319
FXUS65 KTFX 181401 CCA
AFDTFX

Area Forecast Discussion...corrected format
National Weather Service Great Falls MT
801 AM MDT Fri Oct 18 2024

.SYNOPSIS...

Snow ends this morning across Southwest Montana with dry and sunny
conditions by this afternoon for all of north-central and
Southwest Montana. Strong winds develop tonight along the Rocky
Mountain Front and persist through Saturday evening with windy
conditions across much of north-central Montana this weekend.

&&

.DISCUSSION...

KEY MESSAGES...

-Snow ending this morning across Southwest MT

-Strong winds developing tonight along the Rocky Mountain Front
 and Glacier county and persisting through Saturday

-Temperatures moderate back to near and above seasonal averages
 this weekend

.DISCUSSION...

A splitting upper level trough continues to shift east across the
region early this morning with the main energy diving SE through the
eastern Great Basin. Snow is ongoing early this morning, mainly
along and south of a line from Lima to Ennis to Bozeman Pass, where
some weakening frontogenic forcing lingers along with moist
northerly flow. This should continue to decrease and end from west
to east through this morning. The winter weather advisory for
western portions of SW MT has ended with remaining highlights for
eastern and southeast portions of Southwest MT continuing through
this morning. Road temperature observations/reports and webcams
suggest primarily wet surfaces at elevations below 5000 ft
(including much of the Gallatin valley) with some scattered slush
and snow-cover possible across elevations above 5500ft (including
Bozeman Pass and portions of US-191/287 and MT-87 in southern
Gallatin/Madison counties. Upper level ridging already nosing
into the Northern Rockies this morning will slump southeast across
the area this afternoon for mainly sunny and dry conditions.

Upper level troughing across western Canada and an incoming upper
level jet from the North Pacific set up a fast zonal/westerly flow
across the Northern Rockies and MT this weekend, with main impact
being periods of windy conditions and locally strong winds across
potions of north-central MT as a series of disturbances move across
BC and AB beneath the upper level jet. Lee-side surface toughing
intensifies this evening with the arrival of the stronger westerly
flow with a mid level wind maximum moving east across southern AB
tonight through Saturday morning. High wind warnings remain in
place for the Northern Rocky Mtn Front and Glacier/western Toole
counties beginning tonight, where probabilities for gusts in excess
of 55 mph are 80% or higher. A strong pressure gradient across the
Rockies and favorable temperature/wind profiles for mountain wave
development tonight could support some gusts in excess of 85 mph,
primarily right along the east slopes. Wind gusts are likely to peak
Saturday morning further east across Glacier and western Toole
counties. Most of north-central MT is likely to see windy conditions
Saturday with 60-80% probabilities for gusts in excess of 45 mph but
lower (<40%) probabilities for gusts greater than 55 mph. Mid-level
winds decrease some late Saturday and Saturday night but fast
westerly flow aloft and a moderate pressure gradient remains across
the Rockies through the rest of the weekend for continued windy
conditions. Additional mid level disturbances and wind maximums
looks to move across the Canadian Rockies on Sunday and Sunday
night, which along with continued favorable temp/wind profiles could
produce additional periods of strong winds, primarily along the
Rocky MTn Front and Glacier/Toole counties. The westerly flow will
also promote warming across the area with daytime temperatures
reaching back above seasonal averages Saturday and Sunday.

Upper level troughing across western Canada begins to shift east
Monday with some moisture and a weak frontal system moving across
the area followed by some cooling back to near seasonal averages by
Tuesday. Longer range model ensembles generally support a return to
upper level ridging across the western US by the middle of next week
with temperatures back to near above above seasonal averages by
Wednesday. Hoenisch

&&

.AVIATION...
18/12Z TAF Period

Snow showers in the vicinity of SW MT terminals will decrease
through this morning with primary impacts of mountain obscuration
but some brief MVFR ceilings and even some patchy fog are possible
at KBZN, KEKS and KWYS through as late as 16z. Any lingering mid to
higher level clouds across central MT this morning should also clear
out after 16z with overall VFR conditions prevailing at all
terminals through the remainder of the TAF period. Westerly flow
aloft develops today and increases tonight with breezy southwest
winds developing this afternoon across the plains and increasing
tonight. Hoenisch

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  56  39  67  48 /   0   0   0   0
CTB  54  38  62  47 /   0  10   0   0
HLN  55  33  67  42 /   0   0   0   0
BZN  49  23  61  33 /  40   0   0   0
WYS  44  15  53  20 /  60   0   0   0
DLN  44  25  57  32 /  10   0   0   0
HVR  58  38  72  46 /   0   0   0   0
LWT  53  33  68  43 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 6 PM this evening to 6 PM MDT Saturday
for East Glacier Park Region-Northern High Plains.

Winter Weather Advisory until noon MDT today for Big Belt,
Bridger and Castle Mountains-Gallatin Valley-Madison River
Valley.

Winter Storm Warning until noon MDT today for Gallatin and
Madison County Mountains and Centennial Mountains.

High Wind Warning from 3 AM to 6 PM MDT Saturday for Eastern
Glacier, Western Toole, and Central Pondera.

&&

$$

http://www.weather.gov/greatfalls