291
FXUS65 KTFX 021131
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
530 AM MDT Thu May 2 2024

Updated Aviation Discussion

.SYNOPSIS...

A storm system slowly tracking east along the Montana and
Saskatchewan border will bring wet snow or snow showers to  much of
the region today with the most impactful snow looking to fall over
the central Montana Mountains. Temperatures rise back toward normal
Saturday as ridging builds in before another precipitation producing
system arrives late this weekend into next week.

&&

.DISCUSSION...

Low pressure at the surface roughly co-located beneath a broader mid-
upper level low centered over southern Saskatchewan will track
slowly east along the International Border today and tonight,
maintaining a moist/cyclonic northwesterly flow across the area. An
area of widespread precipitation continues to pivot across north-
central MT early this morning with an embedded disturbance and lower
level boundary supporting an area of moderate precipitation that is
expected to sag south into the MT-200/US-87 corridor from Great
Falls to Lewistown by around 6 AM. This boundary slowly continues
south, reaching the US-12 corridor from Helena to White Sulphur
Springs this afternoon before dissipating. Lower to mid level flow
turns more northwesterly behind this disturbance, shifting the focus
for ongoing widespread precipitation to the central MT mountains and
adjacent areas to the north later this afternoon through tonight
while cold/cyclonic flow and emebedded disturbances support more
showery precipitation coverage elsewhere across north-central and
central MT this afternoon into this evening.

Precipitation is primarily snow above 3500 ft with winter weather
impacts likely to be limited to areas where heavier precipitation
rates occur, especially this morning. This includes areas from
near Glacier NP, where snow has been falling through the overngiht
period, south along the Rocky Mtn Front and east across the MT-
200/US-87 corridor. Winter storm warnings and advisories are in
effect for these areas with worst road conditions likely along
US-89 NW of Browning and over Kings Hill in the Little Belts.
US-87 from Belt to Geyser will also see enhanced snowfall rates
this morning with potential for a greater buildup of slush on
road surfaces there. One area to watch this afternoon will be
Lewis and Clark County where hi-resolution models suggest a
greater coverage of convective snow showers will develop. While
accumulations on road surfaces are less likely during peak
afternoon heating, periods of low visibility in areas of briefly
more intense snow could affect travelers there. Snow showers
gradually decrease in coverage tonight across lower elevation
areas but are likely to persist through much of the overnight
period across the Little Belts/Highwoods, Snowies and Bears Paw
mountains under continued moist NW flow.

A transient/weak upper level ridge develops Friday across the
northern Rockies and shifts east across the area Saturday for a
brief period of drier weather between the current upper level low
affecting the region and the next one moving onto the west coast
this weekend. Temperatures warm some on Friday but remain below
seasonal averages with widespread overnight low temperatures
likely to fall below freezing under lighter winds and clearing
skies Friday night before a seasonably mild and dry day on
Saturday. Multi-model ensembles are in broad agreement to take the
next next upper level low eastward into the Great Basin by Sunday
with southerly flow ahead of this feature importing warmer air
and moisture into the region on Sunday. This will bring an
increased risk for showers as well as thunderstorms from south to
north across the area Sunday afternoon and evening with confidence
in timing and additional details decreasing by early next week,
though an overall pattern featuring above average precipitation
chances is likely, especially for eastern portions of north-
central MT. Hoenisch

&&

.AVIATION...
530 AM MDT Thu May 2 2024 (02/12Z TAF Period)

MFVR/IFR conditions persist across north-central MT terminals this
morning in widespread precipitation with lowest cigs/vis at KGTF and
KLWT where some brief LIFR is possible. Widespread precipitation and
mountain obscuration continues into this evening across the central
MT mountains with scattered to numerous snow showers moving across
north-central and central MT terminals and continued periods of
MVFR/IFR through this evening. KHLN will see snow showers this
afternoon with scattered or less coverage of snow showers south of
KBTM to KBZN. Gusty northwest winds develop at most terminals today
and persist into this evening before gradually diminishing
overnight. Hoenisch

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  40  30  50  26 / 100  70  40   0
CTB  39  29  51  26 /  90  50  10   0
HLN  50  32  57  31 /  80  50  20   0
BZN  50  26  53  28 /  40  30  10   0
WYS  44  19  48  20 /  30  40  10   0
DLN  51  28  55  30 /  10  30   0   0
HVR  43  29  51  27 / 100  50  30   0
LWT  36  26  44  23 / 100  70  50   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until noon MDT today for East Glacier Park
Region.

Winter Weather Advisory until noon MDT today for Cascade County
below 5000ft-Judith Basin County and Judith Gap-Northern High
Plains-Southern Rocky Mountain Front.

Winter Weather Advisory until 6 AM MDT Friday for Bears Paw
Mountains and Southern Blaine.

Winter Storm Warning until 6 PM MDT this evening for Little Belt
and Highwood Mountains.

Winter Weather Advisory until 6 PM MDT this evening for Big
Belt, Bridger and Castle Mountains-Snowy and Judith Mountains.

&&

$$

http://www.weather.gov/greatfalls