Winter Storm Warning 2, NWS Pocatello, ID

Area Forecast Discussion
National Weather Service Pocatello ID
306 PM MST Wed Jan 10 2024

.SHORT TERM...Tonight through Thursday Night.
Today's cold front and the main push of snow is through most of
the area by now. That said, some light snow will continue into
tonight and we'll still be dealing with some wind gusts around 30
to 40 mph in the eastern Magic Valley, Snake Plain, and Eastern
Highlands. Wind gusts overall have been decreasing in the Central
Mountains and only light snow showers will continue this evening.
So, have expired the Winter Weather Advisory early and the Winter
Storm Warning for the Central Mountains/Sawtooths and Shoshone
areas. The other headlines will continue until 5 PM. Once all of
these headlines come down, look for a Winter Storm Watch to
replace them ahead of our next system arriving late Thursday.
Winds will begin to slowly diminish after sunset in the Snake
Plain and Eastern Highlands, but will still be a bit breezy in the
eastern Magic Valley and portions of the Central Mountains as
cold air works its way in over the Divide tonight, though
certainly much lighter than what we've dealt with lately. Any snow
accumulation tonight in the valleys looks light, about a half
inch to an inch and an inch or two in the mountains.

Tomorrow will be a colder day with morning temperatures in the
single digits below zero up north and single digits above zero for
the rest of the upper Snake Plain and Arco Desert/Mud Lake areas and
Eastern Highlands. The lower Snake Plain and eastern Magic Valley
will see a mix of upper single digits and low to mid teens.
Afternoon highs will range from mid teens up north to low to mid 20s
in the Magic Valley. Snow showers will continue on Thursday, though
accumulate up until midnight Friday doesn't look all that impressive
for the Magic Valley and Snake Plain with totals generally between a
half inch to an inch and a less than 20 percent chance of two inches
of snow. As for mountain snow, it'll be the Sawtooths, Albion
Mountains, and Bear River Range that see the most out of Thursday
with totals generally in the 5 to 8 inches range. The Albion
Mountains and Bear River Range are showing about a 20 to 40 percent
chance of more than 5 inches of snow while the Sawtooths is closer
to a 50 to 70 percent chance, though that likely is beginning to
pick up on the next big push of moisture beginning to move in late
Thursday into Friday. While the wind stays breezy in the eastern
Magic Valley through most of Thursday with gusts around 30 to 35
mph, expect winds to begin to increase for everyone around/after 5
PM Thursday with gusts in that 30 to 35 mph and increasing to closer
to 40 to 45 mph range by midnight.
AMM

.LONG TERM...Friday through Wednesday. Active pattern continues,
front loaded in the first couple days of the extended forecast. Very
robust shortwave features shifts inland, bringing deep moisture and
very strong winds to East Idaho. 700mb jet pushes inland Thursday
night, and spreads across East Idaho during the day Friday. Models
have been wiggling the jet north and south the past few runs, but
overall still peaks across the southern half of the forecast area
Friday afternoon between 55-60kts per the NAM. This translates to 25-
40 mph SUSTAINED winds at the surface during the day Friday, with
gust potential again pushing 50+ mph. Strongest winds subside Friday
night, but remain gusty with blowing snow potential continuing into
at least early Saturday for at least higher elevations in the south.

At the same time, deep moisture transport works into the region.
Orographics would favor the leading edge of the central mountains,
and the southern and eastern highlands for this event, perhaps
spreading into the southern and eastern edges of the Snake Plain.
Model probabilities support at least Advisory snows for most of the
region (3+" for the Snake Plain), with high-end estimates for the
southern end of the Snake Plain (I-86/84 corridor) exceeding a foot
Friday-Saturday. Normally shadowed NW flow regions of the Snake
Plain (Mud Lake and surrounding areas) and the Island Park area are
least-favored for snowfall, generally around an inch or so (2-4: for
Island Park), but is not expected to escape the winds. For the
leading edge of the central mountains (Hailey/Wood River to
Stanley), and the southern highlands from the Southern Sawtooth east
to the Bear River Range, and then north to the Big Hole mountains,
model averages are running 8-10" at the low end with high-end
probabilities suggesting potential for around 2 feet or more of
snow. Given the current headlines in place, will NOT be issuing a
Winter Storm Watch with the afternoon package, but expect an area-
wide headline once those drop off.

Models differ with how the system evolves through the remainder of
the weekend, with some implications on continuing snowfall for
Saturday night into Sunday. GFS holds on to some moisture and
continued slight snowfall over the eastern highlands through Sunday
night. Both however, agree on onset of much colder airmass settling
into the region behind the main storm. Ensembles still show a high
amount of spread on the temperatures, but means bring overnight lows
to single digits or lower most areas Saturday night, and subzero
almost everywhere Sunday night. Deep northerly flow begins to
moderate Tuesday into Wednesday, but that's likely due to models
trying to bring next system to the coast late in the period. DMH

&&

.AVIATION...For the 18Z today to 18Z Thursday terminals.
Combination of snow and wind continue to create aerodrome
complications for East Idaho, though some improvement is possible
for the evening/early overnight hours. MVFR CIGS/VIS dropping to
occasional IFR in SHSN/BLSN, especially where gusts exceed 30kts.
SHSN continue overnight, particularly for KDIJ. Elsewhere expect
MVFR CIGS to return overnight and continue into Thursday. Winds
increase again during the Thursday especially for KPIH/KIDA/KBYI,
along with the potential for at least VCSH. DMH

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 5 PM MST this afternoon for
IDZ053>066.

&&