Mar 23, 2011 1300 UTC Day 1 Convective Outlook
Updated: Wed Mar 23 12:50:43 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110323 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110323 1300 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20110323 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20110323 1300 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 231247
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0747 AM CDT WED MAR 23 2011
   
   VALID 231300Z - 241200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR
   CENTRAL/ERN KY...SRN OH...AND CENTRAL/WRN WV...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FOR MUCH OF THE TN/OH VALLEY
   REGION EWD TO THE MID ATLANTIC COAST...
   
   ...SYNOPSIS...
   A MIDLEVEL TROUGH OVER IA/SRN MN THIS MORNING WILL PROGRESS ESEWD TO
   THE OH VALLEY THIS AFTERNOON AND THE MID ATLANTIC REGION BY EARLY
   THURSDAY...WHILE AN ASSOCIATED 90-110 KT MIDLEVEL JET DEVELOPS EWD
   OVER TN/KY THIS AFTERNOON AND THE CAROLINAS TONIGHT.  AT THE
   SURFACE...A CYCLONE IN CENTRAL IL THIS MORNING WILL MOVE EWD TO OH
   THIS AFTERNOON...PRIOR TO DEVELOPMENT OF A NEW CYCLONE OFF THE MID
   ATLANTIC COAST OVERNIGHT.  A COLD FRONT/REMNANT DRYLINE WILL MOVE
   EWD/SEWD ACROSS THE OH/TN VALLEY REGION THROUGH THIS EVENING IN
   CONJUNCTION WITH THE SURFACE CYCLONE...AND THEN APPROACH THE SE
   ATLANTIC COAST BY 24/12Z.  THE AREA NEAR THE SURFACE
   CYCLONE...ALONG/E OF THE COLD FRONT/DRYLINE...AND W OF THE
   APPALACHIANS...WILL EXPERIENCE THE PRIMARY SEVERE STORM THREATS
   TODAY.
   
   ...OH/TN VALLEYS EWD TO THE ATLANTIC COAST THROUGH TONIGHT...
   A SWATH OF 55-60 F BOUNDARY LAYER DEWPOINTS IS SPREADING NEWD FROM
   MS/AL/TN/AR TOWARD THE OH VALLEY ON A 40-50 KT WSWLY LLJ.  THIS
   MOISTURE WILL COMBINE WITH DAYTIME HEATING AND 8 C/KM MIDLEVEL LAPSE
   RATES N OF THE JET CORE TO SUPPORT MODERATE INSTABILITY /MLCAPE
   VALUES AROUND 1500 J PER KG/ IN THE WARM SECTOR THIS AFTERNOON. 
   CONVECTIVE INHIBITION WILL WEAKEN BY MIDDAY OVER A RATHER BROAD
   AREA...AND MULTIPLE BANDS OF THUNDERSTORMS ARE EXPECTED TO DEVELOP
   BY EARLY AFTERNOON.  THOUGH LOW-LEVEL FLOW IS EXPECTED TO WEAKEN
   SOME AND VEER TO MORE WLY DURING THE DAY...DEEP-LAYER VERTICAL SHEAR
   AND STRAIGHT HODOGRAPHS WILL BE FAVORABLE FOR BOTH SPLITTING
   SUPERCELLS AND FAST-MOVING LINE SEGMENTS.
   
   THE COLD MIDLEVEL TEMPERATURES /NEAR -20 C AT 500 MB/...STEEP LAPSE
   RATES...AND SUPERCELL WIND PROFILES APPEAR SUPPORTIVE OF A
   RELATIVELY WIDESPREAD THREAT FOR LARGE HAIL...SOME OF WHICH COULD BE
   SIGNIFICANT.  DAMAGING WINDS CAN ALSO BE EXPECTED AS A RESULT OF
   HIGH MOMENTUM /35-50 KT/ FLOW IN THE LOWEST FEW KM AGL...IN
   COMBINATION WITH STEEP LOW-LEVEL LAPSE RATES.  THE TORNADO THREAT IS
   LESS CERTAIN GIVEN THE LIMITED LOW-LEVEL HODOGRAPH CURVATURE...BUT A
   FEW TORNADOES WILL STILL BE POSSIBLE GIVEN THE LIKELIHOOD OF
   MULTIPLE SUPERCELLS OVER A BROAD AREA THIS AFTERNOON/EVENING.
   
   THUNDERSTORMS WILL ALSO SPREAD E OF THE APPALACHIANS LATE THIS
   AFTERNOON INTO TONIGHT AS THE SYNOPTIC SYSTEM PROGRESSES EWD/ESEWD. 
   STRONG WIND PROFILES WILL CONTINUE...BUT LESSER INSTABILITY COMPARED
   TO AREAS W OF THE MOUNTAINS SHOULD RESULT IN A GRADUAL LESSENING OF
   THE DAMAGING WIND/HAIL THREAT OVERNIGHT TOWARD THE ATLANTIC COAST.
   
   THE SRN EXTENT OF THE SEVERE STORM THREAT IS SOMEWHAT UNCERTAIN. 
   DEEP-LAYER VERTICAL SHEAR WILL BE VERY STRONG BENEATH THE JET CORE
   AS FAR S AS NRN AL...WHERE BOUNDARY LAYER DEWPOINTS SHOULD REMAIN
   NEAR 60 F.  MIDLEVEL LAPSE RATES WILL BE MUCH LESS FAVORABLE
   COMPARED TO AREAS FARTHER N...ON THE CYCLONIC SIDE OF THE JET...AND
   THIS WILL LIMIT CAPE.  STILL...THE STRONG WIND PROFILES AND
   SUBSTANTIAL LOW-MIDLEVEL BUOYANCY COULD SUPPORT STORMS WITH DAMAGING
   WINDS.
   
   ..THOMPSON/GRAMS.. 03/23/2011
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z