248
FXUS65 KTFX 281408
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
808 AM MDT Sun Sep 28 2025

.KEY MESSAGES...

- One more nice day today, before a slow change in the weather
  pattern begins on Monday.

- Showers and thunderstorms will slowly increase in coverage area
  over North Central and Southwest MT from Monday through
  Wednesday.

- Monday looks to be the warmest day this week, before a slow and
  steady cool down then occurs for the rest of the week.

&&

.UPDATE...

A dry cold front continues to move through the plains this morning
and will gradually weaken and fade out as it moves southward into
the central MT island ranges. Other than a period of gusty winds
and a slight cool down for northern areas, not expecting any
significant impacts. - RCG

&&

.DISCUSSION...
/Issued 355 AM MDT Sun Sep 28 2025/

 - Meteorological Overview:
An upper level ridge of high pressure continues to build over MT.
This will result in more more nice day over the CWA, with
generally quiet conditions expected. By this evening, a few
showers/thunderstorms could drift northward from Idaho into far
Southwest MT, but the forecast models continue to decrease the
probability for this occurring.

Otherwise, on Monday, the upper level ridge starts to move
eastward, as an upper level trof approaches the west coast. One
more very warm afternoon is expected on Monday with the
southwesterly flow. Additionally, showers/thunderstorms will try
to develop over Western MT by the afternoon and then move eastward
into the western portions of the CWA by Monday evening. The
chance for showers/thunderstorms really start to increase though
on Tuesday, as the upper level trof pushes further eastward.

For Wednesday through Friday...expect cooler air to slowly move
into the CWA each day. Afternoon temperatures will start to trend
cooler and likely fall closer to normal by Friday. There will be
small chances for precipitation during this period, as weak upper
level pieces of energy move across the CWA.

For next weekend, it is still looking like another upper level
trof will move across MT. Additionally, below normal temperatures
are also expected to accompany this disturbance, which could
result in snow falling at higher elevations.

 - Forecast Confidence & Scenarios:
The main concern early in the week is the thunderstorm potential,
especially Monday night into Tuesday. Right now the main concern
is lightning and wind gusts around 45 mph as the storms move
through.

For next weekend, the main concern will be how low the snow levels
get, along with how much precipitation falls. The latest GFS model
is not as cold as previous runs, thus snow levels are a bit
higher. It also has reduced the expected precipitation a bit,
with some of the higher totals coming in now ranging from about
0.50 to 1.00 inches. Overall, there is still quite a bit of
uncertainty about snow levels/precipitation amounts for next
weekend. Brusda

&&

.AVIATION...
28/12Z TAF Period.

VFR will generally prevail across the CWa through the period. Do
expect a surface wind shift to the north/northeast this morning
over North Central MT. Additionally, showers/thunderstorms will
develop this evening over southern ID and move northward towards
Southwest MT. However, they will not make it very far north of the
border tonight, mainly affecting the West Yellowstone area after
06z Mon. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  77  48  86  55 /   0   0   0  10
CTB  69  41  82  48 /   0   0   0  10
HLN  81  50  83  53 /   0   0   0  30
BZN  81  48  80  50 /   0   0  10  20
WYS  72  37  69  39 /  10  10  20  30
DLN  79  45  77  48 /   0  10  10  30
HVR  77  47  85  53 /   0   0   0  10
LWT  79  50  83  53 /   0   0   0  10

&&

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

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