869
FXUS65 KTFX 111404
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
804 AM MDT Tue Mar 11 2025

.KEY MESSAGES...

 - Temperatures moderate back to above seasonal averages through
   Thursday with breezy to windy conditions at times and locally stronger
   winds possible across parts of southwest Montana.

 - A Pacific storm system moving across the interior western US
   late this week will bring cooler temperatures Friday and
   Saturday along with areas of precipitation and potentially
   impactful snowfall to some southwest Montana mountain ranges.

&&

.UPDATE...

Moisture streaming eastward across the Continental Divide within a
zonal flow aloft is resulting in light radar returns this
morning, mostly in eastern areas. The only mentionable update
this morning was to expand the slight chance mention for rain/snow
this morning and early afternoon across the plains and adjacent
areas.

Otherwise the primary concern today will be for breezy
winds to develop with daytime mixing, decreasing again around
sunset this evening. -AM

&&

.DISCUSSION...
/Issued 439 AM MDT Tue Mar 11 2025/

 - Meteorological Overview:

A zonal/westerly flow remains in place across the Northern Rockies
and MT today with an embedded plume of Pacific moisture contributing
to considerable mid-high level cloud-cover. An subtle shortwave
disturbance moving east along the US/Canadian border and weak lift
near the rear entrance of an upper level jet max moving across
the Canadian prairies will help produce some light snow showers
along portions of north-central MT near the divide with a few
flurries/sprinkles potentially tracking further east across north-
central MT. Otherwise, dry conditions prevail with temperatures
several degrees warmer than yesterday.

Weak upper ridging shifts across the area tonight through Wednesday
night with flow aloft backing to southwesterly for mainly dry
conditions with temperatures warming a bit more above average.
Afternoon mixing will support breezy winds today and again Wednesday
for most areas with developing surface low pressure and increased
southwest mid-level flow supporting windier conditions across
southwest MT Wednesday afternoon. There is still potential for a
period of stronger winds in/near the Madison River Valley and
southwest MT mountains late Wednesday afternoon/overnight as 700MB
flow increases to 40-50kts and becomes more aligned with the terrain

Pacific upper level trough shifts inland Thursday and splits with
the stronger southern portion tracking across the SW US and emerging
in the southern US plains Friday with the weaker northern portion
shifting east across the Northern Rockies and MT Thursday night into
Friday. While the more impactful precipitation/snow with this system
looks to be southeast of the area, there is period of larger scale
ascent with the trough passage and somewhat anomalous moisture (PWAT
~0.5"/150% of normal) in place to support a period of widespread
precipitation across primarily SW MT, with several inches of snow
across the Gallatin/Madison/Centennial ranges. Temperatures cool
back to near or slightly cooler than average Friday/Saturday and
look to remain near seasonal averages going into early next week
with the next Pacific trough and associated moisture/precipitation
moving into the area late this weekend or early next week.

 - Forecast Confidence & Scenarios:

The risk for strong winds late Wednesday is mainly confined to the
Madison River Valley and adjacent terrain with probabilities for
sustained winds >40mph or gusts >55mph as has as 70% over Norris
Hill and around 50% near Ennis and further south up the valley.

Probabilities for precipitation amounts in excess of 0.10" Thursday
night/Friday range from 10% or less along the Hi-line to 30-50%
across central MT and 80% or higher along/south of I-90. Snow
accumulation in excess of 4" is likely (60-80%) across the
Madison/Gallatin/Centennial ranges during this period with adjacent
mountain areas including Bozeman Pass and Monida pass having a
60% or higher risk of 2" or greater snowfall, while the risk for
similar amounts in the Bozeman area is 30% or less. Hoenisch

&&

.AVIATION...
11/12Z TAF Period

VFR conditions prevail at area terminals through the period.
Somewhat moist westerly flow across the region will maintain
broken mid-high level clouds through much of the TAF period with
clouds decreasing from south to north tonight. A few light showers
near the continental divide and central MT mountains this morning
may obscure higher peaks. Breezy surface winds develop at most
terminals this afternoon and diminish this evening. Hoenisch

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  53  37  58  37 /  20  10   0  10
CTB  48  32  53  30 /  10  10  10   0
HLN  52  33  56  36 /  20  10   0  10
BZN  51  28  53  31 /  10  10   0  10
WYS  43  18  44  28 /  10  10   0  50
DLN  53  30  53  34 /   0   0   0  20
HVR  53  31  56  32 /  20  10   0   0
LWT  49  31  54  36 /  20  20   0  10

&&

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

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