079 
FXUS65 KMSO 022144
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
244 PM MST Sun Mar 2 2014

...A wintry mix of precipitation expected for the valleys...
...More snow for the mountains...

.DISCUSSION...
Tonight through Tuesday...A complex weather scenario shaping up
for the Northern Rockies during the next couple of days. A
westerly flow aloft will provide a steady influx of Pacific
moisture to the region. This moist influx has also been warming
the lower atmosphere from about mid-slope to 7000 feet (temps in
the mid 30s) across north-central Idaho and west-central Montana.
Warmer air has also made its way into the lower valleys of
western Idaho and Clearwater counties where precipitation will
likely remain as rain. The mountains across north-central Idaho
and western Montana will remain mostly snow, although snow will
have a higher water content. Mountain passes will be impacted by
snow-covered roadways during the next few days with few breaks.

Now for the most tricky part of the forecast. Since stubborn cold
air remains trapped in the valleys of western Montana, a wintry
mix of precipitation is expected, including freezing rain, as
valley temperatures moderate and transition from snow to rain. In
addition to precipitation, hard-packed snow and existing ice on
secondary roads, city streets, parking lots and sidewalks during
this transition will become slick. West-central Montana will see
this transition tonight and Monday morning, while locations across
northwest Montana may not occur until Tuesday morning. Winter
highlights have been issued or remain in effect to deal with the
various types of precipitation and their impacts.

Wednesday and Thursday mornings freezing rain is still a major
concern for some valleys in western Montana. Otherwise, the
tropical connection continues to pour moisture of the northwest
and into the northern Rockies. A system associated with this moist
flow will impact the region Wednesday with a warm front and then a
cold front Thursday morning. Over a 36 hour period ending Thursday
morning the Bitterroot and northern Clearwater mountains will
receive around inch of water in the form of a rain and snow mix.
The Bob Marshall wilderness and Glacier Park will receive three
quarters to an inch of water mainly as snow. Meanwhile in the
valleys there will be a quarter to a half inch of rain, except for
the Butte-Anaconda and Lemhi county areas which will receive much
less.

Snow melt combined with rainfall is also becoming a bigger concern.
With rising temperatures and rain later this week, runoff and
standing water will be at least a nuisance in the valleys. Some
damage to structures in poorly drained areas is possible. At this
time, no river or stream flooding is expected. 

&&

.AVIATION...Periods of snow and lower ceilings will be obscuring
higher terrain today and tonight. Valleys locations will also see
lower ceiling and snowfall reducing visibilities from time to
time. These conditions will be impacting most airfields, especially
KGPI and KMSO. In addition to snow, periods of freezing rain are
expected in the valleys of west-central Montana tonight and Monday
morning...impacting mainly KMSO.

KBTM will see light snow, but major interruptions to aviation
operations are not anticipated at this time.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING until 11 AM MST Monday Lower Clark Fork 
     Region.

     WINTER WEATHER ADVISORY until 11 AM MST Monday 
     Bitterroot/Sapphire Mountains.

     WINTER WEATHER ADVISORY until 11 AM MST Monday 
     Missoula/Bitterroot Valleys.

     WINTER STORM WARNING until 11 AM MST Monday Flathead/Mission 
     Valleys...Kootenai/Cabinet Region.

     WINTER STORM WARNING until 11 AM MST Monday West Glacier Region.

     WINTER WEATHER ADVISORY until 11 AM MST Monday Butte/Blackfoot 
     Region...Potomac/Seeley Lake Region.

ID...WINTER STORM WARNING until 10 AM PST Monday Northern Clearwater 
     Mountains.

     WINTER WEATHER ADVISORY until 10 AM PST Monday Southern 
     Clearwater Mountains.

&&

$$

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