Butte-Silver Bow, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

725
FXUS65 KMSO 152059 CCA
AFDMSO

Area Forecast Discussion...CORRECTED
National Weather Service Missoula MT
259 PM MDT Thu May 15 2025

.DISCUSSION...

KEY MESSAGES:

-  Friday morning valley fog, followed by showers.

-  Mild/dry start Saturday morning then increasing showers.

-  A very wet Sunday with cold/wet backcountry conditions and
   mountain pass snow.

Showers will linger into this evening before tapering off
overnight. Valleys that receive late-day rain and partial clearing
may see patchy fog Friday morning. However, the next round of
showers and increased cloud cover will quickly arrive Friday
morning, with precipitation chances increasing through the day.

Model guidance continues to support a cool and wet Sunday as a low
pressure system tracks through north-central Idaho and western
Montana. Snow levels are now forecast to drop to 4,5005,500 feet,
making slushy accumulations increasingly likely across higher
terrain and mountain passes. Expected valley rain (25th75th
percentile) totals have increased to:

 - 0.30 to 0.80 inch for north-central Idaho and Lemhi County
 - 0.20 to 0.60 inch for western Montana

Slushy snow and lowered visibility may lead to slow travel over
passes including Lost Trail, Williams Creek Summit, Bannock,
Lemhi, Nez Perce, and Gilmore.

Patchy fog is possible again Monday morning, with lingering
clouds through the day. A gradual warming trend is expected next
week, though unsettled conditions may persist through Tuesday. By
mid to late week, a southwest flow pattern brings milder
temperatures and potential for spring thunderstorms. An upper
ridge is forecast to build next weekend, with the NBM showing a
5075% chance of highs returning to the 80s.

&&

.AVIATION...Showers taper off overnight, but areas of MVFR to IFR
due to patchy valley fog are possible Friday morning, especially
where skies partially clear. Expect showers to redevelop in the
Camas Prairie, Idaho by daybreak and mid- morning in western
Montana, with obscured terrain and occasional MVFR ceilings into
the afternoon.

&&

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

$$