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 310557
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1257 AM CDT SUN JUL 31 2011
   
   VALID 311200Z - 011200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE NRN
   PLAINS INTO THE UPPER MS VALLEY...
   
   ...SYNOPSIS...
   
   UPPER RIDGE WILL BUILD OVER THE CNTRL AND NRN PLAINS IN WAKE OF
   SHORTWAVE TROUGH MOVING EWD THROUGH ONTARIO. SERIES OF VORTICITY
   MAXIMA WILL ROTATE ALONG PERIPHERY OF THE UPPER RIDGE INCLUDING THE
   NRN PLAINS AND UPPER MS VALLEY. ONE SUCH FEATURE LOCATED OVER NWRN
   WY AS OF EARLY THIS MORNING WILL ADVANCE INTO CNTRL ND SUNDAY
   AFTERNOON. AT THE SURFACE A COLD FRONT WILL CONTINUE EWD THROUGH
   SERN CANADA AND NRN GREAT LAKES IN ASSOCIATION WITH PROGRESSIVE
   TROUGH...WHILE TRAILING PORTION OF THIS BOUNDARY LIFTS NWD THROUGH
   THE DAKOTAS.
   
   ...NRN PLAINS THROUGH UPPER MS VALLEY AREA...
   
   A CORRIDOR OF RICHER LOW LEVEL MOISTURE WITH UPPER 60S TO NEAR 70
   DEWPOINTS WILL PERSIST IN VICINITY OF RETREATING FRONT FROM THE
   UPPER MS VALLEY INTO THE DAKOTAS. STEEP MID LEVEL LAPSE RATES AND
   DIABATIC WARMING WILL CONTRIBUTE TO AN AXIS OF MODERATE TO STRONG
   MLCAPE ALONG MOIST AXIS FROM MN INTO NRN SD...SRN ND AND ERN MT
   DURING THE DAY. THE POTENTIAL WILL EXIST FOR SURFACE BASED STORM
   DEVELOPMENT THIS AFTERNOON WITHIN ZONE OF FRONTAL CONVERGENCE FROM
   NRN SD INTO SRN ND...POSSIBLY AIDED BY THE PROGRESSIVE IMPULSE. WARM
   TEMPERATURES WITH EML PLUME /700 MB TEMPERATURES FROM 12-14C/ ALONG
   WITH MODEST FORCING SUGGEST STORM COVERAGE WILL PROBABLY REMAIN
   ISOLATED. WITH EFFECTIVE SHEAR FROM 35-40 KT AND 2500-3000 J/KG
   MLCAPE...ANY STORMS THAT DEVELOP WILL LIKELY BECOME SUPERCELLULAR
   WITH A THREAT OF LARGE HAIL AND DAMAGING WIND. STORM COVERAGE IS
   EXPECTED TO INCREASE DURING THE EVENING AND OVERNIGHT OVER ND WITHIN
   ZONE OF STRENGTHENING WARM ADVECTION AND ISENTROPIC ASCENT. PRIMARY
   THREATS WILL BE ISOLATED LARGE HAIL AND DAMAGING WIND...BUT AT LEAST
   A SMALL WINDOW WILL EXIST FOR ISOLATED TORNADOES BEFORE THE BOUNDARY
   LAYER BEGINS TO DECOUPLE AND STORMS GROW UPSCALE. ACTIVITY WILL
   SHIFT EWD TOWARD THE UPPER MS VALLEY OVERNIGHT.
   
   ...GREAT LAKES AREA...
   
   A FEW STORMS COULD DEVELOP WITHIN AXIS OF MODERATE TO STRONG
   INSTABILITY AHEAD OF FRONT OVER THE GREAT LAKES REGION WHERE 30-40
   KT VERTICAL SHEAR WILL EXIST. HOWEVER...WEAK FORCING AND DRY
   MID-LEVEL THERMODYNAMIC PROFILES SUGGEST STORM COVERAGE WILL
   PROBABLY REMAIN VERY ISOLATED. THIS AREA WILL CONTINUE TO BE
   MONITORED...AND A SLIGHT RISK MAY BE INTRODUCED IF IT BECOMES
   APPARENT STORM COVERAGE WILL BE MORE THAN CURRENTLY ANTICIPATED.
   
   ..DIAL/ROGERS.. 07/31/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z