Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 251017

Area Forecast Discussion
National Weather Service Missoula MT
417 AM MDT Sun Sep 25 2016

.DISCUSSION...After a cool start this morning, the forecast for
today looks very pleasant, with temperatures near seasonal
normals, partly cloudy skies, and light winds. Skies will continue
to clear up throughout the day, leading to a cool night tonight
into Monday morning. Patchy fog and frost will again be threats.
Atmospheric moisture profiles and the upper level flow pattern is
more supportive of good radiational cooling than in previous
nights, so valley frost or fog could be more widespread. However,
confidence is still only moderate, given overall warm temperatures
aloft, and lack of recent moisture.

Tuesday will be a relatively warm day, with highs 5 to 10 degrees
above normal and mostly sunny skies. The axis of the high pressure
ridge will move over during the afternoon, with the upper level
flow becoming more southwesterly by Tuesday.

Wednesday through Friday, models have consistently depicted
southwesterly flow aloft over the Northern Rockies, however the
trend is for that southwest flow to be mostly dry on Wednesday.
Shower activity is anticipated to increase Thursday and Friday,
with temperatures remaining very mild for late September.
Conditions are expected to become quite unstable Friday afternoon,
increasing the threat for thunderstorms across the region.

Next weekend through early the following week, a series of Pacific
storm systems are anticipated to move over the Northern Rockies.
Temperatures will trend below normal during this time, with low-
elevation rain and high-elevation snow plausible. There may be
snow impacts related to travel at elevations over 7000 feet during
this time.


.AVIATION...Mid-level moisture and scattered high cirrus have
prevented fog from forming around TAF sites as of 25/1000z this
morning. Current valley webcams around airports do not show any
fog. However, some additional cooling is possible before 25/1400z,
so there is still a small chance for patchy fog formation,
especially around bodies of water where surface dew points are
higher. After sunrise, aviation weather concerns are minimal, with
light winds and mostly clear skies prevailing under building high



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