988
FXUS65 KMSO 191927
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
127 PM MDT Tue Aug 19 2025

.DISCUSSION...

KEY MESSAGES:

- Thunderstorms capable of strong-to-severe outflow wind gusts and
  briefly heavy rain late this afternoon into this evening.

- Less hot (closer to normal) rest of the week with another warm
  up for this weekend.

- Patchy wildfire smoke from nearby fires will continue to
  decrease air quality and visibility at times.

This afternoon will be the peak of the current heat wave with
temperatures running about 10 degrees above normal for this time
of year.

A passing mid-level shortwave will help induce a round of convection
late this afternoon and evening. Ample mid-level moisture will
support localized brief heavy rainfall under any storms that
develop. Thirty to forty degree surface dew point depressions
will support multiple 40-50 mph gusts (30-40% chance) from
thunderstorm outflow. A marginal risk (5-10%) for severe (>= 58
mph) wind gust potential exists especially as storms track through
the northern Bitterroot Valley and across the I-90 corridor into
Missoula and eastern portions of Lake County. Some slight chances
for lingering showers and a couple rumbles of thunder lasts into
early Wednesday morning especially near the Continental Divide.

A dry and weak cold front pushes in from the west-northwest
through the day on Wednesday. Afternoon background wind gusts
15-25 mph will be common and t-storm chances will remain isolated
to southwest Montana & along the Continental Divide. Temperatures
will cool slightly to within 2-6 degrees above normal for the
rest of the week (normal highs now into the mid and low 80s).

A pool of even cooler air will slide to the south along the east
side of the divide forcing a back door front / shift to northeasterly
winds Thursday afternoon and into Friday. Though tangible cooling
will be felt east of the Divide, this airmass intrusion will
merely help to stabilize temperatures on the western side and
produce east/northeast winds capable of gusting to 25 mph or
greater especially near the mouths of canyons Friday afternoon.

A strong ridge of high pressure works back into the region for
this weekend reinforcing dry conditions and leading to
increasingly hot temperatures (similar to recent, 8-15 degrees
above normal).

&&

.AVIATION...Convection likely this afternoon and evening
19/2300z-20/0600z especially in the vicinity of KSMN, KHRF, and KMSO.
Surface wind gusts could reach 35-50 knots from outflow. Isolated
brief heavy rain may bring temporary reductions to visibility and
lowered ceilings to near and below 5,000ft AGL. Light, & widely
scattered, showers are possible into Wednesday morning. A dry
cold front will produce widespread westerly surface gusts 15-25
mph during the afternoon. Convective showers and storms will be
possible 20/2100z - 21/0100z in southwest Montana as far north
and west as Anaconda/Deer Lodge (3U3/38S) which would include
nearby KBTM. Patchy intermittent wildfire smoke will continue to
impact areas near KHRF, KSMN, and KBTM through the next couple
days.

&&

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

$$