Categorical Graphic
Probabilistic Tornado 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
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
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 261627
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1127 AM CDT TUE APR 26 2011
   
   VALID 261630Z - 271200Z
   
   ...THERE IS A HIGH RISK OF SVR TSTMS LATE THIS AFTERNOON INTO
   TONIGHT FOR NE TX...FAR SE OK...EXTREME NW LA...THE SRN HALF OF
   AR...SOUTHWEST TN...AND NORTHWEST MS...
   
   ...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK...FROM
   NE TX/SE OK TO THE CONFLUENCE OF THE MS/OH RIVERS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN OK/EAST TX INTO MUCH
   OF THE LOWER/MID MS VALLEY...TN AND OH VALLEYS...AND INTO PA/NY...
   
   ...AN OUTBREAK OF SEVERE THUNDERSTORMS INCLUDING STRONG TORNADOES
   AND WIDESPREAD DAMAGING WINDS IS FORECAST TO OCCUR LATER TODAY AND
   TONIGHT...
   
   MORNING WATER VAPOR LOOPS SHOW A BROAD UPPER TROUGH OVER MUCH OF THE
   UNITED STATES...WITH TWO SIGNIFICANT SHORTWAVE FEATURES TRACKING
   ACROSS THE NATION.  THE FIRST TROUGH IS CURRENTLY OVER THE MID MS
   AND OH VALLEY AND WILL EJECT NORTHEASTWARD TODAY INTO THE NORTHEAST
   STATES.  THIS WILL LEAD TO A RELATIVELY LARGE AREA OF POTENTIAL FOR
   ISOLATED SEVERE THUNDERSTORMS AS FAR NORTHEAST AS PORTIONS OF NY/PA.
    ANOTHER SHORTWAVE TROUGH IS OVER CO/NM AND WILL QUICKLY TRANSLATE
   INTO OK/TX BY EVENING.  THIS FEATURE IS EXPECTED TO RESULT IN
   SIGNIFICANT SEVERE WEATHER OVER THE ARKLATEX AND LOWER/MID MS
   VALLEY.
   
   ...OK/TX INTO THE LOWER/MID MS VALLEY...
   LOW LEVEL MOISTURE IS RAPIDLY RETURNING NORTHWARD THIS MORNING
   ACROSS THIS REGION...WITH MID/UPPER 60S DEWPOINTS NOW AS FAR NORTH
   AS SOUTHERN AR.  THE 12Z FWD RAOB SHOWED A PRONOUNCED CAPPING
   INVERSION...WHICH SHOULD INHIBIT STRONG CONVECTIVE DEVELOPMENT UNTIL
   MID AFTERNOON.  BY THAT TIME...STRONG DAYTIME HEATING AND CONTINUED
   MOISTENING OF THE BOUNDARY LAYER WILL YIELD MLCAPE VALUES OF
   3000-4000 J/KG AND A WEAKENED CAP OVER NORTHEAST TX/NORTHWEST
   LA/SOUTHWEST AR.  ISOLATED DISCRETE SUPERCELL THUNDERSTORMS ARE
   EXPECTED TO FORM IN THIS REGION...WHICH SHOULD TRACK NORTHEASTWARD
   ACROSS SOUTHERN AR/NORTHERN LA DURING THE EVENING.  LOW LEVEL WINDS
   WILL BE STRENGTHENING DURING THIS PERIOD AS SURFACE CYCLOGENESIS
   OCCURS OVER TX...LEADING TO INCREASINGLY FAVORABLE SHEAR PROFILES
   FOR TORNADIC ACTIVITY.
   
   MOST MODEL SOLUTIONS SUGGEST A SECOND ROUND OF INTENSE SUPERCELLS
   DEVELOP NEAR THE DRYLINE ACROSS NORTH TX AND SOUTHEAST OK BY EARLY
   EVENING.  THESE STORMS WILL ALSO TRACK EAST-NORTHEASTWARD INTO AR/LA
   /ROUGHLY THE SAME AXIS AS THE FIRST WAVE OF STORMS/ AND WILL BE IN A
   MUCH MORE FAVORABLE VERTICAL SHEAR PROFILE FOR RISKS OF
   STRONG/DAMAGING TORNADOES.
   
   TONIGHT...VERY STRONG LOW LEVEL WINDS ARE FORECAST TO DEVELOP OVER
   EASTERN AR/NORTHWEST MS/WEST TN NORTHWARD INTO IL/IND.  THERE IS
   CONSIDERABLE UNCERTAINTY REGARDING THE EVOLUTION OF STORMS AS THEY
   PROGRESS INTO THIS ENVIRONMENT.  THE STORMS MAY REMAIN DISCRETE
   ACROSS AR WITH A RISK OF STRONG/VIOLENT TORNADOES...OR THEY MAY GROW
   UPSCALE INTO A FAST-MOVING BOW ECHO WITH THE RISK OF WIDESPREAD
   SIGNIFICANT WIND DAMAGE AND ISOLATED TORNADOES. IN EITHER
   CASE...CONDITIONS ARE CLEARLY FAVORABLE A HIGH-END SEVERE WEATHER
   EVENT WELL INTO THE NIGHT.  FOR THESE REASONS...HAVE EXTENDED THE
   HIGH RISK FARTHER EAST.
   
   ...TN/OH VALLEY INTO THE NORTHEAST STATES...
   THE LEAD SHORTWAVE TROUGH EXTENDS FROM IL/IND INTO MS/AL.  A BAND OF
   THUNDERSTORMS ASSOCIATED WITH THIS TROUGH HAS BEEN SLOWLY
   DIMINISHING THIS MORNING...BUT IS LIKELY TO REJUVENATE BY EARLY
   AFTERNOON.  WIDESPREAD STRONG MID LEVEL WINDS AND MODERATE CAPE WILL
   LEAD TO A RISK OF HAIL AND LOCALLY DAMAGING WINDS OVER A RELATIVELY
   BROAD AREA FROM AL/GA NORTHEASTWARD INTO PA/NY.  DETAILS ON SPECIFIC
   AREAS OF THIS THREAT WILL BE ADDRESSED THROUGH THE DAY IN
   FORTHCOMING MESOSCALE DISCUSSIONS.
   
   ..HART/GRAMS.. 04/26/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z