Winter Storm Warning 4, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
1040 AM MST Sat Feb 18 2023

...Aviation Section Update...

.SYNOPSIS...
For the next several days, wintry weather is in the forecast.
Winds will be gusty at times. Periods of accumulating snow is
forecast. Blowing snow may, significantly, reduce visibility, at
times. Next week, temperatures become increasingly colder courtesy
of the next Arctic airmass passing through The Treasure State.

&&

.UPDATE...
Updated forecast is out. Main adjustment was to add the Northern
Rocky Mountain Front to a winter weather advisory from now until
7 PM this evening. Otherwise, the band of snow west of the divide
will move southeastward into our CWA. Temperatures are near/above
freezing in some areas of SW MT, so impacts from snowfall during
the day should be on the lower side. If needed, and SPS will be
issued.

Otherwise attention turns more towards the prolonged snow expected
early next week. Some adjustments to the start timing of the
winter storm watch are possible for the afternoon package after
further coordination with neighboring NWS/WPC offices. Brusda

&&

.AVIATION...
1040 AM MST Sat Feb 18 2023 (18/18Z TAF Period)

KCTB and KHVR:

VFR conditions prevail for the duration of the TAF period. Gusty
westerly and southwesterly winds are forecast, with stronger, gusty
winds along the front range of the Rockies.

KGTF, KLWT, KHLN, KBZN and KEKS:

Begin this TAF period under VFR conditions, but begin to slide into
the MVFR/IFR range in snow and blowing snow, and with low ceilings.
Gusty northwesterly to southwesterly winds are forecast for KGTF,
KLWT and KHLN.

Generally:

Expect mountain obscuration with areas of snow showers and virga.

Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.

&&

.PREV DISCUSSION...
/ISSUED 531 AM MST Sat Feb 18 2023/

This discussion is written for north central, central and
southwest, Montana.

This weekend, an upper level trof slides southeastward across the
region. A tight northwesterly upper level flow favors some strong
gusty winds which are forecast to remain below High Wind Warning
criteria. A Winter Weather Advisory is valid for portions of
central and southwest Montana from 11am this morning to tomorrow
morning. Between 2 and 5 inches of accumulating is snow is
forecast, with up to 8 inches above 7000 foot elevation. Travel
may be difficult. at times. Blowing snow may significantly reduce
visibility, at times.

After this event, the area receives only a brief break, before the
next upper level trof enters the region. Snowfall begins across
The Continental Divide and some of the mountains of central
Montana. Strong gusty non-warning criteria winds are forecast,
again. And again, blowing snow reduces visibility. Travel will be
difficult, at times. As the week progresses, a deep upper level
trof digs into the area. An arctic airmass settles in across The
Treasure State causing temperatures to plummet through Thursday.
This Trof is attended by abundant moisture, and some significant
snow amounts are forecast. A Winter Weather Watch has been issued,
beginning Sunday, and continuing through midnight Thursday night.
There is high confidence in the approach of the forecast arctic
airmass. There's moderate confidence in timing and snow amounts.

Looking beyond this very cold and snowy event, next weekend,
temperatures are forecast to rebound, courtesy of gusty
downsloping westerly winds.
- Fogleman

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  40  25  42  33 /  50  50  10  60
CTB  39  22  39  28 /  20  10   0  50
HLN  37  23  39  33 /  70  60  20  70
BZN  31  12  34  24 /  80  70  20  70
WYS  22  -1  24  11 /  90  80  50  80
DLN  30  13  33  26 /  40  30   0  30
HVR  36  19  36  25 /  30  10  10  50
LWT  36  19  36  28 /  50  50  20  80

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 7 PM MST this evening for East
Glacier Park Region.

Winter Storm Watch from Sunday morning through Wednesday evening
for Big Belt, Bridger and Castle Mountains-East Glacier Park
Region-Little Belt and Highwood Mountains-Southern Rocky
Mountain Front.

Winter Storm Watch from late Sunday night through Wednesday
evening for Bears Paw Mountains and Southern Blaine-Beaverhead
and Western Madison below 6000ft-Canyon Ferry Area-Cascade
County below 5000ft-Eastern Glacier, Western Toole, and Central
Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and
Liberty-Elkhorn and Boulder Mountains-Fergus County below 4500ft-
Gallatin Valley-Gallatin and Madison County Mountains and
Centennial Mountains-Gates of the Mountains-Helena Valley-Hill
County-Judith Basin County and Judith Gap-Madison River Valley-
Meagher County Valleys-Missouri Headwaters-Northern Blaine
County-Northern High Plains-Northwest Beaverhead County-Ruby
Mountains and Southern Beaverhead Mountains-Snowy and Judith
Mountains-Southern High Plains-Upper Blackfoot and MacDonald
Pass-Western and Central Chouteau County.

Winter Weather Advisory until 5 AM MST Sunday for Big Belt,
Bridger and Castle Mountains-Gallatin and Madison County
Mountains and Centennial Mountains-Little Belt and Highwood
Mountains.

&&

http://www.weather.gov/greatfalls

Special Weather Statement
National Weather Service Great Falls MT
1219 PM MST Sat Feb 18 2023

MTZ308>310-312>314-316>318-182130-
Southern High Plains-Eastern Pondera and Eastern Teton-
Western and Central Chouteau County-Cascade County below 5000ft-
Judith Basin County and Judith Gap-Fergus County below 4500ft-
Gates of the Mountains-Little Belt and Highwood Mountains-
Snowy and Judith Mountains-
Including the cities of Bynum, Choteau, Pendroy, Brady, Conrad,
Ledger, Floweree, Carter, Fort Benton, Great Falls, Raynesford,
Geyser, Stanford, Windham, Benchland, Hobson, Moccasin, Hilger,
Lewistown, Canyon Creek, Wolf Creek, Craig, Monarch, Neihart,
and Kings Hill Pass
1219 PM MST Sat Feb 18 2023

...Snow showers this afternoon...

Scattered snow showers will move southward through North Central
MT this afternoon. Visibility could fall down to a half mile a
times as the snow moves through.

Snow accumulations at lower elevations will mainly be confined to
bridges and grassy areas, while an inch or snow is possible in
the mountains.

Those traveling through North Central MT this afternoon should be
alert for areas of poor visibility and changing road conditions.

Brusda