887
FXUS65 KGGW 210530
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1130 PM MDT Mon Jul 20 2026

.KEY MESSAGES...

- Slightly cooler temperatures today with a warming trend through
  the week bringing triple digit temperatures by Friday or
  Saturday.

- Daily rounds of isolated showers and thunderstorms in the
  afternoons and evenings by mid week.

- Drier and windier conditions this weekend will increase fire
  weather concerns.


&&

.DISCUSSION...

WEATHER PATTERN OVERVIEW:
Upper ridging over the western and central portions of the U.S.
extends into eastern Montana through the beginning of the week,
continuing the warm, but seasonally average, temperatures. Given
NE Montana will be on the northeast quadrant of the ridge under
northwest flow aloft, a weak embedded shortwave may be enough to
set off a few isolated showers around mid-day today.

For Wednesday into Friday, upper ridging amplifies as the ridge
axis pushes across central Montana and adjacent Canada with a
warming trend resuming. Conditions will largely be dry save for an
isolated thunderstorm forming over the central Montana mountains
in the afternoon with the diurnal heating and instability, and the
weak embedded disturbances that might drag it across northeast
Montana in the evening hours. Most places however will remain dry
through this period. As of now monsoonal moisture looks to remain
just south of the region across southern Montana, giving an
overall drier setup.

The ridge axis will begin to slide east Into the region on Friday
into the weekend, lending to a return to triple digit heat across
the area as well as a continuation of thunderstorm chances at
times. If the current ensemble means hold, eventual heat related
products will be necessary. Some ensemble members begin to slide
the ridge axis farther east into North Dakota Sunday night through
Tuesday which should open up higher chance for monsoonal showers
across the region and may drop temps a little into early next
week. But confidence in this ridge axis slide is low.

Haze from smoke across Washington and Oregon has thankfully not
quite reduced visibility below 10 SM, and therefore has not yet
become nuisance enough to place in the grids directly. So, Big
Sky Country may have to wait awhile longer to get its namesake
back.


FORECAST CONFIDENCE & DEVIATIONS:
Changed hourly default NBM PPI01 PoPs with a CAMs Blend of NPoPs
for mentionable mid-day shower chances today. Ensemble consensus
is fairly solid depicting upper ridging over the foreseeable
future. No changes to NBM otherwise.

GAH


&&

.AVIATION...
LAST UPDATE: 0530Z

FLIGHT CAT RANGE: VFR

DISCUSSION: Upper ridging extending over the region will keep
mostly clear skies and dry weather over area terminals through
the TAF period. Some virga with downdrafts may be possible just
south of the terminals mid-day Wednesday.

WIND: N to E and 10 kts or less tonight through Tuesday
afternoon. Becoming all E Tuesday evening thorugh the night.

DENSITY ALTITUDE issues will begin to return to the terminals Friday
through the Weekend.

/GAH


&&

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


&&

$$

weather.gov/glasgow