159
FXUS65 KGGW 112103
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
303 PM MDT THU SEP 11 2025
DISCUSSION
KEY MESSAGES:
- SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE TODAY THROUGH
THIS WEEKEND, SOME OF WHICH MAY BECOME MARGINALLY SEVERE.
WEATHER PATTERN OVERVIEW:
THIS APPROACHING LOW PRESSURE SYSTEM, NOW MOVING THROUGH IDAHO IS
SETTING UP THE REGIONAL ATMOSPHERE DYNAMICS THAT SUPPORT THE
DEVELOPMENT OF SCATTERED RAIN SHOWERS AND ISOLATED THUNDERSTORMS.
THE OVERALL CONVECTIVE FORCING FOR SEVERE STORMS IS RATHER WEAK AT
THIS TIME, BUT MAY STRENGTHEN LATER THIS EVENING OVER THE
YELLOWSTONE RIVER VALLEY WITH A STRENGTHENING LOW LEVEL JET STREAK.
DETAIL UNCERTAINTY IS HIGH GIVEN THE AMOUNT OF MODEL
DISAGREEMENT. NEEDED TO MAKE MANY MANUAL FORECAST ADJUSTMENTS ON
THE FLY TO BRING THE GRIDS IN LINE WITH REALITY. ANY DEVELOPING
STORMS WILL NEED TO BE CLOSELY WATCHED FOR SEVERE POSSIBILITY
THROUGH THIS EVENING.
FRIDAY AND SATURDAY MAY ALSO SEE MARGINALLY SEVERE THUNDERSTORMS
WITH MORE DETAIL (HOPEFULLY) GETTING WORKED OUT LEADING UP TO
THOSE TIMES.
IT IS STILL ANTICIPATED THAT SATURDAY WILL BE THE DAY THAT THE
CIRCULATION LINES UP AND STALLS OVER SOUTHERN MONTANA FOR A BIT,
ALLOWING FOR A MORE WIDESPREAD COVERAGE OF RAINFALL. RECENT MODEL
DATA HAS TRENDED TO FAVOR OUR EASTERN ZONES WITH MORE RAINFALL,
AND THEN LESS FOR OUR WESTERN ZONES DURING THIS TIME.
EARLY NEXT WEEK, THE LOW PRESSURE CENTER OPENS INTO AN OPEN WAVE
AND GETS ABSORBED INTO THE LARGER-SCALE TROUGH IN THE CANADIAN
ROCKIES.
FORECAST CONFIDENCE & DEVIATIONS:
DEVIATED FROM THE NBM WITH HI-RES CAMS FOR POPS AND WINDS TO
LINE UP BETTER WITH REALITY.
THERE IS LOW CONFIDENCE ON STORM SEVERITY, LOCATION, AND TIMING
OF THUNDERSTORMS TODAY AND TOMORROW. THERE IS MODERATE
CONFIDENCE ON THE AFOREMENTIONED RAINFALL AMOUNTS FOR THIS
WEEKEND.
AVIATION
UPDATE: 2102Z
FLIGHT CAT RANGE: VFR, MVFR IN THUNDERSTORMS.
DISCUSSION: LOW PRESSURE SYSTEM NOW APPROACHING OUR REGION IS
SETTING OFF ENOUGH SHOWERS AND THUNDERSTORMS THAT ALL NE MT TAF
SITES ARE UNDER THE GENERAL THREAT OF OCCASIONAL PASSING STORMS
THROUGH THIS TAF CYCLE. THIS UNSTABLE PERIOD WILL LAST THROUGH
THIS WEEKEND.
WIND: GENERALLY LIGHT AND VARIABLE, BECOMING ERRATIC AND GUSTY
NEAR THE STRONGER STORMS.
EQUIPMENT: COMMS ISSUES WITH THE KSDY OBSERVATION REMAIN. AMD NOT
SKED WILL REMAIN WITH THE TAF THERE UNTIL TRANSMISSION OF OBS
BECOMES MORE STABLE.
GGW WATCHES/WARNINGS/ADVISORIES
NONE.
WEATHER.GOV/GLASGOW
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