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 220102
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0802 PM CDT SAT MAY 21 2011
   
   VALID 220100Z - 221200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE SRN
   THROUGH CNTRL PLAINS INTO THE LOWER-MID MS VALLEYS...
   
   ...CNTRL PLAINS THROUGH MID MS VALLEY REGION...
   
   SEVERAL VORTICITY MAXIMA ARE ROTATING THROUGH LARGE UPPER LOW
   CIRCULATION CENTERED OVER WRN SD. NUMEROUS STORMS ARE DEVELOPING IN
   ASSOCIATION WITH THESE FEATURES FROM SERN SD...SRN MN...ERN
   NEB...WRN IA AND NERN KS. COOL TEMPERATURES ALOFT ASSOCIATED WITH
   UPPER LOW AS WELL AS REMNANT EML HAVE RESULTED IN STEEP /7.5-8 C/KM/
   MID LEVEL LAPSE RATES. THIS IN CONJUNCTION WITH LOW 60S BOUNDARY
   LAYER DEWPOINTS ARE PROMOTING 2000-2500 J/KG MLCAPE AND HIGH VALUES
   OF NORMALIZED CAPE WHICH COMBINED WITH EFFECTIVE SHEAR SUPPORTIVE OF
   SUPERCELLS WILL CONTINUE TO PROMOTE A THREAT OF VERY LARGE HAIL THIS
   EVENING. LATEST VWP DATA ALSO INDICATE SIZEABLE HODOGRAPHS WITH 0-1
   KM STORM RELATIVE HELICITY FROM 200-300 J/KG SUGGESTING A WINDOW
   STILL EXISTS FOR ISOLATED TORNADOES FROM ERN KS...NWRN MO INTO SWRN
   IA BEFORE THE BOUNDARY LAYER BEGINS TO STABILIZE. A FEW STORMS MAY
   EVENTUALLY EVOLVE INTO SMALL CLUSTERS AS THEY DEVELOP EWD WITH A
   CONTINUED THREAT FOR ISOLATED DAMAGING WIND AND LARGE HAIL OVER THE
   MID MS VALLEY REGION BEFORE WEAKENING LATER TONIGHT.
   
   
   ...SRN PLAINS THROUGH LOWER MS VALLEY...
   
   
   A RETREATING DRYLINE EXTENDS FROM THE BIG BEND AREA OF TX NWD
   THROUGH CNTRL OK INTO S-CNTRL KS WHERE IT INTERSECTS THE PACIFIC
   FRONT. SUPERCELL CLUSTER THAT DEVELOPED EARLIER ALONG THIS BOUNDARY
   CONTINUE ACROSS CNTRL TX. LARGE HAIL...ISOLATED DAMAGING WIND AND A
   TORNADO OR TWO WILL REMAIN POSSIBLE THIS EVENING WITH THIS ACTIVITY.
   EWD EXTENT OF DEVELOPMENT OF THESE STORMS WILL PROBABLY BE LIMITED
   BY STRONGER CONVECTIVE INHIBITION DOWNSTREAM ACROSS SERN TX.
   
   OTHER MORE ISOLATED STORMS HAVE DEVELOPED ALONG RETREATING DRYLINE
   ACROSS E-CNTRL THROUGH S-CNTRL OK WHERE STRONG INSTABILITY EXISTS
   WITH 2500-3500 J/KG MLCAPE. A MID LEVEL JET ROTATING THROUGH BASE OF
   UPPER LOW IS CONTRIBUTING TO 50 KT EFFECTIVE SHEAR AND STORMS HAVE
   DEVELOPED SUPERCELL STRUCTURES. IN ADDITION TO VERY LARGE HAIL...0-2
   KM HODOGRAPHS WILL ALSO SUPPORT A THREAT OF ISOLATED TORNADOES AS
   THE LLJ STRENGTHENS AND BEFORE THE BOUNDARY LAYER STABILIZES. FUTURE
   EVOLUTION OF THESE STORMS IS COMPLICATED BY LOW CLOUDS BENEATH
   INVERSION OVER SERN OK...SUGGESTING STORMS WILL MOVE INTO A MORE
   HOSTILE ENVIRONMENT AS THEY DEVELOP EWD. NEVERTHELESS PRESSURE
   PERTURBATIONS WITHIN THE ROTING UPDRAFTS MAY HELP TO SUSTAIN THE
   STORMS ANOTHER FEW HOURS DESPITE A STABILIZING BOUNDARY LAYER.
   
   OTHER STORMS ARE DEVELOPING ALONG AND NORTH OF AN OLD OUTFLOW
   BOUNDARY ACROSS SRN AR. EFFECTIVE SHEAR OF 40-50 KT IS SUPPORTIVE OR
   ORGANIZED STORM STRUCTURES INCLUDING SUPERCELLS. HOWEVER...THE
   STORMS CURRENTLY MIGHT BE SLIGHTLY ELEVATED ABOVE THIS BOUNDARY.
   ISOLATED LARGE HAIL...DAMAGING WIND AND PERHAPS A BRIEF TORNADO OR
   TWO WILL BE POSSIBLE AS THIS ACTIVITY DEVELOPS NEWD.
   
   ..DIAL.. 05/22/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z