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 210549
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1249 AM CDT SAT MAY 21 2011
   
   VALID 211200Z - 221200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER ERN PORTIONS OF THE SRN
   AND CNTRL PLAINS INTO THE LOWER-MID MS VALLEY...
   
   ...SYNOPSIS...
   
   LARGE CUTOFF UPPER LOW SITUATED OVER THE HIGH PLAINS WILL DRIFT
   SLOWLY EWD TODAY WHILE SEVERAL SHORTWAVE TROUGHS ROTATE THROUGH THIS
   FEATURE. EARLY SATURDAY AN OCCLUDED FRONT WILL EXTEND FROM A SURFACE
   LOW OVER THE DAKOTAS SWD INTO THE CNTRL PLAINS. THERE IT WILL
   TRANSITION TO A PACIFIC FRONT/DRYLINE AND EXTEND SWD THROUGH THE
   REMAINDER CNTRL OK TO NEAR THE BIG BEND AREA OF TX. SRN PORTION OF
   THIS FRONT WILL ADVANCE INTO ERN OK AND NERN TX DURING THE DAY
   BEFORE RETREATING WWD ONCE AGAIN OVERNIGHT.
   
   ...CNTRL AND SRN PLAINS INTO THE LOWER-MID MS VALLEY...
   
   THE ONGOING MCS FROM THE LOWER MS VALLEY SWWD THROUGH SERN TX WILL
   CONTINUE THROUGH THE EARLY MORNING WHILE GRADUALLY WEAKENING. IN
   WAKE OF MCS...MODEST SLY BOUNDARY LAYER FLOW WILL MAINTAIN MID TO
   UPPER 60S DEWPOINTS IN THE SRN PLAINS AND LOWER MS VALLEY WARM
   SECTOR WITH LOW-MID 60S FARTHER NORTH THROUGH THE CNTRL PLAINS. THIS
   IN CONJUNCTION WITH EWD ADVECTING EML PLUME WILL CONTRIBUTE TO
   POTENTIAL FOR AXIS OF STRONG INSTABILITY. AS THE MOIST BOUNDARY
   LAYER WARMS MLCAPE WILL LIKELY INCREASE TO 3000+ J/KG FROM ERN TX TO
   AROUND 2000+ J/KG FARTHER NORTH INTO THE CNTRL PLAINS AND THE MID MS
   VALLEY.
   
   VORT MAX NOW LOCATED OVER THE SWRN STATES WILL ROTATE THROUGH THE
   BASE OF THE UPPER LOW AND INTO THE SRN PLAINS AND MID MS VALLEY
   DURING THE AFTERNOON AND EVENING. DEEPER FORCING ACCOMPANYING THIS
   FEATURE WILL AUGMENT POTENTIAL FOR ISOLATED TO WIDELY SCATTERED
   STORMS TO DEVELOP ALONG DRYLINE/PACIFIC FRONT FROM CNTRL TX NWD
   THROUGH ERN OK...ERN KS AND NEB AS CAP WEAKENS. EFFECTIVE VERTICAL
   SHEAR WILL SUPPORT SUPERCELLS FROM TX THROUGH OK AND KS INTO THE
   LOWER MS VALLEY WITH MORE MARGINAL SHEAR WITH NWD EXTENT THROUGH ERN
   KS AND NEB. PRIMARY INITIAL THREAT WILL BE LARGE HAIL WITH ISOLATED
   VERY LARGE HAIL ALSO POSSIBLE GIVEN EXPECTED HIGH VALUES OF
   NORMALIZED CAPE ASSOCIATED WITH STEEP LAPSE RATES. ISOLATED
   TORNADOES WILL ALSO BE POSSIBLE...ESPECIALLY TOWARD EARLY EVENING
   OVER THE SRN PLAINS AND LOWER MS VALLEY AS LLJ STRENGTHENS AND
   BEFORE THE BOUNDARY LAYER BEGINS TO STABILIZE. ACTIVITY WILL
   CONTINUE INTO THE LOWER-MID MS VALLEYS OVERNIGHT POSSIBLY EVOLVING
   INTO MCS CLUSTERS WITH A THREAT FOR ISOLATED DAMAGING WIND AND HAIL.
   
   ..DIAL/GARNER.. 05/21/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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