642
FXUS65 KGGW 070520
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1120 PM MDT TUE OCT 6 2026
KEY MESSAGES
- WARM TEMPERATURES ABOVE NORMAL AND MOSTLY CLEAR SKIES INTO
FRIDAY.
- FRIDAY WILL BE MONITORED FOR ANY FIRE WX CONCERNS AS A RIDGE
BREAKS DOWN AND COLD FRONT MOVES THROUGH.
- OVERCAST SKIES, POSSIBLE PRECIPITATION, AND LOW TEMPERATURES
ANTICIPATED THIS WEEKEND AND INTO MONDAY. ISOLATED SNOW POSSIBLE
AT HIGHER ELEVATIONS.
DISCUSSION
SYNOPTIC SETUP: FORECAST BEGINS WITH RELATIVELY ZONAL TO NW FLOW
FROM MONTANA THROUGH THE PCNW AND ACROSS SW CANADA. TO THE S, HOT
HIGH PRESSURE SITS OVER THE DESERT SOUTHWEST WITH A RIDGE
BUILDING INTO THE INTERMOUNTAIN WEST. FARTHER WEST A HIGHLY
AMPLIFIED TROUGH IS WORKING ITS WAY INTO THE GULF OF ALASKA.
TODAY THROUGH THURSDAY NIGHT: ZONAL TO NW FLOW REMAINS RELATIVELY
INTACT WITH TEMPS REMAINING 5 TO 15 DEGREES ABOVE NORMAL WITH
RELATIVELY DRY CONDITIONS. THERE IS A SMALL CHANCE (5-15%) DURING
THIS TIME THAT ANY FIRES OVER THE PCNW COULD BEGIN TO POOL SMOKE
ACROSS MONTANA FOR LIGHT HAZE, BUT CURRENT HRRR AND RAP SMOKE
MODELS SUGGEST THAT IT WILL NOT MAKE IT TO EASTERN MT AT ALL.
MEANWHILE, THE INTERMOUNTAIN WEST RIDGE WILL DRIFT EAST AND THE
CREST WILL START TO BUMP UP AGAINST MT ZONAL/NW FLOW WHILE THE
GULF OF ALASKA TROUGH BEHIND IT WILL BEGIN SLAMMING UP AGAINST
THE PCNW COAST.
FRIDAY: RIDGE CREST WILL MOVE ACROSS EASTERN MONTANA RAISING
TEMPS TO 10 TO 20 DEGREES ABOVE NORMAL WITH HIGHS INTO THE 70S
AND 80S. DOWNSLOPE WINDS COULD BEGIN TO LOWER RH A BIT MORE THAN
NORMAL AS WELL HERE LEADING TO POSSIBLE FIRE WEATHER CONCERNS.
CURRENTLY WINDS SPEEDS SEEM JUST UNDER CRITERIA. THIS RIDGE WILL
CONTINUE BE MONITORED FOR BREAKDOWN TIMING AND ANY INCREASE IN
WIND SPEED. MEANWHILE, THE PCNW TROUGH WILL SMASH INTO THE LARGE
RIDGE AND BREAK APART WITH THE SOUTHERN SECTION DIGGING S INTO THE
LOWER INTERMOUNTAIN WEST AND SOUTHERN CALIFORNIA WHILE THE
NORTHERN PART PROGRESSES EASTWARD ALLOWING COOL CANADIAN AIR TO
FILL IN BEHIND IT ON THE PLAINS.
FRIDAY NIGHT INTO MONDAY: NEWLY MINTED SW FLOW REGIME WILL DRAG A
COLD FRONT ACROSS MONTANA FRIDAY NIGHT AND LEAD TO SOME PACIFIC
MOISTURE INCREASING INTO THE REGION. BY SATURDAY TO SATURDAY
NIGHT RAINS SHOWERS WILL BEGIN TO FORM AS HIGHS DROP INTO THE 40S
AND 50S BY SUNDAY OR NEARLY 20 DEGREES BELOW NORMAL. EXPECT A
STRONG NW T N WIND BEHIND THIS FRONTAL PASSAGE SATURDAY AND
SATURDAY NIGHT. LOWS ARE SUGGESTING THAT SNOW MAY BE POSSIBLE
OVERNIGHT SUNDAY NIGHT AT HIGHER ELEVATIONS BUT TOTALS WILL BE
LESS THAN AN INCH IF IT SNOWS AT ALL. ALSO, WARM GROUND SHOULD
MELT OFF ANY ACCUMULATIONS. COOLER, WETTER PERIODS HOLD THROUGH
ABOUT MONDAY BEFORE BEGINNING TO CLEAR OUT.
FORECASTS BEYOND SUNDAY COME INTO QUESTION AS ENSEMBLE DATA MOVES
OUT OF PHASE WITH EACH OTHER. IN ADDITION, THE SOUTHERN PRAIRIE RIDGE
TO THE EAST APPEARS TO BECOME PERSISTENT ENOUGH TO BLOCK FORWARD
PROGRESS OF THE SOUTHERN FLOW WHICH MAY MEANS THE COOLER
CONDITIONS STAY A BIT LONGER BUT DRY CONDITIONS COULD RETURN TO
MONTANA MONDAY EVENING THROUGH ABOUT MID-WEEK. EXPECT THESE
PERIODS TO CHANGE IN FUTURE UPDATES. SO, LOW CONFIDENCE.
FORECAST CONFIDENCE & DEVIATIONS:
- NO CHANGES FROM NBM.
- THERE IS MODERATE TO HIGH CONFIDENCE (50-70%) IN FRONTAL TIMING
FRIDAY NIGHT/SATURDAY MORNING.
- THERE IS HIGH CONFIDENCE (80-100%) IN WARMER TEMPERATURES
THROUGH FRIDAY AND COOLER TEMPS THIS WEEKEND.
- THERE IS MODERATE TO HIGH CONFIDENCE (50-80%) IN ANY
PRECIPITATION OCCURING BETWEEN SATURDAY NIGHT AND MONDAY
MORNING.
AVIATION
LAST UPDATED: 0400Z
FLIGHT CAT RANGE: VFR
LLWS: THERE IS A SMALL CHANCE(30-60%) FOR A COUPLE HOURS OF LOW
LEVEL WINDS SHEAR NOW THROUGH 12Z FOR KGGW, KOLF AND KSDY.
DISCUSSION: SCT/BKN MID-TO-HIGH CLOUDS WILL PERSIST THROUGH THE
CYCLE.
WINDS: LIGHT AND VARIABLE THROUGH MID MORNING. NBECOMING N LATE
MORING THORUGH THE AFTERNOON. THEN TRANSITIONING BACK TO VARIABLE
THIS EVENING THROUGH TONIGHT.
/GAH
GGW WATCHES/WARNINGS/ADVISORIES
NONE.
WEATHER.GOV/GLASGOW
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