Geyser, Montana Weather Forecast Discussion

403
FXUS65 KTFX 080850
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
Issued by National Weather Service Missoula MT
250 AM MDT Mon Sep 8 2025
.KEY MESSAGES...
- Isolated showers and thunderstorms today.
 - Scattered to widespread precipitation Tuesday through the
   weekend.
 - A cool down in temperatures expected mid to late week.
&&
.DISCUSSION...
- Meteorological Overview:
A trough building along the Pacific coast will slowly translate
east throughout the week and weekend. This brings an extended
period of southwest flow aloft and an influx of moisture to the
region. An active pattern is expected throughout the week and
weekend with a series of disturbances aloft moving through.
Today, precipitation will remain more isolated and generally stay
north of the I-90 corridor. Weak instability in the afternoon
will allow for thunderstorms to develop, with one or two storms
capable of a 40-50 mph wind gust. Smoke and haze has improved
overnight, with better surface visibilities expected today.
However, pockets of smoke and haze will linger today across North-
Central MT.
Coverage in precipitation increases to more scattered to
widespread Tuesday and beyond. For Tuesday, slightly higher CAPE
and inverted V vertical profile soundings will allow for an
isolated chance for strong wind gusts. Models hint at buoyancy
and shear increasing heading into Wednesday and Thursday, which
will increase the overall organization of storms. Heading into the
weekend, there is still some variation of the evolution to this
trough. This brings in some uncertainty in how much precipitation
and where the corridor of wetter precipitation sets up. However,
ensembles are in an agreement for an active period to continue
through the weekend.
- Forecast Confidence & Scenarios:
Hi-res models show that thunderstorms today will remain on the
weaker side, but one or two storms will have a stronger wind gust
between 40-50mph. A few storms on Tuesday will also be capable of
producing strong wind gusts as well. Models still hint at CAPE
and shear increasing Wednesday and Thursday, mainly towards
Central MT. Deep layer shear doesn`t look too impressive (~30kts)
but CAPE nearing 1,000 J/kg (with some higher end scenarios
showing 1,500 J/kg) will be sufficient enough for some organized
storms producing gusty winds and a low end chance for hail.
However, there are still variations in how much instability
builds in and where that organized thunderstorms corridor sets
up. Right now, it looks to be Central MT or a bit farther east of
the CWA where this sets up.
There is still quite a spread in precipitation amounts throughout
the weekend. Ensemble guidance is showing a 40-70% chance for
0.5" of rain across the region over the 72 hour period between
Friday morning-early Monday morning. So far, higher end solutions
show some areas (more towards Central and Eastern MT) getting over
an inch over this time period (20-50% chance). However, how much
rain and where this corridor sets up will largely depend on how
this trough evolves. -Wilson
&&
.AVIATION...
07/06Z TAF Period
Pockets of smoke and haze will linger throughout the TAF period.
Periodic isolated showers and afternoon thunderstorms remain
across the region throughout the TAF period. Though, confidence
is low that thunderstorms will effect the Southwest MT terminals
at this time. -Wilson
Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  82  50  83  52 /  20  20  20  40
CTB  78  46  81  49 /  20  20  20  40
HLN  81  52  80  52 /  20  10  40  40
BZN  80  47  79  48 /   0   0  30  30
WYS  72  37  70  37 /   0   0  50  40
DLN  78  47  73  45 /   0  10  40  30
HVR  81  51  84  55 /  20  20  10  50
LWT  78  51  81  52 /  20  20  20  50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion