Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 252044
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
244 PM MDT Tue Apr 25 2017

.DISCUSSION...Northwesterly flow with a subtle disturbance will
continue to cause widespread shower and isolated thunderstorms,
especially across Northwest Montana this afternoon and evening.
The shower activity will diminish some during the evening hours.
Then a feature will move in from the west which will enhance the
precipitation across north central Idaho by Wednesday morning.
This feature will continue to push through the remainder of the
Northern Rockies Wednesday morning causing widespread
precipitation. The shower activity will continue to be numerous
across the region as a secondary feature moves through during the
afternoon and evening. Snow levels will be hovering around 5000
feet during this period, so the valleys will receive rain with
snow in the mountains. The mountain passes could experience some
light snow, but impacts should be minimal. Snow levels continue to
decrease throughout Wednesday night with linger showers, which
could start causing issues for mountain passes.

Thursday morning a few area passes, especially Lookout, Lolo, and
Marias Passes will have a few inches of snow. Due to the recent
long, relatively warm days and above freezing nights road
temperatures have warmed considerably. So significant snow
accumulation on the roads is unlikely to last very long, except at
the passes. Once the sun comes up, it will be difficult for snow
to accumulate on the roads. Even though the shower intensity will
be less, the mountain passes could be impacted once again on by
Friday morning. Most valley locations throughout the region have
the potential of a rain/snow mix during this period, but any snow
accumulations will be on non-paved surfaces.

For the weekend a brief ridge builds Saturday afternoon, but
quickly breaks down. So late next weekend and early next week with
the jet stream remaining south of the region in northwest flow, it
will remain cool and showery.

&&

.AVIATION...Northwesterly flow with a subtle disturbance will keep
numerous showers and isolated thunderstorms lingering across the
region, especially northwest Montana. KGPI has already been
impacted by a thunderstorm earlier today and will continue to be
through the remainder of the afternoon and evening. If a storm
goes over the terminal, conditions could drop to MVFR or even IFR
for a brief period. The shower activity should diminish some
during the evening. A second disturbance will be making its way
into central Idaho later tonight and through western Montana on
Wednesday morning. This feature will be steadily lowering ceilings
throughout the Northern Rockies and causing widespread steady
precipitation for much of the region. All terminals will be
impacted by this system at some point tonight into Wednesday,
KGPI & KMSO during the morning around 26/12z and KSMN & KBTM
around 26/18z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$



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