Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

368
FXUS65 KTFX 040746
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
146 AM MDT Mon May 4 2026

.KEY MESSAGES...

 - Cooler temperatures and breezy north winds with a few showers
   through Tuesday.

 - Overnight low temperatures in the upper 20s Tuesday night.

 - Warmer but with a continued chance for showers and a few
   thunderstorms later this week into the weekend.

&&

.DISCUSSION...

 - Meteorological Overview:

A highly amplified upper level pattern is in place with ridging in
the NE Pacific and deep troughing across central/eastern Canada.
Energy diving south around the Canadian trough will maintain a
cyclonic northerly flow across MT through Tuesday with a cooler
airmass and surface high pressure building southward into the area
today and maintaining below average temperatures through Tuesday.
Gusty north winds with the initial cold front and surge of higher
pressure across central and southwest MT this morning will decrease
some by late morning but expect breezy to windy conditions to be
fairly widespread across north-central MT this afternoon and again
Tuesday afternoon beneath moderate northerly mid level flow. Moisture
in this cyclonic northerly flow is fairly shallow and largely below
600MB but is supporting an area of showers moving south across north-
central MT this morning with weak afternoon instability and northerly
uspslope flow supporting widely scattered showers this afternoon and
again Tuesday. Daytime temperatures will be around 10 degrees below
seasonal averages today and tomorrow with the coldest temperatures
likely Tuesday night/early Wednesday morning as clouds and winds
decrease, allowing overnight minimum temperatures to reach the
upper 20s across much of the area.

The larger scale upper level pattern de-amplifies later this week
with model ensembles showing broad upper level ridging shifting
inland and supporting a return to near and above average temperatures
through next weekend. There are however several embedded disturbances
including a shortwave tracking through NW flow around Thursday
and another crossing the region next weekend. There is uncertainty
still with the timing and strength of each of these disturbances
but each will bring an increased risk of showers and potentially
some thunderstorms. Hoenisch

 - Forecast Confidence & Scenarios:

Wind gusts in excess of 40 mph are most likely (>50% probability)
this morning through the N-S oriented southwest MT valleys as
surface high pressure surges south from Canada with wind gusts
peaking again in these areas tonight as additional pressure rises
occur. Similar probabilities for gusts in excess of 40mph exist
today across portions of Hill, Blaine and Fergus counties as well as
the Judith Gap area beneath stronger mid level northwesterly flow
where winds will peak this afternoon.

&&

.AVIATION...
04/06Z TAF Period

The cold front should clear central MT by dawn before continuing
southward into the southwest later this morning. Northerly winds
gusting up to 40 kts at times will be the initial concern,
followed by increased showers, scattered to broken MVFR/IFR
clouds, and mountain obscuration. Scattered shower and isolated
thunder activity will maintain periodic degraded flight categories
during the second half of the TAF period, especially for areas
near higher terrain. Winds will begin to decrease in a north to
south fashion this afternoon, but will remain gusty over the
narrow north to south oriented valleys of central and southwest
MT. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  34  53  30 /  40  10  20   0
CTB  55  30  51  27 /  20   0  10   0
HLN  58  34  54  30 /  30  10  20   0
BZN  60  30  51  25 /  20  20  30  10
WYS  60  29  48  20 /  10  10  20  10
DLN  63  32  54  27 /  10  10  10   0
HVR  58  27  54  26 /  10   0  10   0
LWT  52  28  48  25 /  50  10  40  10

&&

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

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