Butte-Silver Bow, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

679
FXUS65 KMSO 172052
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
252 PM MDT Thu Apr 17 2025

.DISCUSSION...

KEY MESSAGES:

-  Gusty north winds to 25 mph this afternoon, along with showers.

-  Chilly start Friday with teens/20s, but becoming sunny & mild.

-  Unsettled weather Saturday through early next week with pass-
   level snow at times

Yesterday was quite a day...with some places getting well into
the 60s before crashing down into the 40s as the cold front
blasted southwards across western Montana. The upper trough was
situated in a position to produce ample lift, which resulted in
strong snow showers, some of which produced lightning
(thundersnow!). There were almost a dozen cloud-to-ground
lightning strikes across northwest Montana yesterday. When the
arctic cold front made it south towards Missoula by 4 pm, it was
mostly a dry cold front passage, but the winds gusted up to 51
mph. As the area of strong lift shifted south over west-central
and southwest Montana, snow showers materialized in the valleys.
Other interesting things to share from this event: our COOP
observer in Essex reported 5.1 inches of snow, the GPI airport saw
a peak northeast wind gust to 45 mph with the Flathead Valley
experiencing heavy snow at times, and there were a fair amount of
power outages especially in the Heron area where our COOP there
reported tree limbs and even a tree down due to the strong winds.
The system was slow-moving which allowed for further snow showers
and winter-like conditions at area passes this morning.

Today, there continues to be a northerly wind/pressure gradient
and the mesonet depicts wind gusts between 20 and 30 mph across
the region. The University of Montana Flathead Lake Bio Station
mesonet shows northerly winds between 8 and 15 mph. We don`t
anticipate the winds getting much stronger than 20 mph at Flathead
Lake into the early evening hours. A shortwave embedded in the
flow will trigger showers this afternoon, but then dissipate by
nightfall.

This weather system brought in some drier air from Canada and dew
points are in the teens this afternoon. This combined with
clearing skies and weakening winds from a 1025 millibar surface
high building in tonight, will support good radiational cooling.
Forecast low temperatures have been trended downwards. If you live
in the surrounding areas outside of towns and near the river
bottoms in western Montana, there is a 50 percent chance that low
temperatures could be in the upper teens Friday morning. So
protect any sensitive plants. For example, even though the
Missoula Airport may experience a low of 22, areas to the south
and west could get down to 16 or 17 degrees. If you`ve planted
sensitive bulbs like Dahlia`s, you may want to cover or put extra
mulch on top. Box stores may want to bring in their plants for the
night.

After dry and partly sunny start on Saturday, a cold front will
bring clouds, showers and breezy west winds to 25 mph by the
afternoon. Total precipitation amounts will generally be several
hundredths in the mountains.

A much colder trough, originating over the central Aleutians
yesterday, will dig south over our region Sunday into Monday. On
Sunday, instability showers will develop in the afternoons. Snow
levels will generally be around 4500 feet on Sunday then falling
to 3500 feet on Monday, so some passes could experience periods of
snow. Looking at a 2 day snowfall total, mountains could receive
several inches of snow with the most likely range between 2 and 5
inches, except some of the more favored western slopes could get 6
or more inches through Monday night. This trough will also bring
breezy westerly winds across the region.

Beyond this, ensemble models depict us staying under a trough
and/or northwest flow Tuesday and possibly Wednesday. This could
support continued daily showers and moderating temperatures.
Another trough may dig further to our west mid to late next week.
This could induce brief ridging over us, but also produce a setup
conducive for Yellowstone cutoff lows and additional unsettled
weather!


&&

.AVIATION...Across western Montana and north-central Idaho, breezy
northerly winds to 25 kts is expected through the early evening
hours then diminish. Scattered snow showers will bring periodic
mountain obscuration, and gusts to 35 kts through 18/0200Z(8 pm
MDT this evening). A chilly morning is on tap Friday before
warming up with plenty of sunshine and VFR flying. A cold front
will bring light showers and gusty west winds to 25 kts on
Saturday afternoon.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...ID...Wind Advisory until 6 PM MDT this evening for Eastern Lemhi
     County.

&&

$$