288 
FXUS65 KMSO 022059
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
159 PM MST Sat Jan 2 2021

.DISCUSSION...Mixed valley precipitation, mountain snow, and 
gusty winds remain the main focus for tonight and Sunday’s 
weather system. Well above normal atmospheric moisture is moving 
into the Pacific Northwest with the arrival of a warm front, that 
will reach the Northern Rockies this evening. Strong winds are 
likely to develop in the high terrain overnight with southerly 
wind prone lower elevation spots such as Grangeville. Most of the
valleys in central Idaho and western Montana will have down- 
sloping affects which will limit showers, but the high terrain, 
including Lookout Pass will have periods of heavy snow overnight 
and during Sunday morning. One inch per hour snow rates are 
expected in the high terrain and a winter storm warning remains in
effect for Lookout Pass. Rising snow levels will keep most 
valleys in mixed precipitation or rain, but snow levels are less 
certain in northwest Montana so those near the ID/MT border may 
have more snow than is currently reflected in the forecast. 

A cold front is currently forecast to pass through the region 
during Sunday morning, which will cause gusty winds and lowering 
snow levels. Wind gusts over 40 mph look to be common with the 
cold front passage but gusts over 50 mph are also possible.
Western Montana appears to receive the brunt of the wind, the 
strongest winds are expected along the Highway 200, Highway 12 
and I-90 corridors east of Missoula. Multiple wind highlights have
been issued. 

Moisture profiles show quickly drying conditions behind the front
so showers are expected to decrease in coverage by late morning. 

Additional fronts are lined up in the Pacific and forecast to 
bring showers. The next weather system is expected Monday through 
Tuesday morning, initially with higher snow levels, and another is
possible Wednesday through Thursday morning. These system will
bring accumulating snow to the higher terrain, while the valleys
will be experience a wintry mix. Each disturbance appears to cause
gusty westerly winds to the Northern Rockies.



&&

.AVIATION...Water vapor loops show a warm front moving into the
region that is expected to spread cloud cover and heavy mountain
snow to central Idaho and western Montana. Strong winds are likely
with the incoming weather system, first in the the mountains
followed by widespread valley winds Sunday morning. Terrain 
winds overnight and Sunday morning could gust over 50 knots which
will cause wind shear concerns at all TAF sites. Gusty winds will
then associate with the cold front mainly between 03/1500z and 
03/1800z. 


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Wind Advisory from 8 AM to 5 PM MST Sunday Missoula/Bitterroot
     Valleys.

     Winter Storm Warning from 5 PM this afternoon to 1 PM MST Sunday 
     Lower Clark Fork Region.

     Wind Advisory from 2 AM to 5 PM MST Sunday Flathead/Mission 
     Valleys...Kootenai/Cabinet Region.

     Winter Weather Advisory from 11 PM this evening to 1 PM MST 
     Sunday West Glacier Region.

     Winter Weather Advisory from 5 PM this afternoon to 1 PM MST 
     Sunday Bitterroot/Sapphire Mountains.

     Wind Advisory from 8 AM to 5 PM MST Sunday Potomac/Seeley Lake 
     Region.

     Wind Advisory from 8 AM to 5 PM MST Sunday Butte/Blackfoot 
     Region.

ID...Winter Weather Advisory from 4 PM this afternoon to noon PST 
     Sunday ABOVE 3500 FEET for the Northern Clearwater 
     Mountains...Southern Clearwater Mountains.

&&

$$