016
FXUS65 KTFX 200905
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
305 AM MDT Wed Aug 20 2025

.KEY MESSAGES...

 - Warm today with a chance for scattered showers and
   thunderstorms in the afternoon and evening.

 - Cooler and more seasonable temperatures expected Thursday
   through the weekend.


&&

.DISCUSSION...

 - Meteorological Overview:

The upper level ridge will start to break down this afternoon and
evening as a trough moves through across central and southern
Canada. An associated cold front will make its way across the
region allowing for scattered showers and thunderstorms through
the late evening hours. Similar to previous days, the main
concerns will be gusty, erratic winds and lightning with small
hail being a secondary threat today.

Behind the cold front, cooler and more seasonable temperatures
will persist through the weekend. An upper level ridge will start
to build over the western CONUS which will bring northwesterly
flow to the region and, depending on exactly where the ridge sets
up, may bring a chance for afternoon showers and thunderstorms to
the region, particularly across southwestern Montana.


 - Forecast Confidence & Scenarios:

Regarding thunderstorms this afternoon, there is still some
lingering uncertainty as to how exactly this event will play out.
The NBM remains very dry while hi-res guidance brings in the first
showers and thunderstorms along the Montana/Idaho border as early
as 10 AM to 12 PM in some cases and slowly spreading northward
while precipitation coverages also fill in along the Hi-Line as
the cold front approaches. The concern, particularly across
southwestern Montana, will be how dry these thunderstorms end up
being. Model soundings have pointed to drier thunderstorms south
of the I-90 corridor with increasing PWATs. A mix of wet and dry
thunderstorms is expected across central and north-central Montana
which may bring some localized heavier rain but otherwise these
storms are expected to bring little in the way of accumulation.
Rather instead gusty, erratic winds and more lightning is expected
which will be a concern for fire weather concerns.  -thor


&&

.AVIATION...
20/00 TAF Period

VFR conditions will predominately prevail throughout the 2000/2100
TAF period; however, showers and thunderstorms developing along
the Continental Divide and over the terrain of Western Montana
will lift northeast and over portions of Central and North Central
Montana plains and valleys and provide the opportunity for low-VFR
conditions, generally along and northwest of a KHLN, to KGTF, to
KHVR line. Shower and thunderstorm development will be during the
early evening hours tonight, with this activity then persisting
through the remainder of the evening hours and into the early
morning hours on Wednesday. Main concern with any thunderstorm
will be gusty and erratic wind gusts of between 30-40kts.
Additional concerns throughout the TAF period will be reductions
in slantwise visibility upon descent/ascent, most notably at the
KEKS, KBZN, and KWYS terminals due to local wildfires burning in
Southwest Montana. Mountain obscuration through the next 24 hours
will be limited to beneath/near precipitation. - Moldan

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

&&

.FIRE WEATHER...

Critical fire weather concerns are expected this afternoon across
portions of southwest Montana with highs in the upper 80s to low
90s, minimum RH values as low as 12%, winds gusting up to 30 mph,
and the potential for dry thunderstorms in the afternoon.

Elevated fire weather concerns are expected across the remainder
of the region with highs across the plains reaching up into the
low 90s, minimum RH values in the upper teens to low 20s, winds
gusting up to 20 mph, and a chance for thunderstorms in the late
afternoon through the evening.

A cold front will pass through this afternoon into Thursday which
will allow for temperatures to cool down and allow for better
overnight recovery heading into Thursday and Friday which will, at
least temporarily, ease some of the worst concerns.  -thor

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  91  54  80  53 /  10  10   0   0
CTB  85  48  76  47 /  10   0   0   0
HLN  90  56  85  52 /  10  20   0   0
BZN  93  51  85  48 /  10  20   0   0
WYS  84  41  82  39 /  20  20   0   0
DLN  89  48  84  47 /  20  20   0   0
HVR  92  53  78  49 /  10  20   0   0
LWT  86  53  76  51 /  10  30   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
&&

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