FXUS65 KMSO 232040

Area Forecast Discussion
National Weather Service Missoula MT
240 PM MDT Wed Aug 23 2017

As we shift into a southwest flow pattern, cloud cover and virga
have been drifting over central Idaho this afternoon. Above the
stable valley conditions in place, cumulus have been developing
over terrain in the more unstable mid-level conditions. Isolated
to scattered showers/thunderstorms are forecast to spread
northward across north-central Idaho and southwest Montana
tonight, producing gusty outflow winds, lightning, and very little
rainfall. Though we are not expecting any severe winds, these
strong outflow wind gusts could impact those recreating in the
outdoors. Continue to monitor our social media pages and any
thunderstorm-related products that we may issue later on for
further details.

By early Thursday morning, a cold front will move from west to
east into the forecast area, producing showers and thunderstorms
along the front, especially through northwest and west-central
Montana through the morning hours. In addition, strong gusty
westerly winds are also anticipated with the front, and should
peak throughout the afternoon hours. These winds should provide
some improvement to air quality from trapped wildfire smoke. As
greater instability ensues Thursday afternoon, scattered
thunderstorms are possible. This may be particularly true in the
post-frontal environment for northwest Montana, and also along the
frontal boundary in southwest Montana and central Idaho.

Thunderstorms will taper off Thursday night, though the breezy
and cooler conditions should last through Friday. A strong high
pressure pattern will return over the weekend to bring dry,
stable, warm air with degrading air quality.


.AVIATION...Degraded visibility from wildfire smoke will continue
for all terminals, but particularly for KMSO where MVFR/IFR
conditions have persisted. Isolated showers and thunderstorms are
possible in the vicinity of KMSO, KBTM and KSMN after 24/0000Z
through the overnight period. Gusty winds and lightning are the
main threats with storm activity. Increased westerly winds are
expected by Thursday morning with cold front passage, with gusts
peaking through the afternoon hours.



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