599
FXUS65 KTFX 040541
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1141 PM MDT Mon Jun 3 2024

.Aviation Section Updated...

.SYNOPSIS...

Scattered rain showers continue and a few thunderstorms this evening
across Central and Southwest Montana with primary concern being
gusty winds. Strong winds tonight through Wednesday. Dry conditions
and warm afternoon high temperatures Thursday into the weekend.

&&

.Update...

A compact shortwave was moving over the Northern Rockies towards
the High Plains early this evening, with a surface low moving
across Southern Alberta towards Saskatchewan and an associated
Pacific front sweeping east across Eastern Montana. Wind gusts of
between 45-55 mph were common this afternoon as the aforementioned
front swept eastward across Southwest through North Central
Montana, with wind gusts of between 55-65 mph already occurring
along and west of a Great Falls to Chester line thanks to a
combination of mountain wave activity and/or strong subsidence
behind the departing shortwave. As the evening progresses, expect
mountain wave activity to strengthen along the Rocky Mountain
Front and the northern slopes of the Central Montana mountains
(i.e. Montana Hwy 200 corridor), with wind gusts increasing to as
high as 80 mph and 65 mph respectively. Travel along the Rocky
Mountain Front will be especially dangerous overnight and into the
morning hours on Tuesday, most notably on US Hwy 89 north of
Choteau and US Hwy 2 west of Shelby where a stationary mountain
wave combined with terrain funneling will lead to very strong
cross winds. Travelers, especially those in high profile vehicles,
are urged to exercise caution and know their vehicles limits. In
addition to impacts to travel, tree damage and power outrages will
be a concern tonight and through the day on Tuesday given the
emergence of foliage. - Moldan

&&

.AVIATION...

04/06Z TAF Period

VFR conditions will prevail through the TAF period with cloud decks
at multiple layers across all sites. Strong westerly flow aloft will
continue through the rest of Tuesday into Wednesday creating a
hazard for strong mountain wave turbulence. Conditions will be
generally dry through the period with some light showers possible
near the Rocky Mountain Front (but not expected to impact KCTB).

At airport level, expect maximum wind gusts of:
- KCTB: up to 60 kts
- KGTF, KHVR, KLWT: up to 52 kts
- KHLN: up to 40 kts
- KBZN, KEKS, KWYS: up to 30 kts

Winds will start to ease up after 04/03Z and continue diminishing
through the overnight hours into Wednesday morning. -thor

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

&&

.PREV DISCUSSION...
/ISSUED 610 PM MDT Mon Jun 3 2024/

Rest of today through Wednesday night...Upper level troughing
continues across the state today bringing unsettled weather
conditions through tomorrow. A cold front from the Pacific Northwest
continues to move across the state this evening. Scattered light
rain showers across Central and Southwest Montana, and along the
Rocky Mountain Front continues through this evening. A few
thunderstorms have potential to develop this evening across
Southwest Montana from a Bozeman to Lewistown line into Central
Montana as the front pushes through. Primary concerns for any
developed thunderstorms are gusty winds. Scattered rain shower and
thunderstorm activity diminishes between 6 pm and 9 pm this
evening. Along the Hi-Line, there`s a 30 to 40 percent probability
of a rain shower coming down from Canada between midnight and 3
am. Otherwise, conditions become drier this evening and strong
winds reaching warning criteria start along the Rocky Mountain
Front into North Central Montana. We are strongly advising
limiting outdoor recreation between tonight and Wednesday along
the Rocky Mountain Front as wind probabilities are high (greater
than 75 percent) for wind gusts reaching over 65 mph periodically
during this timeframe. High profile vehicles will have difficulty
traveling over mountain passes due to these strong winds. High
Wind Warnings continue through Wednesday for the Rocky Mountain
Front. For everywhere else for the High Wind Warnings, timing is
still on track to start this evening for tonight into tomorrow
morning and continue through the Wednesday morning hours. We held
off on including Helena as latest probabilities are still not
supporting high wind criteria. It`ll still be windy nevertheless.

As the upper level trough departs tomorrow, upper level ridging
builds in for Wednesday with dry and windy conditions, especially
along the Rocky Mountain Front Wednesday morning into the
afternoon and across the eastern portion of North Central and
Central Montana.

Thursday through this upcoming weekend...Ensemble model guidance
is still in support for upper level ridging to continue during
this timeframe. Drier conditions are favored for our region under
surface high pressure. Beyond Sunday remains uncertain on whether
upper level ridging continues or begins to move out and upper
level troughing moves in from the west. The Climate Prediction
Center has our region in likely above (60-70% probability) of
above normal temperatures for this weekend into early next week.
This could mean we see temperatures 2 degrees above normal or 10
degrees in some locations. Our normal high temperatures this time
of year (middle of June) is between 75 and 80 degrees, with the
exception of higher mountainous terrain where it`s cooler. We`ll
continue to monitor ensemble model trends for heat risk potential
for this upcoming weekend as well as when upper level ridging will
begin to move. Webb

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  46  67  47  71 /  10   0   0   0
CTB  43  61  43  67 /  20   0  10   0
HLN  47  69  51  76 /  20  10  10   0
BZN  38  70  49  77 /  60  10   0   0
WYS  38  61  42  73 /  80  10   0   0
DLN  41  67  48  78 /  20  10   0   0
HVR  48  71  48  71 /  50  10   0   0
LWT  41  67  46  68 /  40   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until noon MDT Wednesday for Bears Paw
Mountains and Southern Blaine-Big Belt, Bridger and Castle
Mountains-Cascade County below 5000ft-East Glacier Park Region-
Eastern Glacier, Western Toole, and Central Pondera-Eastern
Toole and Liberty-Fergus County below 4500ft-Judith Basin County
and Judith Gap-Little Belt and Highwood Mountains-Meagher County
Valleys-Northern High Plains-Snowy and Judith Mountains-Southern
High Plains-Southern Rocky Mountain Front-Upper Blackfoot and
MacDonald Pass.

High Wind Warning from 9 AM Tuesday to noon MDT Wednesday for
Eastern Pondera and Eastern Teton-Hill County-Northern Blaine
County-Western and Central Chouteau County.

&&

$$

http://www.weather.gov/greatfalls