273 FXUS65 KGGW 220924 AFDGGW NORTHEAST MONTANA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 320 AM MDT SUN JUN 22 2003 .SHORT TERM... MAIN FORECAST CHALLENGE THROUGH THE PERIOD IS CHANCE OF PRECIP. UPPER TROF SPINNING ACROSS WESTERN CANADA THIS MORNING WITH SHORTWAVE PUSHING OUT OF OREGON. EXPECT SHORTWAVE TO TRACK ACROSS SOUTHERN MONTANA/NORTHERN WYOMING TODAY WITH BEST CHANCE OF THUNDERSTORMS OVER SOUTHERN ZONES THIS AFTERNOON AND EVENING. DRIER DAY ON MONDAY AS CANADA TROF MOVES INTO CENTRAL CANADA AND ANOTHER UPPER LOW FORM OVER PACIFIC NORTHWEST. SOUTHWEST FLOW AHEAD OF THIS LOW PUMPS MOISTURE AND VORTICITY INTO SOUTHERN MONTANA. SURFACE LOW TRACKS THROUGH GREAT BASIN AND HIGH PRESSURE PUSHING OUT OF CANADA SUGGEST LIKELYHOOD OF PRECIP HIGHEST OVER SOUTHERN MONTANA. WILL KEEP CHANCE POPS FOR MONDAY NIGHT THROUGH TUESDAY WITH HIGHEST VALUES OVER SOUTHERN ZONES. TEMPERATURES CONTINUE TO COOL AS MEAN UPPER TROF DIGS SOUTH THROUGH THE PERIOD. EBERT .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY NOT MANY MAJOR CHANGES FOR INHERITED EXTENDED FORECAST. MODELS IN GOOD AGREEMENT UNTIL END OF THE PERIOD. ACTIVE PATTERN LOOKS TO CONTINUE FOR THE FIRST PART OF THE EXTENDED WITH WELL BELOW AVERAGE TEMPERATURES. SPLITTY PATTERN OVER THE AREA WITH UPPER LOW CENTER/TROUGH OVER WYOMING AND SECOND LOW NEAR HUDSON BAY. PATTERN LEAVES NORTHEAST MONTANA BETWEEN MAIN SYSTEMS...SO HAVE ADJUSTED POPS TO REFLECT LOWER CHANCE IN THE NORTH CLOSER TO SPLIT THROUGH WEDNESDAY. BIGGEST CHANGE TO FORECAST WITH HIGHS ON WEDNESDAY. DROPPED THEM A FEW DEGREES WITH RATHER COLD AIR ALOFT...AND MIXING ONLY SUPPORTING HIGHS IN THE MID AND UPPER 60S. BY WEDNESDAY AFTERNOON AND THURSDAY...LOW/TROUGH FILLS IN AND AXIS MOVES THROUGH THE STATE. ENSEMBLE SOLUTIONS SUPPORTING SLOWER TROUGH PASSAGE...AND THIS IDEA ALREADY COVERED IN INHERITED FORECAST BY KEEPING CHANCE POPS IN THROUGH THURSDAY MORNING. GFS AND ECMWF SHOWING WNW FLOW AFTER TROUGH PASSES...AND WILL CONTINUE GOING DRY FORECAST FOR FRIDAY AS SURFACE HIGH POSITIONED TO THE SOUTH AND GOOD SUBSIDENCE BEHIND TROUGH SHOULD KEEP ANY CHANCES FOR PRECIP MINIMAL. MODELS DIFFER BY SATURDAY WITH GFS SHOWING ZONAL FLOW WHILE ECMWF BRINGS ANOTHER TROUGH THROUGH ASSOCIATED WITH MUCH STRONGER SYSTEM IN CANADA. WILL LEAVE GOING CHANCE POPS AS IS UNTIL MODELS COME INTO BETTER AGREEMENT. STROOZAS KGGW EBE /068 047/072 049/068 9022033 EEBT 047/068 051/075 053/077 052/079 054/ 96323300033 KGDV TBW /071 049/074 048/069 9033044 TTBE 047/067 051/075 048/078 053/080 056/ 96433300033 .GGW...NONE. $$