May 23, 2011 0100 UTC Day 1 Convective Outlook
Updated: Mon May 23 01:13:07 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms expected over parts of the mid and upper mississippi valley to the ozark plateau this afternoon and evening....   Please read the latest public statement about this event.

Categorical Graphic
20110523 0100 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110523 0100 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
20110523 0100 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
20110523 0100 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 230109
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0809 PM CDT SUN MAY 22 2011
   
   VALID 230100Z - 231200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS FAR WEST CENTRAL
   ILLINOIS...PORTIONS OF CENTRAL AND SOUTHERN MISSOURI...NORTHEAST
   OKLAHOMA...AND NORTHWEST ARKANSAS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES/OH
   VALLEY/CENTRAL APPALACHIANS REGION SWWD INTO THE SRN PLAINS...
   
   ...UPPER GREAT LAKES REGION SWWD TO SWRN TX...
   AN EXTENSIVE/BROKEN BAND OF THUNDERSTORMS -- INCLUDING
   LARGE/EMBEDDED SUPERCELLS -- EXTENDS FROM UPPER MI/WI SWWD INTO THE
   TRANSPECOS REGION OF TX AND ADJACENT NRN MEXICO.  NRN PORTIONS OF
   THE BAND ARE ASSOCIATED WITH THE SURFACE COLD FRONT...WITH THE MORE
   SRN PORTIONS OF THE BAND INTO OK/TX MORE TIED TO A DRYLINE.  
   
   WIDESPREAD STORMS HAVE OVERTURNED THE AIRMASS IN MANY
   LOCALES...EFFECTIVELY REDUCING WHAT WAS STRONG INSTABILITY --
   PARTICULARLY ACROSS MANY AREAS FROM NRN IL NWD.  HOWEVER...STRONG
   INSTABILITY /MIXED-LAYER CAPE RANGING FROM 2000 TO 4000 J/KG/
   REMAINS FROM CENTRAL MO SWWD TO SWRN TX...AND ANOTHER RESERVOIR OF
   MIXED-LAYER CAPE UP TO 2000 J/KG REMAINS ACROSS LOWER MI.  
   
   GIVEN FAVORABLE SHEAR FOR SUPERCELLS ACROSS THE MAJORITY OF THIS
   AREA...WILL MAINTAIN SLIGHT RISK FROM LOWER MI SWWD TO SWRN TX...AND
   WILL MAINTAIN MODERATE RISK FROM THE STL /ST. LOUIS MO/ VICINITY
   SWWD INT NWRN AR/NERN OK.  DAMAGING WINDS AND LARGE HAIL WILL REMAIN
   THE PRIMARY SEVERE THREATS...THOUGH ISOLATED TORNADOES REMAIN
   POSSIBLE THIS EVENING -- PARTICULARLY ACROSS THE MODERATE RISK AREA.
   
   
   ...OH AND TN VALLEYS INTO THE CENTRAL APPALACHIANS...
   TWO CLUSTERS OF STRONG/LOCALLY SEVERE STORMS CONTINUE ATTM -- ONE
   ACROSS NERN INDIANA/NWRN OH/SRN LOWER MI AND THE OTHER CROSSING THE
   CENTRAL APPALACHIANS REGION IN CONJUNCTION WITH AN UPPER SHORT-WAVE
   TROUGH.  WHILE THESE STORMS SHOULD WEAKEN SLOWLY WITH TIME...WILL
   MAINTAIN SLIGHT RISK ACROSS THIS AREA FOR MARGINAL HAIL/DAMAGING
   WIND POTENTIAL.  FINALLY...ALL HIGH-RES MODELS HINT THAT STORMS NOW
   ONGOING ACROSS MO MAY EVOLVE INTO AN MCS AND SHIFT ACROSS MO/NRN AR
   AND THE MID MS VALLEY INTO THE OH AND TN VALLEYS OVERNIGHT.  WHILE
   LESS UNSTABLE AIR IS EVIDENT ACROSS MUCH OF KY AND TN IN THE WAKE OF
   EARLIER STORMS NOW IN THE CENTRAL APPALACHIANS...HAIL AND ISOLATED
   DAMAGING WINDS WILL BE POSSIBLE -- MAINLY FROM SRN INDIANA/WRN
   KY/WRN TN WWD.
   
   ..GOSS.. 05/23/2011
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z