIVER...WHILE A COUPLE OF
   WEAKENING/DISSIPATING CONVECTIVE CLUSTERS ARE LOCATED S OF THE FRONT
   FROM WV TO CENTRAL KY.  OUTFLOW WITH THIS CONVECTION...ALONG WITH
   REMNANT MCV/S AND DAYTIME HEATING IN CLOUD BREAKS...WILL SUPPORT
   ADDITIONAL THUNDERSTORM DEVELOPMENT TODAY ALONG THE SAME CORRIDOR AS
   THE PAST TWO DAYS.  ASIDE FROM LOCALLY HEAVY RAINFALL...ISOLATED
   DAMAGING WINDS WILL BE THE PRIMARY CONCERN WITH STORM CLUSTERS
   MOVING ALONG THE FRONT/OUTFLOWS...WITHIN A BELT OF 500-1500 J/KG
   MLCAPE AND THE SRN FRINGE OF THE STRONGER MIDLEVEL FLOW.
   
   ..THOMPSON/COHEN.. 04/24/2011
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z