SPC AC 251103
   
   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0503 AM CST THU MAR 25 2004
   
   VALID 271200Z - 281200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SRN AND CNTRL
   PLNS...
   
   ...SYNOPSIS/FORECAST...
   LARGE SCALE TROUGH ASSOCIATED WITH UPPER LOW NOW OFF THE WA/ORE CST
   EXPECTED TO PROGRESS E INTO THE WRN PLNS ON SATURDAY AS DOWNSTREAM
   RIDGE AMPLIFIES SLIGHTLY OVER THE OH/TN VLYS.  THIS WILL RESULT IN
   CONTINUED BACKING OF UPPER FLOW OVER A LARGE PART OF THE CNTRL U.S.
   
   WHILE CONFIDENCE IS HIGH REGARDING THE VERY GENERAL SCENARIO JUST
   DESCRIBED...CONSIDERABLE UNCERTAINTY EXISTS REGARDING THE DETAILS
   ASSOCIATED WITH IT.  THIS CAN BE SEEN VIVIDLY IN THE LATEST SREF
   /SHORT RANGE ENSEMBLE FORECAST/ "SPAGHETTI" PROGS WHICH DEPICT
   WIDESPREAD VARIANCE OVER THE WRN AND CNTRL U.S. AMONGST THE
   ETA/GFS/CMC/UKMET AND ECMWF MODEL 500 MB HEIGHT FORECASTS.  SIMILAR
   WIDESPREAD DISPARITY IN MEDIUM RANGE MODEL GUIDANCE HAS BEEN NOTED
   IN RECENT DAYS.
   
   THERE IS SOME AGREEMENT...AT LEAST...THAT A MAJOR PORTION OF WRN
   STATES TROUGH WILL EJECT NEWD INTO CANADA EARLY SATURDAY...LEAVING
   SRN PART OF SYSTEM TO PROGRESS MORE SLOWLY E INTO THE SRN PLNS LATER
   SATURDAY/EARLY SUNDAY. THIS IDEA SEEMS PLAUSIBLE GIVEN EXPECTED
   HEIGHT RISES OVER THE TN VLY BETWEEN NOW AND SATURDAY...AND APPARENT
   JET MAX IN WV IMAGERY ATTM DROPPING SEWD FROM NEAR 45N/145W.
   
   AT ANY RATE...WHAT CAN BE SAID IS THAT LARGE SCALE BACKING OF UPPER
   FLOW SHOULD GREATLY DIMINISH MID LEVEL LAPSE RATES OVER THE CNTRL
   AND NRN PLNS AND THE UPR MS VLY.  THUS...WHILE THUNDERSTORMS MAY
   ACCOMPANY TRAILING COLD FRONT ASSOCIATED WITH EJECTING NRN TROUGH...
   THREAT FOR WIDESPREAD SEVERE ACROSS THE UPR MS VLY/CNTRL PLNS REGION
   SHOULD REMAIN MINIMAL.
   
   FARTHER S...A BETTER CHANCE FOR SEVERE THUNDERSTORMS WILL EXIST OVER
   PARTS OF TX/OK AND SRN KS...WHERE UPPER FLOW WILL LIKELY REMAIN
   SOMEWHAT MORE WLY...AND LARGE SCALE FORCING FOR ASCENT SHOULD
   INCREASE AS SRN PART OF UPPER TROUGH APPROACHES REGION DURING THE
   DAY.  LINEAR FORCING SUGGESTS GOOD LIKELIHOOD FOR SQUALL LINE/
   QUASI-LINEAR MCS AS THE MAIN CONVECTIVE MODE...ALTHOUGH DEEP SHEAR
   /AOA 40 KT/ AND INSTABILITY /MLCAPE OF 1000-2000 J/KG/ WOULD
   CERTAINLY SUPPORT EMBEDDED SUPERCELLS.
   
   ..CORFIDI.. 03/25/2004
   
   ...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