Grant, Montana Weather Forecast Discussion

556
FXUS65 KTFX 220521
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
1121 PM MDT Sun Sep 21 2025
Aviation Section Updated.
.KEY MESSAGES...
- Scattered showers and thunderstorms through tonight.
- A cooler, but seasonable day expected on Monday.
- It turns dry and warm from Tuesday into next weekend.
&&
.UPDATE...
/Issued 818 PM MDT Sun Sep 21 2025/
Showers and a few isolated thunderstorms continue to track N/NE
across much of north-central and southwest MT this evening in
association with a cold front progressing east across the area.
Gusty winds remain the primary weather impact this evening across
much of the area from the combined effects of shower/thunderstorm
downdrafts as well as pressure rises associated with the frontal
passage. Areas along the Rocky Mountain Front also saw a period of
mountain wave wind enhancement earlier this evening, resulting in
a few isolated strong wind gusts. The probability for wind gusts
in excess of 40 mph will gradually decrease through the overnight
period with only areas along the immediate east slopes of the
Rocky Mtn Front and portions of southern Blaine and eastern Fergus
county having some potential (20-40%) for stronger gusts
lingering later through the overnight period. Additional upper
level energy will swing across the region overnight, maintaining a
wider coverage of showers across southwest MT while precipitation
across north-central MT ends from west to east overnight. A final
upper level disturbance moving out of Alberta later tonight does
look to bring some showers along with shift to northerly surface
winds across portions of north-central MT Monday morning. Hoenisch
&&
.DISCUSSION...
/Issued 818 PM MDT Sun Sep 21 2025/
- Meteorological Overview:
A Pacific cold front is approaching the Rocky Mountain Front
currently. Scattered showers and thunderstorms are developing
ahead and along the cold front. The cold front will move eastward
across the CWA this evening and overnight tonight. There will be a
few stronger storms, with the main impact being gusty winds. By
Monday morning, snow levels will fall down to about 8000 or 9000
feet, with a rain/snow mix possible at ridge tops. For Monday,
afternoon temperatures will be cooler than they have been, but
still close to seasonal normals. The cool air will not last long,
as warmer air moves back into the CWA on Tuesday. By Wednesday,
afternoon highs will be in the mid 80s to near 90 degrees, which
will be about 15 to 20 degrees above normal for this time of year.
The above normal temperatures, will continue into next weekend,
just not as hot as the mid week temperatures though.
This system will be rather quick moving, and there will only be a
few lingering showers on Monday morning, especially over the
central mountains, otherwise dry conditions are expected until
late next weekend.
- Forecast Confidence & Scenarios:
An isolated strong wind gust is possible with the thunderstorms
tonight, but the threat/possibility for any severe storms is quite
low. Most areas will see rainfall less than 0.20 inches, but an
isolated stronger storm could produce near a half inch of
rainfall.
After this system exits the region on Monday morning, the chance
for rainfall is almost near zero until late next weekend. Even the
system for late next weekend only has very low chances for precip
at this time.
Afternoon temperatures for Wednesday continue to increase as well.
Thus some areas will once again approach 90 degrees for afternoon
high temperatures.
&&
.AVIATION...
22/06Z TAF Period
VFR conditions will prevail across all terminals except for the KBZN
terminal during the duration of this TAF Period. Rain showers will
affect the KBZN, KEKS, KWYS, KHVR, and KLWT terminals during the
beginning of this TAF Period. Between now and 22/12Z there is a 15 -
30% chance for thunderstorms at the KBZN, KWYS, and KEKS terminals.
Any thunderstorm will bring gusty winds and a heavy downpour. During
the beginning of this TAF Period through about 22/20Z across
Southwestern Montana there will be periods of mountain
obscuration. During the first six hours of this TAF Period there
will be periods of mountain wave turbulence across North-central,
Central, and Southwestern Montana. -IG
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  48  67  42  77 /  80  20   0   0
CTB  44  67  37  78 /  40  30   0   0
HLN  46  66  40  76 /  90  10   0   0
BZN  44  62  35  71 /  90  30   0   0
WYS  35  56  24  67 /  90  60   0   0
DLN  41  61  33  70 /  90  10   0   0
HVR  49  67  40  78 /  60  20   0   0
LWT  46  59  39  74 /  80  20   0   0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion