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FXUS65 KTFX 031153 CCA
AFDTFX

Area Forecast Discussion...CORRECTED
National Weather Service Great Falls MT
553 AM MDT Thu Apr 3 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Light snow and fog will continue to spread south from North
   Central Montana into Central and Southwest Montana throughout
   this afternoon, then decrease from the northwest this evening
   and overnight.

 - High pressure ridging is still on track to bring warming and
   drying conditions into early next week.

 - A disturbance is then forecast to bring slightly cooler
   temperatures, gusty westerly winds, and a chance of mainly
   mountain precipitation to the area Tuesday and Wednesday.

&&

.DISCUSSION...
/Issued 422 AM MDT Thu Apr 3 2025/

553 am Update... Light snow has developed in the Gallatin Valley
area this morning, mainly causing accumulation from the city of
Bozeman east to Bozeman Pass. Have updated the forecast to address
this and have the snow decreasing after 8 am. -Coulston


 - Meteorological Overview:

Today through Friday... The push of cooler and more moist surface
air behind a Canadian cold front has spread low clouds with areas
of dense fog over the plains of North Central and Central Montana
as of 330 am. The light snow associated with this push has also
remained mostly along the Hi-Line for most of the night, except
for a few passing snow showers across Central Montana. This main
area of snow along the leading edge of a shortwave, and is
forecast to continue spreading south over the plains throughout
the day, mostly reaching Southwest Montana by late this afternoon.
Forecast snowfall amounts remain in the Advisory range for the
Rocky Mountain Front and the plains of North Central Montana,
where the bulk of the snow will occur through this morning. Have
also issued a Dense Fog Advisory for the plains areas not included
in the Winter Weather Advisory, as many areas are reporting
visibility of 1 mile or less prior to the snow moving in there.
Snowfall amounts for much of Central Montana remain marginal for
Winter Weather Advisories, so have held off on issuing any more
there, other than the previously issued Advisory for the Little
Belt and Highwood Mountains. Upslope enhanced snow is possible on
the north-facing slopes of the Central Montana mountains along the
MT Highway 200 corridor, but the concern there is that the bulk of
the snowfall there will occur this afternoon, and solar radiation
may hinder snow accumulation due to melting on road surfaces.

The area of snow will become more focused over Southwest Montana
this evening and overnight, likely bringing mainly mountain
accumulation. Amounts of 3 to 7 inches are possible in the
Bridger, Gallatin, Madison, and Ruby Mountains, and also
potentially over Bozeman Pass. Have therefore issued a Winter
Weather Advisory for that area starting at 3 pm and continuing
through 9 am Friday morning. Have also included the Gallatin and
Madison Valley areas, as the mid-level flow will shift more
northwesterly, which enhances snowfall there. 1 to 3 inches are
mostly expected, but the city of Bozeman could receive up to 5
inches.

Overall, temperatures today and tonight will remain well below
normal. However, the exit of the low pressure trough will allow a
high pressure ridge from the Pacific to start to influence the
weather with drying and warming conditions.

Saturday through next Thursday... Forecast ensemble model clusters
continue to agree on moving the strong high pressure ridge on the
Pacific coast east into Montana through Monday. This will keep the
area mostly dry as temperatures warm to around 15 degrees above
normal by Monday. However, a shortwave trough is forecast to break
down the ridge somewhat Monday night through Wednesday, bringing
increasing westerly winds, slightly cooling temperatures, and a
chance of mainly mountain precipitation. Once this disturbance
exits the area, dry and warming conditions return for Thursday.
-Coulston

 - Forecast Confidence & Scenarios:

Snow Today and Tonight... Confidence remains high that Advisory
criteria snowfall will occur where the Advisories are in place, as
there is at least a 60 percent probability for 2 inches of
snowfall. Mountain probabilities for at least 4 inches of snow in
the Advisory areas are also at least 60 percent. In contrast, the
probabilities for greater than 9 inches in the mountains (Warning
criteria) remain very low, with the highest values being 40
percent or less on the highest peaks of the Rocky Mountain Front.

Winds Tuesday and Wednesday... NBM probabilistic guidance
indicates mostly a 50 to 80 percent probability of 50+ mph wind
gusts both days for the Rocky Mountain Front and east into the Cut
Bank area, with a 30 to 50 percent probability of exceeding 70 mph
wind gusts right along the Front. These probabilities warrant
monitoring for potential High Wind highlights there. Elsewhere
across North Central, Central, and Southwest Montana, the
probabilities of 50+ mph wind gusts increase Tuesday into
Wednesday, ranging mostly between 20 and 50 percent on Wednesday,
which will also need to be watched.
-Coulston

&&

.AVIATION...
03/12Z TAF Period

A cold front pushing southward across Montana will bring a mix of
VFR to IFR conditions with LIFR conditions possible in heavier
snow showers and early morning fog. Expect snow and fog to mainly
be found around KCTB, KGTF, and KHVR through 15z before snow
spreads further south to KHLN, KBZN, and KEKS Thursday morning.
Snow showers capable of LIFR conditions will be possible during
the daylight hours on Thursday. While they have not been put into
the TAFs at this time, the greatest threat for LIFR conditions
will exist at KHLN, KEKS, and KBZN. Ludwig

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  33  19  43  22 / 100  30   0   0
CTB  32  15  41  21 / 100  10   0   0
HLN  41  20  44  22 /  70  50   0   0
BZN  41  20  38  16 /  70  80  10   0
WYS  38  14  38   6 /  50  60  10   0
DLN  42  23  41  20 /  50  40   0   0
HVR  36  16  42  20 / 100  10   0   0
LWT  35  17  37  20 / 100  50  10   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM MDT this evening for Bears
Paw Mountains and Southern Blaine-East Glacier Park Region-
Eastern Glacier, Western Toole, and Central Pondera-Eastern
Toole and Liberty-Hill County-Northern Blaine County-Northern
High Plains-Southern High Plains-Southern Rocky Mountain Front.

Dense Fog Advisory until 11 AM MDT this morning for Cascade
County below 5000ft-Eastern Pondera and Eastern Teton-Fergus
County below 4500ft-Gates of the Mountains-Judith Basin County
and Judith Gap-Western and Central Chouteau County.

Winter Weather Advisory from 9 AM this morning to midnight MDT
tonight for Little Belt and Highwood Mountains.

Winter Weather Advisory from 3 PM this afternoon to 3 AM MDT
Friday for Big Belt, Bridger and Castle Mountains-Gallatin
Valley-Gallatin and Madison County Mountains and Centennial
Mountains-Madison River Valley.

&&

$$
http://www.weather.gov/greatfalls