Winter Weather Advisory 9, NWS Missoula, MT

829 
WWUS45 KMSO 022132
WSWMSO

URGENT - WINTER WEATHER MESSAGE
National Weather Service Missoula MT
232 PM MST Tue Feb 2 2021

IDZ007-008-030800-
/O.EXB.KMSO.WW.Y.0009.210203T0000Z-210203T0800Z/
Orofino/Grangeville Region-Lower Hells Canyon/Salmon River Region-
132 PM PST Tue Feb 2 2021

...WINTER WEATHER ADVISORY IN EFFECT UNTIL MIDNIGHT PST TONIGHT...

* WHAT...Snow expected. Total snow accumulations of 2 to 4 
  inches.

* WHERE...Camas Prairie, Grangeville and vicinity, and White Bird
  Grade.

* WHEN...Until midnight PST tonight.

* IMPACTS...Travel could be affected with slippery roadways and 
  low visibility in snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

&&

$$

MTZ007-031200-
/O.EXB.KMSO.WW.Y.0009.210203T0200Z-210203T1200Z/
Butte/Blackfoot Region-
232 PM MST Tue Feb 2 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO
5 AM MST WEDNESDAY...

* WHAT...Snow expected. Total snow accumulations of 2 to 5 
  inches.

* WHERE...Butte, Georgetown Lake, Highway 12 Garrison to 
  Elliston, Homestake Pass, and MacDonald Pass.

* WHEN...From 7 PM this evening to 5 AM MST Wednesday.

* IMPACTS...Travel could be affected with slippery roadways and 
  low visibility in snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

&&

$$

MTZ004-030300-
/O.CON.KMSO.WW.Y.0009.000000T0000Z-210203T0300Z/
Lower Clark Fork Region-
232 PM MST Tue Feb 2 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 8 PM MST THIS
EVENING ABOVE 4500 FEET...

* WHAT...Snow above 4500 feet. Additional snow accumulation of 1 
  to 3 inches.

* WHERE...Lower Clark Fork Region, primarily near Lookout Pass.

* WHEN...Until 8 PM MST this evening.

* IMPACTS...Travel could be affected with slippery roadways and 
  low visibility in snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling.

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

&&

$$

326 
WWUS45 KMSO 030150
WSWMSO

URGENT - WINTER WEATHER MESSAGE
National Weather Service Missoula MT
650 PM MST Tue Feb 2 2021

IDZ007-008-030300-
/O.CAN.KMSO.WW.Y.0009.000000T0000Z-210203T0800Z/
Orofino/Grangeville Region-Lower Hells Canyon/Salmon River Region-
550 PM PST Tue Feb 2 2021

...WINTER WEATHER ADVISORY IS CANCELLED...

Snow is winding down. Drivers should remain cautious for recently
fallen rain and slush icing up the roads overnight.

$$

MTZ004-030300-
/O.CAN.KMSO.WW.Y.0009.000000T0000Z-210203T0300Z/
Lower Clark Fork Region-
650 PM MST Tue Feb 2 2021

...WINTER WEATHER ADVISORY IS CANCELLED...

Snow is winding down. Drivers should remain cautious for recently
fallen rain and slush icing up the roads overnight.

$$

MTZ007-031200-
/O.CON.KMSO.WW.Y.0009.210203T0200Z-210203T1200Z/
Butte/Blackfoot Region-
650 PM MST Tue Feb 2 2021

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 5 AM MST
WEDNESDAY...

* WHAT...Snow expected. Total snow accumulations of 2 to 5 
  inches.

* WHERE...Butte, Georgetown Lake, Highway 12 Garrison to 
  Elliston, Homestake Pass, and MacDonald Pass.

* WHEN...From 7 PM this evening to 5 AM MST Wednesday.

* IMPACTS...Travel could be affected with slippery roadways and 
  low visibility in snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling.

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

&&

$$

Area Forecast Discussion...CORRECTED
National Weather Service Missoula MT
619 AM MST Tue Feb 2 2021

.DISCUSSION...First off, Happy Groundhog day. A long line of
precipitation extends from northeast Oregon through the Idaho
Panhandle and northwest Montana. Snow levels, now above 6000 feet,
will begin to decrease from Northwest to southeast as a cold front
begins to make its way into the Northern Rockies. Lookout and
Marias passes can expect a few inches of snow this morning. Lolo
Pass can expect a few inches of snow this afternoon. Some higher
elevations above pass levels may receive 3 to 6 inches of snow.
Valley locations can expect rain through much of the day, then
switch to snow during the evening hours as the front punches its
way eastward.

As a result, this evening may bring some winter impacts to west
central and southwest Montana as wet roads from afternoon rains
may quickly freeze during the cold frontal passage during the
early to mid evening hours. Depending on the timing of frontal
passage, some valley locations could also receive 1 to 2 inches
of snow. Colder, unstable air behind the front will result in
scattered snow showers Wednesday and Thursday.

The biggest winter impacts this week will occur Thursday night
through Saturday morning. A short wave will move from British
Colombia through northwest Montana. A large area of arctic air
will move into central Canada, then southward into eastern
Montana, the Northern Plains, and finally the Great Lakes. The
big question over the last several days has been: will that deep
arctic air mass make it far enough west to be able to spill over
the Continental Divide into the Northern Rockies? The latest
couple of model runs are in a little better agreement with the
scenario of some arctic air reaching far enough west to cross the
Continental Divide. The question then becomes how much cold air
will impact us? That is something that remains very uncertain.

Nevertheless, the short wave moving into the region should
interact with enough cold air to produce accumulating snows along
the Continental Divide. At this time, the most confidence we have
for winter impacts is right along the Continental Divide, which
will impact travel over Marias, MacDonald, and Homestake passes.
Valley impacts are still a toss up, but the trends are leaning
more toward a solution of arctic air able to make into the western
Montana valleys, which would lead to more impacts such as gusty
east to northeast winds and valley snow. There are a lot of "Ifs"
out there regarding details of potential winter impacts, HOWEVER
our confidence is pretty high for the timing of this
system being Thursday night through Saturday morning.

Models become somewhat inconsistent after this weekend, either by
keeping cold temperatures over the region or building a high
pressure ridge with warmer temperatures

&&

.AVIATION...Expect cloudy skies over the next 24 hours. A cold
front will move through the Northern Rockies today through this
evening, impacting all terminals. All terminals can expect rain
this afternoon with a switch to snow behind the frontal passage.
Expect mountain obscurations, reduced visibility, and lowering
ceilings. In addition, some breezy west-northwest winds are
possible during frontal passage.

&&

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