Flash Flood in Idaho, July 4 to 6, 2025

Area Forecast Discussion
National Weather Service Missoula MT
149 PM MDT Fri Jul 4 2025

.DISCUSSION...

KEY MESSAGES:

-  Thunderstorms capable of producing gusty winds and locally
   heavy rain through early evening.

-  A warming trend starts early next week that will culminate in
   another extended period of hot, dry weather.

A well defined disturbance will move northward across the
Northern Rockies through Saturday. Showers and embedded
thunderstorms will continue to move south to north this afternoon
and evening bringing several rounds of precipitation. Clearing
across southern Idaho has allowed for increased instability and
will help with initiation of additional thunderstorms. High
resolution models indicate the opportunity for gusty outflow winds
over 45 mph and locally heavy rain across Lemhi County into
southwest Montana through early evening. There is a slight
probability (20%) this threat could expand northward into the
Bitterroot Valley. Additionally, the heavy rain could cause
localized flooding concerns especially over flood prone basins and
recent burn scars.

As the disturbance lifts northward, areas of light to moderate rain
will become focused in northwest Montana tonight into Saturday.
Occasional showers/isolated thunderstorms continue across the rest
of the area through Saturday evening. Prepare for the wet
conditions if you will be in the backcountry or have outdoor plans.
Also notable is high temperature running 5 to 10 degrees below
normal today and Saturday.

Zonal flow on Sunday becomes ridging through the middle part of next
week causing a warming and drying trend. Daytime temperatures
once again warm 10 to 15 degrees above normal by Tuesday with heat
risk charts indicating a return of moderate to locally major heat
risk. Breezy winds will also be common each afternoon.

The extended models are showing a weak disturbance flattening the
ridge late Wednesday through the latter part of the week. The
timing and strength of this disturbance is still uncertain, but
expect it to cool slightly but remain above normal temperatures
with increased westerly winds. This disturbance could also bring
scattered showers and thunderstorms back to the Northern Rockies.

&&

.AVIATION...A well defined disturbance will move northward across
the Northern Rockies through Saturday. Showers and embedded
thunderstorms will continue to move south to north this afternoon
and evening bringing several rounds of precipitation. Moderate to
occasionally heavy rain will bring periodic reduced visibility and
lowered ceilings. High resolution models indicate the opportunity
for gusty outflow winds over 45 mph across Lemhi County into
southwest Montana through early evening. There is a slight
probability (20%) this threat could expand northward into the
Bitterroot Valley.

Areas of light to moderate rain will become focused in northwest
Montana tonight into Saturday with occasional showers/isolated
thunderstorms across the rest of the area through Saturday
evening.

&&

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