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000
FXUS65 KTFX 171802
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1202 PM MDT Wed Apr 17 2024

...AVIATION SECTION UPDATED...

.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...
1202 PM MDT Wed Apr 17 2024 (17/18Z TAF Period)

A broad trough will maintain a cold and relatively moist
northwesterly flow aloft for at least the next 24 hours. Snow and
associated MVFR/IFR/LIFR conditions, most widespread over North-
central Montana, will slowly improve as the afternoon progresses. A
more scattered brand of snow shower activity is then expected this
evening into the overnight hours, mostly impacting areas near higher
terrain. Flight categories will continue to trend towards MVFR/VFR
tonight, with Southwest and the eastern portions of North-central
Montana being most likely to hang onto MVFR clouds and mountain
obscuration. - RCG

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

&&

.PREV DISCUSSION...
/ISSUED 953 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