912
FXUS65 KGGW 120709
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
109 AM MDT WED AUG 12 2026
KEY MESSAGES
- ISOLATED SHOWERS WILL DRIFT ACROSS NORTHEAST MONTANA TODAY AS
WINDS BEGIN TO PICK UP AHEAD OF A MAJOR PATTERN SHIFT.
- THURSDAY AND FRIDAY WILL SEE THE MANIFESTATION OF THAT PATTERN
SHIFT WITH COOLER AND POTENTIALLY SIGNIFICANTLY WETTER
CONDITIONS. OVER A 48 HOUR PERIOD, MANY LOCATIONS COULD SEE OVER
OF AN INCH OF ACCUMULATED RAINFALL.
- PRECIPITATION CHANCES DON'T COMPLETELY GO AWAY THIS WEEKEND AND
INTO EARLY NEXT WEEK, BUT OVERALL CONDITIONS WILL TREND TOWARDS
DRIER AND WARMER.
DISCUSSION
WEATHER PATTERN OVERVIEW:
TODAY AND TONIGHT, THE FLOW ALOFT WILL TRANSITION FROM AN UPPER
RIDGE TO SW FLOW ALOFT ACROSS MONTANA. MEANWHILE, AN UPPER TROUGH
MOVE INTO THE CANADIAN ROCKIES AND PACIFIC NW. THE PATTERN CHANGE
WILL LEAD TO INCREASING DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS,
WITH HEAVY RAIN POTENTIAL AS SOME SOUTHWESTERN MONSOONAL MOISTURE
DOES TRANSPORT ITS WAY THIS FAR NORTH.
THERE WILL BE CHANCES FOR SHOWERS AND THUNDERSTORMS AT TIMES
TODAY. CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE TONIGHT
WITH WIDESPREAD RAIN EXPECTED BETWEEN THURSDAY, THURSDAY NIGHT AND
FRIDAY MORNING WITH HEAVY RAIN POSSIBLE AT TIMES. THE CURRENT
PROBABILITY FOR ONE INCH OR MORE RAIN BETWEEN TONIGHT AND FRIDAY
IS 60 TO 80 PERCENT ACROSS NE MONTANA. THE PROBABILITY FOR 2 OR
MORE INCHES OF RAIN BETWEEN TONIGHT AND FRIDAY IS BETWEEN 10 AND
40 PERCENT. IF MORE THAN 2 INCHES OF RAIN OCCURS, FLOODING COULD
BECOME A POSSIBILITY DEPENDING ON HOW QUICKLY THE RAIN FALLS IN A
GIVEN LOCATION. WPC CURRENTLY HAS A SLIGHT RISK OF EXCESSIVE
RAINFALL FOR NE MONTANA THURSDAY AND FRIDAY AT THIS TIME. WILL
HOLD OFF ON ANY FLOOD WATCHES FOR NOW GIVEN THAT THE GROUND IS DRY
AND RAINFALL HAS BEEN LIGHT OVER THE LAST 4 WEEKS.
FLOW ALOFT FRIDAY NIGHT AND SATURDAY TURNS INTO A DRIER WSW ALOFT
AS THE UPPER TROUGH MOVES EAST ACROSS THE CANADIAN PRAIRIES.
RAIN CHANCES DIMINISH FRIDAY AFTERNOON AND FRIDAY NIGHT AND
SATURDAY LOOK MAINLY DRY WITH ISOLATED SHOWERS POSSIBLE.
FREQUENT WAVES MOVING ACROSS EASTERN MONTANA WILL BRING SHOWER AND
THUNDERSTORM CHANCES AT TIMES EARLY NEXT WEEK.
FORECAST CONFIDENCE & DEVIATIONS:
GENERALLY TWEAKED POPS TONIGHT AND THURSDAY TO PROVIDE BETTER HOUR
TO HOUR CONSISTENCY IN RAIN CHANCES.
LOW CONFIDENCE IN SHOWER AND THUNDERSTORM CHANCES TODAY. CONFIDENCE
IN PRECIPITATION CHANCES INCREASE TONIGHT AND THURSDAY AND ARE
HIGH THURSDAY NIGHT AND FRIDAY MORNING. HIGH CONFIDENCE IN MANY
AREAS GETTING AN INCH OR MORE RAIN OVERALL BUT LOW CONFIDENCE
POSSIBILITY OF AMOUNTS HIGHER THAN AN INCH.
AVIATION
UPDATED: WEDNESDAY, AUGUST 12, 0700Z
EXPECTED FLIGHT CATEGORY: VFR MOST OF TIME, AREAS OF MVFR AFTER
09Z THURSDAY.
SYNOPSIS: SKIES WILL VARY FROM CLEAR TO BROKEN MID AND HIGH CLOUDS
TODAY WITH ISOLATED SHOWERS AND THUNDERSTORMS POSSIBLE. MID LEVEL
CLOUDS AND CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE
TONIGHT WITH LOW CLOUDS MOVING IN FROM THE WEST AFTER 09Z
THURSDAY.
WINDS: NE 5 TO 15 KNOTS THIS MORNING AND 10 TO 15 KNOTS THIS
AFTERNOON AND EVENING BECOMING EAST TO NE 5 TO 10 KNOTS LATE
TONIGHT.
GGW WATCHES/WARNINGS/ADVISORIES
NONE.
WEATHER.GOV/GLASGOW
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