Snow Squall Warning 1, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
412 AM MST Mon Feb 11 2019

...PROLONGED SNOW WITH PERIODS OF MODERATE SNOW THROUGH THE MIDDLE
OF THE WEEK...

.DISCUSSION...

A surge of Pacific moisture over the Northern Rockies today will
quickly moderate temperatures well above zero, as well as produce
widespread light snowfall. Most locations will experience a quick
few inches of snow, further exacerbating hazardous winter driving
conditions throughout the region.

A period of overrunning (warm, moist air riding over the top of
cold air at the surface) will produce moderate to heavy snow
tonight into Wednesday. While snow will initially impact most all
of central Idaho and western Montana tonight, forecast models show
the main surge of moisture will focus through the Idaho panhandle
into northwest Montana during the day Tuesday. Hefty snow amounts
of 6 to 9 inches will be possible in these areas, with over a
foot of snow in the higher terrain near the Idaho/Montana border.
Locations from Missoula south and east will see much lower
snowfall, generally in the 1 to 3 inch range. In addition, a
southerly pressure gradient will set up tonight into Tuesday,
bringing some increasing wind through the Camas Prairie in Idaho
and southwest Montana. The wind coupled with snowfall could make
for a period of lowered visibility due to blowing snow, mainly
tonight into early Tuesday morning, before the focus of
precipitation shifts further north. Travel could become difficult
during this timeframe, especially near the Idaho/Montana border,
including over Lookout and Lolo Passes.

As a low pressure system dives southward along the Pacific
northwest coastline on Wednesday, the moisture focus will begin to
trend further south with time. This low will also help pull cold
Canadian air back along the Continental Divide. This colder air could
provide a focus for another period of moderate to heavy snowfall
for the Wednesday into Thursday morning time frame. Forecast
models continue to struggle a bit with the details around this
system, thus confidence is somewhat diminished. However, the
overall trend over the last few models runs is towards another
period of potentially significant snowfall, this time focused
generally along and south of the Highway 12 corridor.

Beyond Thursday, forecast models show little change in the
overall pattern, with continued surges of moisture capable of
producing widespread snow into the weekend, and possibly even into
early next week!

&&

.AVIATION...

A surge of Pacific moisture will move over the Northern Rockies
today, bringing widespread light snow and obscuring much of the
high terrain. All area terminals, including KBTM, KGPI, KMSO, and
KSMN, will experience high variability in ceilings and visibility
due to snowfall. Much of the snow activity will shift northward
after 12/1200Z and continue to impact primarily KGPI and KMSO with
lowered visibility and ceilings at times.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...     Winter Weather Advisory until 11 AM MST this morning
     Missoula/Bitterroot Valleys.

     Winter Weather Advisory until 11 AM MST this morning
     Flathead/Mission Valleys.

     Winter Storm Watch from this afternoon through Wednesday
     afternoon Flathead/Mission Valleys.

     Winter Weather Advisory until 11 AM MST this morning West
     Glacier Region.

     Winter Storm Watch from this afternoon through Wednesday
     afternoon West Glacier Region.

     Winter Weather Advisory until 11 AM MST this morning
     Kootenai/Cabinet Region.

     Winter Storm Watch from this afternoon through Wednesday
     afternoon Kootenai/Cabinet Region.

     Winter Weather Advisory until 11 AM MST this morning
     Bitterroot/Sapphire Mountains.

     Winter Weather Advisory until 11 AM MST this morning
     Potomac/Seeley Lake Region.

     Winter Storm Watch from this afternoon through Wednesday
     afternoon Potomac/Seeley Lake Region.

     Winter Weather Advisory until 11 AM MST this morning Lower Clark
     Fork Region.

     Winter Storm Watch from this afternoon through Wednesday
     afternoon Lower Clark Fork Region.

ID...Winter Weather Advisory until 10 AM PST this morning Lower Hells
     Canyon/Salmon River Region.

     Winter Storm Watch from this afternoon through Wednesday
     afternoon Northern Clearwater Mountains...Southern
     Clearwater Mountains.

     Winter Weather Advisory until 10 AM PST this morning
     Orofino/Grangeville Region.

     Winter Storm Watch from this afternoon through Wednesday
     afternoon Orofino/Grangeville Region.

     Winter Weather Advisory until 10 AM PST this morning Northern
     Clearwater Mountains...Southern Clearwater Mountains.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
847 AM MST MON FEB 11 2019

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

0846 AM     SNOW             3 WNW KALISPELL         48.21N 114.37W
02/11/2019  M2.5 INCH        FLATHEAD           MT   COCORAHS

            2.5 INCHES SINCE 1 PM SUNDAY.

&&

AL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1004 AM MST MON FEB 11 2019

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

0815 AM     SNOW             4 NW NOXON              48.03N 115.85W
02/11/2019  M3.0 INCH        SANDERS            MT   COCORAHS

            COCORAHS STATION MT-SN-2, 4 WNW NOXON.

&&

AL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1005 AM MST MON FEB 11 2019

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

0700 AM     SNOW             3 ENE BIGFORK           48.07N 114.01W
02/11/2019  M2.0 INCH        FLATHEAD           MT   COCORAHS

            COCORAHS STATION MT-FH-16, 2 E BIGFORK.

&&

AL

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