Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 041156
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
456 AM MST Sun Dec 4 2016

.DISCUSSION...

Today through Monday...Current WV imagery starting to show
moisture increasing into the area with a strong westerly jet...with
the winter disturbance and cold front staging in Canada. Snow
showers are expected to develop across mainly western and southern
portions through the morning...with gusty winds across central and
eastern portions. As the afternoon progresses...our disturbance
begins to push across the region...spreading snow...possibly mixed
with rain at the lowest elevations...eastward. The mentioned cold
front then moves across the region this evening through
tonight...bringing widespread snow..some moderate to heavy at
times. The best snowfall still looks to come from along the Rocky
Mountain Front and adjacent plains to Great Falls...to
Lewistown...and South. The Moderate to heavy snow looks to
diminish Monday morning...however...moist nw flow with embedded
disturbances and weak upslope components could linger light snow
across much of the CWA through the day Monday. Snow accumulations
by early Monday evening still look to range in the 1 to 2 feet
across the Rocky Mountain Front...2 to 6 inches across central and
southern areas...with up to 9 inches across the southern
mountains. With that...Winter Storm Warnings remain across the
Rocky Mountain Front and central Montana given some higher impacts
and accumulations with this storm. Winter Weather Advisories
remain across portions of northern and central Montana. Adjusted
highlights across southern Montana. Now areas above 6000 feet are
in a Winter Storm Warning for heavy snow...difficult driving
conditions at pass level...and winter storm conditions with
elevated avalanche concerns to those in the back country. Areas
below 6000 feet are in a Winter Storm Advisory for difficult
driving conditions at times and accumulations of 1 to 4 inches.
Breezy to windy conditions are also possible leading up to the
snow today...however...should remain below high wind criteria.

Monday night through Tuesday...Lingering moisture could bring some
flurries or scattered light snow across the northern half Monday
night into Tuesday morning...while a weak secondary disturbance
returns light snow to much of the south during the same time
period. Models then indicate snow should begin to diminish Tuesday
afternoon...however...still cant rule our a few lingering flurries
or widely scattered light snow due to lingering moisture. The
other big story for this time period will be the potentially cold
temperatures. A lot of it will depend on how much snow actually
falls...however...right now it is looking like widespread below
zero temperatures Monday night into Tuesday morning...with high
temperatures struggling to get into the single digits or teens
Tuesday afternoon. Anglin

Tuesday night through Saturday...High pressure will build over
Central and Southwest Montana Tuesday night as the low pressure trof
continues to move east. The air mass will dry and winds will
continue to weaken as the ridge builds. The ridge will be over the
Northern Rockies Thursday with the next low pressure trof over the
Eastern Pacific. Moisture ahead of this trof will be moving
underneath the ridge and across the Rockies. This will bring
increased chances of precipitation mainly across the Rockies and
Southwest Montana. The trof will move on shore late Thursday night
and Friday morning. Moisture will increase ahead of this system
however some splitting of the trof will occur and dynamics over the
forecast region will be quite weak. Most snow will be over areas
affected by west flow aloft.  High pressure will build again
Saturday however a shortwave will be moving into the area and keep a
chance of precipitation in the forecast. Temperatures will begin the
period well below normals but the air mass will trend warmer through
the period. Temperatures, by  Saturday, will be near seasonal
normals again. Zelzer


&&

.AVIATION...
Updated 1126Z.

An upper level low pressure trof will approach the Rockies today.
Gust surface winds will continue as this trof approaches during the
day. The associated cold front will cross the Canadian border late
this afternoon and push south through Central and Southwest Montana.
Widespread snow will develop with MVFR/IFR conditions along with
mountain obscuration through Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  39  15  20  -4 /  50  60  60  30
CTB  36   9  12  -8 /  50  60  30  30
HLN  42  18  28   6 /  30  40  30  20
BZN  38  16  23   4 /  40  50  20  20
WEY  27   5  16  -3 /  90  80  30  20
DLN  37  13  23   5 /  40  50  10  20
HVR  39  13  16  -1 /  30  40  30  20
LWT  39  14  17  -3 /  30  50  50  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 8 AM this morning to 5 PM MST
Monday Central and Southern Lewis and Clark...Jefferson.

Winter Weather Advisory from 8 AM this morning to 5 PM MST
Monday below 6000 feet for Beaverhead...Gallatin...Madison.

Winter Storm Warning from 8 AM this morning to 5 PM MST Monday
above 6000 feet for Beaverhead...Gallatin...Madison.

Winter Storm Warning from 1 PM this afternoon to 5 PM MST Monday
Cascade...Judith Basin...Meagher.

Winter Weather Advisory from 2 PM this afternoon to 5 PM MST
Monday Chouteau...Fergus.

Winter Weather Advisory from noon today to 5 PM MST Monday
Broadwater.

Winter Weather Advisory from noon today to 5 PM MST Monday
Eastern Glacier...Eastern Pondera...Eastern Teton...Toole.

Winter Storm Warning until 5 PM MST Monday Northern Rocky
Mountain Front...Southern Rocky Mountain Front.

&&

$$

weather.gov/greatfalls



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