988
FXUS65 KMSO 221906
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
106 PM MDT Sun Jun 22 2025

.DISCUSSION...

KEY MESSAGES:

- Showers continue tonight and Monday.

- Frost potential Monday morning.

- A weak ridge builds in causing fair weather on Tuesday.

- Transition to a thunderstorm pattern on late Wednesday that
  lasts into next weekend.

An upper level low continues to spin over the region causing
showers. Some locations, like Lemhi County, ID and Glacier
National Park have picked up quite a bit of snow. As the low moves
east this evening and tomorrow, showers will continue, but snow
levels and temperatures will start to rise, so any remaining
showers should be rain.

In areas that clear out a bit tonight, cold temperature are a
concern for Monday morning. The main area of concern is in the
Bitterroot valley of Montana and near Salmon, Idaho. Further
north in western Montana, there should be enough cloud cover with
the shortwave coming through to prevent any frost impacts. Places
like Seeley Lake, Ovando, and the higher elevation valleys of
western Montana frequently get frost in June anyway, so it`s not
really an impact there, but this would be a very late frost event
for Salmon and the Bitterroot Valley, so we`ve issued a frost
advisory for these valleys.

By Tuesday a weak ridge builds over the region, but it is embedded
in a broader trough pattern. As a result, there will still be some
convection Tuesday, but we expect it will be a bit subdued and
mostly over the mountains. On Tuesday temperatures will also
rebound to slightly above average for this time of year and remain
there for the rest of the week and into next weekend.

Late Wednesday southwest flow returns to the region. Current
forecasts have several shortwaves embedded in the southwest flow,
and this is a classic pattern for thunderstorms in the region.
With the warmer temperatures in place, plenty of recent moisture,
and short waves moving through we expect scattered thunderstorm
coverage most days through the weekend. There are no strong
indicators of severe thunderstorms at this time, but depending on
the timing of the shortwaves that is possibility. Characterizing
the convection and whether or not there will be severe storms will
be the main focus of our efforts this week.


&&

.AVIATION...The upper level low over the region is moving eastward
today. Moist northerly to northwesterly flow will continue over
night causing some showers, especially near terminal KGPI. The
main impact will be occasional showers and mid-level ceilings
causing intermittent MVFR and IFR conditions. For back country
fliers, the snow levels are rising, but low ceilings and fog /
mist will likely impact back country air strips through at least
Tuesday morning.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Frost Advisory from 2 AM to 9 AM MDT Monday for
     Missoula/Bitterroot Valleys.

ID...Frost Advisory from 2 AM to 9 AM MDT Monday for Eastern Lemhi
     County.

&&

$$