Special Weather Statement, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
307 AM MDT Sun Mar 21 2021

.DISCUSSION...Showers increased in coverage overnight and are
forecast to linger through this morning. Brief snow accumulations
are expected over mountain passes but unlikely at lower
elevations. Much like yesterday, breezy westerly winds return for
the afternoon.

A moist upslope flow arrives tonight as the next trough moves
into the Pacific Northwest. There has been a trend for higher
snow amounts in the terrain of north-central Idaho, along the
ID/MT border, and into the Glacier Region tonight through Monday
morning. Impacts from the snow above around 4000 feet, and
especially over mountain passes, may warrant winter weather
advisories for Monday.

As the previous discussion mentioned, a backdoor cold front
remains possible for Monday night in northwest Montana and along
the Divide. Model guidance is converging to a better agreement for
the front, so confidence is increasing for impacts from snow
along Highway 2 east of Kalispell. There is still a question on
how far west the front will advance, but the GFS maintains a
westerly track which could cause snow impacts into more of western
Montana.

Brief drier conditions hold for Tuesday night and early Wednesday
before the next weather system arrives. There are differences in
the depth of the Wednesday night-Thursday trough but low elevation
snow chances continue to exist.

&&

.AVIATION...Snow showers are obscuring terrain and are forecast
to decrease in coverage after mid-morning. Breezy westerly winds
again return for the afternoon and shower activity is also
forecast to increase in coverage. Widespread lowered ceilings and
mountain snow arrive during the evening with the arrival of the
next trough. Snow levels will lower to around 2500 feet but most
of the accumulations are expected above around 4000 feet, with
many inches of new snow expected in north-central Idaho through
northwest Montana by Monday morning.

&&

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

Special Weather Statement
National Weather Service Missoula MT
708 AM MDT Sun Mar 21 2021

MTZ004>006-043-211345-
Bitterroot/Sapphire Mountains MT-Missoula/Bitterroot Valleys MT-
Lower Clark Fork Region MT-Potomac/Seeley Lake Region MT-
708 AM MDT Sun Mar 21 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL MISSOULA AND
NORTHWESTERN GRANITE COUNTIES UNTIL 745 AM MDT...

At 705 AM MDT, Doppler radar was tracking an intense snow shower near
Lolo, or near Missoula, moving east at 25 mph.

Visibility one-half mile or less will be possible, creating quickly
changing conditions and potential slick spots.

Locations impacted include...
Missoula, Lolo, Bonner-West Riverside, East Missoula, Clinton and
Turah.

LAT...LON 4679 11437 4696 11432 4683 11364 4664 11370
TIME...MOT...LOC 1305Z 286DEG 21KT 4680 11405