Heath, Montana Weather Forecast Discussion

193
FXUS65 KTFX 211755
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
1155 AM MDT Sun Sep 21 2025
Aviation Section Updated.
.KEY MESSAGES...
- It will be windy today with the strongest winds along the Rocky
   Mountain Front.
- This afternoon through Monday morning showers will spread
   across the area from southwest to northeast.
&&
.UPDATE...
/Issued 1016 AM MDT Sun Sep 21 2025/
Current forecast on track, no updates planned for this morning.
Clouds are on the increase from the west, as the next weather
system pushes eastward towards MT. Expect showers and a few
thunderstorms to develop by late afternoon along the divide and
then spread east over the Plains this evening and overnight. Some
snow will be possible at ridge tops by Monday morning, but
nothing impactful. Breezy west winds are expected ahead of this
system over the Northern Plains this afternoon. Brusda
&&
.DISCUSSION...
/Issued 1016 AM MDT Sun Sep 21 2025/
- Meteorological Overview:
Today there will be an upper-level ridge over North-central,
Central, and Southwestern Montana before a cold front associated
with an upper-level trough pushes southeast through North-central,
Central, and Southwestern Montana this afternoon through this
evening. Due a strong surface pressure gradient and strong mid and
upper-level winds combined with the cold front it will be windy
across the area today. It will be the windiest across North-central
Montana with the strongest winds along the Rocky Mountain Front and
adjacent plains. Due to the approaching upper-level trough rain
showers will begin in Southwestern Montana this afternoon and spread
northeast to North-central Montana by this evening. Due to upper-
level and surface temperatures cooling behind the cold front snow-
levels across Southwestern Montana will lower this evening through
tonight. This will bring light snow to mountain peaks in
Southwestern Montana tonight.
On Monday the upper-level trough remains over North-central,
Central, and Southwestern Montana. This will bring cooler
temperatures (near seasonal averages) to the area on Monday. Rain
showers will linger across portions of the lower-elevations of
North-central, Central, and Southwestern Montana Monday morning
with snow showers lingering across some of the mountain peaks in
Southwestern Montana on Monday morning. On Tuesday an upper-level
ridge moves over North-central, Central, and Southwestern Montana.
This will dry out the area and allow temperatures to warm up to
slightly above seasonal averages. On Wednesday the upper-level
ridge remains over North-central, Central, and Southwestern
Montana which will allow temperatures to warm up to well above
seasonal averages with dry weather. Thursday through Saturday an
upper-level ridge will remain over North-central, Central, and
Southwestern Montana. This will bring warm and dry weather to the
area Thursday through Saturday. -IG
- Forecast Confidence & Scenarios:
Today there is a 50 - 80% chance for wind gusts of 45 mph or greater
along the Rocky Mountain Front and adjacent plains. Across the rest
of North-central, Central, and Southwestern Montana there is a 30 -
60% chance for winds gusts of 35 mph or greater today. This
afternoon through Monday morning there is a 35 - 45% chance for a
quarter inch of rain or greater across the lower-elevations of
Central and Southwestern Montana. Across the mountains of
Southwestern Montana there is a 45 - 65% chance for a quarter inch
of liquid precipitation or greater this afternoon through Monday
morning. Across the mountain peaks of Southwestern Montana there is
a 30 - 60% chance for a tenth of an inch of snow or greater between
this afternoon and Monday morning. Today there is a 20 - 40% chance
for a thunderstorm across Central and Southwestern Montana with the
highest probability in Southwestern Montana.
There is high confidence in this forecast through Wednesday.
Thursday through Saturday there remains some uncertainty in the
upper-level pattern as shown in differences between ensemble
clusters and deterministic models. Each day Thursday through
Saturday one of the four ensemble clusters has the upper-level ridge
breaking down and being replaced by a upper-level trough over North-
central, Central, and Southwestern Montana while the other three
ensemble clusters have the upper-level ridge remaining over the
area. The upper-level ridge breaking down scenario would bring
cooler, wetter, and windier weather than the upper-level ridge
remaining over the area scenario. -IG
&&
.AVIATION...
21/18Z TAF Period
North-Central Montana (KCTB, KHVR): Strong westerly winds with
gusts up to 40kts are possible through 22/06Z at KCTB. Breezy
conditions are expected at KHVR with gusts up to 30kts possible.
KCTB will generally remain dry through the period but KHVR will
have a period between 22/00Z and 22/10Z where isolated showers are
expected to make their way across portions of the Hi-Line. Towards
the end of the period, low clouds will move across the Hi-Line
bringing low-VFR CIGS to the region with a potential for short
periods of high-MVFR conditions.
Central Montana (KGTF, KHLN, KLWT): VFR conditions are expected
through the first 6 hours of the period with increasing cloud
cover ahead of showers and thunderstorms making their way into
central Montana by 22/00Z. Periods of MVFR/IFR are possible around
heavier showers with mountain obscuration remaining a concern
through most of the period. Shower activity will diminish for KGTF
and KHLN after 22/06Z but will continue on and off around KLWT
through the remainder of the period as showers move further into
central and eastern Montana.
Breezy west/northwest winds will impact KGTF and KHLN this
afternoon with additional gusty and erratic winds expected for all
terminals around thunderstorms. After the winds start to
diminish, low clouds will move into the region bringing low-VFR to
high-MVFR CIGS through the rest of the period.
Southwest Montana (KBZN, KEKS, KWYS): Showers and thunderstorms
will start to develop this afternoon and become more widespread
through the overnight hours. Periods of MVFR/IFR are possible
under heavier showers with mountain obscuration remaining a
concern through most of the period. Breezy south/southwest winds
are expected at KEKS through at least 22/06Z with gusty, erratic
winds expected at all terminals this afternoon around
thunderstorms.  -thor
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  84  47  67  41 /  20  60  10   0
CTB  75  44  67  39 /  20  30  10   0
HLN  80  46  67  41 /  30  70  10   0
BZN  79  44  62  36 /  30  90  30   0
WYS  65  36  57  25 /  60  90  60   0
DLN  76  40  63  34 /  50  80  10   0
HVR  85  49  68  41 /   0  60  20   0
LWT  82  46  61  39 /  10  80  40   0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion