Categorical Graphic
Probabilistic Tornado Graphic
Probabilistic Damaging Wind Graphic
Probabilistic Large Hail Graphic

   SPC AC 230557
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1257 AM CDT MON APR 23 2007
   
   VALID 231200Z - 241200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS LATER THIS AFTERNOON AND TONIGHT
   ACROSS E CENTRAL CO...W CENTRAL AND SWRN KS...THE OK/TX PANHANDLE
   AND A SMALL PART OF NWRN OK....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDS THE MDT RISK ACROSS
   PARTS OF THE CENTRAL AND SRN HIGH PLAINS....
   
   ...SIGNIFICANT SEVERE WEATHER EVENT IS EXPECTED ACROSS PARTS OF THE
   CENTRAL AND SOUTHERN HIGH PLAINS LATE THIS AFTERNOON AND TONIGHT...
   
   ...SYNOPSIS...
   
   MID/UPPER LEVEL LOW DEEPENING OVER W CENTRAL/SRN NV THIS MORNING IS
   FORECAST TO MOVE EWD OVER THE FOUR CORNERS AREA AND INTO CENTRAL/SRN
   COLORADO BY THE END OF THE PERIOD.  MODELS ARE DIFFERENT IN HANDLING
   OF SURFACE FEATURES WITH THE NAM BEING THE MOST AGGRESSIVE IN
   BRINGING A DRYLINE/SURFACE TROUGH EWD INTO THE NERN TX PANHANDLE/WRN
   OK BY 24/00Z.  HOWEVER...THE UKMET AND GFS MODELS ARE ALL SLOWER
   PLACING THIS FEATURE FROM A LOW BETWEEN PUB AND DEN THEN SEWD/SWD
   THROUGH THE CENTRAL PARTS OF THE OK/TX PANHANDLE WHICH IS THE
   PREFERRED LOCATION AT THIS TIME.
   
   ...E CENTRAL CO AND WRN KS INTO PARTS OF THE OK/TX PANHANDLE/NWRN
   OK...
   
   LOW LEVEL JET IS EXPECTED TO INCREASE THIS AFTERNOON AS BROAD
   CYCLONIC CIRCULATION ASSOCIATED WITH MID/UPPER LEVEL TROUGH MOVING
   EWD ACROSS THE SOUTHERN INTERMOUNTAIN REGION.  THIS JET WILL
   INCREASE FROM 30-35 KT THIS AFTERNOON EXTENDING FROM NWRN PARTS OF
   TX NWD/NWWD INTO NWRN KS.  A WARM FRONTAL BOUNDARY IS EXPECTED TO
   MOVE NWD FROM NRN OK THIS MORNING INTO E CENTRAL CO EXTENDING SEWD
   INTO SERN KS BY TONIGHT.  LOW LEVEL THERMAL AND MOISTURE ADVECTION
   IS EXPECTED IN THE VICINITY OF THE LOW LEVEL JET/FRONTAL BOUNDARY BY
   THIS EVENING AS EXIT REGION OF 50-70 KT SWLY MID LEVEL JET EXTENDS
   OVER THE BOUNDARY ENHANCING VERTICAL SHEAR PROFILES ACROSS PARTS OF
   ERN CO INTO SWRN KS AND THE OK AND NRN TX PANHANDLES.
   
   AIR MASS WILL BECOME MODERATELY UNSTABLE DURING THE DAY AS FORECAST
   SURFACE TEMPERATURES ARE EXPECTED TO BE INTO THE LOW/MID 70S ALONG
   THE CO/KS BORDER GIVING MLCAPE VALUES BETWEEN 2000 AND 2300 J/KG. 
   THIS COMBINED WITH DEEP LAYER SHEAR VALUES BETWEEN 50-60 KT CREATES
   VERY FAVORABLE ENVIRONMENT TO SUPPORT STRONG UPDRAFTS/DISCRETE
   SUPERCELLS IN THE VICINITY/JUST OFF THE DRYLINE BY LATE AFTERNOON. 
   GIVEN THAT LOW/MID LEVEL LAPSE RATES ARE BETWEEN 7.0 AND 8.0C/KM BY
   LATE AFTERNOON...LARGE HAIL MAY BE THE INITIAL THREAT WHEN THE
   STORMS DEVELOP.  BY 24/00Z...FORECAST SOUNDINGS SHOW EXIT REGION OF
   MID/UPPER LEVEL JET COUPLING WITH SSELY LOW LEVEL FLOW TO ENHANCE
   THE LOW/MID LEVEL SHEAR PROFILE INCREASING 0-3KM HELICITY TO AROUND
   325 M2/S2 AND 0-1 KM HELICITY TO NEAR 150 M2/S2 SUFFICIENT
   MESOCYCLONE/TORNADO DEVELOPMENT NEAR THE CO/KS BORDER INTO SWRN KS.
   
   THERE ARE INDICATIONS THAT A FEW DAMAGING TORNADOES COULD OCCUR WITH
   THESE STORMS GIVEN THE SUFFICIENT 0-1KM SHEAR AND LCL/LFC HEIGHTS
   BETWEEN 1000 AND 1500 M.
   
   ...LOWER OHIO VALLEY NEWD INTO PARTS OF THE LOWER GREAT LAKES...
   
   COLD FRONTAL BOUNDARY WILL MOVE SLOWLY SEWD TODAY AND TONIGHT
   EXTENDING FROM CENTRAL LAKE ERIE SWWD THROUGH CENTRAL INDIANA AND
   SRN MO.  SCATTERED THUNDERSTORMS ARE EXPECTED ALONG THE FRONTAL
   BOUNDARY THIS AFTERNOON AND EARLY TONIGHT AS AIR MASS JUST AHEAD OF
   THE BOUNDARY WILL BECOME UNSTABLE WITH MLCAPE BETWEEN 500 AND 1000
   J/KG.  SOME OF THIS ACTIVITY COULD PRODUCE SOME STRONG GUSTY WINDS
   GIVEN DRY AIR AT MID LEVELS AND THE PRESENCE OF 30-40 KT OF DEEP
   LAYER SHEAR.  GIVEN THE LIMITED INSTABILITY IS REASON FOR LIMITING
   SEVERE POTENTIAL WITH THIS ACTIVITY.
   
   ..MCCARTHY/JEWELL.. 04/23/2007
   
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