Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

167
FXUS65 KTFX 292037
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
237 PM MDT Sun Jun 29 2025

.KEY MESSAGES...

 - This afternoon and evening there will be isolated showers along
   the Hi-Line.

 - Temperatures will warm up Monday through Thursday before
   cooling down by Saturday.

 - Tuesday through Saturday there will be daily chances for
   showers and thunderstorms.

&&

.DISCUSSION...

 - Meteorological Overview:

This afternoon an upper-level ridge builds in over North-central,
Central, and Southwestern Montana. This will gradually warm up
temperatures and bring mostly dry weather to the area on Sunday. Due
to northwest flow aloft this afternoon and evening there will be
isolated showers along the Hi-Line. On Monday the upper-level ridge
remains over North-central, Central, and Southwestern Montana which
will keep mostly dry weather and warm temperatures up further.

On Tuesday the upper-level ridge remains over North-central,
Central, and Southwestern Montana. This combined with southwest flow
aloft will bring showers and thunderstorms to Southwest Montana
Tuesday afternoon and evening. On Wednesday the upper-level ridge
remains over North-central, Central, and Southwestern Montana. This
combined with an upper-level disturbance and southwest flow aloft
will bring showers and thunderstorms to the area Wednesday afternoon
and evening. Tuesday through Wednesday it will warm up to be the
hottest day of year so far on Wednesday across North-central,
Central, and Southwestern Montana.

A cold front will move through North-central, Central, and
Southwestern Montana Thursday afternoon into Friday morning. This
will bring showers and thunderstorms to Central and Southwestern
Montana Thursday afternoon and evening. On Friday an upper-level
ridge builds back in over North-central, Central, and Southwestern
Montana. Then an upper-level shortwave will move through the upper-
level flow Friday afternoon/evening which will bring another round
of showers and thunderstorms to the area. On Saturday a quick moving
upper-level shortwave trough will move over North-central, Central,
and Southwestern Montana which will bring another round of showers
and thunderstorms to the area Saturday afternoon and evening.

 - Forecast Confidence & Scenarios:

This afternoon and Monday there is a 10 - 20% chance for
thunderstorms across North-central, Central, and Southwestern
Montana. On Tuesday there is a 15 - 40% chance for thunderstorms in
Central and Southwestern Montana. On Wednesday there is a 20 - 45%
chance for thunderstorms across North-central, Central, and
Southwestern Montana. On Thursday there is a 25 - 60% chance for
thunderstorms along and south of the Montana 200/US Highway 87
Corridor between Great Falls and Lewistown. On Friday there is a 30 -
60% chance for thunderstorms across North-central, Central, and
Southwestern Montana.

On Monday there is a 10 - 30% chance for a high of 90 degrees or
greater across the Helena Valley and the Golden Triangle Region (the
triangle area from Cut Bank to Great Falls to Havre to Cut Bank). On
Monday the Gallatin Valley has an 80% chance for a high of 90
degrees or greater. On Tuesday there is greater than an 80% chance
for a high of 90 degrees or greater across North-central Montana,
the Helena Valley, and the valleys of Southwestern Montana. On
Tuesday there is a 25 - 50% chance for a high temperature of 95
degrees or greater across much of North-central Montana and the
Helena Valley. On Tuesday the Milk River Valley near Havre and the
Gallatin Valley have greater than a 70% chance for high
temperatures of 95 degrees or greater.

On Wednesday there is greater than a 80% chance for highs of 90
degrees or greater across the lower- elevations of North-central,
Central, and Southwestern Montana. On Wednesday there is greater
than a 65% chance for high temperatures of 95 degrees or greater
across much of North-central Montana and the Gallatin Valley. On
Wednesday there is a 20 - 50% chance for high temperatures of 100
degrees or greater along the Milk River Valley. On Thursday there
is a 50 - 80% chance for high temperatures of 90 degrees or
greater across North-central Montana east of I-15. On Wednesday
and Thursday morning there is a 50 - 80% chance for morning low
temperatures of 65 degrees or greater across southern Blaine
County, Northeastern Fergus County, the Highwood Mountains, and
the Sweet Grass Hills. Due to all of those probabilities if
temperatures continue to trend upward, then there is a high
likelihood that heat products will be needed. -IG

&&

.AVIATION...
29/18Z TAF Period

With high pressure in place across North Central and Southwestern
Montana this afternoon, expect skies to remain mostly clear with
generally light winds out of the west to northwest. Ludwig

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  51  88  56  91 /   0   0   0   0
CTB  48  84  52  87 /   0   0   0   0
HLN  52  90  58  92 /   0   0   0   0
BZN  47  91  53  94 /   0   0   0  10
WYS  37  82  41  83 /   0   0   0  10
DLN  46  87  52  88 /   0   0   0  10
HVR  50  88  54  93 /   0   0   0   0
LWT  47  81  54  87 /   0   0   0   0

&&

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

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