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fxus65 kmso 211009 
afdmso

Area forecast discussion
National Weather Service Missoula Montana
409 am MDT Sat Sep 21 2019

Discussion...

Light shower activity interspersed with areas of valley fog will
be present across the northern rockies through this morning. The
fog will be most pronounced across northwest Montana, especially
for the Kootenai river country and Highway 200 corridor plains to
the Idaho border. Motorists should be prepared for sudden reduced
visibility. The remaining showers this morning will be fairly
light, almost drizzle-like at times. High pressure will develop
over the region this afternoon, allowing conditions to warm and
dry. However, temperatures will still be a bit below the seasonal
average.

Fog will return to valleys across the northern rockies late
tonight through Sunday morning, however the intensity and coverage
of fog may be greater than this morning. Once again, motorists
should prepare for sudden reductions in visibility creating
hazardous driving conditions. High pressure overhead will allow
fog to burn off by late morning, as temperatures warm above the
seasonal average.

Sunday night through Monday, a fast-moving Pacific storm system
is expected to traverse the northern rockies. Much of the
precipitation with this storm system will exist along the surface
cold front, that will be most pronounced over north central Idaho
during overnight Sunday and western Montana Monday morning. Rain
showers will remain across the entire region for Monday afternoon.

Northwest flow will be present over the northern rockies Tuesday
and Wednesday, with some embedded waves within the flow. Likewise,
waves of showers will move over the region at times during this
period, with daytime temperatures kept below the seasonal average.

The models have become very consistent for a late week, cold
airmass trough. The questions continue to be exact timing of
feature and extent of where the cold air will be going. Suffice it
to say, the end of September through the first couple days of
October will be a significant change, with a good possibility most
valleys of western Montana to experience the first freeze of the
season.

&&

Aviation...the possibility of a shower in the vicinity of kgpi,
kmso, and kbtm has decreased and will continue to decrease
towards sunrise. Alike Friday morning, anticipate the development
of fog/mist and lower ceilings around kgpi through 21/1400z. The
potential also exists for low level fog, especially south and west
of kmso, through 21/1400z.

&&

Mso watches/warnings/advisories...

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