Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

113
FXUS65 KTFX 071749
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1149 AM MDT Sat Jun 7 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Breezy today across the plains, especially in Hill and Blaine
   Counties.
 - Turning warm again early next week, with 90s likely on Monday.
 - Cooler and potentially stormy weather conditions return for
   the middle of next week.

&&

.UPDATE...
/Issued 916 AM MDT Sat Jun 7 2025/

There were two main changes with this update. The first was
lowering precipitation chances a little bit in accordance with
updated model guidance. While some showers are still possible
behind the cold front, the majority of the precipitation is
expected to stay in Canada and move off more towards northeastern
Montana. As a result, it is unlikely that our portion of hi-line
Montana will see any accumulation this morning.

The other change of note was adding haze to the forecast as
wildfire smoke from Canada is expected to get dragged south over
our area starting this afternoon. In general, the majority of the
smoke is expected to stay aloft through the next 24 hours with
little to no impact to surface air quality expected.  -thor


&&

.DISCUSSION...
/Issued 916 AM MDT Sat Jun 7 2025/

 - Meteorological Overview:

A cold front will push across the Plains of North Central Montana
this morning, which will usher in a brief cooldown along with a
few isolated rain showers to the area this morning. Behind this
cold front, a quickly moving high pressure system will follow,
which will shut off rain shower activity along with producing some
gusty westerly winds for parts of the area, particularly in and
around Hill and Blaine Counties. As this high pressure slides
eastward, southwesterly flow at the surface and mid levels will
advect noticeably warmer air into the area for Sunday and Monday,
resulting in a very warm day Monday with many lower elevation
locations seeing highs reach the upper 80s and lower 90s. This
heat will not last long, however, as a weak surface low pressure
system and cold front will push through late Monday or early
Tuesday, bringing cooler surface temperatures in its wake. A
second, stronger system will likely develop over Eastern
Washington and Oregon, which will help funnel moisture into the
area, kicking off scattered to widespread showers and
thunderstorms, a few of which could be on the stronger side if
sufficient shear (change in wind speed and direction with height)
develops to help storms become a bit more organized. An unsettled
pattern looks to persist through the remainder of the week as
southwesterly flow develops over the area, allowing Pacific
moisture to work into the area.

 - Forecast Confidence & Scenarios:

Temperatures on Monday: Confidence in very warm temperatures on
Monday is fairly high at this time, though just how warm it gets
is subject to some uncertainty. Looking at the big picture first,
models are in very good agreement that a strong upper level ridge
will be in place across the area, which will set the stage for a
very warm day across the area. Where the uncertainty comes into
play will be the arrival of a cold front, at this time expected
late Monday or early Tuesday. There are a few models that bring
this front in a bit earlier, which would keep temperatures from
reaching the current forecast. With that said, here are the
probabilities for reaching 90 degrees in select locations across
the area on Monday:
Helena: 70%
Great Falls: 70%
Cut Bank: 80%
Havre: 90%
Lewistown, Bozeman, Dillon: <5%
Ludwig

&&

.AVIATION...
07/18Z TAF Period

Cold front has made it through all TAF sites shifting winds to the
north. KHVR and KLWT terminals will see more persistent gusts in
excess of 20kts develop early this afternoon and continue through
early this evening before diminishing. Broken mid-level cloud
decks may thicken a bit more through early this afternoon with
some higher mountain obscuration possible and perhaps a few light
showers, but VFR conditions area likely to prevail at TAF sites.
Clouds and winds decrease tonight with some potential for enough
smoke to spread south from Canada to bring haze into some
locations. KHVR already is seeing some haze reported and would be
first to see some impact to visibility later this afternoon into
this evening. Hoenisch

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  68  46  77  49 /  20  10   0   0
CTB  67  41  77  46 /  10   0   0   0
HLN  78  49  80  52 /  10  10   0   0
BZN  79  46  76  46 /  10  20   0   0
WYS  73  39  72  35 /  10  10   0   0
DLN  78  46  76  47 /   0  10   0   0
HVR  69  43  76  45 /  20   0   0   0
LWT  65  44  69  46 /  20  10   0   0

&&

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

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