174 FXUS65 KTFX 231714 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1015 AM MST SUN NOV 23 2008 UPDATED AVIATION SECTION .UPDATE... NO MAJOR CHANGES TO FORECAST PACKAGE. SLIGHT TWEAKS TO SKY CONDITIONS FOR TODAY TO SHOW A QUICKER CLEARING OUT OF CLOUDS THAN PREVIOUSLY ANTICIPATED. HIGH PRESSURE RIDGE THAT IS DEVELOPING IS BEING HANDLED WELL BY CURRENT FORECAST. SUK && .AVIATION... UPDATED 1715Z. EXPECT VFR CONDITIONS WITH ONLY CEILINGS NEAR AND ABOVE 25000 FT DEVELOPING LATE THIS AFTERNOON AND EVENING AND CONTINUING THROUGH MONDAY MORNING. THERE WILL BE SOUTHWEST TO WEST WINDS 10 TO 15 KNOTS OVER THE PLAINS THIS AFTERNOON WHICH WILL DECREASE BY EARLY EVENING THEN PICK UP AGAIN AFTER SUNRISE ON MONDAY. WINDS ARE EXPECTED TO STAY LESS THAN 10 KNOTS IN THE SOUTHWEST VALLEYS. BLANK && .PREV DISCUSSION... /ISSUED 441 AM MST SUN NOV 23 2008/ SUNDAY THROUGH MONDAY NIGHT...UPPER LEVEL TROUGH OF LOW PRESSURE CONTINUES TO PUSH EAST THIS MORNING WITH LIGHT PRECIPITATION FALLING ACROSS FAR EASTERN MONTANA. SOME RADAR RETURNS WERE NOTED EARLY THIS MORNING ALONG THE CONTINENTAL DIVIDE BUT SURFACE OBSERVATIONS INDICATED THAT NOTHING WAS REACHING THE GROUND. LATEST GFS AND ECMWF RUN SHOWED SOME PRECIPITATION LINGERING OVER THE NORTHERN ROCKIES AS WELL AS OVER SOUTHERN MONTANA WHILE THE NAM REMAINED DRY...SO DECIDED TO KEEP SMALL CHANCE OF POPS OVER GALLATIN COUNTY IN COORDINATION WITH SURROUNDING OFFICES. BOZEMAN PASS MAY ENCOUNTER LIGHT SNOW SHOWERS THROUGH EARLY THIS AFTERNOON AS THE TROUGH EXITS. QUIET WEATHER EXPECTED THROUGH THIS PERIOD WITH AN UPPER LEVEL RIDGE BUILDING IN BY SUNDAY AFTERNOON AND SURFACE HIGH PRESSURE ARRIVING FROM THE PACIFIC NORTHWEST. SEASONAL TEMPERATURES ANTICIPATED ON SUNDAY WITH SLIGHTLY ABOVE AVERAGE TEMPERATURES ON MONDAY. MLS TUESDAY THROUGH FRIDAY NIGHT...THE CWA WILL REMAIN UNDER THE INFLUENCE OF HIGH PRESSURE ALOFT TUESDAY ALTHOUGH THE RIDGE WILL HAVE MOVED OVER EASTERN MONTANA. A LOW PRESSURE TROF OVER THE EASTERN PACIFIC WILL BE MOVING TOWARDS CENTRAL CALIFORNIA BUT SOUTHWEST FLOW ALOFT AHEAD OF THIS SYSTEM...MAINLY OVER THE SOUTHWEST ZONES...WILL BE LIGHT AND THE INCREASE IN MOISTURE OVER THE AREA WILL BE SLIGHT. THE UPPER LEVEL TROF WILL HAVE MOVED WELL SOUTH OF THE ZONES BY WEDNESDAY...AND THE AIRMASS OVER THE NORTH AND CENTRAL PORTIONS OF THE CWA WILL BECOME QUITE DRY. SURFACE HIGH PRESSURE IN ALBERTA WILL SLIDE OVER NORTH CENTRAL MONTANA AND BRING COOLER TEMPS TO THE AREA. THE GFS HAS NOT BEEN HANDLING THIS TIME PERIOD CONSISTENTLY AND THE UPSLOPE FLOW FROM EARLIER RUNS HAS LARGELY DISAPPEARED...JUST A QUICK SHOT WEDNESDAY AND WEDNESDAY NIGHT. A SECOND LOW PRESSURE TROF WILL MOVE NEAR THE WEST COAST FRIDAY BUT THIS TROF WILL ALSO MOVE INTO CALIFORNIA. THIS LEAVES THE CWA IN A DRY...NORTH FLOW ALOFT. TEMPS WILL REMAIN ABOVE NORMALS UNTIL DROPPING TO NEAR NORMALS ON FRIDAY. ZELZER SATURDAY AND SUNDAY...GFS/ECMWF MODELS SHOW AN UPPER LEVEL RIDGE OF HIGH PRESSURE OVER THE PACIFIC NORTHWEST AND MONTANA THROUGH THE PERIOD. HOWEVER...AN UPPER LEVEL LOW IS PROGGED TO MOVE INTO THE DESERT SOUTHWEST WITH GFS BEING FURTHER NORTH. THUS...WILL GO FOR MILD AND MOSTLY DRY WEATHER THROUGH THE PERIOD. HOWEVER...SOME MOISTURE MAY MOVE INTO SOUTHWEST MONTANA AND UP ALONG THE DIVIDE FOR AT LEAST ISOLATED MOUNTAIN SNOW SHOWERS. WILLIAMSON DC && .PRELIMINARY POINT TEMPS/POPS... GTF 42 24 51 33 / 0 0 0 0 CTB 42 24 51 31 / 0 0 0 0 HLN 43 20 46 21 / 0 0 0 0 BZN 40 17 46 20 / 10 0 0 0 WEY 33 12 35 15 / 10 0 0 0 DLN 39 19 45 23 / 0 0 0 0 HVR 41 18 47 21 / 0 0 0 0 LWT 39 21 50 26 / 10 0 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM... LONG TERM... AVIATION... WEATHER.GOV/GREATFALLS