Area Forecast Discussion
Issued by NWS Missoula, MT

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000
FXUS65 KMSO 232053
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
253 PM MDT Tue May 23 2017

...STRONG WINDS ACROSS NORTHERN ROCKIES ON WEDNESDAY...

.DISCUSSION...

High pressure will remain over the Northern Rockies through
tonight. Light winds and mild overnight temperatures will be
present.

A strong, yet dry, cold front will sweep across the Northern
Rockies on Wednesday, creating strong wind gusts region-wide.
Wind highlights are in effect for Wednesday, covering all of
western Montana and Lemhi County Idaho. The strongest winds,
gusting over 60 mph at times, will exist over high terrain and
across southwest Montana. Elsewhere, gusts over 40 mph will
develop during Wednesday daytime. These strong winds will damage
trees and create dangerous crosswinds for highway travelers. The
winds will be strong enough to also create unrelenting waves up to
5 feet high on Flathead Lake Wednesday afternoon. Some shower and
thunderstorm activity will follow the cold front, but even this
will be sparse compared to most cold fronts. Very little
precipitation is anticipated through Wednesday night, as winds
slowly subside after sunset.

Shower and afternoon thunderstorm activity will linger over the
Northern Rockies through the end of the week; however,
expectations for widespread precipitation remain fairly low.

Memorial Day Weekend, high pressure is expected to develop along
the Pacific Northwest coast and then slowly creep east over time,
steadily warming and drying the Northern Rockies. Memorial Day
may actually be warmer than 80 degrees for low elevations, a
notable rarity over the past several decades.

&&

.AVIATION...No impacts to aviation are expected this afternoon and
evening, with warm, summer-like temperatures and light winds.
Overnight into early Wednesday morning, winds will rapidly
increase 1000 to 2000 ft above the surface, causing significant
speed sheer as one rises in the atmosphere. A dry cold front will
push south Wednesday morning through Northwest Montana, eventually
reaching southwest Montana by the afternoon and evening. Winds
will be strong tomorrow afternoon, with gusts in the 30 and 40
knot range becoming common at most western Montana sites.
Airstrips in Idaho and Clearwater county Idaho will be spared the
strongest winds, but it will still be a breezy day across the
Northern Rockies. Very little precipitation is expected with this
dry front.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Watch from Wednesday morning through Wednesday evening
     Butte/Blackfoot Region.

     Wind Advisory from 9 AM to 9 PM MDT Wednesday
     Bitterroot/Sapphire Mountains...Missoula/Bitterroot
     Valleys...Potomac/Seeley Lake Region.

     Wind Advisory from 9 AM to 9 PM MDT Wednesday Kootenai/Cabinet
     Region...Lower Clark Fork Region.

     Wind Advisory from 9 AM to 9 PM MDT Wednesday Flathead/Mission
     Valleys...West Glacier Region.

ID...Wind Advisory from 9 AM to 9 PM MDT Wednesday Eastern Lemhi
     County.

&&

$$



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