Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 180932

Area Forecast Discussion
National Weather Service Missoula MT
332 AM MDT Sun Mar 18 2018

.DISCUSSION...Two circulations are currently impacting the
Northern Rockies this morning. The first circulation is over
Missoula and the second is over Great Falls. These features are
causing widespread precipitation with most locations receiving
snow or a rain/snow mix. The precipitation is a bit farther to the
north then previously forecasted so winter weather advisories have
been issued for the I-90 corridor from Nine Mile to Bearmouth and
over Evaro Hill. The rising of the sun will help with road
conditions by mid morning, so the advisories are set to expire at
noon today even though snow will linger across north central Idaho
and west central Montana well into the afternoon.

The latest model runs are now indicating that another mid level
circulation will drop southward out of Alberta tonight and linger
into Monday morning. This feature appears to bring a round of
snow to northwest Montana, particularly Glacier park. Kalispell up
to Eureka could receive 1 to 2 inches of snow while Glacier park
could get 2 to 4 inches of accumulation.

Showery and cool early spring weather will continue Monday
through Wednesday. The most prevalent showers are expected across
the terrain of Northwest Montana and north-central Idaho where
several inches of snow will be possible. Temperatures will
gradually moderate through mid-week returning to seasonable

Showers will then increase on Thursday and become widespread
ahead of a cold front which is anticipated for Thursday night.
Snow levels ahead of the front will be at 5000-6000 feet, dropping
to valleys floors behind the cold front for Friday. Roadways
through the passes will likely become snow covered leading to
slower travel.

A large trough of low pressure will settle over the Pacific
Northwest Friday into next weekend leading to unsettled and
showery weather with temperatures falling to below normal levels.
Snow levels will be low enough for occasional snow on the valley


.AVIATION...The main mid level circulation appears to be over
Missoula this morning causing widespread precipitation across
north central Idaho into west central Montana. KMSO will be
impacted the most by the precipitation with periods of low
visibility and ceilings. While KBTM and KSMN will be dealing with
vicinity showers which could momentarily impact the terminals.
KGPI will receive the least amount of impact from this first
system, but a second system later tonight into Monday morning
could cause snow at the terminal.


MT...Winter Weather Advisory until noon MDT today
     Bitterroot/Sapphire Mountains...Butte/Blackfoot Region.

     Winter Weather Advisory until noon MDT today Potomac/Seeley Lake

     Winter Weather Advisory until noon MDT today Lower Clark Fork

     Winter Weather Advisory until noon MDT today Missoula/Bitterroot

ID...Winter Weather Advisory until 11 AM PDT this morning ABOVE 3000
     FEET for the Lower Hells Canyon/Salmon River Region...
     Northern Clearwater Mountains...Orofino/Grangeville
     Region...Southern Clearwater Mountains.

     Winter Weather Advisory until 6 AM MDT early this morning
     Eastern Lemhi County...Western Lemhi County.


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