SPC AC 260820
   
   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0320 AM CDT MON APR 26 2004
   
   VALID 281200Z - 291200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS NORTH CENTRAL STATES...
   
   ...NORTH CENTRAL U.S...
   SOME DIFFERENCES IN THE GFS VS ETA ON PROGRESSIVE TROUGH MOVING SEWD
   INTO PLAINS AND CENTRAL ROCKIES ON WEDNESDAY. GFS HAS A MORE
   PRONOUNCED SPLIT OF THE TROUGH WITH SRN PORTION STRONGER AND SLOWER
   THAN ETA CENTRAL ROCKIES WHILE BOTH MOVE NRN PORTION EWD VICINITY
   UPPER MS VALLEY/CANADIAN BORDER.  WITH REGARDS TO EFFECT ON ANY
   SEVERE WEATHER THREAT BOTH MODELS SUPPORT A VERY STRONG COLD FRONT
   TRAILING SWWD FROM A VIGOROUS SURFACE LOW THAT WILL BE MOVING EWD
   JUST N OF ND/MN BORDER.
   
   WHILE MOISTURE FROM GULF IS NOT AVAILABLE FOR THIS FAST MOVING
   SYSTEM...THERE WILL BE RAPID MOISTURE ADVECTION FROM SRN HI PLAINS
   OF  50F DEWPOINTS AHEAD OF COLD FRONT IN THE STRONG SWLY FLOW.
   
   MODELS ARE CONSISTENT IN SPREADING A DEEPLY MIXED AIR MASS EWD
   ACROSS PLAINS INTO UPPER MS VALLEY WITH 850-500 LAPSE RATES TO NEAR
   9C/KM. THUS EVEN WITH EXPECTED ONLY MODEST AMOUNTS OF LOW LEVEL
   MOISTURE...THE WARM SECTOR IS PROGGED BY THE ETA TO BECOME
   MODERATELY TO VERY UNSTABLE AS FAR NE AS THE UPPER MS VALLEY WITH
   THE STRONG AFTERNOON HEATING.
   
   EVEN WITH STRONG SFC HEATING THE CAP WILL WEAKEN BUT LIKELY HOLD
   OVER MUCH OF THE WARM SECTOR UNTIL ARRIVAL OF THE COLD FRONT. 
   THUNDERSTORMS ARE MOST LIKELY TO OCCUR IN THE AREA OF LOW LEVEL
   CONVERGENCE WITHIN THE FRONTAL ZONE. WITH DEEP LAYER SHEAR OF
   40-50KT AND SUCH STEEP LAPSE RATES...DAMAGING WINDS ARE THE MOST
   LIKELY THREAT WITH THESE STORMS.  THE FREEZING LEVELS WILL BE
   SUFFICIENTLY LOW WITH THE STRONG INSTABILITY TO SUPPORT AT LEAST
   SOME LARGE HAIL THREAT.
   
   SEVERE THUNDERSTORM POTENTIAL SHOULD CONTINUE INTO THE EARLY
   NIGHTTIME HOURS AS THE STRONG COLD FRONT PUSHES EWD ACROSS UPPER MS
   VALLEY TRAILING SWWD THROUGH THE CENTRAL PLAINS.
   
   ..HALES.. 04/26/2004
   
   ...NOTICE...
   FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
   LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
   GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
   HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
   INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.
   
   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED FOR 1200Z