289
FXUS65 KGGW 311921
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
121 PM MDT Sat Oct 31 2026

.KEY MESSAGES...

- Patchy fog continues through tomorrow morning.

- Light rain spreads north in the afternoon, continuing into
  trick or treating hours.

- Widespread precipitation begin on Monday as a frontal system
  moves across the region.


&&

.DISCUSSION...

Upper ridge over the northern plains will slowly drift eastward
through the weekend as an upper trough digs into the western
states. Southwest flow and weak embedded shortwaves will bring
periodic chances for rain into the region.

Light rain will continue to slowly move northeast through the
evening and linger overnight. Most locations look to have a damp
and chilly Halloween evening. Fog will continue to impact portions
of the region through the morning with some locally dense fog,
reducing visibility in spots to 2 mile or less.

As the Pacific upper trough moves through the Great Basin, a
Colorado low is expected to develop ahead of it. This will spread
precipitation northward, and will generally favor the Yellowstone
basin for Sunday night into Monday. Splitting in the upper trough
near the Canadian boarder will keep cold air from being drawn
southward, and result in little to no mixed precipitation or snow.
As the surface low deepens, an increase in winds will result by
Monday afternoon.

A progressive, unsettled pattern will keep next week interesting
with repeated upper level troughs.

FORECAST CONFIDENCE & DEVIATIONS:

Adjusted PoPs by blending SREF for slightly expanded coverage.
Otherwise no changes to NBM.

A lot of uncertainty regarding fog, low cloud and precipitation
today.

System for Monday continues to slide southward, which is common,
and could result in less precipitation, especially across the
north, than expected.


&&

.AVIATION...
LAST UPDATED: 1900Z

FLIGHT CAT RANGE: MVFR, IFR during patchy fog.

DISCUSSION: Lingering MVFR/IFR stratus will continue through
tomorrow. Low stratus and patchy fog cannot be ruled out again
overnight. Light rain at times through the late evening.
Widespread rain begins after 0z Monday.

WIND: Light and variable through tomorrow afternoon.

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/glasgow