Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

358
FXUS65 KTFX 150529
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1129 PM MDT Tue Oct 14 2025

Aviation Section Updated.

.KEY MESSAGES...

- Scattered rain or snow showers this evening, mostly over North
  Central MT.

- Another round of lower elevation rain and mountain snow
  Wednesday into Wednesday night.

- A slow warming trend through the beginning of the weekend,
  before another weather system moves into the region by early
  next week.

&&

.UPDATE...
/Issued 832 PM MDT Tue Oct 14 2025/

Main concern tonight through Wednesday morning will be the
development of fog and lower stratus across much of the area.
Lower level moisture remains trapped beneath gradually warming
mid-levels overnight which has already lead to widespread low
clouds and some areas of fog across primarily north-central MT.
Low level east to northeast upslope flow and some surface cooling
should lead to lowering cloud bases and an expansion of fog
overnight with enough moisture in place for some areas of drizzle
as well, especially across locations from the southern Rocky Mtn
Front east across Cascade and Judith Basin counties. The next
upper level disturbance lifting out of ID will bring some light
precipitation to far southwest and eastern portions of central MT
late tonight through Wednesday morning with snow levels generally
at or above 7000 ft. With nearly iso-thermal temperatures beneath
this, cannot rule out some light snow at or mixed precipitation
at lower elevations. Road and surface air temperatures are likely
to stay near or above freezing in areas where drizzle occurs
overnight, but this will also need to be monitored. Hoenisch

&&

.DISCUSSION...
/Issued 832 PM MDT Tue Oct 14 2025/

 - Meteorological Overview:
Scattered showers continue to push northward through the CWA this
afternoon. A few isolated thunderstorms are trying to move into
the West Yellowstone area as well. Overall, precip diminishes this
evening, with the potential for patchy fog later tonight. However,
cloud cover will limit the coverage area.

For Wednesday, another round of showers and mountain snow
develops. Snow levels will be rather high, above 7000 feet in most
areas.

Afternoon temperatures will continue a very slow warming trend
over the next few days, but likely to average a bit below normal
until Sunday. Additionally, the next upper level low from the west
moves into the western portions of the CWA by Sun/Mon...increasing
the chances for precipitation.

 - Forecast Confidence & Scenarios:
Overall, precipitation is light tonight. For Wed/Thu...the
heaviest snowfall is expected in the mountains around and just
east of Big Sky. Snow accumulations of 2 to 4 inches is possible,
mostly above 7000 feet. Since most/all of the snow is expected
above pass level with this event, no advisory will be issued at
this time.

For Sunday, the GFS/EC have different solutions on the timing of
the next weather system. The EC is much quicker, thus cooler
temperatures on Sunday. The GFS is warmer/drier on Sunday, with
the potential for afternoon temperatures above 70 degrees. With
confidence low on either solution at this time, the blend of the
NBM is on track. Brusda

&&

.AVIATION...
15/06Z TAF Period

Main concerns for the TAF period is precipitation, fog, and IFR
ceilings developing Wednesday morning. A band of precipitation
will move north through Southwest MT after 15/08z-15/10z, and
reach North Central MT mid to late morning. Guidance hints at the
decent potential for patchy fog to set up across North Central MT
before the precipitation arrives. If fog develops, then IFR
conditions can develop. Light snow/rain and snow mix will impact
Southwest MT in the morning, bringing IFR cigs at times before
switching to rain in the afternoon. Mountain obscuration persists
due to lower clouds and precipitation. -Wilson

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  27  47  35  53 /  10  40  60  50
CTB  22  49  31  58 /  10  10  20  10
HLN  28  50  35  53 /  10  50  60  60
BZN  29  50  33  47 /  40  60  70  80
WYS  28  50  28  44 /  90  80  80  90
DLN  31  48  33  50 /  30  60  60  50
HVR  25  49  35  55 /  10  50  60  50
LWT  27  49  33  45 /  40  70  70  80

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

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