919
FXUS65 KTFX 080101 CCA
AFDTFX

Area Forecast Discussion...CORRECTED
National Weather Service Great Falls MT
601 PM MST Fri Feb 7 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Drier conditions are expected this weekend into early next
   week, although passing weather systems will maintain scattered
   areas of light snow.

-  Bitterly cold temperatures moderate some through the
   weekend before returning early next week.

&&

.DISCUSSION...
/Issued 423 PM MST Fri Feb 7 2025/

423 pm Update...
The winter weather advisory has ended for our CWA, as the
impactful snowfall has moved east. Just some scattered light snow
showers expected the rest of this evening. Brusda

157 pm Issuance...
Snow continues across North Central and portions of Southwestern
Montana this afternoon, with a few areas of localized heavy snow
showers. With this in mind, the previous Winter Storm Warning has
been replaced with an advisory, and given that snow is beginning
to exit the region, I have elected to bring the expiration time
of all Winter Weather Advisories up by 3-6 hours depending on
location. For more details, please see the previous discussion
below. Ludwig


402 am Issuance...

 - Meteorological Overview:

Partial clearing takes place tonight in the wake of the departing
shortwave with temperatures dipping in the single digits and
teens below zero. Patchy fog development can also be expected,
particularly in the river valleys of North- central Montana.

A northwesterly flow aloft is then expected for the remainder of
the weekend into next week. A series of clipper systems will pass
through the Northern Rockies and squeeze out rounds of lighter
end snow every 24 to 48 hours.

Temperatures moderate some this weekend with highs reaching the
teens and 20s for most locations, but the aforementioned clipper
systems will bring reinforcing shots of colder air early next
week with highs generally falling to the single digits above and
below zero and lows in the teens and 20s below. - RCG/Ludwig

 - Forecast Confidence & Scenarios:

Periods of light snow this weekend into next week:

Clipper systems will bring periods of scattered light snow every
24 to 48 hours this weekend and next week. The most widespread
snowfall looks to occur Sunday night into Monday over the plains.
Exceedence probabilities suggest most locations have less than a
20% chance for accumulations exceeding 2 inches. More widespread
snowfall may return next Thursday into Friday with a more
westerly flow aloft introducing Pacific moisture, but
probabilities for snowfall over 2 inches is less than 30% for
lower elevations.

Cold temperatures:

Partial clearing tonight will encourage low temperatures to drop
into the single digits and teens below zero, with the best chance
(70%+) for lows -10F or less reserved for the Hi-Line and the
wind protected central and southwest valleys. Temperatures
moderate some Saturday and Sunday with highs mostly in the teens
and 20s and lows around zero to 10 above. Reinforcing shots of
Arctic air return as early as Sunday night, peaking in strength
and areal coverage Monday night into Tuesday. Widespread lows of
10 to 20 below zero F can be expected during this time with highs
in the single digits above and below zero. The cold eases some
for the second half of the week, but will still remain well below
average. Also, areas along the Hi-Line will hang onto the Arctic
Chill longer than other areas. - RCG

&&

.AVIATION...
08/00Z TAF Period

A few light flurries may linger through around 03Z, but the
overall trend is for skies to partially clear, leaving mostly VFR
conditions. However, this partial clearing after the snow from the
last 24 hours will cause areas of terrain-obscuring MVFR/IFR fog
to form through 06Z, but there is some uncertainty as to the
location of the more dense fog, as it will be very dependent upon
where the greatest clearing occurs. Forecast models indicate that
this should be over the plains, so have focused the lower
visibility there for now; cannot rule out periods of LIFR/VLIFR at
times. However, light southwest to winds are forecast to develop
on the east slopes of the Rockies around and after 06Z, which
should help mix out any fog that forms at the KCTB and KGTF
terminals. Otherwise, fog that forms elsewhere should dissipate
after 16Z, as gusty southwest to west winds spread east across the
plains, but VFR ceilings are also forecast to spread over the
plains. -Coulston

Equipment note: The observation at KEKS stopped transmitting after
07/2355Z due to a power outage in the area. Have therefore added
AMD NOT SKED to the TAF. Will update the TAF to remove it when the
situation is resolved.

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

&&

.HYDROLOGY...
The flood warning continues for the Madison River in Ennis, as
local DES continues to monitor the situation and report flooding
in Ennis State Park. Because this is an ice jam, it is unknown
when the jam will break up. Thus the flood warning will continue
until the ice jam breaks up and the water reseeds. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  -8  24   7  17 /  10   0  30  30
CTB -10  23  -1  11 /   0  10   0  10
HLN  -6  22   4  22 /   0   0  10  10
BZN  -9  19   2  21 /  10   0  10   0
WYS  -3  18  -3  19 /  40  30  10  10
DLN  -2  21   0  22 /  10   0   0   0
HVR -10  16  -3  13 /   0   0   0   0
LWT  -8  22   3  17 /  10   0  20  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

Flood Warning for the Madison River in Ennis.

&&

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