Highwood, Montana Weather Forecast Discussion

661
FXUS65 KTFX 151106
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
506 AM MDT Mon Sep 15 2025
Aviation Section Updated.
.KEY MESSAGES...
- Unsettled conditions with daily chances for shower and
   thunderstorms will continue into the day on Tuesday.
- Near normal temperatures through Tuesday will warm back above
   normal through the remainder of the work week and then well
   above normal for the weekend.
- Winds begin to increase from Sunday into next Monday.
&&
.DISCUSSION...
/Issued 239 AM MDT Mon Sep 15 2025/
- Meteorological Overview:
Daily chances for showers and thunderstorms will continue through
the day on Tuesday as a slow moving upper level disturbance moves
over the Northern Rockies. High temperatures through this unsettled
timeframe will be near normal across all of Southwest through North
Central Montana, with overall light winds outside of shower and
thunderstorm activity. Upper level ridging will then begin to build-
in over the Northern Rockies from the middle through the end of the
work week, which will in-turn bring predominately dry conditions and
warming temperatures. High temperatures beneath this ridge will warm
back above normal on Thursday and Friday, with readings warming
further to well above normal for the upcoming weekend as the upper
level ridge begins to flatten. This flattening of the upper level
ridge will not only bring increasing temperatures for the weekend,
but also increasing winds to much of the Northern Rockies. -
Moldan
- Forecast Confidence & Scenarios:
Brief Heavy Downpours through Tuesday :
Scattered to numerous showers and thunderstorms are expected across
portions of Southwest through North Central Montana as a slow moving
upper level disturbance drifts east over the Northern Rockies, most
notably across Central Montana between the Montana Hwy 200 and US
Hwy 12 corridors and then west of the I-15 corridor up to the Rocky
Mountain Front. With PWATS running between 1 to 2 standard
deviations above normal and storm motions of between 10-30 mph some
brief periods of heavy rain are possible beneath the strongest
showers and thunderstorms. With the latest 75th Percentile HREF
guidance supporting hourly rainfall rates of between 0.1-0.25" it is
not out of the realm of possibilities (25% chance for hourly
rainfall amounts to be in excess of 0.1-0.25") for some ponding of
water in poor drainage or urban areas over this timeframe if a
strong shower or storm moves overhead.
Gusty Winds from Saturday night through next Monday :
Increasing cross barrier flow within a quasi-zonal pattern aloft
will lead to increasing south to west surface winds across Southwest
through North Central Montana, most notably along the Rocky Mountain
Front and the immediate plains out to the I-15 corridor. While
climate anomaly indicators such as the ECMWF EFIs and NAEFS do not
currently support any unusual or extreme winds values throughout the
period, several individual ensemble members within the ECMWF and
GEFS do support wind gusts in excess of 45 mph across the
aforementioned areas. Additionally, latest NBM probabilistic data
for wind gusts in excess of 45 mph range from a 30-55% chance on
both Sunday and Monday, with generally a 10-30% chance for wind
gusts in excess of 55 mph on each respective day. While these wind
gusts (i.e. 45 and 55 mph) are not atypical for September they will
mark a change from the relatively light winds as of late. - Moldan
&&
.AVIATION...
15/12Z TAF Period.
Patchy morning fog within the Helena Valley will continue to slosh
in and out of the KHLN terminal through 14-15z this morning, with
VIS/CIGS fluctuating between VFR to LIFR/IFR. Outside of the patchy
fog this morning VFR conditions will otherwise predominately prevail
through the 1512/1612 TAF period across all terminals of Southwest
through North Central Montana; however, scattered to numerous
showers and thunderstorms may reduce CIGS/VIS to MVFR/low-VFR at
times. Areal coverage of showers and thunderstorms will be greatest
along and southeast of a KEKS to KBZN line from 15/12z to 16/00, and
then along the Montana Hwy 200 corridor from KGTF to KLWT from
15/21z to 16/12z. Mountain obscuration is likely at times over the
next 24 hours. - Moldan
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  72  52  73  49 /  40  60  20   0
CTB  68  49  73  43 /  30  30  20   0
HLN  69  50  73  49 /  30  30  30   0
BZN  66  44  67  43 /  60  50  50  10
WYS  59  31  62  31 /  70  30  30   0
DLN  63  40  67  41 /  50  40  20   0
HVR  76  52  77  47 /  10  20  20   0
LWT  71  48  69  47 /  30  60  60  20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion