Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 122206

Area Forecast Discussion
National Weather Service Missoula MT
306 PM MST FRI FEB 12 2016

.DISCUSSION...Another cold front will begin to impact northwestern
Montana and north-central Idaho overnight tonight, with a mix of
valley rain and mountain snow. The snow levels will start off
relatively high ahead of the front, somewhere around 7000 feet. As
the front slides to the southeast through the rest of western
Montana, snow levels will lower, and could be as low as 3500 feet
by tomorrow morning. The mountain passes along the MT/ID border,
should see somewhere around 2 to 4 inches of snow, though not
expecting much of it to stick to the roads, mainly grassy and
elevated areas. The valleys of western Montana will see rain,
mixing with snow in the afternoon behind the front. A few
moderately intense graupel showers are possible, but no
accumulation is expected. Most valleys below 4000 feet in central
Idaho, will predominately see all rain. Gusty northwest winds
tomorrow afternoon will also impact western Montana. Winds could
gust as high as 20-25 mph in some of the showers.

Another weather system will move in on Saturday night and is
expected to be more of an impact than the first weather system.
Mountain passes along the MT/ID border and Marias pass will see
periods of moderate snow Saturday night and into Sunday morning.
Travelers during this time should expect slick road conditions
over mountain passes. Snow will begin to decrease during the day
Sunday but winds will be on the increase across valleys during the
afternoon. Wind gusts of around 20 to 30 mph will be possible
across western Montana.

The third weather system will bring rising snow levels and rain to
many locations across central Idaho and western Montana by Sunday
evening. Snow levels will begin to rise, and by Monday, snow
levels are expected to be in the 6000-7000 feet range across the
region. Mountain passes could initially see snow Sunday evening
but by Monday morning most passes with the exception of Lost Trail
Pass should see all rain. The rise in snow levels combined with
warmer temperatures and rain will lead to snow melt. Many valleys
will begin to experience ponding on roadways and rises in streams
on Monday. The greatest moisture is expected to be across the
Clearwaters of Idaho, which could lead to possible rock fall and
mudslides on prone roadways. Lastly, we could see increased
avalanche concerns as snow levels rise and rain falls on the snow
pack. Those with newborn livestock should be prepared to protect
sensitive animals from the prolonged period of cool, wet rain into

High pressure largely builds back over the region on Tuesday into
Wednesday, although some moisture will likely continue to stream
into northwest Montana during this time frame. This ridge looks
quite warm for this time of year, especially for west central
Montana and central Idaho where the forecast largely remains dry.
Valleys and low elevations that still have significant snow on the
ground, such as around Salmon, could see continued ponding of
water due to snowmelt.

Another weather system will cool things off and drop snow levels
back to at least the passes by Thursday. There continue to be some
slight model differences with this system, including timing and
precipitation amounts, but in any case cooler, more seasonal
conditions are expected.


.AVIATION...With exception of KGPI, most of the valley fog has
lifted at area terminals, leaving just a mid level cloud deck. For
KGPI, the lower visibility and ceilings will likely stick around
until the onset of precipitation with our next weather
disturbance, which will be sometime around 12/0600Z. However,
there could be very brief improvements between now and then, but
not expecting an extended period of improvement. Snow levels will
lower close to the valley floors in western Montana by tomorrow
morning (13/1500Z), but still expecting a rain/snow mix.
Moderately intense graupel showers will also be possible at times
during the afternoon for KMSO, KGPI, and KBTM that could
temporarily reduce visibility and ceilings.



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