Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

448
FXUS65 KTFX 041104
AFDTFX

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

Aviation Section Updated.

.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...
/Issued 146 AM MDT Mon May 4 2026/

 - 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 valleys of southwest MT
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...
04/12Z TAF Period

Cold front continues to push south through SW MT early this
morning, shifting winds to the north at KBZN and KEKS by 14z.
Broken mid level cloud-cover and areas of mountain obscuration are
likely to exist through the TAF period. An area of light rain/showers
affects some north-central MT terminals this morning with low
VFR/MVFR cloud ceilings. By this afternoon VFR conditions prevail
again though a few light showers may linger over the mountains.
Gusty northerly surface winds become widespread again this afternoon
with gusts in excess of 30kts most likely across eastern portions
of north-central MT and through N-S oriented valleys of southwest
MT. Hoenisch

&&

.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