Malmstrom A F B, Montana Weather Forecast Discussion

917
FXUS65 KTFX 201710
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
1110 AM MDT Sat Sep 20 2025
Aviation Section Updated.
.KEY MESSAGES...
- Unseasonably warm today and Sunday, and turning breezy Sunday
   into Monday.
- Rain moves across Southwestern Montana on Sunday.
- After a cooler day on Monday, temperatures return to above
   average for midweek before potentially moderating a bit later
   in the week.
&&
.UPDATE...
/Issued 831 AM MDT Sat Sep 20 2025/
Slight adjustments were made to the short term forecast based on
the latest NBM guidance but otherwise the going forecast remains
on track.  -thor
&&
.DISCUSSION...
/Issued 831 AM MDT Sat Sep 20 2025/
- Meteorological Overview:
Upper level ridging over the area today will result in an
unseasonably warm day across North Central and Southwestern
Montana, with highs around 10 degrees above average today. This
warmth will extend into Sunday as well, but an approaching upper
level trough will result in a breezy day across the area,
particularly across the plains and along the Rocky Mountain Front.
While winds will be noticeable (and maybe the strongest we have
had in the past few months), dont expect this to be a disruptive
event, but rather just a reminder that we are heading back into
our windy season. The axis of this trough will move overhead
Monday, which will result in the coldest day of the week with
temperatures just slightly (5 degrees or so) below average.
However, warmth quickly returns to the area by midweek as upper
level ridging quickly returns to the Treasure State.
- Forecast Confidence & Scenarios:
There are two main areas of uncertainty in the short term, with
increasing uncertainty again as we head into late next week. The
first area of uncertainty with regards to impactful weather will
be with the rainfall expected on Sunday across Southwestern
Montana. For the most part, rain is expected to be beneficial,
though with some of this moisture being tropical in nature (from
the remnants of Tropical Storm Mario), I wouldnt be surprised to
see a few locations come in quite a bit higher than the current
forecast suggests. Indeed, the NBM 95th percentile across the
higher terrain of Southwest Montana does show some potential for
over an inch of precipitation, but keep in mind that any area has
a 5% chance of seeing this high end. But it does show that there
is potential for some minor flooding to develop. Winds will be the
other area of some concern on Sunday, but the probability of any
location seeing even 50 mph is generally under 10%, save for some
pockets of near 50% around Cut Bank and along the immediate Rocky
Mountain Front.
Later in the week uncertainty is higher than normal with the WPC
cluster analysis showing a wide range of possibilities, from a
moderately strong upper level ridge to a potent upper level trough
pushing into the area. NBM shows things trending to near average
for the end of the week, but keep in mind that this solution is
unlikely to verify and cant tell the entire story when the
extended appears to be an either/or scenario between warm and dry
vs cooler, wetter, and potentially windier. Ludwig
&&
.AVIATION...
20/18Z TAF Period
VFR conditions persist through the TAF period. There will be
breezy west winds across the Rocky Mountain Front this afternoon
affecting mainly the KCTB terminal. -Wilson
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  85  52  83  49 /   0   0  10  40
CTB  83  48  75  44 /   0   0   0  10
HLN  84  51  80  47 /   0   0  20  70
BZN  82  46  78  44 /   0   0  20  80
WYS  73  35  65  35 /   0   0  50  90
DLN  80  45  74  42 /   0   0  30  80
HVR  85  51  85  49 /   0   0   0  30
LWT  81  51  82  46 /   0   0  10  70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion