694
FXUS65 KMSO 021943
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
143 PM MDT Sat Aug 2 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.

- Brief intrusion of drier air gives the region a day off from
  storms for most on Sunday.

- Trough with active weather returns for Monday and Tuesday.

- Chances for showers and thunderstorms increasing again by the
  end of next week.

This afternoon, satellite confirms modeled estimates of anomalous
amounts of moisture which continues to remain in place across the
Northern Rockies (nearing, and in excess of, 1 of precipitable
water). A severely negatively-tilted upper level trough moving
through the region will induce large-scale lift resulting in
scattered showers and thunderstorms through the evening. Mid and
upper level westerly steering flow has increased in contrast with
the last couple days. So, while most of the environmental
ingredients are in favor of significant heavy rain under developed
showers or storms, west-to-east progression will keep storms
moving enough that the concern for long-duration heavy rain and
flash flooding has been reduced. There is still some potential,
where storms build upstream or over the same location again and
again, that localized flash flooding, rock/mud/debris flows, and
ponding of low-lying areas is still possible especially north of
I-90. Otherwise, small hail and wind gusts up to 35 mph will be
possible with stronger storms.

An intrusion of much drier air (in all vertical layers of the
atmosphere) moves into the region for Sunday which will subdue
most convection. The most likely regions to see remaining dry and
gusty thunderstorm threats will be in southwestern Montana and
north-central Idaho where decreased but sufficient moisture will
still linger.

By Monday and into Tuesday, another trough will lift through the
area once again producing numerous showers and thunderstorms
particularly during the afternoon and evening hours. Relatively
weak but noticeable cold advection aloft will help to destabilize
the atmosphere as well as continue the progression of downward
temperature trends. Highs in the 70s and low 80s will be common
through much of next week. An extended fetch of stronger
southwesterly flow on Wednesday will invoke inverted-V profiles,
isolated high-based gusty thunderstorm potential, and a brief bump
of high temperatures back to near-normal before another trough
approaches late in the week, again, cooling temperatures and
increasing chances for precipitation Thursday into Friday.

Ensembles are in modest agreement for a ridge signal over much of
the Pacific Northwest by late next weekend and into the 2nd week
of August. The one difference is in how amplified or subdued the
ridge feature will be, about 70% of members show nearly zonal
flow overhead with a subtle ridge in place and the other 30%
indicates a much stronger ridge with higher heights regionwide.
Regardless of those exact details, there is concern for increasing
critical fire weather conditions during this time period even
though recent weather trends have subdued those concerns as of
late.



&&

.AVIATION...Satellite and radar imagery this afternoon show
showers and thunderstorms developing across north-central Idaho
and western Montana. Brief heavy rain and visibility less than 3
miles has been observed, and will continue to be the main threats
from storms into early afternoon. Sunday looks to be much drier
with lower chances for thunderstorms, mostly confined to south of
Highway 12.


&&

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

$$