Nashua, Montana Weather Forecast Discussion

944
FXUS65 KGGW 200733
AFDGGW
Area Forecast Discussion
National Weather Service Glasgow MT
133 AM MDT Sat Sep 20 2025
.DISCUSSION...
KEY MESSAGES:
1) There is a possibility of patchy fog in the valleys this
morning.
2) A warmup this weekend ahead of a cold front on Sunday evening
may allow thunderstorm chances on Monday.
WEATHER PATTERN OVERVIEW:
With reasonable surface moisture still in place across much of the
area, there is low to moderate confidence of patchy fog forming
across the area, with the largest confidence in the east through
around 10 AM this morning. Then an upper ridge will build today
and tomorrow to bring above average temperatures. Then a cold
front with breezy conditions on Sunday night into Monday will move
through the area. There is moderate confidence of locations close
to central Montana receiving rainfall. There is high confidence
rainfall will remain below one tenth of an inch through Monday
evening though. There is moderate confidence a Lake Wind Advisory
will be necessary for Fort Peck Lake on Monday.
Another ridge will begin building on Tuesday to bring
temperatures up. There is little to no precipitation in the
current forecast beyond Monday as there is low to moderate
confidence of a persistent upper ridge occurring late next week.
FORECAST CONFIDENCE & DEVIATIONS:
Manually increased PoPs for most of the area on Sunday night into
Monday. Increased winds with a mix of NBM and NBM90 on Day 1.
Forecast confidence is described in the above discussion.
&&
.AVIATION...
UPDATE: 0830Z, September 20th
FLIGHT CAT RANGE: MVFR through 15Z, then VFR.
DISCUSSION: Mainly clear skies and light winds bring moderate (50
percent) confidence of patchy fog occurring through 15Z before
dissipating. There is high confidence that MVFR conditions may be
the lowest flight category. Then VFR conditions are expected the
remainder of the TAF cycle.
WIND: For KGGW, southeast at 6 to 12 kts, becoming south at 7 to
13 knots after 18Z. For all other sites, light and variable,
becoming south at 5 to 11 knots after 18Z.
EQUIPMENT: Comms issues with the KSDY observation remain. AMD NOT
SKED will remain in place until METARs are available.
&&
.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
weather.gov/glasgow

NWS GGW Office Area Forecast Discussion