Basin, Montana Weather Forecast Discussion

668
FXUS65 KTFX 111104
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
504 AM MDT Thu Sep 11 2025
Aviation Section Updated.
.KEY MESSAGES...
- There will be showers and thunderstorms today and Friday with isolated
   strong thunderstorms in Fergus and Blaine Counties and
   isolated thunderstorm will produce heavy rainfall.
- Slightly above seasonal averages for temperatures are expected
   through the middle of next of week.
- Early next week there will be daily chances for rain showers.
&&
.DISCUSSION...
/Issued 245 AM MDT Thu Sep 11 2025/
- Meteorological Overview:
Today an upper-level trough is over North-central, Central, and
Southwestern Montana. This will cool temperatures down slightly
and bring rounds of showers and thunderstorms to the area. Due to
the upper-level trough moving slightly eastward there will be
greater coverage in showers and thunderstorms today than
yesterday. The strongest thunderstorms will produce strong winds,
frequent lightning, small hail, and a heavy downpour. On Friday
the upper-level trough remains over North-central, Central, and
Southwestern Montana and moves slightly east. This will cool
temperatures down slightly across the area and bring showers and
thunderstorms to the area. The strongest thunderstorms will bring
a heavy downpour, frequent lightning, small hail, and gusty
erratic winds.
On Saturday the upper-level trough remains over North-central,
Central, and Southwestern Montana. This will keep slightly above
seasonal averages for temperatures with very isolated showers
across the area with isolated thunderstorms in Southwestern
Montana. On Sunday the upper-level trough remains over North-
central, Central, and Southwestern Montana. This will bring mostly
dry weather with very isolated showers and thunderstorms. Monday
through Wednesday a strong upper-level low will move over North-
central, Central, and Southwestern Montana. This will bring daily
chances for showers to the area with about seasonal averages for
temperatures each day Monday through Wednesday.
- Forecast Confidence & Scenarios:
Today there is some uncertainty in if clouds and morning showers
will end/clear early enough to allow for maximum daytime heating.
Maximum daytime heating would allow for the maximum instability to
build up across North-central Montana. This would lead to isolated
strong to severe thunderstorms affecting North-central Montana.
Today the Storm Prediction Center (SPC) issued a Marginal Risk (5%
chance for wind gusts in excess of 58 mph within 25 miles of a
point) for Fergus County and eastern Blaine County. Today there is a
15 - 40% chance for thunderstorms across North-central, Central, and
Southwestern Montana.
On Friday the SPC issued a Marginal Risk (5% chance for hail one
inch in diameter or greater within 25 miles of a point) for Fergus
County. On Friday there is a 20 - 40% chance for thunderstorms
across North-central, Central, and Southwestern Montana. On Saturday
there is a 15 - 35% chance for thunderstorms in Central and
Southwestern Montana. On Sunday there is a 20 - 30% chance for
thunderstorms in Central and Southwestern Montana.
Today and Friday across North-central and Central Montana there is a
15 - 40% chance for a quarter inch of rain or greater. On Saturday
across Hill, Choteau, Judith Basin, Blaine, and Fergus Counties
there is a 15 - 30% chance for a quarter inch of rain or greater. -IG
&&
.AVIATION...
11/12Z TAF Period
VFR conditions will prevail across all terminals during this TAF
Period outside of during any thunderstorms.  At the KGTF, KHLN,
KCTB, and KLWT terminals there is a 20 - 50% chance for showers and
thunderstorms during the majority of this TAF Period. At the KBZN,
KEKS, and KWYS terminals there is a 20 - 50% chance for showers and
thunderstorms between now and 12/00Z. Any thunderstorm will produce
frequent lightning, a heavy downpour, and gusty erratic winds. The
strongest thunderstorms, which have the greatest likelihood of
affecting KLWT and KHVR, will produce strong winds and small hail in
addition to lightning and a heavy downpour. There will be mountain
obscuration during any thunderstorm. -IG
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  77  52  76  51 /  40  50  50  30
CTB  76  48  74  48 /  40  30  40  30
HLN  77  51  74  51 /  60  50  60  30
BZN  77  44  75  45 /  60  20  30  20
WYS  69  34  68  33 /  60  10  40  20
DLN  75  42  70  43 /  50  20  30  20
HVR  79  53  75  51 /  50  60  50  40
LWT  73  49  73  48 /  70  40  60  50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion