098
FXUS65 KTFX 220538
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1138 PM MDT Mon Jul 21 2025

Aviation Section Updated.

.KEY MESSAGES...

- Scattered showers and thunderstorms this afternoon and evening
  with strong to severe thunderstorms possible in Central MT.

- Another round of showers and thunderstorms Tuesday afternoon
  with an isolated chance for a few strong possible again in
  Central Montana.

- A warm up in temperatures through the forecast period with low
  end chances for afternoon showers and thunderstorms through the
  weekend.

&&

.UPDATE...
/Issued 837 PM MDT Mon Jul 21 2025/

Showers and thunderstorms will continue across North-central
Montana this evening into tomorrow morning with thunderstorm
coverage diminishing after midnight. Tomorrow it will be another
rainy and cool day across North-central, Central, and Southwestern
Montana. For the update low temperatures across North-central
Montana were decreased to reflect the latest model guidance and
current observations and trends. Pops and QPF across North-
central Montana were adjusted to better reflect current radar
imagery and trends as well as the latest hi-res model guidance.
The rest of the forecast is on track. -IG

&&

.DISCUSSION...
/Issued 837 PM MDT Mon Jul 21 2025/

 - Meteorological Overview:

A more potent shortwave will pass through this evening, bringing
scattered showers and thunderstorms across the region. Good
moisture, shear, and instability will bring the potential for
strong to severe thunderstorms, primarily in Central MT.
Precipitation coverage increases to more widespread throughout the
evening and overnight hours into Tuesday. Precipitation continues
off and on Tuesday, with another round of afternoon showers and
thunderstorms expected. Favorable deep layer shear profiles as
well will bring another risk for stronger thunderstorms across
Central MT. A frontal passage will keep temperatures below normal
today through Wednesday.

On Thursday, we transition back to a zonal flow aloft pattern
briefly before shift back to more southwesterly flow aloft Friday
through the weekend. Moisture looks to be lower Thursday through
the weekend, but embedded waves look to pass through daily. Weak
instability suggests there is a low end chance for thunderstorms
chances to continue through the weekend, but lower moisture
suggests little rainfall amounts with them. Temperatures also
warm back to near or slightly above normal by the weekend as
well. - Wilson

 - Forecast Confidence & Scenarios:

Hi-Res model guidance continues to signal at thunderstorms, and
even a couple of supercells, developing initially over Southwest
and into portions of Central Montana through the mid-afternoon,
with this activity then lifting to the northeast through the
remainder of the afternoon and evening hours tonight. Guidance has
generally honed in on convection initiating over the
Boulder/Elkhorn, Bridger, Big Belt, and Little Belt Mountains
between 2-4PM, with this activity then quickly spreading northeast
over the adjacent plains and valleys. Sunny skies through the
morning and early afternoon hours has led to sufficient
destabilization as evident by the developing cumulus fields over
the aforementioned terrain. The "highest" window for severe
thunderstorms, especially across Central Montana (generally along
and north of I-90, south of MT Hwy 200, and east of the I-15),
remains to be between 3PM and 9PM today. All severe weather modes
will be possible through this timeframe, with large hail and
damaging winds being the primary hazard; however, a isolated
tornado (2-4% chance of occurring) can not be ruled out across
Eastern Meagher, Southern Judith Basin, and Southern Fergus
Counties. - Moldan

Tuesday`s storms are more conditional depending on where the
shortwave tracks. Currently, this risk resides just to the east of
the CWA. However, there is good deep layer shear of 50-60kts from
0-6km. This will provide the environment again for strong to
severe storms in Central MT if the shortwave moves farther west.

Lower moisture content later this week will keep precipitation
chances limited overall. However, southwest flow aloft bringing
embedded waves will keep low end chances for precipitation
through the weekend. -Wilson

&&

.AVIATION...
22/06Z TAF Period

VFR conditions will prevail at the KBZN, KEKS, KWYS, and KHLN
terminals during this TAF Period outside of any thunderstorms. At
the KGTF, KCTB, and KHVR terminals ceilings will be MVFR to IFR
levels during a portion of this TAF period. There will be mountain
obscuration during any thunderstorms and across North-central
Montana during this TAF period. All thunderstorms will produce
gusty, erratic winds, frequent lightning, small hail, and a brief
heavy downpour. Showers and thunderstorms will affect all terminals
during the duration of this TAF period with the greatest risk for
thunderstorms before after 22/18Z. -IG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  53  74  51  80 /  90  40  20  10
CTB  49  63  45  74 /  90  70  20  10
HLN  55  77  52  82 /  60  50  30  10
BZN  53  79  49  82 /  50  70  40  30
WYS  45  79  41  77 /  30  40  20  20
DLN  49  77  44  82 /  30  50  10  10
HVR  54  72  51  78 / 100  70  20  10
LWT  52  69  49  73 /  90  70  60  50

&&

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

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