430
FXUS65 KMSO 010848
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
248 AM MDT Tue Jul 1 2025

.DISCUSSION...

KEY MESSAGES:

- Today will be another hot, dry day with low relative humidity.

- Thunderstorms move into Lemhi County today, and then much of
  western Montana tomorrow.

- Strong to severe wind gusts are expected to be the main impact
  from thunderstorms.

Today will be very hot and dry again. Temperatures will rise into
the mid 90s in most valleys, with the lower elevation valleys of
central Idaho, like near Orofino, rising above 100F this
afternoon. Along with the high temperatures, relative humidity
will drop down into the low to mid teens. These hot and dry
conditions are always a concern if there are any new wildfire
starts.

A weak disturbance will move through the ridge and cause some
thunderstorms this afternoon over Lemhi county, Idaho. With such
hot, dry conditions ahead of the storms, strong winds are always a
concern, and this time is no different. An ensemble of convection
allowing models are showing peak wind gusts around 57-58 mph in
Lemhi county with storms this evening. That`s very close to the
severe thunderstorm wind threshold of 59 mph. We will be watching
this system very closely for damaging winds coming from
thunderstorms.

Wednesday will be another hot day, but it will be a few degrees
cooler than Tuesday due to more cloud cover. Humidity will also
only drop into the low 20s as more moisture moves into the region
ahead of a trough. This is overall a better pattern for severe
thunderstorms. There`s more low level moisture to fuel the
updrafts, and with a trough approaching there will be a little
more shear to get the updrafts rotating. However, current
ensembles have peak wind gusts from these storms mostly in the low
to mid 50s. That`s still pretty close to the severe storm
threshold, so we`ll need watch these storms closely. The better
shear also means there is more potential for large hail. Right now
the moisture, instability, and shear levels are all high enough to
make us concerned about severe weather, but the probability of
being directly impacted by severe weather still remains around 5%.

As we get into the Independence Day weekend a trough will be over
the region fueling near daily thunderstorms. That pattern
currently does look to support severe weather. However, storms
south of Interstate-90 may produce heavy rain, which is a concern
for recent burn scars. One we will be watching closely for the
holiday weekend will be the Daly Fire scare which affects the road
over Skalkaho summit. It you`re in that area this weekend and
there is heavy rain, be alert for possible debris flows or
excessive run off near the falls on Skalkaho creek.



&&

.AVIATION...A ridge remains over the region today causing hot, dry
conditions. The HRRR smoke model is showing some minor smoke
impacts in the region today mostly affecting terminal KMSO. Some
thunderstorms this afternoon may produce strong or severe winds,
with terminals KSMN and KBTM most likely to be impacted between
01/19Z and 01/24Z.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...Heat Advisory until 9 PM PDT this evening for Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

&&

$$