Area Forecast Discussion
Issued by NWS Great Falls, MT

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000
FXUS65 KTFX 242351
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
454 PM MST Sat Feb 24 2018

Aviation Section Updated.

.SYNOPSIS...

Periods of light snow are possible Saturday evening across
Southwest Montana. Strong west winds return on Sunday, creating
areas of blowing snow across much of North-central Montana.
Travel west over the Continental Divide will be difficult on
Sunday due to a combination of falling and blowing snow.

&&

.DISCUSSION...

Tonight through Monday...Radar and satellite imagery shows an area
of light snow beginning to spread across Southwest Montana. Light
snow will continue this evening, then end by the early morning
hours. A winter weather advisory is in effect for Southwest
Montana this evening to address expected impacts to travel over
mountain passes. New snow accumulations of around 1-4 inches are
possible. Light snow showers are also seen moving into Hill and
Blaine counties. These are expected to move quickly and produce
little new snow accumulation.

Strong west winds return along the Rocky Mountain Front early
Sunday, then spread across the North- central plains through the
day Sunday. Travel over the continental divide will be difficult
Sunday due to a combination of falling and blowing snow. The
previous Winter Storm Watch has been converted to a Winter Weather
Advisory for blowing snow. Winds gusting 35 to 50 mph will cause
widespread blowing and drifting snow. Localized wind gusts to 70
mph are possible along the immediate east slopes of the Rocky
Mountain Front. Warmer temperatures, combined with the intense
scouring and compaction of existing snow cover that occurred
Friday provides reserved confidence that ground blizzard
conditions will not redevelop over western Glacier County.
However, this remains a sensitive area in critical snow recovery
operations, so will monitor carefully for any blowing snow
conditions that may develop on Sunday. Winds speeds decrease
Sunday night. Another shortwave tracks through Southwest MT on
Monday, providing a new round of light snow that could slow travel
in some areas Monday evening.

Monday Night through Saturday...Medium range forecast models are in
much better agreement with the forecast solution during this period
than they were last night. A broad upper level low pressure trough
over the western and central portions of Canada and the United
States is still forecast to be the dominant feature through this
period. One embedded shortwave trough will exit the state Monday
night, then another shortwave will swing through Montana Tuesday
through Tuesday night, resulting in periods of light mountain snow.
A shortwave high pressure ridge will then move into the state for
Wednesday through Thursday ahead of a deep upper level low pressure
area. This ridge will help decrease the chance of snow over the
mountains, while breezy westerly downslope winds help keep the lower
elevations dry. The low pressure area will be off the Pacific
Northwest coast Thursday through Friday, but forecast models differ
on what to do with it after then; the Canadian model keeps it off
the coast, the ECMWF moves it slowly into the Pacific Northwest, and
the GFS moves it quickly into Montana. Will go closer to the
GFS/ECMWF solution of bringing the low towards the forecast area for
an increasing chance of snow for Friday through Saturday. However,
this solution is fairly different than the forecast depicted last
night, so confidence in the details of this part of the forecast is
only low to moderate. Regardless, the overall temperature trend
keeps temperatures between 5 and 10 degrees below normal through
Thursday, with the potential for at least a minor cooldown for
Friday and Saturday.
Coulston

&&

.AVIATION...
Updated 0000Z

Expect MVFR with temporary IFR conditions over Southwest MT this
evening in mid/low level ceilings and snow showers. Conditions
improve after midnight. VFR conditions prevail to the north. Strong
west winds return on Sunday, with gusts of 30-40kt possibly
producing drifting snow and localized blowing snow. PN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  16  34  14  30 /  10  20  20  10
CTB  15  31  10  29 /  10  20  30  10
HLN  18  33  16  29 /  30  40  30  20
BZN  12  31  17  28 /  40  30  40  40
WEY   2  20  13  25 /  70  80  80  60
DLN   9  26  13  25 /  30  30  50  30
HVR  10  31  11  24 /  10  10  10  10
LWT  14  31  17  28 /  20  10  20  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to midnight MST
Sunday night Central and Southern Lewis and Clark...Northern
Rocky Mountain Front...Southern Rocky Mountain Front.

Winter Weather Advisory from 6 AM Sunday to midnight MST Sunday
night Blaine...Cascade...Chouteau...Eastern Glacier...Eastern
Pondera...Eastern Teton...Fergus...Hill...Judith Basin...
Liberty...Toole.

Winter Weather Advisory until midnight MST tonight above 6500
feet for Beaverhead...Gallatin...Madison.

&&

$$

http://www.weather.gov/greatfalls



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