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000
FXUS65 KTFX 171553
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
953 AM MDT Wed Apr 17 2024

.UPDATE...

Unstable northwesterly flow aloft continues across the region this
morning, allowing for areas of mainly light snow to persist.
Given recent warm temperatures, snow at lower elevations is
largely failing to accumulate on roadways. For this reason most
Winter Weather Advisories across northern portions of the region
have been canceled. Impacts are still being seen mainly at higher
elevations in Central and Southwest Montana, largely in the form
of slick roads near pass level. Impactful snow ends in these areas
late this morning. Northwesterly surface winds will increase in
magnitude through the day today across the plains, but are not
forecast to pose any impacts from a wind magnitude or blowing snow
perspective.

Later in the day, daytime heating looks to result in weak surface
based instability across the region. Scattered snow showers and
perhaps a few graupel showers will be likely before sunset.

Tweaks to the forecast were relatively minor, largely just
adjusting to current trends and latest guidance. -AM

&&

.SYNOPSIS...

Areas of snow and gusty winds continue through this afternoon
before incoming high pressure arrives later this afternoon and
evening. Cool and dry conditions are expected to close out the
week, with a warming trend beginning across North Central and
Southwestern Montana over the weekend.

&&

.AVIATION...
545 AM MDT Wed Apr 17 2024 (17/12Z TAF Period)

Mountain-obscuring low VFR/MVFR conditions with occasional IFR
conditions in snow and blowing snow will continue across North
Central, Central, and Southwest Montana will continue through at
least 16Z. Northerly winds will also mostly gust between 20 and 30
kt, but gusts up to 40 kt are possible over the plains, mainly
between through 21Z. Conditions will gradually improve to mostly
scattered to broken low VFR cloudiness from the northwest after 18Z
as the system starts exiting the area. However, scattered snow
showers with periods of MVFR/IFR conditions, possibly with a
thunderstorm or two, will likely not exit the area south of
Interstate 90 (including KEKS) until 00Z or so. Winds will also
decrease after 00Z, as skies become partly cloudy.
-Coulston

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

&&

.PREV DISCUSSION...
/ISSUED 545 AM MDT Wed Apr 17 2024/

Key Points:

-Areas of snow expected today, particularly in the higher
terrain
-Cooler temperatures linger through Friday, with warmer
temperatures arriving for the weekend and next week

Short Term (through Friday)... Areas of snow continue across
North Central and Southwestern Montana this morning as an upper
level low slides into Northeastern Montana and North Dakota from
Alberta and Saskatchewan. As this low moves southeastward, deep
northerly flow will continue to generate mostly upslope snow, with
the highest amounts today expected to be in the Highwood, Little
Belt, and Snowy Mountains where as much as 8 to 10 inches of snow
are expected, with a secondary maxima of snowfall accumulations in
the Mountains of Madison and Gallatin Counties, where up to an
additional 3-6 inches will fall in the higher terrain. Outside of
these areas, snowfall will generally be light and should not
accumulate more than 2 or 3 inches. We will have to watch for some
isolated blowing and drifting snow across the plains as winds
increase to 20-30 mph this afternoon, but with only a few inches
of snow at most, it seems unlikely that this will be a widespread
issue and mainly confined to areas near fields that are barren
thanks to prescribed burns or other methods of plant matter
removal.

Any snow and wind should begin to dissipate this evening as a
surface high pressure begins to settle into the area from Canada,
gradually putting an end to the lingering snow showers and gusty
winds. This high pressure system will then linger across the area
through Thursday and Friday, keeping us cool but quiet to close
out the work week.

Extended (Saturday through next Wednesday)... A warming trend
will begin on Saturday as the high pressure system begins to slide
off to the east, allowing southwesterly flow to work into the
area and advect warmer air in from Northern California and Eastern
Oregon. While this should not be an eventful warmup on Saturday,
a passing disturbance on Sunday will bring some localized gusty
winds, mainly across the plains, and a few showers to the area
Sunday afternoon. While this small disturbance will prevent
further warming between Sunday and Monday, upper level ridging
will begin to build over the Northern Rockies early next week,
which will cause temperatures to continue to warm through the
middle of next week, with 60s and even some low 70s back in the
forecast by the middle of next week. Ludwig

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  37  23  42  21 /  60  20  10   0
CTB  36  21  38  18 /  50   0   0   0
HLN  41  25  45  24 / 100  10  10  10
BZN  39  19  43  20 /  50  10   0  10
WYS  35   9  40  11 /  60  10  10   0
DLN  38  20  42  22 /  60  40   0  10
HVR  40  23  41  22 /  30  20  10   0
LWT  32  21  37  16 /  50  20  10   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT today for Big Belt,
Bridger and Castle Mountains-Gallatin Valley-Little Belt and
Highwood Mountains-Upper Blackfoot and MacDonald Pass.

Winter Storm Warning until 6 PM MDT this evening for Gallatin
and Madison County Mountains and Centennial Mountains.

&&

$$

http://www.weather.gov/greatfalls