Apr 11, 2011 1300 UTC Day 1 Convective Outlook
Updated: Mon Apr 11 12:31:45 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110411 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110411 1300 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20110411 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20110411 1300 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 111228
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0728 AM CDT MON APR 11 2011
   
   VALID 111300Z - 121200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS VALLEY INTO
   NY/PA AND WESTERN NEW ENGLAND...
   
   MORNING SATELLITE LOOPS SHOW AN IMPRESSIVE UPPER SHORTWAVE TROUGH
   ROTATING ACROSS TX.  THIS FEATURE WILL TRACK NORTHEASTWARD AND
   AFFECT THE GULF COAST AND TN/OH VALLEY REGIONS TODAY.  A REMNANT
   LINE OF CONVECTION CURRENTLY EXTENDS FROM SOUTHERN AR INTO WESTERN
   KY AND NORTHEASTWARD INTO OH.  THIS BAND OF STORMS WILL LIKELY
   PERSIST THROUGH THE DAY...WITH GRADUAL INTENSIFICATION EXPECTED BY
   EARLY AFTERNOON AS DAYTIME HEATING AND CONTINUED INFLUX OF MOISTURE
   OCCURS.  THE RESULT WILL LIKELY BE A RATHER LARGE AREA OF SEVERE
   THUNDERSTORM POTENTIAL TODAY FROM NY/PA SOUTHWARD INTO TN/MS/AL.
   
   ...PORTIONS OF TN/OH AND LOWER MS VALLEY...
   ALL MODELS ARE IN GENERAL AGREEMENT THAT ONGOING CONVECTIVE LINE
   WILL ONLY SLOWLY INTENSIFY THIS MORNING DUE TO WARM MID LEVEL
   TEMPERATURES SHOWN ON 12Z BMX/JAN/BNA RAOBS.  HOWEVER...APPROACH OF
   UPPER TROUGH AND DAYTIME HEATING WILL ERODE CAP AND LEAD TO SEVERE
   STORMS BY EARLY AFTERNOON.  LOW LEVEL CYCLOGENESIS IS EXPECTED OVER
   KY/TN BY MID AFTERNOON...WITH INCREASING LOW LEVEL VERTICAL SHEAR
   OVER THE WARM SECTOR.  FORECAST SOUNDINGS SUGGEST 0-3KM SRH VALUES
   EXCEEDING 300 M2/S2...BUT ALSO SHOW A CONTINUED MID LEVEL INVERSION
   WHICH MAY LIMIT UPDRAFT STRENGTH.  FOR THIS REASON...HAVE NOT
   UPGRADED TO MODERATE RISK AT THIS TIME.  HOWEVER...AN UPGRADE MAY
   OCCUR LATER TODAY IF CONCERNS REGARDING THERMODYNAMICS ARE LESSENED.
    REGARDLESS...POTENTIAL FOR A FEW TORNADOES AND CONSIDERABLE WIND
   DAMAGE REMAINS FROM NORTHEAST MS INTO MUCH OF MIDDLE TN/AL AND
   SOUTHERN KY.  STORMS MAY AFFECT PORTIONS OF NORTH GA TONIGHT BEFORE
   DIMINISHING.
   
   ...NY/PA INTO CENTRAL APPALACHIANS.
   MODEL GUIDANCE IS IN AGREEMENT THAT A RATHER POTENT ENVIRONMENT WILL
   DEVELOP LATER TODAY AHEAD OF THE COLD FRONT FROM SOUTHERN NY AND
   MUCH OF PA INTO WV/VA.  STRONG DAYTIME HEATING AND DEWPOINTS IN THE
   LOWER 60S WILL YIELD AFTERNOON MLCAPE VALUES OF AROUND 1000 J/KG. 
   RATHER STRONG DEEP LAYER EFFECTIVE SHEAR WILL ALSO BE PRESENT AS
   80-100 KT MID LEVEL JET OVERSPREADS THE REGION.  CURRENT INDICATIONS
   ARE THAT SCATTERED THUNDERSTORMS WILL DEVELOP BY MID AFTERNOON OVER
   PORTIONS OF NY/PA INTO THE CENTRAL APPALACHIANS AND SPREAD QUICKLY
   EASTWARD.  ONSHORE FLOW AND ASSOCIATED MORE STABLE AIR MASS WILL
   LIMIT EASTWARD PROGRESSION OF STORMS TO THE COAST.  HOWEVER...IT
   APPEARS POSSIBLE THAT A RATHER CONCENTRATED AREA OF DAMAGING WINDS
   AND ISOLATED TORNADOES MAY OCCUR TODAY OVER THIS REGION.
   
   ..HART/GARNER.. 04/11/2011
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z