211
FXUS65 KTFX 211140
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
540 AM MDT Thu Aug 21 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Noticeably cooler temperatures expected today through the
   weekend.
 - Generally calm conditions expected the next few days with
   light easterly winds and mostly clear skies.
 - Isolated showers and thunderstorms return next week, first
   near the MT/ID border before spreading north over the course of
   the week.&&

.DISCUSSION...

 - Meteorological Overview:

Upper level flow will become northwesterly today as the trough
that brought about a breakdown of the upper level ridge that
brought very warm temperatures to the area earlier this week,
which will bring cooler temperatures to the Treasure State today.
This overall pattern will not change much in the short term, as
ridging over the West Coast slowly degrades and an upper level low
stalls out around the Great Lakes. Our pattern will only begin to
change a bit early next week as a weak perturbation in the flow
moves over the ridge to our west and stalls out over SW Montana
and Idaho, allowing for afternoon showers and thunderstorms to
develop. Another weak disturbance embedded in the flow will likely
move into North Central and North Eastern Montana later in the
week, but at this point the only impact that appears likely will
be some light showers and/or thunderstorms.

- Forecast Confidence & Scenarios:

Confidence is generally high in the forecast through the weekend,
as surface high pressure and a stagnant upper level flow present
few opportunities for deviations from the forecast. Confidence
even remains fairly high into next week as our weak disturbances
move through, as the overall weather pattern remains pretty
consistent, though pinpointing where and how these weak
disturbances will ultimately move through can sometimes be like
throwing darts at a dart board with a blindfold on because models
can struggle with weak weather systems. Even with these
uncertainties, there isnt much of an alternate scenario other
than to say that the showers/thunderstorms may wind up either not
happening, be slightly more widespread, or be shifted in timing or
location, but forecasting where exactly light showers will be
next week is beyond the capability of the science at this point.
Ludwig

&&

.DISCUSSION...
/Issued 252 AM MDT Thu Aug 21 2025/

 - Meteorological Overview:

Upper level flow will become northwesterly today as the trough
that brought about a breakdown of the upper level ridge that
brought very warm temperatures to the area earlier this week,
which will bring cooler temperatures to the Treasure State today.
This overall pattern will not change much in the short term, as
ridging over the West Coast slowly degrades and an upper level low
stalls out around the Great Lakes. Our pattern will only begin to
change a bit early next week as a weak perturbation in the flow
moves over the ridge to our west and stalls out over SW Montana
and Idaho, allowing for afternoon showers and thunderstorms to
develop. Another weak disturbance embedded in the flow will likely
move into North Central and North Eastern Montana later in the
week, but at this point the only impact that appears likely will
be some light showers and/or thunderstorms.

- Forecast Confidence & Scenarios:

Confidence is generally high in the forecast through the weekend,
as surface high pressure and a stagnant upper level flow present
few opportunities for deviations from the forecast. Confidence
even remains fairly high into next week as our weak disturbances
move through, as the overall weather pattern remains pretty
consistent, though pinpointing where and how these weak
disturbances will ultimately move through can sometimes be like
throwing darts at a dart board with a blindfold on because models
can struggle with weak weather systems. Even with these
uncertainties, there isnt much of an alternate scenario other
than to say that the showers/thunderstorms may wind up either not
happening, be slightly more widespread, or be shifted in timing or
location, but forecasting where exactly light showers will be
next week is beyond the capability of the science at this point.
Ludwig

&&

.AVIATION...
21/12Z TAF Period

Aside from KCTB, building surface high pressure will keep all
terminals VFR, though smoke will occasionally reduce slantwise
visibility at KEKS, KBZN, and possibly KHLN. At KCTB, expect low
ceilings through 18z when clouds should begin to dissipate. Ludwig

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  81  54  75  48 /   0  10   0   0
CTB  76  48  72  45 /   0  10   0   0
HLN  85  54  80  50 /   0   0   0   0
BZN  86  49  83  45 /   0   0   0   0
WYS  82  40  81  38 /   0   0   0   0
DLN  83  47  82  45 /   0   0   0   0
HVR  80  51  75  47 /   0   0   0   0
LWT  78  51  72  45 /  10  10   0   0

&&

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

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