480
FXUS65 KTFX 161005
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
405 AM MDT Sun Jun 16 2024

.SYNOPSIS...

Gusty west winds along the Rocky Mountain Front and Plains
continue through the morning. Widespread precipitation bringing
mountain snow and lower elevation rain arrives Sunday night and
lasts through Tuesday evening. Below average temperatures
forecasted for Monday and Tuesday. Temperatures gradually warm up
through the rest of the week. Daily low chances for precipitation
remains through the week.

&&

.DISCUSSION...

Today through monday...Water vapor satellite shows mountain wave
activity producing strong winds along the Rocky Mountain Front.
High winds across the Rocky Mountain Front and and plains continue
through the morning hours as High Wind Warning for the Rocky
Mountain Front is set to expire by 9am. Be prepared for strong
crosswinds if traveling this morning.

A surface front swinging down from Canada will create
some light showers along the northern Hi-Line/Rocky Mountain Front
region this morning ahead of the main system moving in later in the
day. Energy from this upper level trough will move into the region
during the evening hours, bringing in lower elevation rain and
snow for elevations generally above 6,000ft. Precipitation will
become more widespread and heavier Monday morning with the upper
level low moving passing through the region. There may be a few
embedded thunderstorms with precipitation on Monday/Tuesday
afternoon due to a little amount of instability present.
Precipitation lingers into Tuesday along another wave of passing
through the region. Snow probabilities in the mountains are
between 30-50% for exceeding 8" of snow. Considering the bulk of
the snow being above pass level and probabilities for
accumulations to reach winter warning criteria (9 inches) remain
on the lower side, I have opted to transition the Winter Storm
Watches for mountain zones into Winter Weather Advisories. Another
change I`ve made to the winter highlights is to move up the
timing to 6pm Sunday to 6pm Tuesday to account for the earlier
start and end times for precipitation. Greatest QPF amounts look
to set up across Central MT, where they have around a 50% of
exceeding 1". Most other lower elevations across the CWA have at
least a 50% of exceeding 0.25". In terms of possible higher end
QPF amounts, the 75th NBM percentile ranges between 1.25-1.5"
across Central MT and 0.35-0.75" across most other lower
elevations.

With the upper level low bringing down colder air, cold overnight
temperatures are forecasted for Monday and Tuesday morning.
Tuesday morning wind chills in the mountains can drop down to the
teens and 20s. Those in the backcountry should prepare for
cold/raw conditions.

Wednesday and looking beyond...The main upper level low will move
off to the east, and a zonal/southwest flow aloft pattern will
settle in behind for the remainder of the week. There looks to be
enough moisture around and small disturbances that passes through to
keep low chances of precipitation daily. With the southwest flow
aloft bringing in warmer air, temperatures will gradually warm up
through the weekend. By Saturday, lower elevations have a 60-80% of
high temperatures reaching 80 degrees or higher. -Wilson

&&

.AVIATION...
16/06Z TAF Period

VFR conditions will prevail for across all terminals through 12z
Sunday after which increasing shower activity and lowering CIGS
along the International Border may begin to usher MVFR conditions
south towards the KCTB and KHVR terminals. Confidence in these MVFR
conditions occurring is approximately 20-40% at this time, so
withheld mention of MVFR conditions for the TAF package given the
low probabilities. Otherwise the biggest concern to terminals will
be strong and gust west winds, particularly at the KCTB terminal
where frequent wind gusts approaching 50kts are expected through 12-
15z Sunday. Strong mid-level winds will also contribute to mountain
wave turbulence and instances of low level wind shear through 12-18z
Sunday over the plains of Central and North Central Montana. Winds
will gradually begin to subside from late Sunday morning and through
the afternoon hours. Mountain obscuration is likely along the
Continental Divide and North Central Montana for most of the next 24
hours. - Moldan

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  66  42  50  40 /   0  40 100  80
CTB  59  36  54  37 /  30  10  70  50
HLN  68  43  53  41 /   0  50 100  80
BZN  67  41  55  36 /   0  30 100 100
WYS  61  38  51  30 /   0  10  70  70
DLN  65  38  51  34 /   0  40 100  60
HVR  63  42  57  42 /  30  10  80  60
LWT  63  38  50  35 /   0  30 100 100

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 9 AM MDT this morning for East Glacier
Park Region-Eastern Glacier, Western Toole, and Central Pondera-
Northern High Plains-Southern High Plains.

Winter Weather Advisory from 6 PM this evening to 6 PM MDT
Tuesday for Big Belt, Bridger and Castle Mountains-East Glacier
Park Region-Elkhorn and Boulder Mountains-Gallatin and Madison
County Mountains and Centennial Mountains-Little Belt and
Highwood Mountains-Northwest Beaverhead County-Southern Rocky
Mountain Front.


&&

$$

http://www.weather.gov/greatfalls