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 271621
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1121 AM CDT WED JUL 27 2011
   
   VALID 271630Z - 281200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM NERN WY/SD/NEB ACROSS THE
   UPPER MS VALLEY...
   
   ...ERN NEB/IA/SRN WI/NRN IL...
   ELEVATED MCS IS PROGRESSING EWD ACROSS WI/NERN IL AND LAKE MI...WITH
   AN APPARENT MCV NOTED IN ANIMATED RADAR IMAGERY OVER NERN IA.  THIS
   SYSTEM IS OVER THE ERN EDGE OF THE LOW LEVEL MOISTURE AND
   INSTABILITY GRADIENT...SUGGESTING THE STORMS WILL GRADUALLY DIMINISH
   IN INTENSITY INTO THE EARLY AFTERNOON.
   
   THE MCS HAS GENERATED A DIFFUSE OUTFLOW BOUNDARY EXTENDING WWD
   ACROSS NWRN IL AND SRN/CENTRAL IA INTO SERN NEB.  THINNING CLOUDS IN
   THE WAKE OF THE MCS SHOULD PERMIT AREAS OF STRONG DIABATIC HEATING
   TO OCCUR NORTH OF THE BOUNDARY ALTHOUGH WEAK LOW LEVEL CONVERGENCE
   MAY PERSIST ALONG THE REMNANT BOUNDARY. THIS WILL RESULT IN DIURNAL
   DESTABILIZATION WITH MLCAPE OF 2000-3000 J/KG EXPECTED THIS
   AFTERNOON.  HOWEVER...EML AXIS ASSOCIATED WITH VERY WARM 700 MB
   TEMPERATURES EXTENDING FROM THE CENTRAL HIGH PLAINS OVER THE MIDDLE
   MO VALLEY SHOULD LIMIT SURFACE-BASED CONVECTION FROM DEVELOPING
   THROUGH MUCH OF THE AFTERNOON.  MODELS INDICATE A MODERATE LOW LEVEL
   JET /30-40 KT/ WILL CONTINUE FROM ERN KS INTO NWRN MO/SWRN IA THIS
   AFTERNOON SUPPORTING A HIGHER PROBABILITY OF STORMS ALONG THE NRN
   EDGE OF THE EML FROM NERN NEB INTO NRN/CENTRAL IA...INCLUDING THE
   POSSIBILITY OF SURFACE-BASED STORMS BY MID/LATE AFTERNOON AND
   EVENING.
   
   DEEP LAYER SHEAR OF 30-40 KT WILL BE SUPPORTIVE OF ORGANIZED
   CONVECTIVE STRUCTURES INCLUDING A FEW SUPERCELLS.  STRONGER STORMS
   WILL BE CAPABLE OF PRODUCING DAMAGING WINDS...HAIL...AND POSSIBLY A
   FEW TORNADOES IF DISCRETE SURFACE-BASED STORMS CAN BE MAINTAINED. 
   ACTIVITY IS LIKELY TO SPREAD EWD THIS EVENING INTO PARTS OF SRN WI
   AND NRN IL BEFORE SEVERE POTENTIAL DIMINISHES AFTER 06Z.
   
   ...HIGH PLAINS FROM NERN WY ACROSS PARTS OF SD INTO NEB...
   WEAK UPSLOPE FLOW IS FORECAST OVER WRN SD INTO NERN WY IN THE WAKE
   OF A SWD MOVING COLD FRONT...MAINTAINING 55-60F DEW POINTS OVER THE
   AREA.  STRONG HEATING WILL CONTINUE WITH MLCAPE REACHING 1000-2000
   J/KG THIS AFTERNOON.  WATER VAPOR IMAGERY SHOWS AN APPARENT SHORT
   WAVE TROUGH MOVING ENEWD ACROSS NWRN WY WHICH MAY ENHANCE
   THUNDERSTORM DEVELOPMENT...INITIALLY OVER THE MOUNTAINS AND BLACK
   HILLS THIS AFTERNOON AND THEN SPREADING EWD INTO THE PLAINS. 
   VEERING WIND PROFILES WITH HEIGHT WILL SUPPORT SUPERCELLS WITH
   PRIMARY THREATS FOR LARGE HAIL AND STRONG WIND GUSTS.  STORMS ARE
   EXPECTED TO PERSIST THROUGH THE EVENING HOURS BEFORE WEAKENING
   THEREAFTER.
   
   ...SRN/EAST CENTRAL MN INTO NWRN WI...
   VISIBLE IMAGERY SHOWS CLEARING HAS OCCURRED OVER PARTS OF
   CENTRAL/SRN MN NEAR THE COLD FRONT IN THE WAKE OF THE DOWNSTREAM
   MCS.  THIS WILL PROMOTE STRONG DIABATIC HEATING/DESTABILIZATION
   WHERE SURFACE DEW POINTS REMAIN IN THE LOW/MID 70S. ALTHOUGH
   WEAK/NEUTRAL FORCING FOR LARGE SCALE ASCENT MAY LIMIT CONVECTIVE
   STORM COVERAGE...THERE IS POTENTIAL FOR A FEW STRONG THUNDERSTORMS
   TO DEVELOP DURING THE LATE AFTERNOON AND EVENING.  THE 5% HAIL AND
   WIND PROBABILITY CONTOURS HAVE BEEN EXTENDED NWD INTO THIS AREA TO
   REFLECT THIS POTENTIAL...AND AREA WILL BE MONITORED FOR SEVERE
   POTENTIAL THIS AFTERNOON.
   
   ...CO/KS...
   CLEAR SKIES THIS MORNING OVER EASTERN CO AND WESTERN KS WILL SUPPORT
   STRONG HEATING THROUGH THE AFTERNOON AND HOT MAX TEMPERATURES. 
   STEEP LOW LEVEL LAPSE RATES AND MODERATE INSTABILITY WILL PROMOTE
   THE DEVELOPMENT OF HIGH-BASED THUNDERSTORMS IN THIS REGION DURING
   THE AFTERNOON AND EARLY EVENING. A FEW OF THE STORMS WILL BE CAPABLE
   OF DAMAGING WINDS AND PERHAPS HAIL.
   
   ..WEISS/HURLBUT.. 07/27/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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