May 25, 2011 2000 UTC Day 1 Convective Outlook
Updated: Wed May 25 19:43:07 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...major tornado and severe weather outbreak 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 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110525 2000 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 2000 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 2000 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 251939
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0239 PM CDT WED MAY 25 2011
   
   VALID 252000Z - 261200Z
   
   ...THERE IS A HIGH RISK OF SVR TSTMS ACROSS ERN MO/NERN AR...SRN
   IL/IND...WRN TN/KY...
   
   ...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK FROM
   SRN AR INTO WRN OH...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM SCNTRL TX TO SRN LOWER MI
   AND WRN UPSTATE NY/WRN PA...
   
   ...MAJOR TORNADO OUTBREAK IS UNDERWAY...
   
   BASED ON LATEST TRENDS IN TORNADIC SUPERCELL EVOLUTION HAVE MADE A
   NWWD ADJUSTMENT TO HIGH RISK ACROSS MO.  RADAR AND DIAGNOSTIC DATA
   SUGGEST A SIGNIFICANT TORNADO RISK EXTENDS ALONG THE WARM FRONT
   DRAPED ALONG THE I-70 CORRIDOR FROM CNTRL MO...EWD INTO THE STL
   AREA.  FOR THIS REASON HAVE INCREASED THE PROBABILITY FOR
   SIGNIFICANT TORNADOES TO ACCOUNT FOR NUMEROUS...POTENTIALLY
   LONG-TRACK AND DAMAGING TORNADOES SPREADING ACROSS ERN MO TOWARD
   WCNTRL/SRN IL.  ADDITIONALLY...CU FIELD IS EXPANDING/DEEPENING
   ACROSS MUCH OF AR AND SCT-NUMEROUS TORNADIC SUPERCELLS SHOULD EVOLVE
   OVER THIS REGION THEN SPREAD INTO WRN TN/KY BY EARLY EVENING.
   
   FARTHER SOUTH...VERY HOT CONDITIONS HAVE DEVELOPED ACROSS SCNTRL TX
   WHERE TEMPERATURES HAVE WARMED INTO THE 90S.  VIS IMAGERY DEPICTS AN
   UPWARD EVOLVING CU LINE ALONG DRYLINE/COLD FRONT THAT MAY WITH TIME
   DEVELOP FURTHER INTO SEVERE TSTM ACTIVITY.  GIVEN THE STRONG DEEP
   LAYER SHEAR AND EXTREME INSTABILITY ALONG THE TRAILING FRONTAL ZONE
   IT SEEMS APPROPRIATE TO EXTEND HIGHER SEVERE PROBS FOR POSSIBLE
   SUPERCELL DEVELOPMENT.
   
   ..DARROW.. 05/25/2011
   
   .PREV DISCUSSION... /ISSUED 1123 AM CDT WED MAY 25 2011/
   
   ...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.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z