Harlem, Montana Weather Forecast Discussion

407
FXUS65 KTFX 050922
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
322 AM MDT Sun Oct 5 2025
.KEY MESSAGES...
- Much colder air surges south across the area today behind an
   early morning cold front with gusty north winds.
- Accumulating snowfall will primarily occur in the mountains but
   some lower elevations areas will see a mix or change to snow
   this morning before precipitation ends from north to south this
   afternoon.
- The first widespread hard freeze is expected tonight.
- Warmer and drier conditions return for the week ahead.
&&
.DISCUSSION...
- Meteorological Overview:
A fairly potent shortwave continues to drop south through the
Northern Rockies early this morning within the broader upper level
trough situated across the region. Height falls and cooling aloft
have already lowered snow levels across much of the area to
5500-6500 ft overnight with a significant push of lower level
cooling occurring as colder air surges south along the high plains
east of the Rockies in tandem with the shortwave dropping south
through western MT. Widespread precipitation occurring across
western portions of north-central and central MT early this
morning will shift southward through mid-day as the shortwave
rotates through the broader upper trough with precipitation ending
from north to south this afternoon. Heaviest snowfall will occur
across the mountains near the Rocky Mtn Front early this morning,
shifting south and east across the central and southwest MT
mountains later this morning with decreasing intensity.
Surface high pressure and the associated cold airmass slide south
across the area tonight behind the departing upper level trough.
Clearing skies, drier conditions and generally light winds will
set the stage for the coldest night of the season so far with most
locations expected to see temperatures fall to the mid-upper 20s
by early Monday morning. Temperatures rebound fairly quickly as
upper level ridding develops across the interior western US
through the first half of the upcoming week and potentially
amplifies later this week for additional warming. Confidence in
the overall pattern evolution decreases later this week into next
weekend as the next upper level approaches from the west.
- Forecast Confidence & Scenarios:
The only change to ongoing winter weather statements was to add a
Winter Weather Advisory for the Upper Blackfoot/Macdonald pass
zone. Snow developed overnight at Flesher pass where road surface
data would support some slush accumulation possible. Areas from
Rogers Pass south through Flesher Pass and adjacent portions of
central/southern Lewis and Clark county will be in a favorable
position for enhanced snowfall in northerly upslope flow for
several hours early this morning. Similar conditions but less
intense snowfall is expected over MacDonald pass.
Snow levels fall to as low as around 3500 ft across western
portions of north-central MT early this morning with a mix or
change to wet snow likely across many areas along the I15
corridor, primarily north of Helena. While snow will likely not
impact roads or accumulate at elevations this low, it may bring a
period of lower visibility. Hoenisch
&&
.AVIATION...
05/06Z TAF Period
Periods of rain and mountain snow will continue through Sunday
morning before tapering off Sunday afternoon across the region.
Moderate bands of rain will bring down visibilities to MVFR/IFR
at times. MVFR ceilings continue to build in overnight across the
region. Terminals across North-Central MT have a 30-80% chance
for IFR ceilings Sunday morning. Breezy north winds bringing in
cold air will allow for some snow to mix down to the lower
elevations Sunday morning. Though, no accumulations are expected
on the runways except for KCTB, where there is a slight chance for
a little accumulation. There remains some uncertainty in end
times for precipitation. It`ll depend on how strong the upslope
component is with precipitation. There will be mountain
obscuration during the TAF period due to precipitation and low
ceilings. -Wilson
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF  44  27  59  33 /  90   0   0   0
CTB  43  23  58  31 /  40   0   0   0
HLN  44  27  58  32 /  90   0   0   0
BZN  44  26  55  26 /  90  10   0   0
WYS  44  17  51  16 /  70  20   0   0
DLN  47  24  55  28 /  50   0   0   0
HVR  51  25  62  32 /  20   0   0   0
LWT  43  24  58  31 /  70   0   0   0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until noon MDT today for East Glacier Park
Region.
Winter Weather Advisory until noon MDT today for Little Belt and
Highwood Mountains-Northern High Plains-Northwest Beaverhead
County-Snowy and Judith Mountains-Southern High Plains-Southern
Rocky Mountain Front-Upper Blackfoot and MacDonald Pass.
Winter Weather Advisory until 6 PM MDT this evening for Gallatin
and Madison County Mountains and Centennial Mountains.
&&
$$
http://www.weather.gov/greatfalls

NWS TFX Office Area Forecast Discussion