259
FXUS65 KTFX 170229
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
829 PM MDT Wed Apr 16 2025

.KEY MESSAGES...

 - Rain and snow will continue to make their way through the area
   today, bringing periods of reduced visibility and some areas
   of slick roads.

 - Gusty winds could result in some drifting of the snow,
   particularly along the Rocky Mountain Front and in Southwestern
   Montana.

 - After a warm and tranquil end to this week, the cool and
   unsettled weather pattern returns for next week.

&&

.UPDATE...
Updated evening forecast is out. Rain/snow continue to push
southward, with the heaviest snowfall shifting over Southwest MT
tonight. Snow is ending along the divide/northern Rockies now,
thus the current statement ending time for this area looks good.
However, snow continues over the Southern Rockies, and a portion
of that area might need to be extended overnight, just depending
how much the snow decreases in that area over the next few hours.
Overall, snow accumulations at lower elevations will be on the
light side, generally 1 to 3 inches. Impacts will be limited with
melting, but as colder air moves into the CWA overnight, some wet
roadways could begin to freeze over by daybreak. Overall, current
forecast lows for tonight look on track. Brusda

/Issued 454 PM MDT Wed Apr 16 2025/
Updated pops over North Central MT this evening, with a widespread
area of moderate snowfall moving northeastward through the CWA.
Most snow accumulations are on the grassy areas at lower
elevations at this time, but do expect reduced driving visibility,
along with some slushy snow accumulations, especially on bridges.
Brusda

&&

.DISCUSSION...
/Issued 300 PM MDT Wed Apr 16 2025/

 - Meteorological Overview:

An upper level trough will continue to dig into the Northern
Rockies today, bringing a cold front and a round of precipitation
to the area. Precipitation will start out as a period of rain at
lower elevations before quickly changing over to snowfall within a
few hours of precipitation beginning. Snowfall will continue to
move southward this evening and overnight tonight as the cold
front and trough slide further south, and winds will also pick up
across Southwestern Montana as the cold front slows, allowing the
pressure gradient to strengthen, with the strongest winds expected
in the North South oriented valleys. Snow should generally be on
the decrease by sunrise on Thursday as this system gets further
south, but a reinforcing upper level disturbance could help kick
off a few convective snow showers during the afternoon on
Thursday.

Upper level ridging will build back into the area for Friday and
Saturday, which will bring a period of warmer and more tranquil
weather to the area for the end of this week. However, zonal flow
will set back up as early as Sunday, which will allow for another
period of cooler and unsettled weather that will likely last
through next week.

 - Forecast Confidence & Scenarios:

Snowfall accumulations through the next 12-24 hours will largely
be dependent on the timing of the changeover to snowfall today and
tonight, along with ground temperatures. So far, precipitation
has been changing to snow slightly faster than originally
forecast, but the strong April sun angle has been keeping
accumulations low and generally on elevated/grassy surfaces.
Furthermore, pavement temperatures will generally be the biggest
factor in impacts with this system, as how quickly the pavement
cools off will play a large role in whether or not roadways ice up
overnight tonight, along with determining how much accumulates on
any paved surfaces.

For next week, while confidence is generally high in the overall
pattern being on the unsettled side, confidence in any individual
system or details that follow from that is quite low at this time.
Ludwig

&&

.AVIATION...
17/00Z TAF Period

North Central Montana: The main area of light to moderate snow has
mostly moved out of this area as of 00Z, allowing conditions to
improve to VFR with broken mid- and high-level cloudiness. If
winds and clouds continue to decrease, areas of fog will be a
concern between 06Z and 16Z, but am not expecting a significant
decrease in either. Northerly surface winds should increase again
after 16Z.

Central Montana: Gusty northerly upslope winds will help maintain
mountain-obscuring MVFR/IFR conditions in snow through around
06Z. After then, winds and snow should decrease, but VFR/MVFR
ceilings will likely improve to VFR after 12Z. After 16Z, weak
instability will allow scattered snow showers to form once again,
possibly causing periods of MVFR conditions with a return of gusty
northerly winds.

Southwest Montana: Gusty northerly winds will gradually decrease
at KHLN after 04Z and at KBZN after 06Z before increasing again
after 16Z, but they should remain gusty at KEKS through the
remainder of the period. A mix of rain and snow with VFR/MVFR
conditions will likely become all snow with mountain- obscuring
MVFR/IFR conditions by 05Z. This widespread snow should decrease
somewhat from north to south between 12Z and 18Z, but similar to
Central Montana, weak instability will bring scattered snow
showers with periods of MVFR conditions after 18Z.
-Coulston

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  29  42  23  50 / 100  30  10   0
CTB  23  39  20  51 / 100  20   0   0
HLN  31  42  24  51 /  80  50  10   0
BZN  27  35  16  43 / 100  90  20  10
WYS  22  33  13  40 /  90  90  40   0
DLN  26  34  19  42 /  90  80  10   0
HVR  26  46  21  53 / 100  10   0   0
LWT  26  36  20  44 / 100  60  20  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until midnight MDT tonight for East Glacier
Park Region-Southern Rocky Mountain Front.

Winter Weather Advisory until midnight MDT tonight for Northern
High Plains-Southern High Plains.

Winter Weather Advisory until 6 AM MDT Thursday for Gates of the
Mountains-Judith Basin County and Judith Gap-Little Belt and
Highwood Mountains-Snowy and Judith Mountains-Upper Blackfoot
and MacDonald Pass.

Winter Weather Advisory until midnight MDT Thursday night for
Beaverhead and Western Madison below 6000ft-Canyon Ferry Area-
Elkhorn and Boulder Mountains-Gallatin Valley-Helena Valley-
Meagher County Valleys-Missouri Headwaters-Northwest Beaverhead
County-Ruby Mountains and Southern Beaverhead Mountains.

Winter Storm Warning until midnight MDT Thursday night for Big
Belt, Bridger and Castle Mountains-Gallatin and Madison County
Mountains and Centennial Mountains-Madison River Valley.

&&

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