Apr 22, 2011 0730 UTC Day 3 Severe Thunderstorm Outlook
Updated: Fri Apr 22 12:34:10 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110422 0730 UTC Day 3 Outlook Graphic
Probabilistic Graphic
20110422 0730 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
   SPC AC 220728
   
   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0228 AM CDT FRI APR 22 2011
   
   VALID 241200Z - 251200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM CENTRAL TX NEWD INTO
   OK/WRN AR...
   
   ...SYNOPSIS...
   LARGE WRN U.S. TROUGH ALOFT WILL BEGIN MAKING SLOW EWD PROGRESS THIS
   PERIOD...CROSSING THE ROCKIES AND REACHING THE SRN HIGH PLAINS BY
   THE END OF THE PERIOD.  
   
   AS THE TROUGH BEGINS TO EJECT...SURFACE CYCLOGENESIS IS FORECAST
   INVOF ERN NM/W TX DURING THE AFTERNOON.  THIS WILL ALLOW THE
   LINGERING SURFACE FRONT EXTENDING FROM TX ENEWD ACROSS THE OH VALLEY
   TO BEGIN LIFTING SLOWLY NWD THROUGH THE END OF THE PERIOD.  THIS
   FRONT -- AND A DRYLINE FARTHER S ACROSS W TX -- SHOULD BE A FOCUS
   FOR STRONG/LOCALLY SEVERE CONVECTION THIS PERIOD.
   
   ...SRN PLAINS...
   SHOWERS AND THUNDERSTORMS SHOULD BE ONGOING FROM THE NWRN TX/OK
   REGION ENEWD AT THE START OF THE PERIOD...ALONG AND N OF THE SURFACE
   FRONT EXTENDING FROM CENTRAL TX INTO THE OH VALLEY.  
   
   AS THE UPPER SYSTEM BEGINS TO SHIFT EWD...LARGE-SCALE ASCENT SHOULD
   SLOWLY WEAKEN THE WARM SECTOR CAP...AND BY AFTERNOON...SURFACE- AND
   NEAR SURFACE-BASED CONVECTIVE DEVELOPMENT IS EXPECTED ALONG BOTH THE
   DRYLINE OVER WRN PORTIONS OF TX AND NEWD ACROSS CENTRAL AND N TX
   INTO OK AS THE FRONT MIXES/RETREATS NWD.  WHERE STORMS
   INITIATE...DEGREE OF INSTABILITY COMBINED WITH LOW-LEVEL FLOW
   VEERING/INCREASING TO 50 TO 60 KT FROM THE SW AT MID LEVELS WILL
   RESULT IN SHEAR PROFILES FAVORABLE FOR SUPERCELLS.  WHILE LARGE HAIL
   AND DAMAGING WINDS WILL BECOME THE MAIN SEVERE THREATS...PRESENCE OF
   THE SURFACE FRONT AND BACKED FLOW JUST TO THE N INDICATES SOME
   POTENTIAL FOR LOW-LEVEL ROTATION AND THUS ISOLATED TORNADOES.  THE
   SEVERE THREAT SHOULD SHIFT NEWD WITH TIME ACROSS OK...WHILE ELEVATED
   STORMS -- POSING A LARGE HAIL THREAT -- DEVELOP FARTHER N INTO THE
   EVENING AS A SLY LOW-LEVEL JET INTENSIFIES AHEAD OF THE APPROACHING
   UPPER SYSTEM.  MEANWHILE...EXPECT SURFACE-BASED SEVERE POTENTIAL TO
   CONTINUE INTO THE OVERNIGHT HOURS NEAR AND S OF THE RETREATING
   FRONT.
   
   ...MID-ATLANTIC AREA WSWWD ACROSS THE SRN OH/TN/MID MS VALLEYS...
   FORECAST FOR DAY 3 APPEARS SIMILAR TO THAT FOR DAY 2 -- BUT
   DISPLACED JUST A BIT SWD...AS THE FRONT STALLS GENERALLY JUST S OF
   THE OH RIVER BEFORE BEGINNING A SLOW SHIFT BACK NWD LATE IN THE
   PERIOD.
   
   WHILE FLOW ALOFT WILL AGAIN BE SUFFICIENT FOR SOME STORM
   ORGANIZATION AND INSTABILITY SUPPORTIVE OF CONVECTIVE
   DEVELOPMENT...THE SLIGHTLY CONFLUENT FLOW FIELD ALOFT AND WINDS
   ROUGHLY PARALLEL TO THE FRONT AGAIN SUGGESTS THAT THREAT SHOULD
   REMAIN AT LEAST SOMEWHAT LIMITED.  THUS...WILL INTRODUCE ONLY LOW
   SEVERE PROBABILITY ATTM -- FOR HAIL/WIND POTENTIAL WITH A FEW
   STRONGER STORMS OR STORM CLUSTERS.
   
   ..GOSS.. 04/22/2011
   
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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z