Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

750
FXUS65 KTFX 112021
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
221 PM MDT Fri Apr 11 2025

.KEY MESSAGES...

-  Breezy and gusty winds today and Saturday, especially along the
   Rocky Mountain Front.

- A slight chance for few showers and a thunderstorm for
  Southwest and Central Montana this evening.

- Increasing chances for rain and snow Saturday through Sunday
  morning.

- Drier weather and warming temperatures Monday and Tuesday.

&&

.DISCUSSION...

 - Meteorological Overview:

Breezy and gusty winds persists through the rest of the afternoon
today. Increasing moisture and a weak upper-level disturbance
moving through will produce a slight chance develop a few showers
and a low chance for an isolated thunderstorm this afternoon and
evening in Southwest and Central MT. Chances for precipitation
increases Saturday morning along the cold front for Central and
Southwest MT. A vorticity maximum at 500mb and PWAT`s around
0.4-0.5" will develop a band of wetting precipitation stretching
from western Beaverhead County to Fergus County. Rain will fall
across lower elevations, with mountain passes getting wet snow.
Weak instability builds in Saturday afternoon, which allows for a
low end chance for a few thunderstorms to develop in the
Southwest. Stronger winds aloft from the system will bring another
round of gusty winds to the Rocky Mountain Front and breezy winds
elsewhere. A dry slot moving in behind the front will allow for a
brief lull in precipitation in the afternoon before late Saturday
night and Sunday morning. Another wave of precipitation wrapping
around the low pressure system will bring additional mountain
snow, with some light snow mixing in at lower elevations. Snow
quickly diminishes Sunday afternoon.

A ridge building in will warm temperatures up and bring dry
weather Monday and Tuesday. Ensembles hint at a brief breakdown
of the ridge Wednesday, which brings a low end chance for
precipitation.

 - Forecast Confidence & Scenarios:

Precipitation Saturday:

There is a good chance for wetting precipitation with
showers/snow Saturday with the moist atmosphere and enhanced
forcing along the front. There`s a 50-80% for 0.1" of moisture
for areas along and south of the Montana Highway 200 corridor, and
a 40-60% chance for 0.25" of precipitation in Central MT (where
the widespread band of precipitation looks to set up Saturday
morning). For Mountain passes, the main concern is moderate to
heavy bursts of snow quickly creating slushy road conditons
Saturday morning. 1-3" of quick hitting snow will provide variable
road conditons and reduced visibilities for travel. Therefore, A
Winter Weather Advisory was issued to account for these minor
driving impacts on Boulder Hill, Homestake Pass, and Chief Joseph
Pass. The Little Belts, will also get this quick hitting snow.
However, they will be impacted in the late morning/afternoon,
where pavement temperatures look to be warm enough for the snow to
melt off. An earlier start time may warrant an advisory in a
future forecast.

Precipitation Sunday:

There`s a 30% chance for 6" of snow along King`s Hill Pass
Sunday, and about a 30-70% for 2" of snow along the Montana
Highway 200 corridor between Armington Junction and Stanford.
Winds gusting to 40 mph at times can also reduce visibility with
snow. Since this is a quick hitting system, there remains some
uncertainty in exact amounts due to timing, especially for the
northerly upslope regions. The lower elevations will see light
snow mix in Sunday morning, but little to no snow accumulations
are expected. -Wilson


&&

.AVIATION...
11/18Z TAF Period

Gusty westerly winds and mountain wave turbulence along the Rocky
Mountain Front and the plains will slowly diminish as the afternoon
progresses. Otherwise, southwesterly flow aloft will bring an
increase in clouds this afternoon and tonight. A few scattered
showers and perhaps a rumble of thunder remain possible this
afternoon and evening, mostly over Southwest Montana. Then a Pacific
cold front will send a band of rain and snow showers through Central
and Southwest Montana between 12/10 and 12/20Z. This will be more
impactful in terms of precipitation and MVFR/IFR conditions
impacting the terminals. Areas south and east of a KHLN to KHVR li
ne will be most susceptible to this area of precipitation. - RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  42  57  34  48 /  30  50  60  30
CTB  35  53  28  46 /   0  20  80  10
HLN  42  55  33  51 /  50  70  20  40
BZN  39  52  27  47 /  40  90  40  20
WYS  32  54  18  44 /  20  90  40  10
DLN  41  57  25  49 /  20  60  10   0
HVR  36  60  32  50 /   0  30  80  30
LWT  37  50  29  42 /  60  90  50  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 3 AM to noon MDT Saturday for
Elkhorn and Boulder Mountains-Northwest Beaverhead County.

&&

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