MESOSCALE DISCUSSION 1933
   NWS STORM PREDICTION CENTER NORMAN OK
   0658 PM CDT TUE SEP 04 2007
   
   AREAS AFFECTED...PORTIONS NRN UT...SERN ID...EXTREME W-CENTRAL/SWRN
   WY...SMALL PART OF NERN NV.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 665...
   
   VALID 042358Z - 050200Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 665
   CONTINUES.
   
   SCATTERED TSTMS -- A FEW OF WHICH MAY PRODUCE SVR GUSTS -- CONTINUE
   TO MOVE NEWD ACROSS MAINLY CENTRAL/NRN PORTIONS WW AREA.  THREAT MAY
   BRIEFLY/MRGLLY EXTEND E OF WW INTO PORTIONS FAR WRN WY...HOWEVER
   MUCH DRIER AND MORE STABLE AIR MASS IS EVIDENT E AND NE OF WASATCH
   RANGE...WHICH SHOULD PRECLUDE EXTENSION OF WW INTO THOSE AREAS.  AIR
   MASS OVER N-CENTRAL UT -- S AND SE OF ONGOING ACTIVITY -- WILL
   REMAIN FAVORABLY MOIST AND UNSTABLE FOR ANOTHER 2-3 HOURS WITH SFC
   DEW POINTS MID 40S TO LOWER 50S F AND MLCAPES 500-800 J/KG. 
   WELL-MIXED SUBCLOUD LAYER WILL AID POTENTIAL FOR STG-SVR GUSTS TO
   REACH SFC.  ISOLATED LARGE HAIL ALSO IS POSSIBLE IN ENVIRONMENT
   FAVORING STORM ROTATION.  EFFECTIVE SHEAR VALUES INCREASE FROM
   AROUND 35 KT OVER CENTRAL UT TO NEAR 50 KT AROUND GREAT SALT LAKE.
   
   WW MAY BE CLEARED BEHIND STRONG WLY/NWLY WIND SHIFT AND SFC
   DRYING/COOLING ASSOCIATED WITH CONVECTIVE BAND THAT EXTENDS AT 2345Z
   FROM CASSIA COUNTY ID SWWD ACROSS BOX ELDER COUNTY UT TO NRN WHITE
   PINE COUNTY NV.  CONSIDERABLE DECREASE IN SFC THETAE...BUOYANCY AND
   CONVERGENCE WILL CONTINUE W OF THAT ACTIVITY...WITH AIR MASS
   UNFAVORABLE FOR ADDITIONAL/ORGANIZED SVR DEVELOPMENT.
   
   ..EDWARDS.. 09/04/2007
   
   
   ATTN...WFO...RIW...SLC...PIH...LKN...
   
   39531551 40281430 41301327 42171324 43071219 43041060
   42111026 41031000 40161044 39671330