Whitehall, Montana Weather Forecast Discussion

600
FXUS65 KTFX 292000
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
200 PM MDT Mon Sep 29 2025
.KEY MESSAGES...
-A few showers and thunderstorms track north across southwest
 Montana and western portions of central and north-central Montana
 this afternoon and evening.
-Gradual cooling is expected through the work week with seasonably
 cool temperatures by the weekend.
-Additional opportunities for scattered precipitation exist
 through the remainder of the week
&&
.DISCUSSION...
- Meteorological Overview:
An upper-level trough, extending south from a Gulf of Alaska low,
will gradually move inland this week. By late week, the upper low
center will reorganize offshore of the Pacific Northwest.
Southerly flow aloft, preceding the trough, will drive afternoon
temperatures significantly above seasonal averages today. This
flow will also bring increased moisture to the region from the
south and southwest. Expect showers and a few thunderstorms to
develop across central Idaho, tracking north through western and
southwest Montana late this afternoon, and then primarily
along/west of I-15 in central/north-central Montana this evening.
The upper trough will continue to expand inland, bringing a
Pacific cold front across the region late Tuesday as an embedded
shortwave lifts over the Northern Rockies. This will result in a
round of more widespread showers, primarily focused near the
continental divide and southwest Montana. Temperatures will
gradually cool throughout the week, with highs in the 70s on
Tuesday and Wednesday, dropping to the 60s by Thursday and Friday.
Additional shortwave perturbations lifting out of the trough will
produce intermittent showers, though confidence in the timing and
location of these features diminishes as the week progresses.
The passage of the Pacific cold front on Tuesday followed by a
moderate surface pressure gradient and southwesterly mid level
flow will set up the area for breezy to windy conditions at times
through Thursday. Wednesday presents the highest potential
(40-50%) for gusts exceeding 40 mph in parts of north-central and
southwest Montana.
- Forecast Confidence & Scenarios:
Moisture and instability is somewhat limited this
afternoon/evening (MLCAPE ~500 L/Kg) so strong thunderstorms are
not anticipated but boundary layer conditions remain sufficiently
dry to support some enhanced downdrafts with wind gusts mainly in
the 30-40mph range with high resolution model ensembles giving a
20-30% chance for gusts in excess of 40 mph.
Longer-range model ensembles show reasonable agreement on upper
troughing shifting east across the interior western US this
weekend. However, significant variance exists among ensemble
members regarding the evolution and interaction between the
initial, weakening Pacific trough and additional troughing moving
southeast through British Columbia. While most scenarios suggest
some precipitation and temperatures slightly below seasonal
averages, some outlying scenarios show little to no precipitation
if these features remain more separated. Conversely, other
scenarios indicate a more significant coverage of precipitation,
including mountain snow, primarily across southwest Montana.
Hoenisch
&&
.AVIATION...
29/18Z TAF Period.
The main concern this TAF period will be isolated showers and
thunderstorms this afternoon/evening with another round early
Tuesday morning as precipitation moves east off of the
Continental Divide. There is a little uncertainty in how far east
precipitation moves east in the North-Central MT plains. Best
chances for precipitation stays west of the I-15 corridor. There`s
a slight chance for MVFR (40% chance)/borderline IFR ceilings at
KWYS Tuesday morning. -Wilson
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  54  76  49  73 /  10  10  20   0
CTB  48  70  44  66 /  10  20   0   0
HLN  53  73  47  73 /  30  30  30  10
BZN  49  73  45  72 /  10  20  20  10
WYS  38  59  36  60 /  10  60  50  40
DLN  48  68  41  68 /  30  30  10  10
HVR  51  79  48  76 /   0  10  10   0
LWT  52  78  48  73 /  10  20  30   0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion