ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 250915
   SPC AC 250915
   
   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0415 AM CDT SAT APR 25 2009
   
   VALID 281200Z - 031200Z
   
   ...DISCUSSION...
   
   MODELS ARE IN REASONABLY GOOD AGREEMENT WITH HOW UPPER PATTERN
   EVOLVES...AT LEAST THROUGH DAY 5. SEVERAL VORTICITY MAXIMA WILL
   ROTATE THROUGH LARGE UPPER TROUGH OVER THE WRN STATES. BEYOND DAY 5
   MODELS BEGIN TO DIVERGE SIGNIFICANTLY AND HAVE NOT SHOWN RUN TO RUN
   CONSISTENCY DURING THE PAST 24 HOURS.
   
   DAY 4...LOW LEVEL MOISTURE WILL ACCELERATE NWWD THROUGH THE SRN HIGH
   PLAINS EAST OF LEE TROUGH/DRYLINE AND SOUTH OF E-W ORIENTED FRONT
   THAT WILL BEGIN TO RETREAT NWD LATE DAY 4. IMPULSES EMBEDDED WITHIN
   THE SWLY FLOW REGIME WILL BE DIFFICULT TO TIME...BUT POTENTIAL WILL
   EXIST FOR STORMS TO DEVELOP WITHIN THE UPSLOPE FLOW REGIME FROM ERN
   NM INTO WRN TX WHERE STRONG INSTABILITY AND STEEP LAPSE RATES WILL
   LIKELY EXIST. VERTICAL SHEAR WILL BE SUFFICIENT FOR ORGANIZED SEVERE
   STORMS.
   
   DAY 5...SEVERE THREAT MAY EXPAND NWD TO INCLUDE THE CNTRL PLAINS IN
   ADDITION TO A PORTION OF THE SRN PLAINS AS MOISTURE ADVECTS NWD IN
   WAKE OF RETREATING WARM FRONT. THREAT WILL EXIST FOR SUPERCELLS TO
   DEVELOP ALONG AND AHEAD OF DRYLINE DURING THE AFTERNOON. BOTH THE
   GFS AND ECMWF EJECT A SHORTWAVE TROUGH THROUGH THE CNTRL PLAINS
   EARLY IN THE PERIOD WITH WEAKENING MID LEVEL FLOW AND HEIGHT RISES
   IN WAKE OF THIS FEATURE. THOUGH THE OVERALL PATTERN SUGGEST SEVERE
   STORMS WOULD BE POSSIBLE ANYWHERE FROM PARTS OF TX NWD INTO THE
   CNTRL PLAINS...WILL NOT INCLUDE A RISK AREA FOR DAY 5 AT THIS TIME
   DUE TO UNCERTAINTIES AND POTENTIAL LIMITING FACTORS.
   
   ..DIAL.. 04/25/2009

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