Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 252122
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
222 PM MST Sun Feb 25 2018

.SYNOPSIS...

Low pressure tracking east from Alberta to Saskatchewan will
continue to bring windy conditions to the area through this
evening with scattered blowing and widespread drifting snow
impacts across much of north central Montana continuing before
winds diminish slowly overnight. Snow showers along the
continental divide will become more numerous tonight as well with
light snow accumulation of an inch or less expected at lower
elevations while an additional 2 to 4 inches of snow is possible
over the mountainous areas. Somewhat dry but continued breezy and
cool conditions linger through much of the upcoming week.

&&

.DISCUSSION...

Band of strong westerly flow aloft continues across the northern
Rockies and MT ahead of a shortwave trough sagging SE from BC. Low
level wind maximum (at around 6000-8000ft MSL) of 50-60kts remains
over much of north central MT through about 00z before slowly
dissipating, continuing the strong wind threat with strongest winds
primarily west of I15 but gusts to 45kts also widespread across the
remainder of North-central MT. Poor driving conditions are
widespread across much of northcentral MT due to significant
drifting of the snow with some visibility reduction as well in times
of peak gusts. Many N-S highways remain closed just east of the
Rocky Mtn Front, where winds are strongest in combination with a
deep snowpack in place and a Blizzard warning remains through
midnight tonight while a winter weather advisory for blowing snow
continues through midnight for the remainder of north central MT.
Improvement should begin tonight with diminishing winds, however
roadways that became slushy/wet this afternoon as temperatures
neared the freezing point may become icy tonight after sunset adding
an additional localized hazard. Snow has been falling steadily along
and west of the Rocky Mtn Front and as the shortwave and associated
cooling aloft spread south into the area this evening snow showers
should increase in coverage over central and SW MT. Snow
accumulations of over 2 inches will be limited to the mountain
areas, especially near the continental divide with some localized
accumulation up to an inch elsewhere in areas that may be affected
by bands of snow showers. A relatively dry period follows for Monday
and Monday night as weak upper level ridging moves over the region.
Winds will increase again Tuesday as additional shortwave energy
moves into the region, but at this point winds aloft are not as
strong as recent events. Hoenisch

Tuesday Night through Sunday...Models have come into very good
agreement for this period, so confidence is increasing in the
overall solution. A northwest flow aloft on the back side of an
exiting shortwave low pressure trough will likely keep light snow in
the mountains of western and southwest Montana Tuesday night into
Wednesday, but breezy westerly downslope winds will keep lower
elevations dry. A weak shortwave high pressure ridge will then help
dry out most of the forecast area for Wednesday night. The next
system to potentially have a significant impact on the region will
be a deep upper level low pressure trough that will move south along
the Pacific coast of Canada Wednesday night to the Pacific Northwest
coast on Thursday. The increasingly moist southwest flow aloft over
the forecast area will keep a good chance of snow over the western
and southwest mountains Thursday and Thursday night. The trough will
then broaden as it spreads east across the Pacific Northwest and
into Montana Friday through Saturday, which may cause at least light
snow to spread over the forecast area. It is still a bit too early
to tell how much snowfall will occur, but this situation will need
to be monitored for possible winter weather highlights. This system
will begin exiting the area on Sunday for a decreasing chance of
snow. Temperatures will be 5 to 10 degrees below normal for the
beginning of this period. However, they will steadily cool to
between 10 and 15 degrees below normal Saturday through Sunday with
the passage of a Canadian cold front associated with the system.
Coulston

&&

.AVIATION...
Updated 1750Z

Strong west winds will continue to impact the area today as low
pressure tracks from AB to SK tonight with strong west winds aloft
to the south across the Northern Rockies and MT. Variable mid to
high level cloud-cover will stream across the region today with some
local Mtn obscuration, particularly along the continental divide where
snow showers will increase while VFR conditions prevail elsewhere.
Blowing and drifting snow impact will be most significant along the
Rocky Mtn front where gusts as high as 50kts could extend as far
east as KCTB at times today. Farther east on the plains gusts
will primarily  be in the 35-45kt range, contributing to some lower
visibility at times blowing snow though drifting snow will remain a
larger impact. Upper level trough will drop into the area tonight for
increasing clouds and possible snow showers/MVFR conditions at most
terminals with winds slowly decreasing and veering to W/NW. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  20  30  10  31 /  30  10   0  10
CTB  16  29  12  31 /  40  20   0  10
HLN  20  29   7  29 /  40  20   0  10
BZN  23  27   0  28 /  40  60  10   0
WEY  18  24  -9  22 /  90  90  40  10
DLN  19  24  -3  24 /  50  40  10   0
HVR  12  25   6  28 /  20  10   0  10
LWT  18  27   6  29 /  20  10  10   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MST tonight Central and
Southern Lewis and Clark.

Winter Weather Advisory until midnight MST tonight Blaine...
Cascade...Chouteau...Eastern Glacier...Eastern Pondera...Eastern
Teton...Fergus...Hill...Judith Basin...Liberty...Toole.

Winter Weather Advisory from 6 PM this evening to 6 PM MST
Monday Beaverhead...Gallatin...Madison.

High Wind Warning until 6 PM MST this evening Eastern Glacier.

Blizzard Warning until midnight MST tonight Northern Rocky
Mountain Front...Southern Rocky Mountain Front.

&&

$$

http://www.weather.gov/greatfalls



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