Winter Storm Watch 4, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
305 PM MST Thu Feb 15 2018

*** MAJOR WINTER STORM FOR WESTERN MONTANA THIS WEEKEND ***
*** HEAVY SNOW FOR NORTHWEST MONTANA ON SATURDAY ***

.DISCUSSION...Light snow showers linger this afternoon but are
expected to decrease this evening. Snow returns to north-central
Idaho and along the ID/MT border by early Friday morning.
Northwest Montana will again see snow during Friday and west-
central and southwest Montana are expected to see snow during
Friday evening. There has been consistency for the highest snow
rates to be during Friday evening and into the overnight under
snow bands. I-90, Highway 12, Highway 200, and Highway 93 near
Missoula are most likely to see travel impacts due to moderate
snow into Friday night.

The main impact producing weather system is still on track to
bring snow, wind, and quickly dropping temperatures Saturday
through Sunday. Saturday will have mild temperatures with west
winds and either snow or a rain snow mix, but an arctic cold
front will move through the region beginning Saturday afternoon in
northwest Montana and the rest of western Montana by Sunday
morning.

Temperatures will quickly drop from the 30s into the 20s and teens
and winds will become very gusty. The combination of moderate to
heavy snow, quickly dropping temperatures, and gusty
north/east winds will create potentially dangerous to impossible
travel conditions by Sunday morning. The blowing and drifting
snow with very low visibility are very likely with the worst
conditions expected to be in northwest Montana, particularity in
the Flathead/Mission valleys and the Highway 2 corridor. Highway
12/200 east of Missoula, and the I-90 corridor will also have a
combination of heavy snow and blowing and drifting snow. Gusty
easterly winds and continue snow will keep blowing and drifting
snow at least through Sunday night, but the poor conditions may
remain through Monday morning.

Cold temperatures and very cold wind chills of negative 15 to
negative 25 degrees will be common by Sunday night and the coldest
locations, along the divide, may see wind chills as cold as
negative 40. Winds decrease and the rest of the week will be cold
with temperatures below average.

&&

.AVIATION...Snow showers will linger into this afternoon before
decreasing during this evening. The next weather system moves into
the region tonight, first spreading low ceilings and snow into
north-central Idaho, followed by northwest Montana. The most
intense snowfall is possible during Friday evening where model
time-heights are showing favorable profiles for strong snow bands
from KMSO to KBTM. Snow bands and showers will linger into Friday
night.

A major winter storm is likely in western Montana Saturday and
Sunday, starting with moderate to heavy snow and gusty west winds,
before becoming much colder with gusty easterly winds, and blowing
snow with an arctic front.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from 2 PM Friday to 5 AM MST Saturday
     Butte/Blackfoot Region...Potomac/Seeley Lake Region.

     Winter Storm Watch from Saturday afternoon through Sunday
     afternoon Butte/Blackfoot Region...Potomac/Seeley Lake
     Region.

     Winter Weather Advisory from 2 PM Friday to 5 AM MST Saturday
     Bitterroot/Sapphire Mountains.

     Winter Storm Watch from Saturday morning through Sunday
     afternoon Bitterroot/Sapphire Mountains.

     Winter Weather Advisory from 5 AM to 11 PM MST Friday Lower
     Clark Fork Region.

     Winter Storm Watch from Saturday morning through Sunday
     afternoon Lower Clark Fork Region.

     Winter Weather Advisory from 5 PM Friday to 5 AM MST Saturday
     Missoula/Bitterroot Valleys.

     Winter Storm Watch from Saturday morning through Sunday
     afternoon Missoula/Bitterroot Valleys.

     Winter Storm Watch from Saturday morning through Sunday
     afternoon Flathead/Mission Valleys.

     Winter Weather Advisory from 5 AM to 11 PM MST Friday West
     Glacier Region.

     Winter Storm Watch from Saturday afternoon through Sunday
     afternoon West Glacier Region.

     Winter Storm Watch from Saturday morning through Sunday
     afternoon Kootenai/Cabinet Region.

ID...     Winter Storm Watch from Saturday morning through late Saturday
     night Northern Clearwater Mountains...Southern Clearwater
     Mountains.

     Winter Weather Advisory from 4 AM to 1 PM PST Friday Lower Hells
     Canyon/Salmon River Region.

     Winter Weather Advisory from 4 AM to 1 PM PST Friday
     Orofino/Grangeville Region.

     Winter Weather Advisory from 4 AM Friday to 4 AM PST Saturday
     Northern Clearwater Mountains...Southern Clearwater
     Mountains.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1103 AM MST THU FEB 15 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1103 AM     SNOW             3 ENE GRANGEVILLE       45.94N 116.06W
02/15/2018  E4.0 INCH        IDAHO              ID   DEPT OF HIGHWAYS

            4 INCHES OVERNIGHT.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1105 AM MST THU FEB 15 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1104 AM     SNOW             6 NNE WHITE BIRD        45.84N 116.24W
02/15/2018  E7.0 INCH        IDAHO              ID   DEPT OF HIGHWAYS

            SNOW FELL OVER WHITE BIRD HILL YESTERDAY
            EVENING AND THE OVERNIGHT HOURS.

&&