FXUS65 KMSO 021725
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
1125 AM MDT Fri May 2 2025

.DISCUSSION...

KEY MESSAGES:

- Hot, dry weather is expected through Saturday.

- Cold front passage Saturday evening into Sunday, bringing showers
  and thunderstorms. 

- Cooler and wetter conditions Sunday and Monday, especially in
  western Montana. 

A ridge of high pressure will move over the Northern Rockies this
afternoon through Saturday. Warm, dry, and mostly sunny skies are
anticipated. The warmest temperatures of the year so far will 
occur, with many valleys of western Montana reaching 80 degrees, 
and lower valleys of north central Idaho approaching 90 degrees. 
Despite the warm air temperatures, those recreating in area 
rivers/creeks/lakes should remember that cold water can still 
pose a hypothermia risk.

A cold front is anticipated to move through north central Idaho 
late Saturday afternoon, and then through western Montana Saturday
evening into Sunday morning. Increasing clouds and shower 
activity are anticipated, with the potential for a few 
thunderstorms to develop both Saturday and Sunday afternoons. By 
Sunday, temperatures will be 10 to 20 degrees cooler. In 
addition, breezy north to northwest winds will likely create 
choppy conditions on area lakes.

Model ensembles are in strong agreement for a cut off low to 
develop over the Great Basin Sunday. This will lead to wrap 
around moisture within easterly flow into our region. This pattern
typically favors precipitation along the divide and in southwest 
Montana. Guidance has trended higher with precipitation over the 
last 24 hours as a shortwave trough dropping southward from Canada
will provide widespread lift, with east-northeast flow 
transporting moisture into western Montana. The latest 
precipitation forecasts call for 0.40-1.00 inches along the 
divide, with a 50 percent probability for 1.25" or more through 
the end of the day Monday. Along the US-93 corridor, 0.10-0.30 
inches are expected, with between a 20-30 percent probability for 
up to 0.50". The highest precipitation totals will focus along the
divide, where easterly upslope flow will enhance orographic 
precipitation. Finally, snow levels will lower to around 6000-6500
feet Sunday night into Monday morning, allowing for 2 to 4 
inches of snow accumulations in the higher terrain, primarily 
along the divide.

The majority of forecast models continue to indicate another 
period of warm and dry weather beginning mid-week next week as 
another ridge of high pressure builds over the region. There is 
potential for this to be a longer lived ridge than we have seen in
recent weeks. The pattern also may become favorable for 
thunderstorm development, so stay tuned!

&&

.AVIATION...VFR conditions under high pressure will continue into
Saturday. Terrain driven winds will develop by late morning-early
afternoon. Warmer temperatures will promote deeper mixing, leading
to 10-15kt gusts after 02/2100Z. A cold front is still on track 
to move across north-central Idaho Saturday afternoon and western 
Montana in the evening and overnight hours. An increase in 
westerly winds are expected, along with scattered showers and 
thunderstorms along and just behind the front. KGPI, KMSO and KHRF
will have the highest potential for possible nocturnal convection
Saturday night.

&&

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

$$