013
FXUS65 KTFX 111520
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
920 AM MDT Mon Aug 11 2025

.KEY MESSAGES...

 - A weak cold front will stall along the Island Ranges of Central
   Montana, with slightly cooler temperatures over the plains of
   Central and North Central Montana today while the valleys of
   Central and Southwest Montana warm further.

 - Isolated to widely scattered showers and thunderstorms are
   expected along and behind the cold front through this evening.

 - Increasing west to south winds are expected on Tuesday and
   Wednesday, with temperatures warming into the mid-80s to
   mid-90s both days.

&&

.UPDATE...

Slight adjustments were made to the precipitation chances over the
next 24 hours based on updated model guidance but otherwise the
going forecast remains on track.  -thor

&&

.DISCUSSION...
/Issued 442 AM MDT Mon Aug 11 2025/

Northwest flow aloft will prevail across the Northern Rockies
through this evening as upper level ridging over the Pacific
attempts, but largely fails, to builds eastward. At the surface a
weak "cold" front will advance south and across North Central and
portions of Central Montana through the morning hours, with the
"coolest" air stalling along the northern slopes of the Island
Ranges south of the Montana Hwy 200 corridor. Isolated to widely
scattered showers and thunderstorms will develop along and behind
this cold front, in addition to the higher terrain as far south as
the I-90 corridor, with showers and storms lingering into the
late afternoon/early evening hours. High temperatures in wake of
the cold front over the plains of Central and North Central
Montana will be some 5-10 degrees cooler than on Sunday, with the
valleys of Central and Southwest Montana being 3-6 degrees warmer
thanks to the cold air stalling further to the north.

By this evening a shortwave over Northern British Columbia and the
Gulf of Alaska will begin to dig south, which will cause the upper
level ridge over the Pacific Northwest to collapse and flatten out.
Upper level flow over the Northern Rockies will back to the west
through the day on Tuesday due to the flattening ridge, with a
subtle wave sliding east and over Southwest Montana through the
afternoon/evening hours on Tuesday. Isolated showers and
thunderstorms will be possible across Southwest Montana thanks to
this shortwave sliding through the zonal flow, with otherwise dry
conditions expected elsewhere. High temperatures on Tuesday will
climb above normal across all locations thanks to increasing west
surface winds, with breezy and gusty conditions expected along the
Rocky Mountain Front and Montana Hwy 200 corridor.

The aforementioned shortwave from the Gulf of Alaska and Northern
British Columbia will dig into the Pacific Northwest by Wednesday,
with strong warm air advection overspreading the Northern Rockies
through the day. Not only will this strong push of warm air help to
to warm most location an additional 2-5 degrees as compared to
Tuesday, but also help support increasing south to west winds within
the north-south orientated valleys of Southwest and Central Montana
as the upper level flow backs further to the southwest. Continued
breezy and gusty winds will occur along the Rocky Mountain Front and
Montana Hwy 200 corridor over this same timeframe. The upper level
shortwave will then slide east and across the Northern Rockies and
Southern Canada through the day on Thursday, with a cold front
diving southeast across North Central Montana through Wednesday
evening. This cold front, much like today`s (Monday) will once stall
across Central Montana; however, this time slightly further south to
around the US Hwy 12 corridor. Cooler temperature can be expected in
wake of this front, with continued above normal temperatures points
further south across Southwest Montana. Overall dry condtions will
occur from Wednesday through Thursday, but isolated showers and
storms can`t be ruled out.

Relatively moist, southwest flow looks to develop from Friday
through the upcoming weekend over the Northern Rockies, with better
chances for showers and thunderstorms across most locations.
Temperatures will hover near to slightly below normal beneath this

&&

.AVIATION...
11/12Z TAF Period

A cold front advancing south over the plains of Central and North
Central Montana will continue to move south through the valleys of
Central and Southwest Montana through this afternoon and provide a
wind shift to the north. Additionally, isolated showers and
thunderstorms are expected to develop in wake of the front over
the plains of Central and North Central Montana and across the
higher terrain north of the I-90 corridor; however, confidence in
any one shower directly impacting the KCTB, KHVR, KGTF, KLWT, and
KHLN terminals remains to low to mention within this TAF package.
VFR conditions will prevail through the next 24 hours, but CIGS
of 9kft will lead to some mountain obscuration. - Moldan

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  79  54  91  57 /  20  10  10   0
CTB  73  54  86  56 /  20  20   0   0
HLN  85  55  91  56 /  20  10  10  10
BZN  86  51  91  52 /  10  10  10  10
WYS  80  39  83  40 /  10  10  20  10
DLN  82  49  88  50 /   0   0  20  10
HVR  78  55  87  56 /  20  10  10   0
LWT  75  53  84  54 /  20  20  10  10

&&

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

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