328
FXUS65 KMSO 261917
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
117 PM MDT Sat Jul 26 2025

.DISCUSSION...


KEY MESSAGES:

-  KMSO Radar or the local Missoula MT weather radar will continue
   to be offline due to scheduled maintenance through 1st week of
   August.

-  Thunderstorm chances will gradually increase each day, moving
   from south to north, continuing into next week.

-  There is a 30 to 40 percent probability for strong outflow
   gusts in excess of 40 mph through Monday.

Another round of showers and thunderstorms will impact many of the
same areas as yesterday, with coverage extending slightly north
and west into the southern Bitterroot and Sapphire Ranges. There
remains a 20% probability of isolated wind gusts exceeding 50 mph
from Georgetown Lake through Deer Lodge, southward to Butte, as
well as across Lemhi County. The majority of wind gusts are
expected to remain in the 30 to 40 mph range. While the northern
Bitterroot and Missoula valleys may not see thunderstorms today,
gusty outflows in excess of 30 mph will still be possible.

The overall risk of flash flooding remains low over recent burn
scars and flood-prone terrain due to sufficient steering flow from
today through Sunday. However, isolated runoff issues cannot be
entirely ruled out.

The latest high-resolution models are coming into better agreement
regarding nocturnal thunderstorms developing over north-central
Idaho (Idaho and Clearwater Counties) and moving into west-central
Montana tonight.

On Sunday, the threat for scattered thunderstorms remains in the
forecast, with expected coverage over a larger geographical area
of western Montana and north-central Idaho. Sunday`s thunderstorms
will have similar impacts, including gusty outflow winds, frequent
lightning, and brief heavy rainfall.

By the middle of next week, ensemble guidance continues to
indicate an increase in atmospheric moisture associated with
anomalously high values. Simultaneously, a large-scale trough is
forecast to move onshore over the Pacific Northwest, enhancing
wind shear and destabilizing the environment. Precipitable water
values are projected to range from 160 to 180 percent of
climatological normals, increasing the potential for more
efficient rainfall production. Under these conditions, the threat
of runoff, debris flows, and localized flash flooding over steep
terrain and burn scars will increase. Current 48-hour rainfall
probabilities show a 20 to 40 percent chance of exceeding 0.50"
for areas along and north of I-90 in western Montana. Additional
hazards could include frequent lightning, small hail, and strong
wind gusts.

Individuals with outdoor plans today through next week should
remain weather-aware and be prepared to modify activities in
response to increasing thunderstorm potential across western
Montana and north-central Idaho.


&&

.AVIATION...Scattered showers and thunderstorms will develop
across Lemhi County, Idaho and southwest Montana, including
terminals KSMN and KBTM, through roughly 27/0200Z. Seasonally
warm temperatures and elevated cloud bases will favor strong
convective downdrafts, with isolated outflow wind gusts exceeding
35 kts possible (20% chance) in association with the more robust
storms. Heavy downpours and abundant lightning are also threats
with any storms that develop today. Widespread afternoon winds
will impact all terminals through 27/0300Z. Nocturnal convection
is likely for KGIC, KHRF, KMSO, with a lesser threat at KBTM and
KSMN.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$