Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

947
FXUS65 KTFX 100839
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
239 AM MDT Sun Aug 10 2025

.KEY MESSAGES...

 - Temperatures will gradually warm up Monday through Wednesday.

 - There will be isolated showers and thunderstorms today and
   Monday with shower and thunderstorm coverage increasing on
   Tuesday and Wednesday.

 - On Thursday and Friday there will be a brief cool down before
   warming back up for next weekend.

&&

.DISCUSSION...

 - Meteorological Overview:

Today an upper-level ridge will begin to move over North-central,
Central, and Southwestern Montana. This will allow temperatures to
warm up over the area. Wildfire smoke has the potential to linger
for a few hours this morning in Hill and Blaine County. It will
slowly push off to the east through the day today. There will be
northwest flow aloft today. If there is enough instability to
overcome warm air aloft then there will be isolated showers and
thunderstorms today. On Monday the upper-level ridge remains over
North-central, Central, and Southwestern Montana with northwest
flow aloft. This will allow temperatures to warm some more with
isolated showers and thunderstorms across the area.

On Tuesday the upper-level ridge remains over North-central,
Central, and Southwestern Montana with southwest flow aloft. This
will bring showers and thunderstorms to the area on Tuesday with
temperatures warming up some more. On Wednesday an upper-level
trough begins to move over the area. Wednesday afternoon a surface
cold front will move through the area. This combined with the upper-
level trough will bring showers and thunderstorms to the area. Due
to strong upper-level flow combined with a strong surface pressure
gradient it will be windy on Wednesday across Southwestern
Montana and along the Rocky Mountain Front. On Thursday the upper-
level trough remains over North-central, Central, and
Southwestern Montana. This will cool temperatures down with
showers and thunderstorms across the area. On Friday an upper-
level ridge briefly builds back in over North-central, Central,
and Southwestern Montana. This will warm the area back up. On
Saturday an upper-level trough begins to approach North-central,
Central, and Southwestern Montana. This will bring showers and
thunderstorms to the area.

 - Forecast Confidence & Scenarios:

Today and Monday there is a 10 - 20% chance for thunderstorms across
North-central, Central, and Southwestern Montana. On Tuesday and
Wednesday there is a 15 - 30% chance for thunderstorms across North-
central, Central, and Southwestern Montana. On Thursday there is a
15 - 25% chance for thunderstorms in Judith Basin and Fergus County
and a 5 - 15 % chance elsewhere across North-central, Central,
and Southwestern Montana.

On Wednesday and Thursday there is a 40 - 70% chance for wind gusts
of 40 mph or greater across Southwestern Montana and along the Rocky
Mountain Front and adjacent plains. On Wednesday across the lower-
elevations of North-central, Central, and Southwestern Montana there
is greater than a 60% chance for high temperatures of 90 degrees or
greater. Overall there is high confidence in the weather pattern for
this forecast period. The biggest uncertainty is if/where showers
and thunderstorms will form today and tomorrow. -IG


&&

.AVIATION...
10/06Z TAF Period

Isolated showers and thunderstorms have all but ended across the
Northern Rockies late this evening; however, a rogue shower or
storm can`t be ruled out at any time northwest of a KCTB, to KGTF
to KLWT line given continued northwest flow aloft. While the
probability for one of these showers or storms is less than a 10%
chance it is a non-zero chance. Otherwise the main concern through
the 1006/1106 TAF period will be reduced VIS at the KHVR terminal
due to on-going smoke/haze here, which is expected to persist
through 15-18z Sunday before improving thereafter. Scattered
mountain obscuration, mainly for peaks at or above 9kft, will
occur over the next 24 hours. - Moldan

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  83  59  81  56 /   0   0  10   0
CTB  80  57  76  53 /  10  10  10   0
HLN  84  58  86  57 /  10   0  10   0
BZN  82  51  87  52 /   0  10   0   0
WYS  76  38  81  40 /  10   0   0   0
DLN  79  48  84  50 /   0  10   0   0
HVR  84  58  81  56 /  10  10  10   0
LWT  78  55  77  54 /  10   0  10   0

&&

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

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