Snow Squall Warning 22, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
328 PM MST Thu Dec 1 2022

...SNOW WILL CONTINUE TO IMPACT THE NORTHERN ROCKIES THROUGH
FRIDAY MORNING...

.DISCUSSION...

A broad Pacific storm system will continue to move south and east
across the Northern Rockies through Friday morning. The weather
impact focus will shift to west central and southwest Montana
through this evening, with the threat of snow squalls remaining
near 30 percent probability during this time. Homestake Pass and
vicinity appears to be the most plausible area for sudden high-
impact conditions to develop this evening after sunset. Travelers
should consider slowing down in response to sudden onset of
snowfall and over snow-covered roadways.

Snow showers will linger overnight, particularly over the terrain
of southwest Montana and across Lemhi County. Winter weather
impacts will continue to diminish over time. Cold air aloft will
be realized in Friday daytime temperatures that are 5-10 degrees
colder than today.

Cold pools are expected to develop and intensify across much of
the Northern Rockies Friday night through Sunday. Overnight
temperatures will cool between single digits above and single
digits below zero for much of western Montana valleys and high
elevation north central Idaho valleys. Depending on the lack of
cloud cover, some low temperature records may be challenged for
both Saturday and Sunday mornings. Daytime temperatures will
struggle to warm to the teens and 20s for many valley locations
over the weekend as well.

Global models and their ensembles suggest that an arctic airmass
may sneak over the Continental Divide early next week, bringing
frigid temperatures and sub zero wind chill to northwest Montana
valleys and areas further south right along the Continental
Divide. There are a variety of snowfall forecasts among the
ensembles, with very little consensus evident.

Models and ensembles provide very little clarity about the overall
pattern from middle of next week onward. The loose consensus of
model data suggests that weak high pressure will be present
through much of the following weekend.

&&

.AVIATION...The cold front is currently moving through west
central and southwest Montana. This front is anticipated to impact
KBTM between 01/23z to 02/03z causing reduced visibility due to
snow and gusty northeasterly winds. KSMN has been experiencing
rain so far this afternoon, but that should change over to snow
around 02/00z. The snow should impact KSMN until 02/03z. KGPI and
KMSO will have vicinity showers throughout the remainder of the
evening into the overnight hours. If a shower goes over the
terminal visibilities and ceilings should be reduced for about an
hour. Terrain obscurations will be common through midday Friday.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning until 11 AM MST Friday for West Glacier
     Region.

     Winter Weather Advisory until 6 PM MST this evening for
     Flathead/Mission Valleys.

     Winter Storm Warning until midnight MST tonight for Lower Clark
     Fork Region.

     Winter Weather Advisory until midnight MST tonight for
     Missoula/Bitterroot Valleys.

     Winter Weather Advisory until 6 AM MST Friday for
     Bitterroot/Sapphire Mountains.

     Winter Weather Advisory until 6 AM MST Friday for
     Butte/Blackfoot Region.

     Winter Weather Advisory until 6 AM MST Friday for Potomac/Seeley
     Lake Region.

ID...Winter Storm Warning until 5 AM PST Friday for Northern
     Clearwater Mountains...Southern Clearwater Mountains.

     Winter Weather Advisory until 5 AM PST Friday for
     Orofino/Grangeville Region.

     Winter Weather Advisory until 5 AM PST Friday for Lower Hells
     Canyon/Salmon River Region.

     Winter Weather Advisory until 6 PM MST Friday for Eastern Lemhi
     County...Western Lemhi County.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
250 PM MST THU DEC 1 2022

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

0249 PM     SNOW             3 ESE BIGFORK           48.04N 114.00W
12/01/2022  M3.2 INCH        LAKE               MT   COCORAHS

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
334 PM MST THU DEC 1 2022

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

0242 PM     SNOW             4 SW CANFIELD           45.79N 116.42W
12/01/2022  E7.0 INCH        IDAHO              ID   PUBLIC

            ELEVATION 4150 FT.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
344 PM MST THU DEC 1 2022

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

0344 PM     SNOW             1 WNW POLLOCK           45.32N 116.37W
12/01/2022  E5.0 INCH        IDAHO              ID   PUBLIC

            3424 FEET.

&&

Special Weather Statement
National Weather Service Missoula MT
355 PM MST Thu Dec 1 2022

MTZ007-012345-
Butte/Blackfoot Region MT-
355 PM MST Thu Dec 1 2022

...Intense snow showers will impact portions of Deer Lodge,
southeastern Granite, Silver Bow and southeastern Powell Counties
through 445 PM MST...

At 354 PM MST, trained weather spotters reported intense snow showers
along a line extending from 9 miles south of Montana City to 9 miles
northwest of Divide. Movement was east at 15 mph.

HAZARD...Very low visibility of less than one quarter mile and heavy
         snow.

SOURCE...Trained weather spotters.

IMPACT...Hazardous travel through this region.

Locations impacted include...
Deer Lodge, Butte, Anaconda, Silver Bow, Walkerville, Warm Springs,
Galen, Gregson Hot Springs, Divide, West Valley, Nissler,
Crackerville, Fishtrap, Racetrack, Lost Creek, Opportunity, Ramsay,
Janney, Newcomb and Georgetown.

This includes Interstate 90 between mile markers 184 and 230.

LAT...LON 4576 11222 4576 11250 4569 11255 4563 11268
      4576 11277 4581 11300 4588 11311 4588 11321
      4581 11334 4576 11338 4588 11347 4627 11332
      4641 11277 4642 11232 4633 11246 4633 11253
      4624 11260 4618 11257 4618 11251 4585 11243
TIME...MOT...LOC 2254Z 255DEG 14KT 4640 11196 4585 11289

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...<30 MPH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
409 PM MST THU DEC 1 2022

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

0408 PM     HEAVY SNOW       OPPORTUNITY             46.11N 112.83W
12/01/2022  E3.0 INCH        DEER LODGE         MT   TRAINED SPOTTER

            RECEIVED OVER AN INCH OF SNOW IN THE LAST
            HOUR. VISIBILITY IS 100 YARDS. WINDS 10 MPH
            FROM THE NORTH. THE 3 INCHES INCLUDES SNOW
            FROM EARLIER.

&&

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