May 25, 2011 1630 UTC Day 1 Convective Outlook
Updated: Wed May 25 16:27:10 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms expected over parts of the lower mississippi...mid mississippi...and lower ohio valleys this afternoon and tonight....   Please read the latest public statement about this event.

Categorical Graphic
20110525 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110525 1630 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
20110525 1630 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
20110525 1630 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 251623
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1123 AM CDT WED MAY 25 2011
   
   VALID 251630Z - 261200Z
   
   ...THERE IS A HIGH RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
   TONIGHT OVER PARTS OF NORTHEAST AR...WEST TN...SOUTHEAST
   MO...SOUTHERN IL...WESTERN AND CENTRAL KY...AND SOUTHERN IND...
   
   ...THERE IS A MDT RISK OF SVR TSTMS FROM SOUTHERN AR AND NORTHERN MS
   ACROSS MUCH OF THE MID MS/OH AND TN RIVER VALLEYS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM NORTHERN LA INTO THE
   EASTERN GREAT LAKES...
   
   ...MAJOR TORNADO OUTBREAK IS FORECAST LATER TODAY AND TONIGHT OVER
   PORTIONS OF THE MID MS AND LOWER OH VALLEYS...
   
   A STRONG UPPER LOW OVER KS WILL MOVE SLOWLY EASTWARD TODAY...WHILE A
   SHORTWAVE TROUGH ROTATES AROUND THE SOUTHERN PERIPHERY OF THE LOW
   INTO THE MID MS AND LOWER OH VALLEYS.  A LARGE BAND OF 70+ KNOT
   WESTERLY MID LEVEL WINDS STRETCH FROM OK/TX INTO IL/KY/TN THIS
   MORNING...ACROSS A LARGE/MOIST WARM SECTOR.  AN EXPANSIVE AREA OF
   MID/UPPER 60S DEWPOINTS EXTEND FROM THE COLD FRONT OVER WRN MO/AR
   EASTWARD TO EASTERN KY AND NORTHWARD INTO NORTHERN IND.  THE RESULT
   WILL BE A VERY DANGEROUS RISK OF WIDESPREAD SEVERE THUNDERSTORMS
   LATER THIS AFTERNOON AND EVENING...INCLUDING LONG-DURATION
   STRONG/VIOLENT TORNADOES.
   
   MORNING RAOBS AND FORECAST SOUNDINGS SUGGEST THAT WIDESPREAD MOIST
   AND VERY UNSTABLE CONDITIONS WILL BE PRESENT ACROSS THE WARM SECTOR
   TODAY.  BROKEN CLOUDS WILL YIELD AFTERNOON MLCAPE VALUES OF
   2500-3500 J/KG OVER A LARGE AREA...ALONG WITH A RELATIVELY WEAK CAP.
    THIS WILL RESULT IN THE POTENTIAL FOR MULTIPLE ROUNDS OF SEVERE
   THUNDERSTORMS ACROSS THE AREA...BOTH IN THE WARM SECTOR...AND ALONG
   THE SURFACE COLD FRONT AS IT SWEEPS EASTWARD LATER TODAY.
   
   TCU AND THUNDERSTORMS HAVE BEGUN TO DEVELOP AHEAD OF THE UPPER LOW
   AND NEAR THE COLD FRONT OVER WESTERN MO/AR.  THE 15Z SGF RAOB SHOWS
   FAVORABLE VERTICAL SHEAR PROFILES FOR SUPERCELL THUNDERSTORMS
   CAPABLE OF VERY LARGE HAIL AND TORNADOES.  THESE STORMS SHOULD
   INTENSIFY THROUGH THE DAY WITH AN INCREASING RISK OF STRONG/VIOLENT
   TORNADOES.  ONCE THESE STORMS BECOME ESTABLISHED...THEY MAY PERSIST
   THROUGH MUCH OF THE FORECAST PERIOD AND SURGE EASTWARD ACROSS THE
   MDT/HIGH RISK AREAS.
   
   FARTHER EAST...SEVERAL MODEL SOLUTIONS INDICATE THE DEVELOPMENT OF
   CONVECTION IN THE WARM SECTOR OVER PORTIONS OF NORTHEAST
   AR/SOUTHEAST MO/SOUTHERN IL/WESTERN KY...SPREADING INTO WEST TN AND
   SOUTHERN IND.  0-3KM SRH VALUES OF 250-400 M2/S2 COUPLED WITH LONG
   HODOGRAPHS AND HIGH INSTABILITY SUGGEST THESE STORMS WOULD LIKELY BE
   DISCRETE SUPERCELLS WITH AN INCREASING RISK OF MULTIPLE
   STRONG/VIOLENT TORNADOES AND VERY LARGE HAIL.
   
   DURING THE EVENING...MULTIPLE LINES/CLUSTERS OF INTENSE/SUPERCELL
   STORMS AND BOWS MAY BE TRACKING RAPIDLY EAST-NORTHEASTWARD ACROSS
   THE MDT/HIGH RISK AREAS.  GIVEN THE LARGE AREA POTENTIALLY AFFECTED
   BY SEVERE STORMS TODAY...THE STRENGTH OF THE LOW AND DEEP LAYER
   SHEAR...AND THE STRONG INSTABILITY...THE POTENTIAL IS INCREASING FOR
   A MAJOR TORNADO OUTBREAK.  WIDESPREAD WIND DAMAGE AND LARGE HAIL ARE
   ALSO A PROMINENT CONCERN THROUGH THE EVENING HOURS.
   
   BY MID TO LATE EVENING...THUNDERSTORMS ARE LIKELY TO DEVELOP
   SOUTHWARD ALONG THE COLD FRONT INTO SOUTHERN AR/NORTHERN LA.  THIS
   ACTIVITY WILL BE NEAR THE NOSE OF A STRONG WESTERLY MID LEVEL
   JET...AND MAY POSE A RISK OF SIGNIFICANT SEVERE WEATHER AS WELL. 
   UNCERTAINTY EXISTS REGARDING THE COVERAGE OF STORMS IN THIS
   AREA...BUT NONETHELESS HAVE EXTENDED THE MDT RISK SLIGHTLY FARTHER
   SOUTH TO HIGHLIGHT THIS THREAT.
   
   ..HART/GRAMS.. 05/25/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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