541
FXUS65 KGGW 060505
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1105 PM MDT Mon Oct 5 2026

.KEY MESSAGES...
- Warm temperatures above normal and mostly clear skies into
  Friday.

- Friday will be monitored for any Fire Wx concerns as a ridge
  breaks down.

- Overcast skies, possible precipitation, and much colder
  temperatures this weekend and into Monday.


&&

.DISCUSSION...

Synoptic Setup: Forecast begins with relatively zonal to NW flow
from Montana through the PCNW and across SW Canada. To the S, hot
high pressure sits over the desert southwest with a ridge
building into the Intermountain West. Farther West a highly
amplified trough sit south of the Aleutian Islands.

Today through Thursday night: Zonal to NW flow remains relatively
intact with temps remaining 5 to 15 degrees above normal with
relatively dry conditions. There is a small chance during this
time that any fires out west could begin to pool smoke across the
area, but HRRR and RAP Smoke models suggest nothing more than
light haze. Meanwhile, the Intermountain West ridge will drift
east and the crest will start to bump up against MT while the
Aleutian trough behind it will begin slamming up against the PCNW
coast.

Friday: Ridge crest will move across eastern Montana raising
highs to 10 to 20 degrees above normal with highs into the 70s and
80s. There is a chance that some chinook winds could begin to dry
out the atmosphere a bit more than normal as well here leading to
possible fire weather concerns. This ridge will also be monitored
for breakdown timing. Meanwhile, the PCNW trough will smash into
the large ridge and begin digging S into the lower Intermountain
west and southern California instead.

Friday night into Monday: Newly minted SW flow regime will drag a
cold front across Montana Friday night and lead to pacific
moisture streaming into the region. By Saturday to Saturday night
rains showers will begin to form as highs drop into the 40s and
50s by Sunday or nearly 20 degrees below normal. Expect a strong
wind behind this frontal passage Saturday. Temps dropping low are
suggesting that snow may be possible overnight Sunday night but
totals will be less than an inch if it snows at all. Also, warm
ground should melt off all of it. No accumulation would be
expected. Cooler, wetter periods holds through about Monday
before beginning to clear out. However, forecasts beyond Saturday
do become in question as ensemble data moves out of phase with
each other. In addition, the ridge to the east appears to become
persistent and blocks any progress in the flow which may mean the
cooler and wetter air could hold on if the trough is delayed its
exit to the east.

FORECAST CONFIDENCE & DEVIATIONS:
- No changes from NBM.

- There is moderate to low confidence (30-50%) in frontal timing
  Friday night. This could easily shift up to 12 hours in future
  forecasts.

- There is high confidence (70-90%) in warm temperatures through
  Friday and cooler temps for Sunday/Monday.

- There is moderate to high confidence (50-80%) in any precip
  occuring Saturday night through Monday morning.


&&

.AVIATION...
LAST UPDATED: 0400Z

FLIGHT CAT RANGE: VFR

DISCUSSION: FEW/SCT mid-to-high clouds over the next 24 hours.

WINDS: W and light through mid-morning. Veering NW by late morning
and then back to W again in the afternoon. Becoming light and
variable tonight.

/GAH


&&

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


&&

$$

weather.gov/glasgow