848
FXUS65 KTFX 220214
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
814 PM MDT Thu Aug 21 2025

.KEY MESSAGES...

 - Cooler for a few days, with little to no chance for
   precipitation.

 - Monsoonal moisture starts to work into far Southwest Montana as
   early as Sunday, re-introducing low-end precipitation
   opportunities.

 - Warming closer to normal next week, with precipitation chances
   increasing each day from south to north.

&&

.UPDATE...

Tonight it will be cool with some isolated showers across North-
central Montana. There remains some uncertainty in where these
showers will form and if they will produce any precipitation. For
the update PoPs across North-central Montana were adjusted to
better reflect the latest hi-res model guidance. QPF across a
portion of North-central Montana was increased to better reflect
the latest hi-res model guidance. The rest of the forecast is on
track. -IG

&&

.DISCUSSION...
/Issued 523 PM MDT Thu Aug 21 2025/

 - Meteorological Overview:

Potent upper level troughing off to the north in Canada will
progress eastward and eventually southeastward toward the Great
Lakes downstream of a building upper level ridge over the west. The
result over the next few days will be for a mostly dry northwesterly
flow aloft. At the surface a weak cold front continues to drop
southward this afternoon, which will help keep temperatures near to
below average through at least Saturday. Aside from a few showers
tonight associated with a weak wave across Central Montana, this
timeframe is looking dry. Wildfire smoke from across the region will
settle in valleys at times during the overnight periods, resulting
in localized visibility reductions.

Given the apex of the ridge extends well north into Canada and that
the center of the high over the desert Southwest a bit east of the
longitude of the Northern Rockies, monsoonal moisture will gradually
creep further and further north this weekend into early next week.
Shower and thunderstorm chances will increase, initially over far
Southwest Montana as early as Sunday afternoon, but more likely
Monday onward. Thereafter showers and thunderstorms look to creep
further and further north each afternoon and evening as monsoonal
moisture drifts further northward. Temperatures trend closer to
normal toward next week, creeping a bit above normal by mid-week.
-AM

 - Forecast Confidence & Scenarios:

The only uncertainty with the forecast at this point is with respect
to precipitation chances tonight into early Friday morning across
Central Montana. Lower resolution guidance is dry, while higher
resolution guidance shows a few weakly forced showers. Whether or
not these are able to result in measurable precipitation is
difficult to say, but I did increase PoPs to get a mention in the
forecast over this timeframe. -AM

&&

.AVIATION...
22/00Z TAF Period

VFR conditions will largely prevail as upper level ridging
builds in over the Pacific Northwest, which will help to shift
the upper level flow to the northwest over the Northern Rockies.
This shift in the upper level flow will help to focus most of the
smoke/haze from local and regional wildfires southwest of a KHLN
to KWYS line, with the primary impacts to terminals southwest of
this line being reductions in slantwise visibility upon
ascent/descent. Otherwise a weak disturbance moving southeast
within this flow tonight will help to spread scattered to broken
mid-level clouds over the KCTB, KHVR, KGTF, and KLWT terminals
beyond 06z Friday. Latest HREF guidance no longer supports CIGS
falling to MVFR as this disturbance moves overhead, but low-VFR
CIGS are possible through the late morning/early afternoon hours
on Friday. Mountain obscuration is expected along and north of the
US Hwy 12 corridor between 06-21z Friday. - Moldan

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  55  75  49  81 /  20   0   0   0
CTB  48  72  45  77 /   0   0   0   0
HLN  54  80  50  85 /   0   0   0   0
BZN  50  80  45  85 /   0   0   0   0
WYS  39  81  38  83 /   0   0   0   0
DLN  47  82  45  86 /   0   0   0   0
HVR  50  75  48  79 /   0   0   0   0
LWT  51  72  46  77 /  30  20   0   0

&&

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

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