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 220551
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1251 AM CDT FRI APR 22 2011
   
   VALID 221200Z - 231200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OH WWD TO MO THEN SWWD TO
   PORTIONS CENTRAL TX....
   
   ...SYNOPSIS...
   IN MID-UPPER LEVELS...INITIALLY STRONGER SHORTWAVE TROUGH NOW MOVING
   EWD OVER ID IS FCST TO WEAKEN...MOVE SLOWLY SEWD TO WY AND BECOME
   STRONGLY POSITIVELY-TILTED.  MEANWHILE...LEADING SHORTWAVE TROUGH --
   NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER WRN WY...WILL BECOME
   DOMINANT PERTURBATION...EVOLVING INTO CLOSED 500-MB LOW CENTERED
   OVER NWRN SD BY 22/18Z.  THIS FEATURE THEN SHOULD ACCELERATE ENEWD
   TO LS BY END OF PERIOD...EITHER AS MRGL CLOSED CYCLONE OR STG
   OPEN-WAVE TROUGH.
   
   LEE-SIDE SFC CYCLONE -- INITIALLY ANALYZED OVER SERN CO -- IS
   EXPECTED TO LIFT NEWD ALONG STRENGTHENING FRONTAL ZONE FROM SRN KS
   TO WRN IL BY 23/00Z...EVOLVING INTO TRIPLE-POINT CYCLONE FOR
   OCCLUDED SFC LOW OVER SD MORE CLOSELY ASSOCIATED WITH UPPER TROUGH. 
   THIS SHOULD BECOME DOMINANT CYCLONE...OCCLUDE...AND REACH SSM AREA
   BY END OF PERIOD.  MEANWHILE...COLD FRONT WILL SWEEP EWD ACROSS
   MO/IL/OH BY 23/12Z...STALLING OVER SE OK AND NW TX AS SECONDARY/WEAK
   LOW DEVELOPS INVOF SPS.  ADVECTION AND MIXING SHOULD FORCE DRYLINE
   EWD ACROSS W-CENTRAL/NW TX AND SWRN OK DURING DAY...REACHING FROM
   CENTRAL OK SWWD ACROSS W-CENTRAL TX TO EXTREME NRN COAHUILA BY
   23/00Z.  COLD FRONT WILL OVERTAKE DRYLINE OVER CENTRAL/SWRN OK PRIOR
   TO AFOREMENTIONED SFC LOW DEVELOPMENT...WHERE FRONT/DRYLINE TRIPLE
   POINT SHOULD SET UP BY END OF PERIOD.
   
   IN GENERAL...WARM FRONT SHOULD MOVE NEWD ACROSS SERN MO/SRN IL EARLY
   IN PERIOD...INTO CENTRAL PORTIONS IL/INDIANA AND SWRN OH BY LATE
   AFTERNOON.  HOWEVER...EFFECTIVE BAROCLINIC ZONE MAY BECOME
   WAVY/SEGMENTED DUE TO CONVECTIVE EFFECTS ALONG AND N OF IT.
   
   ...OH VALLEY AND ADJOINING STATES...
   MULTIPLE ROUNDS OF TSTMS MAY AFFECT THIS AREA...BEGINNING WITH
   CARRY-OVER CONVECTION FROM PRIOR PERIOD MOVING EWD ACROSS PORTIONS
   IL/INDIANA/OH DURING DAY.  THIS ACTIVITY LARGELY WILL OCCUR ALONG
   AND N OF NEWD-MOVING WARM FRONT WITH ELEVATED EFFECTIVE INFLOW
   PARCELS...AND MRGL HAIL THREAT.  EITHER BACKBUILDING/TRAILING
   PORTION OF THAT ACTIVITY...OR NEWER DEVELOPMENT OVER SERN KS/MO
   BEHIND IT...SHOULD MOVE EWD INTO WARM SECTOR OVER OH VALLEY REGION. 
   FOREGOING/PRECONVECTIVE AIR MASS WILL DESTABILIZE INTO AFTERNOON
   FROM COMBINATION OF DIABATIC HEATING AND BOUNDARY-LAYER THETAE
   ADVECTION.  WEAK MLCINH SHOULD YIELD EFFECTIVE SFC-BASED PARCELS BY
   MIDDAY...WHILE LAPSE RATES INCREASE STRONGLY WITH SWWD EXTENT FROM
   OH TO ERN MO.  CORRESPONDINGLY...MLCAPE SHOULD RANGE FROM 1000 J/KG
   NEAR ERN INDIANA/OH WARM-FRONTAL SEGMENT TO NEARLY 3000 J/KG OVER
   SRN MO.
   
   SRN RIM OF SUBSTANTIAL HEIGHT FALLS ASSOCIATED WITH NRN PLAINS/UPPER
   MIDWEST SHORTWAVE TROUGH ARE EXPECTED TO REMAIN N OF UNDISTURBED
   WARM SECTOR.  HOWEVER...TIGHTENING HEIGHT GRADIENTS ALOFT...ALONG
   WITH LOW-LEVEL MASS RESPONSE AND ISALLOBARIC FORCING...SHOULD RESULT
   IN FAVORABLE LOWER-MIDDLE TROPOSPHERIC SHEAR FOR SVR.  TORNADO
   PROBABILITY ALONG/S OF WARM FRONT APPEARS SUFFICIENT BY ITSELF TO
   WARRANT SLGT CATEGORICAL OUTLOOK...BUT ANYTHING BEYOND THAT WILL
   DEPEND STRONGLY ON MOST PROBABLE CONVECTIVE MODE...WHICH APPEARS TOO
   UNCERTAIN OR MIXED ATTM TO CONCENTRATE ANY CORRIDOR OF GREATER
   THREAT.  EXPECT FAVORABLY LARGE HODOGRAPHS...WITH 0-1 KM AGL SRH
   COMMONLY 200-400 J/KG ALONG AND S OF WARM FRONT.  DAMAGING WIND IS
   LIKELY...AND THREAT FOR LARGE HAIL WILL INCREASE SWWD IN STEP WITH
   HIGHER LAPSE RATES/BUOYANCY.
   
   ...OZARKS TO CENTRAL/SW TX...
   TSTMS ARE EXPECTED TO DEVELOP INVOF COLD FRONT AND DRYLINE DURING
   AFTERNOON...OFFERING VERY LARGE/DAMAGING HAIL AND SVR GUSTS. 
   TORNADO POTENTIAL IS CONDITIONAL ON STORM-SCALE PROCESSES...GIVEN
   MORE DEEPLY MIXED SUBCLOUD LAYERS AND HIGHER LCL THAN FARTHER NE. 
   EXPECT 8-9 DEG C/KM 700-500 MB LAPSE RATES...STG SFC HEATING AND DEW
   POINTS COMMONLY 60S F...YIELDING PRE-STORM MLCAPE 2500-3500 J/KG. 
   CONVECTIVE COVERAGE SHOULD BECOME MORE WIDELY SCATTERED TO ISOLATED
   WITH SWWD EXTENT...BUT ALSO WITH DISCRETE TSTMS FOR LONGER PERIODS
   OF TIME IN SUPPORT OF SUPERCELL POTENTIAL.  ALTHOUGH LOW-LEVEL FLOW
   AND HODOGRAPH SIZE SHOULD WEAKEN FROM SRN OK SWD...DEEP-LAYER SHEAR
   STILL MAY FAVOR SUPERCELLS...WITH INCREASING POTENTIAL FOR STRONGLY
   DEVIANT MOTIONS INTO CENTRAL TX.
   
   THREAT S OF RED RIVER WILL BE MORE STRONGLY TIED TO DIURNAL HEATING
   THAT FARTHER NE...AND AS SUCH...SHOULD WANE AFTER ABOUT 03Z. 
   CONVECTION OVER OH VALLEY AND OZARKS MAY PERSIST IN PROGRESSIVELY
   MORE LINEAR FORM OVERNIGHT...WITH HAIL/TORNADO THREATS BECOMING MORE
   MRGL AND WIND BECOMING DOMINANT SVR RISK.
   
   ..EDWARDS/ROGERS.. 04/22/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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