Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 272038

Area Forecast Discussion
National Weather Service Missoula MT
238 PM MDT Tue Jun 27 2017

.DISCUSSION...A typical summer afternoon and evening still looks
likely today, with seasonal temperatures and breezy valleys winds
in the 15 to 20 mph range, gusting to 30 mph through sunset.
Thunderstorms currently over SW Montana and Idaho & Lemhi county,
ID will continue to produce lightning, strong gusty winds, and
brief heavy downpours throughout this evening. This storm activity
moves to the SE after sunset, with only isolated mountain showers
in this area remaining overnight.

The forecast for Wednesday has changed a bit, with models now
stretching the large-scale trough a bit further southwest over
the Northern Rockies. This will translate to a better chance for
afternoon valley showers than previously thought. Some of these
showers may produce lightning, but storms are not expected to be
overly strong, as there is only modest atmospheric instability.

On Thursday and Friday, the trough of low pressure in Southern
Canada continues moving east, leaving the Northern Rockies in
northwest flow. This should minimize shower chances for most, but
those along the Continental Divide, include Glacier National Park,
will continue to see cumulus build-ups and a few rain showers,
especially during the afternoon and evening hours.

The holiday weekend warms to about 5 degrees above normal, with a
shortwave trough passage Saturday bringing scattered showers to
the region. Sunday, Monday, and Tuesday currently are forecast to
be dry, with breezy valley winds 15 to 25 mph on the 4th of July
(Tuesday) possible.


.AVIATION...Thunderstorms will continue for KSMN and KBTM, and
most of and central Idaho and southwest Montana through this
evening. The main threats with these storms will be bursts of
heavy rainfall, frequent lightning, and strong erratic wind gusts.
Outside of thunderstorms, it will be a typical breezy afternoon
for valleys, with west-northwest winds of 15-25 kts. Thunderstorm
activity will shift southeastward after 28/0300z, with only light
winds and isolated mountain showers remaining for the Northern



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