Malmstrom AFB, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

541
FXUS65 KTFX 141057
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
457 AM MDT Mon Apr 14 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Dry conditions through Tuesday as temperatures climb back above
   seasonal averages.

 - A spring storm system will bring much cooler temperatures and a
   period of wintry precipitation late Wednesday into early Thursday.

 - The risk for heavy snowfall amounts is greatest across the
   central and southwest MT mountains with winter weather impacts
   also possible at lower elevations.

 - Dry and milder conditions return Friday and Saturday with another
   period of active weather possible late this weekend into early
   next week.

&&

.DISCUSSION...
/Issued 409 AM MDT Mon Apr 14 2025/

 - Meteorological Overview:

An upper level ridge with axis extending north into southern BC will
shift east today and tomorrow for dry conditions with temperatures
returning to seasonal averages today and warming further on Tuesday
as the ridge axis shifts across the area. A subtle weather
disturbance in NW flow aloft generating some mid-level clouds across
portions of north-central MT early this morning will exit by this
afternoon with mainly sunny/clear skies following through early
Tuesday.

A fairly deep upper level trough develops across western Canada
Tuesday night into Wednesday with a potent wave digging south out of
this trough across the Northern Rockies Wednesday night, eventually
merging with a Pacific upper low across the Great Basin/SW US by
Friday. While model guidance has settled on this overall evolution,
there are still differences in the timing and interaction between the
northern wave and Pacific low. In any case, a much colder airmass
looks to plunge south across N-central MT on Wednesday and continue
through southwest MT Wednesday night. Precipitation develops initially
on Wednesday near Glacier NP with the passage of a Canadian cold
front and spreads south through central and southwest MT later
Wednesday through Thursday morning as the upper level wave drops
south through the Northern Rockies.

Temperatures look to fall to the 30s by Wednesday evening across
most of north-central MT and with the onset precipitation as the
cooler airmass continues into southwest MT Wednesday night,
leading to a quick transition to primarily snow for most
locations. Focus for highest precipitation amounts and snowfall is
from the southern Rocky Mtn Front southeast through central MT
and eastern portions of southwest MT, but there is still a fairly
wide spread in potential precipitation amounts at this time. Gusty
north winds also look to develop following the frontal passage
Wednesday night, which combined with colder temperatures and
moisture could create difficult conditions for young livestock.

Looking ahead, there is reasonable consensus for a period of drier
conditions to follow by Friday through at least Saturday. Most
longer range models/ensembles support the redevelopment of troughing
in western Canada by late in the weekend, resulting in another
period of active/cooler weather into early next week.

 - Forecast Confidence & Scenarios:

There is still a wide range in precipitation/snowfall amounts late
Wednesday through early Thursday due to differences in timing and
interactions between the northern and Pacific system. GFS model and
most of its ensemble members are on the wetter end of the guidance
envelope, depicting an an earlier onset and longer duration of
northeasterly mid level upslope flow resulting in higher
precipitation amounts. Cluster analysis suggests this is somewhat
in the minority (about 30-40%) of total ensemble members compared
to the generally faster moving EC/CMC model/ensembles.

There is a 50-80% probability for >0.25" precipitation amounts
from the Rocky mountain front SE through central MT and eastern portions
of SW MT, including Great Falls, Lewistown, Helena and Bozeman
and a 50% or higher probability for 0.50" or more precipitation
amounts across the central MT mountains. While there is still fair
amount of uncertainty in specific snowfall amounts, the overnight
timing of snowfall Wednesday night would support a better chance
of impacts to roads continuing into Thursday morning. Hoenisch

&&

.AVIATION...
14/12Z TAF Period

VFR condtions prevail at all terminals through the period as upper
level high pressure shifts across the Northern Rockies. Scattered
mid-level clouds exit eastern terminals (KHVR and KLWT) this
morning with just some thin high clouds in northwest flow aloft
otherwise. Hoenisch

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  59  37  72  39 /   0   0   0   0
CTB  58  32  67  34 /   0   0   0   0
HLN  61  35  72  41 /   0   0   0   0
BZN  57  30  70  36 /   0   0   0   0
WYS  54  19  62  23 /   0   0   0   0
DLN  60  32  70  37 /   0   0   0   0
HVR  57  30  73  36 /  10   0   0   0
LWT  51  32  68  36 /   0   0   0   0

&&

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

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