252
FXUS65 KTFX 231722 CCA
AFDTFX

Area Forecast Discussion...cor
National Weather Service Great Falls MT
1022 AM MST Sun Feb 23 2025

Aviation Section Updated.

.KEY MESSAGES...

- Periods of strong winds over North Central MT from now into
  Tue.

- Accumulating snow in Glacier Park and Beaverhead Mountain range
  today.

- Minor chance for isolated freezing rain in the valleys of
  Southwest MT.

- Overall, above normal afternoon temperatures expected this
  week.

&&

.UPDATE...
/Issued 918 AM MST Sun Feb 23 2025/

Today it will be warm and windy across North-central, Central, and
Southwestern Montana with snow along the Rocky Mountain Front and
the mountains of Southwestern Montana. For the update, temperatures
across North-central, Central, and Southwestern Montana were
adjusted to better reflect current observations and trends. Wind
speeds and wind gusts were decreased slightly to better reflect
current observations and trends. QPF along the Rocky Mountain
Front and in Northwest Beaverhead County were decreased to better
reflect current Hi-res model guidance. Wind gust probabilities
and model guidance increased for MacDonald Pass and so a High Wind
Warning was issued for that area from 11 PM tonight through 2 PM
tomorrow. The rest of the forecast is on track. -IG

&&

.DISCUSSION...
/Issued 918 AM MST Sun Feb 23 2025/

 - Meteorological Overview:
A strong westerly flow aloft will continue to reside over the CWA
for the next several days. This will allow periods of strong winds
to mix down from aloft over North Central MT. As of now, the
strongest winds should occur before 5 PM Monday, with the
potential for some strong winds to continue into Tuesday along the
front range of the Rockies. The GFS is strongest with the winds
this afternoon over North Central MT, which is why the high wind
watch was changed to a warning, but also starting a bit earlier.

In terms of snow today, the westerly flow will allow for snow to
fall for areas right near the divide. Glacier Park and the
Beaverhead Mountain ranges will be most impacted. Since impacts
are low on the east side of these two mountain ranges this time
of year, no statements will be issued at this time.

The main upper level trof moves from west to east across the CWA
on Tuesday. That is the best chance for precip east of the divide
early this week. As of now, precipitation amounts look light, and
no winter statements will be issued at this time. There continues
to be a minor chance for some light freezing rain in the colder
pockets of Southwest MT. Since the probability is low, less than
20 percent, I`ll hold off on any freezing rain wording as well.

It does dry out a bit from Wed thru Fri as an upper level ridge
builds over the CWA. However, a fast moving upper level trof is
progged to move across the CWA next weekend, bringing with it
another chance for rain/snow showers.

Overall, above normal afternoon temperatures are expected in most
areas across our CWA this week.

 - Forecast Confidence & Scenarios:
There is a 90 percent chance for wind speeds above warning
criteria along the front Range of the Rockies and in the Cut Bank
area today/tomorrow. Eastward, over the Plain, it is a bit lower,
near 80 percent probability of warning criteria wind gusts. Thus
there is a high wind warning for all of North Central MT.

The snowfall Mon night into Tue could be a bit more widespread and
at a bit lower snow levels along the divide and across Southwest
MT that a winter weather advisory might be needed for some
mountain areas. Brusda

&&

.AVIATION...
23/18Z TAF Period

The main concern this TAF period will be for gusty surface winds,
periods of low-level wind shear and mountain wave turbulence across
the region. Additionally, mountains will be obscured by rain and
snow, mostly along the Continental Divide. Brief instances of
rain will be around through the overnight, though are not forecast
to reduce conditions to MVFR at this time. -AM

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

&&

.HYDROLOGY...

Warming temperatures through next week will lead to changes in
river ice conditions and an increased risk of river ice breakup
and the potential for ice jams. Lower elevation snowmelt and
still frozen ground could also lead to some increased runoff into
creeks and rivers, adding to the potential for river ice breakup.
Ice jams are unpredictable and flooding can rapidly occur, so
those with interests along waterways should monitor water levels
over the coming week and take action should flooding occur.

Additionally, frozen ground after a prolonged cold period and
melting snow may result in standing water in areas of poor
drainage. This could create difficult access to fields and impact
some rural roads. As temperatures warm up more early next week and
the ground begins to thaw, muddy conditions may create additional
impacts. The greatest risk for overland impacts from snowmelt
look to be from eastern portions of Teton and Pondera counties
across portions of Cascade and Chouteau counties and most lower
elevation areas in Judith Basin and Fergus counties, where water
equivalent in the lower elevation snowpack ranges from around 1.0"
to as much as 3.0 to 4.0" in portions of Fergus county. These
areas are also most susceptible to overnight temperatures
remaining near or above freezing tonight through early next week.
Across Southwestern Montana, there is significant water content in
the snowpack in the Gallatin valley, however melting will likely
be slower with overnight temperatures continuing to fall below
freezing. -IG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  49  37  48  36 /  10  30   0  20
CTB  45  33  42  30 /  20  30   0  20
HLN  46  35  47  31 /  30  70   0  60
BZN  43  28  45  26 /  10  60  10  60
WYS  33  24  38  22 /  60  70  40  70
DLN  41  29  43  26 /  20  50   0  40
HVR  49  31  48  28 /  20  60  10  20
LWT  46  34  43  30 /  10  40   0  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 2 PM MST Monday for Cascade County below
5000ft-East Glacier Park Region-Eastern Glacier, Western Toole,
and Central Pondera-Eastern Pondera and Eastern Teton-Eastern
Toole and Liberty-Judith Basin County and Judith Gap-Madison
River Valley-Northern High Plains-Southern High Plains-Southern
Rocky Mountain Front-Western and Central Chouteau County.

High Wind Warning until 5 PM MST Monday for Bears Paw Mountains
and Southern Blaine-Fergus County below 4500ft-Hill County-
Little Belt and Highwood Mountains-Northern Blaine County-Snowy
and Judith Mountains.

High Wind Warning from 11 PM this evening to 2 PM MST Monday for
Upper Blackfoot and MacDonald Pass.

&&

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