497
FXUS65 KMSO 012016
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
216 PM MDT Fri Aug 1 2025

.DISCUSSION...

KEY MESSAGES:

-  The KMSX Radar (Missoula, MT local weather radar) will remain
   offline due to scheduled maintenance through the first week of
   August.

-  Widespread shower and thunderstorm activity continues today
   and Saturday.

-  Short break from unsettled weather on Sunday, more rain on
   Monday.

A shortwave trough of low pressure over the Northern Rockies will
combine with anomalously high moisture content (200 to 210 percent
of normal), producing another round of widespread shower and
thunderstorm activity this afternoon through the evening. The
primary focus for excessive rainfall rates will be across western
Montana, north of I-90. A Flood Watch has been issued for Lincoln,
Sanders, Flathead, and Lake counties, which will go into effect
this afternoon and remain in place until midnight tonight. There
is a 15 to 20 percent probability that rainfall rates will range
between 1 and 2 inches per hour. Some locations in west-central
Montana experienced rates nearing 1 inch in 30 minutes yesterday,
and isolated areas could see similar rates today.

It`s important to remember that just because you are under a
watch, not every location will experience heavy rainfall. However,
if you are in a flood-prone area, a low-lying location, or near
burn scars, stay informed about local weather conditions.

The rest of western Montana and north-central Idaho will also face
the threat of scattered thunderstorms, though they are expected to
be less consolidated compared to the past couple of days. That
being said, stay alert if a strong thunderstorm develops nearby.

The trough will continue to bring chances for rain on Saturday,
with the focus for precipitation and convection remaining across
northwest Montana. 24-hour precipitation totals ending Saturday
night are expected to be around 0.25" to 0.50", with isolated
higher amounts.

A transient ridge will build over the Northern Rockies on Sunday,
bringing a short break from unsettled weather for most areas,
although some isolated thunderstorm chances will remain along the
Continental Divide. While high pressure builds over the Northern
Rockies, a trough of low pressure will move onshore along the
Pacific Northwest. Ensemble solutions are in good agreement that
this trough will reach the Northern Rockies and bring more rain by
Monday afternoon. Although not all models agree yet, most are
pointing toward a period of mostly dry westerly flow aloft, with
some shortwaves moving along the northern border in the latter
half of the week.

&&

.AVIATION...Satellite imagery shows thunderstorms building over
the terrain early this afternoon, and a low pressure circulation
slowly moving through the Northern Rockies. Convection allowing
models agree on another active thunderstorm afternoon and evening.
Storms will be capable of heavy rain and small hail causing
decreased visibility to about 4SM, frequent lightning, and gusty
winds to about 30-40 kts. Very slow and varied storm motions will
result in slower improvement, than usual, of conditions in
locations with active showers and thundershowers. Ponding and
localized flooding on runways is possible. Shower activity will
move north of about Interstate 90 after sunset and continue into
Saturday. Places that receive heavy rain are likely to have patchy
dense fog Saturday morning. More convection is likely in
Northwestern Montana with similar impacts on Saturday starting
around 02/1800z.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Flood Watch through late tonight for Flathead/Mission Valleys...
     Kootenai/Cabinet Region...Potomac/Seeley Lake Region...West
     Glacier Region.

     Flood Watch through this evening for Lower Clark Fork Region.

ID...None.
&&

$$