000 FXUS65 KTFX 290246 AFDTFX SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST NATIONAL WEATHER SERVICE GREAT FALLS MT 845 PM MDT THU AUG 28 2003 .DISCUSSION...WILL UPDATE ZONES. CLOUDS CONTINUE TO MOVE DOWN TOWARDS NORTHERN ZONES FROM CANADA WITH UPPER TROF PULLING EASTWARD. ANOTHER DISTURBANCE MOVING UP TOWARDS SOUTHWESTERN ZONES SETTING OFF ISOLATED CONVECTION. CLOUDS AND MOISTURE CONVERGENCE OVER CENTRAL AND EASTERN PORTION OF ZONES. LOWS TONIGHT WILL BE ON TRACK IF CLOUDS MOVE OFF OR THIN OUT. DOES NOT LOOK LIKE CLOUDS WILL STAY OVER AREA LONG ENOUGH TO KEEP LOWS WARMER THAN FORECAST. SURFACE HIGH ALONG CANADIAN ROCKIES SLIDING DOWN TOWARDS NORTHWEST MONTANA. WINDS WILL BE A LITTLE STRONGER OVER SOUTHWEST ZONES. CAMP TONIGHT...A CHILLY NIGHT ON TAP FOR THE ENTIRE AREA AS A CANADIAN SURFACE HIGH PRESSURE SYSTEM AND ASSOCIATED COOL AIR SETTLES IN. THE ONLY CHANCE FOR ANY PRECIP TONIGHT WILL BE ACROSS THE EXTREME NORTHEAST WHERE ISOLATED SHOWERS MAY DEVELOP AS MOISTURE WRAPS AROUND A WEAKENING UPPER LEVEL TROUGH. ALSO...A FEW SHOWERS/T-STORMS ACROSS EXTREME SOUTHERN GALLATIN/MADISON/BEAVERHEAD WITH AN AXIS OF MID-LEVEL INSTABILITY AND WEAK LOW-LEVEL CONVERGENCE. OTHERWISE CLOUDS WILL PERSIST ACROSS THE NORTH THEN GRADUALLY DISSIPATE TOWARDS MORNING. FRIDAY AND FRIDAY NIGHT...CLOUDS MAY BE DIFFICULT TO ERODE ALONG THE SPINE OF THE ROCKIES INTO THE MORNING BUT SHOULD DISSIPATE BY AFTERNOON. OTHERWISE A PARTLY CLOUDY DAY FOR MOST AREAS WITH TEMPS MODERATING A FEW DEGREES WITH DRY AIR IN PLACE. THE EXCEPTION WILL BE ACROSS THE FAR SOUTHWEST...WHERE AND UPPER LEVEL LOW CURRENTLY MOVING ONTO THE CALIFORNIA COAST WILL MOVE INTO SOUTHERN IDAHO BY AFTERNOON. GOOD FRONTOGENESIS TO THE NORTH OF THIS SYSTEM WILL SET UP IN SOUTHERN MONTANA. HAVE RAISED POPS TO SCATTERED FAR SOUTHWEST...WITH A SHARP GRADIENT TO THE NORTH. THIS SYSTEM WILL BE SLOW TO MOVE OUT AS IS PHASES WITH THE WEAKENING NORTHERN STREAM TROUGH. CHILLY LOW TEMPS EXPECTED ONCE AGAIN ACROSS THE AREA. SATURDAY AND SUNDAY...DRY CONDITIONS WILL BE THE RULE AS AN UPPER LEVEL RIDGE BUILDS INTO THE AREA. TEMPS SHOULD SLOWLY MODERATE A FEW MORE DEGREES EACH DAY...AS SUNSHINE WARMS THE AIRMASS. WINDS WILL BE GENERALLY LIGHT...MAKING FOR A PLEASANT LATE SUMMER WEEKEND. VILLANI LABOR DAY THROUGH THURSDAY...LOOKING LIKE A DRY PERIOD WITH THE FORECAST UNDER THE INFLUENCE OF AN UPPER RIDGE EITHER OVER THE FORECAST AREA OR NOT TOO FAR UPSTREAM. BOTH THE 12Z WED RUN OF THE ECMWF AND THE 12Z THU RUN OF THE GFS HAVE A SHORTWAVE MOVING THROUGH THE FORECAST AREA ABOUT LABOR DAY MORNING. LATEST GFS DOES NOT HAVE MUCH MOISTURE WITH IT SO DO NOT FEEL TOO UNCOMFORTABLE IN CONTINUING THE DRY FORECAST. MODELS DIFFER SOME ON THE POSITION OF THE UPPER RIDGE TOWARDS MIDWEEK. ECMWF HAS IT FARTHEST WEST WHICH ALLOWED THE MODEL TO SPREAD SOME COOLER AIR FROM CANADA OVER THE AREA BY WED. 00Z GFS ALSO HAD THIS BUT WAS NOT AS COOL AS THE ECMWF. LATEST GFS AND LATEST UKMET RUNS HAVE COME MORE IN LINE WITH THE GFS ENSEMBLES WHICH HAVE THE UPPER RIDGE OVER THE FORECAST AREA BY MIDWEEK. MADE NO CHANGES TO INHERITED FORECAST. BLANK .CCF NUMBERS GTF BU 040/073 041/078 041 16000 UUUUU 080/046 079/047 081/049 082/050 084 00000000000 CTB BU 041/069 040/076 042 16000 UUUUU 078/045 078/045 078/047 079/048 081 00000000000 HLN BU 045/075 043/078 043 16000 UUUUU 080/046 080/047 081/049 082/050 084 00000000000 BZN BB 039/074 037/077 036 16021 UUUUU 079/041 080/042 080/044 081/045 083 10000000000 WEY BB 033/064 031/067 029 16244 UUUUU 069/033 071/035 073/037 074/038 076 20000000000 DLN BU 044/073 043/076 041 16022 UUUUU 078/044 080/044 079/046 080/047 082 00000000000 HVR BU 043/075 042/080 043 16100 UUUUU 082/046 080/046 081/048 082/049 084 00000000000 LWT BU 041/070 038/076 039 16000 UUUUU 078/043 076/045 077/047 078/048 080 00000000000 .TFX...NONE. $$