151
FXUS65 KTFX 020001
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
600 PM MDT Wed May 1 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.

&&

.DISCUSSION...
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

&&

.AVIATION...
600 PM MDT Wed May 1 2024 (02/00Z TAF Period)

Rain and snow showers will affect much of the northern two thirds of
the CWA tonight into Thursday. Any thunderstorms should diminish by
02z. The snow will become a bit more widespread over North Central
MT after 09z, with the snow continuing through Thursday morning. The
precipitation becomes more scattered on Thursday afternoon. MVFR to
at times IFR conditions are possible in/near heavier snow showers.
Mountains/passes will be obscured at times through the period. Brusda

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  30  40  31  50 /  80  90  60  40
CTB  30  40  29  51 /  90  80  30  20
HLN  30  49  32  57 /  50  70  30  20
BZN  23  48  27  54 /  40  40  30  20
WYS  13  43  19  48 /  40  30  20  20
DLN  24  49  27  55 /  20  10  10  10
HVR  31  45  30  51 /  80  80  50  30
LWT  28  37  27  44 /  80  80  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 from 6 PM this evening to 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 from 10 PM this evening to noon MDT
Thursday for Cascade County below 5000ft-Judith Basin County and
Judith Gap.

&&

$$

http://www.weather.gov/greatfalls