480
FXUS65 KMSO 130843
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
243 AM MDT Sun Jul 13 2025

.DISCUSSION...

KEY MESSAGES:

- Moderate heat risk impacts across low elevations of north-
  central Idaho and western Montana this afternoon.

- High confidence for a significant change (>90%) late Monday
  into Tuesday across northwest Montana, with much cooler
  temperatures and widespread precipitation.

- Strong northeast winds 30-45+ mph Monday and Monday night, with
  risk for spotty power outages and tree limb damage.

The hottest temperatures of the week are expected today, as highs
reach into the low-100s for lower elevations of central Idaho and
low/mid-90s across western Montana valleys. These temperatures
will bring a moderate risk of heat impacts. Consider practicing
heat safety by drinking plenty of fluids, and resting in shaded or
air conditioned environments when working outside. Furthermore,
breezy westerly winds will lead to elevated fire weather
conditions.

High confidence exists for a pattern change late Monday into
Wednesday, as a trough of low pressure moves into the region from
British Columbia. Global models suggest a potent cold front will
move across the Continental Divide Monday evening, sweeping into
western Montana Monday night, before reaching central Idaho
Tuesday morning. Strong north-northeast winds of 30-45+ mph will
accompany the front given sharp pressure rises (>10 mb in 6 hrs)
across northwest Montana, including Glacier Park and the Flathead
Valley Monday evening. High resolution model guidance suggests
mountain wave activity with locally higher gusts in excess of 45
mph downstream of mountain crests within Glacier Park and the
Whitefish and Swan Ranges. This is well supported by forecast
soundings that highlight a wind reversal and stable layer near
crest height, creating ideal conditions for mountain wave activity
Monday night. This could trigger spotty power outages, tree limb
damage, and pose a significant risk to those recreating on area
lakes like Flathead Lake.

Widespread precipitation will accompany the front, with rainfall
focusing across Lincoln and Flathead Counties in Northwest
Montana. The higher totals of 0.50-1.00+ will focus along the
divide in Glacier Park, where easterly upslope winds will enhance
orographic precipitation. Rainfall amounts will quickly drop off
along and south of the I-90 corridor, with less than 0.10 inch.
Snow levels will range between 8,000 and 10,000 feet MSL across
northwest Montana. Heavier precipitation rates Monday night into
Tuesday morning could drive the snow down to 7,000 feet in Glacier
National Park. There could be several inches of snow on the
mountain peaks on Tuesday.

By Wednesday, this system will depart the east, with a dry
northwesterly flow pattern taking shape the next several days.

&&

.AVIATION...VFR conditions are expected today under a ridge of
high pressure. Scattered mid-high level clouds will move across
Northwest Montana late this morning into the afternoon. Otherwise,
breezy winds will develop once again this afternoon, with gusts of
15-20kts.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...Heat Advisory until 8 PM PDT Monday for Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

&&

$$