116 
FXUS65 KMSO 060937
AFDMSO

WESTERN MONTANA AND NORTH CENTRAL IDAHO FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
335 AM MDT FRI AUG 6 1999

NO DRAMATIC CHANGE TO THE PATTERN OF THE LAST FEW DAYS...WITH MOIST
SOUTHERLY FLOW OVER THE CWFA TODAY.  MODELS AGAIN STRUGGLING WITH
MOISTURE OVER THE AREA...BUT ETA DOES HANDLE THE SYNOPTIC AND
MESOSCALE FEATURES FAIRLY WELL.  SHORTWAVE...CURRENTLY NEAR
NEVADA/UTAH BORDER...WILL PUSH THROUGH SOUTHWEST MONTANA MIDDAY JUST
BRUSHING OUR SOUTHEASTERN MOST ZONES.  THE REMAINDER OF THE CWFA WILL
LACK A GOOD FORCING MECHANISM TODAY...ALTHOUGH IMPRESSIVE INSTABILITY
PROGGED (1000 TO 1500 J/KG CAPES).  ALSO...INCREASING SURFACE
CONVERGENCE TODAY OVER NORTH CENTRAL IDAHO AS THERMAL TROUGH MOVES
INTO THAT AREA.  SHORTWAVE...ROUNDING UPPER TROUGH INTO CENTRAL
CALIFORNIA THIS MORNING...WILL TRACK NORTH ACROSS SOUTHERN ZONES THIS
EVENING AND INTO NORTHWEST MONTANA LATE TONIGHT.  THERMAL TROUGH
CONTINUES SLOW MOVEMENT EAST OVERNIGHT...AND THIS LOOKS TO BE MOST
ACTIVE CONVECTIVE PERIOD FOR WESTERN MONTANA ZONES.  MODELS
INDICATING LESS INSTABILITY OVER CWFA SATURDAY...BUT THEY APPEAR TO
BE OVERDOING LOW LEVEL COOLING.  THERMAL TROUGH WILL BE DIRECTLY OVER
WESTERN MONTANA...THUS WILL KEEP CHANCE OF THUNDERSTORMS TOMORROW. 
TEMPS NEARLY PERSISTENT THROUGH PERIOD.

EXTENDED...MODELS NOT SURE ON TIMING OF MAIN UPPER TROUGH INTO
NORTHERN ROCKIES...BUT EXPECT SOUTH TO SOUTHWEST FLOW ALOFT TO
CONTINUE OVER OUR AREA.  ONLY CHANGE TO CURRENT EXTENDED WILL BE TO
LOWER HIGH TEMPERATURES.  THERMAL TROUGH SHOULD SLIDE EAST OF US BY
SUNDAY AND WILL NOT REBUILD THROUGH EARLY NEXT WEEK WITH UPPER TROUGH
REMAINING OVER THE WESTERN STATES.             WHITMORE