639
FXUS65 KGGW 060620
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1220 AM MDT SUN SEP 6 2026
KEY MESSAGES
- SHOWER AND THUNDERSTORM CHANCES AT TIMES TODAY WITH A RISK OF A
SEVERE THUNDERSTORM.
- WIDESPREAD RAIN IS EXPECTED TONIGHT THROUGH MONDAY NIGHT AS THE
UPPER LOW MOVES THROUGH MONTANA.
- STRONG WEST WINDS DEVELOP MONDAY AFTERNOON AND CONTINUE THROUGH
TUESDAY.
DISCUSSION
WEATHER PATTERN OVERVIEW:
MONTANA WILL BE IN SW FLOW ALOFT TODAY WITH UPPER LOW OVER THE
PACIFIC NW AND UPPER RIDGE TO THE EAST. A HUMID AIRMASS WILL
COMBINE WITH THE MOIST SW FLOW ALOFT TODAY TO CREATE AN UNSTABLE
ATMOSPHERE WHICH WILL ALLOW FOR CHANCES FOR SHOWERS AND
THUNDERSTORMS AT TIMES. A FEW STORMS COULD BECOME SEVERE WITH
LARGE HAIL AND DAMAGING WINDS. IT LOOKS LIKE THE YELLOWSTONE
VALLEY AND POINTS EAST WILL HAVE ANOTHER HOT DAY WITH HIGHS IN THE
90S.
SURFACE LOW DEVELOPS OVER SE MONTANA THIS AFTERNOON AND TONIGHT.
MEANWHILE, A WAVE ON SW FLOW ALOFT TONIGHT WILL ALLOW WIDESPREAD
RAIN WITH SCATTERED THUNDERSTORMS TO DEVELOP WITH HEAVY RAIN
POSSIBLE AT TIMES. THE UPPER LOW MOVES INTO MONTANA ON MONDAY AS
THE SURFACE LOW MOVES NORTH INTO SASKATCHEWAN. RAIN IS EXPECTED TO
CONTINUE MOST OF THE TIME IN THE NORTH WHILE THE MODELS DIFFER ON
HOW MUCH THE DRY SLOT WILL LIMIT RAIN IN THE SOUTH. THE UPPER LOW
MOVES TO SASKATCHEWAN AND MANITOBA MONDAY NIGHT AND BECOMES
STACKED WITH THE SURFACE LOW. GUSTY WEST WINDS WILL DEVELOP DURING
THE DAY ON MONDAY AND CONTINUE MONDAY NIGHT AND TUESDAY WITH GUSTS
TO 40 TO 50 MPH POSSIBLE. A LAKE WIND ADVISORY WILL MOST
DEFINITELY BE NEEDED FOR MONDAY NIGHT INTO TUESDAY. WRAP AROUND
RAIN IS LIKELY MONDAY NIGHT AND TUESDAY OVER THE NW HALF OF THE
FORECAST AREA WHILE THE SE WILL BE DRY MOST OF THE TIME.
RAINFALL TOTALS 1 TO 2 INCHES ARE LIKELY IN THE NW BETWEEN TONIGHT
AND TUESDAY WHILE SOME AREAS IN THE SE COULD END UP WITH LESS THAN
A TENTH OF AN INCH.
THE SYSTEM EXITS THE REGION TUESDAY NIGHT AND WEDNESDAY AND
THURSDAY ARE EXPECTED TO BE DRY.
FORECAST CONFIDENCE & DEVIATIONS:
THERE IS MODERATE TO HIGH (50 TO 80 PERCENT) CONFIDENCE IN RAIN
AMOUNTS FROM TONIGHT THROUGH TUESDAY, AND WINDS FOR MONDAY
AFTERNOON THROUGH TUESDAY.
THERE IS LOW CONFIDENCE IN THE SHOWERS AND THUNDERSTORM CHANCES
TODAY.
TWEAKED POPS AT TIMES TONIGHT TO PROVIDE BETTER HOUR TO HOUR
CONSISTENCY.
AVIATION
LAST UPDATED: 0630Z
FLIGHT CAT RANGE: VFR MOST OF THE TIME WITH AREAS OF IFR/MVFR
DISCUSSION: THERE WILL BE VARYING AMOUNTS OF LOW AND MID LEVEL
CLOUDS TODAY AND TONIGHT. CIGS WILL BE VFR MOST OF THE TIME BUT
AREAS OF MVFR/IFR CIGS ARE POSSIBLE THIS MORNING AND AGAIN TONIGHT.
SOUTHWEST FLOW ALOFT WILL HELP BRING IN SOME UPPER LEVEL
MOISTURE, SO THERE WILL BE SHOWER AND THUNDERSTORM CHANCES AT
TIMES TODAY AND THIS EVENING. WIDESPREAD RAIN WITH SCATTERED
THUNDERSTORMS WILL DEVELOP LATE TONIGHT AND CONTINUE ON MONDAY.
WINDS: NORTH TO NORTHEAST AT 5 TO 15 KNOTS TODAY BECOMING EAST TO
NE TONIGHT.
GGW WATCHES/WARNINGS/ADVISORIES
NONE.
WEATHER.GOV/GLASGOW
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