415
FXUS65 KTFX 020606
AFDTFX

Area Forecast Discussion National Weather Service Great Falls MT
1206 AM MDT Thu May 2 2024

.Aviation Section Updated...

.SYNOPSIS...
A spring system will bring a mix of rain and snow showers to the
region this afternoon before transitioning to mostly snow this
evening and tonight. Impactful snow looks to fall near terrain
across Central and North-central Montana with this system through
Thursday. Temperatures rise back toward normal Saturday as ridging
builds in before another precipitation producing system arrives late
weekend into next week.

&&

.UPDATE...

Precipitation has begun to become more widespread along the Rocky
Mountain Front and Central Montana, as an upper level front pushes
south. Current webcams show some rain/snow showers falling across
the CWA, with snow mainly sticking to grassy surfaces. Widespread
rain/snow continues overnight and into the morning hours. The
heaviest snowfall remains in the Northern Rockies and Little Belts.
Traveling there will be difficult with slick roadways and greatly
reduced visibility with heavy snow. Lower elevations may see some
light snow overnight, however it will mainly accumulate on grassy
surfaces. Areas where road temperatures drop close to freezing
temperatures overnight and in the morning may develop some lighter
slushy accumulations. -Wilson

&&

.AVIATION...
1205 AM MDT Thu May 2 2024 (02/06Z TAF Period)

North-central Montana (KCTB, KHVR): Snow (KCTB) and rain/snow mix
(KHVR) will impact the hi-line through most of Thursday. Along the
Rocky Mountain front, including KCTB, there is a concern for blowing
snow this morning as winds will be gusty at times. MVFR/IFR
conditions are expected to persist through most of the TAF period
with periods of LIFR conditions possible in stronger showers.

Central Montana (KGTF, KHLN, KLWT): Rain/snow will start moving into
central Montana by 02/06Z. VFR/MVFR is expected to prevail at KGTF
and KHLN with periods of IFR possible during the day. Mountain
obscuration around KHLN will be possible after 02/14Z. KLWT will
start off the TAF period at VFR but deteriorate to IFR/LIFR by
06/12Z with blowing snow possible at times. Conditions are expected
to improve to MVFR at KLWT by 03/02Z.

Southwest Montana (KEKS, KBZN, KWYS): Showers will generally be
confined to the higher elevations of southwestern Montana with
mountain obscuration possible after 02/18Z. VFR conditions will
prevail at southwest Montana terminals with periods of MVFR/high-IFR
possible at KBZN and KWYS as some of the nearby showers may reach
lower elevations at times. Otherwise, significant impacts are not
expected through the TAF period.

Equipment Note: As of 01/18Z, the KWYS TAF has returned to service
for the summer. However, due to an inoperable ceilometer,
amendments are not scheduled until further notice.

-thor

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

&&

.PREV DISCUSSION...
/ISSUED 600 PM MDT Wed May 1 2024/
Through Friday morning...A large cyclonic circulation is in place
aloft across the Northern Rockies, extending out toward the Canadian
Prairies. Given the main circulation center is off to the east, a
cool northwesterly flow aloft is in place. Daytime heating today has
combined with cool temperatures aloft to result in numerous showers
across the region. A mix of rain and snow has been observed in these
showers so far, with that trend forecast to continue through the
early evening. Additionally, a few pockets of lightning have been
observed so far this afternoon in the most intense showers. Isolated
pockets of thunder will remain possible through evening. An embedded
wave within this cyclonic flow aloft will drop south from Canada
this evening, allowing for snow to become more widespread, primarily
across North-central and Central Montana tonight into Thursday. The
greatest impacts from snow with this system look to be along the
Northern Rocky Mountain Front as well as in the Little Belts. The
chance for intermittent snowfall rates in excess of an inch per hour
across Kings Hill Pass late tonight into Thursday is around 60% and
is around 30% along US-89 north of East Glacier Park.

The only change to Winter Storm Warnings and Winter Weather
Advisories was to add lower elevations of Cascade county and Judith
Basin county to an advisory tonight into Thursday morning. Most
impacts in there areas look to be confined in the Belt to Geyser
corridor late tonight into tomorrow morning. The chance for
visibility to drop to a quarter mile or less from snow in these
areas late tonight into Thursday morning is around 60% or so any
given hour. Additionally, surface temperatures look to cool enough
to support accumulating snow on roads in these areas, though that
window is rather narrow (Perhaps around midnight or so until 9 AM
Thursday).

Impactful snow largely tapers off Thursday afternoon, though light
snow will remain in pockets into Thursday night/Friday morning.

Friday afternoon into early Sunday... Transient ridging will
build into the area Friday afternoon. The result will be for a
pleasant Friday evening and Saturday, with daytime temperatures
Saturday rising to around average for early May. Warm
temperatures persist into Sunday, but precipitation chances will
begin to creep in, especially across Southwest Montana, as early
as Saturday night ahead of the next system.

Late Sunday into early next week... Transient upper level ridging
will be short lived, with another upper level disturbance dropping
SE from the Pacific NW toward the Great Basin. This system looks to
be a bit warmer in nature compared to the one passing across the
region over the net day or so, with snow looking to mostly remain in
the mountains. Overall, the chance for a quarter inch worth of
precipitation between Sunday and Wednesday is roughly around 50% at
lower elevations. -AM

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  33  40  31  50 /  80 100  60  40
CTB  32  40  29  51 / 100  80  30  20
HLN  35  49  32  57 /  40  70  30  20
BZN  24  48  27  54 /  20  40  30  20
WYS  16  43  19  48 /  20  30  20  20
DLN  24  49  27  55 /  10  10  10  10
HVR  32  45  30  51 /  80  90  50  30
LWT  29  37  27  44 /  70  90  50  40

&&

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

Winter Weather Advisory until noon MDT Thursday for 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 Thursday for Little Belt and
Highwood Mountains.

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

Winter Weather Advisory until noon MDT Thursday for Cascade
County below 5000ft-Judith Basin County and Judith Gap.

&&

$$

http://www.weather.gov/greatfalls