Dillon, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

873
FXUS65 KTFX 180453
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
953 PM MST Fri Jan 17 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Blowing snow will remain a concern between Great Falls and
   Grass Range again tomorrow morning into the early afternoon.

 - Primarily light, but localized moderate snow lingers into the
   day Saturday across Central Montana.

 - Coldest temperatures of the season this weekend into early next
   week.

&&

.UPDATE...
/Issued 849 PM MST Fri Jan 17 2025/

It will gradually cool off tonight across North-central, Central,
and Southwestern Montana. Tomorrow it will only briefly warm up
before arctic air moves down from Canada. Along the Highway 200/87
Corridor there will be gusty winds and a brief burst of heavy
snowfall tomorrow morning associated with the arctic front. For
the update, I reran the dirunals to better match current
observations and trends. Wind speed and sky grids were adjusted to
better match current observations and trends. The Winter Weather
Advisory for the Southern Rocky Mountain Front, Southern High
Plains, and Gates of the Mountains area will be allowed to expire
at 900 PM due to only light snow continuing through the day
tomorrow. The rest of the forecast is on track. -IG

&&

.DISCUSSION...
/Issued 849 PM MST Fri Jan 17 2025/

 - Meteorological Overview:

Northerly flow both aloft and at the surface in wake of a Canadian
cold front will be the main driver of weather across the region
through the weekend into early next week. Through the remainder of
the day the main concern is transitioning from the combination of
falling and blowing snow to just falling snow, primarily in
northerly upslope areas across Central Montana. Although winds will
continue to slowly diminish, the opportunity for more localized
blowing snow will continue along the US-87 corridor between Great
Falls and Grass Range through the afternoon. The northerly winds
will also continue to cooling trend through the remainder of the day
across the region.

A reinforcing cold front slides southward, initially along the Rocky
Mountain Front late tonight, spreading south and eastward early
tomorrow morning. A period of gusty winds will follow this passage,
with gusts between 30 and 40 mph across the plains. Another period
of blowing snow looks likely between Great Falls and Grass Range on
and adjacent to US-87 through the morning hours Saturday. Hence, the
Winter Weather Advisory for this area was extended into early
afternoon Saturday for the combination of blowing and falling snow.

Northerly winds continue through the day Saturday, ushering the
coldest air of the season for the Saturday evening through Monday
morning timeframe. Given winter so far has been on the mild side,
forecast lows for much of the region Sunday and Monday morning are
at least 10 degrees colder than previous coldest observed
lows this winter.

Upper level ridging attempts to nudge in from the west early next
week, but there remains uncertainty as to how quickly any warming
will take place Monday onward. As quickly as the ridging attempts to
build in, additional disturbances within northwesterly flow look to
pass across the Northern Rockies. This will keep at least a low-end
chance for snow toward the middle of next week.

 - Forecast Confidence & Scenarios:

Snow and blowing snow through Saturday:

Northerly flow will keep light snow in the forecast across much of
the plains over the next day or so, with better chances for
accumulating snow across Central Montana terrain. Guidance usually
struggles with how long this will last so I opted for low-end
mentions for snow across much of the plains through tomorrow
morning. I did opt to extend much of the Winter Weather Advisory for
areas along and west of I-15 through the evening, as the snow should
pose at least minor impacts where the plains meet terrain.

Additional blowing snow will develop tomorrow morning, now looking
to last a bit longer, into early afternoon, across Judith Basin
and Fergus counties. As such, the Winter Weather Advisory in these
areas was extended a bit into the afternoon Saturday.

Cold:

The first period of impactful cold develops late tonight in the
Cut Bank area and points westward as the reinforcing cold shot
slides southward. The cold temperatures and wind should combine
for at least a few hours of wind chills below 25 below. A Cold
Weather Advisory has been issued for this area as a result.
Additional Cold Weather Advisories will be necessary for much more
of the region beginning Saturday night, though the exact extent
is still questionable at this time. Given this uncertainty I have
opted to wait on issuing additional Cold Weather Advisories. -AM

&&

.AVIATION...
18/06Z TAF Period

VFR conditions will prevail at the KBZN and KHLN terminals for the
duration of this TAF period. At the KBZN, KEKS, and the KHLN
terminals there is a 20 - 40% chance for snow between 18/06Z and
18/21Z. At the KCTB terminal between 18/06Z and 18/16Z there is
20 - 30% chance for snow. At the KGTF, KHVR, and KLWT terminal
there is a 20 - 40% chance for snow between 18/00Z and 18/10Z.
Blowing snow at the KLWT and KGTF terminals will reduce visibility
to IFR levels between 18/10Z and 18/18Z. There will be mountain
obscuration during the duration of this TAF period. -IG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  -1   5 -15   3 /  40  70   0  10
CTB  -4   0 -19   2 /  30  20   0   0
HLN   4   8  -4  12 /  20  40   0  10
BZN  -5   8 -11  13 /  40  40   0  10
WYS -23  11 -26  13 /  10  10   0  10
DLN   3  14  -2  17 /  30  20   0   0
HVR  -3   5 -21  -3 /  60  40   0   0
LWT   0   4 -14   1 /  50  70   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory from 3 AM to noon MST Saturday for East
Glacier Park Region-Eastern Glacier, Western Toole, and Central
Pondera-Northern High Plains.

Winter Weather Advisory until 3 PM MST Saturday for Cascade
County below 5000ft-Fergus County below 4500ft-Judith Basin
County and Judith Gap-Little Belt and Highwood Mountains-Snowy
and Judith Mountains.

&&

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