526
FXUS65 KPIH 180006
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
506 PM MST Wed Dec 17 2025

.KEY MESSAGES...

- Widespread high winds continue behind a cold frontal passage.
  Everyone under a high wind warning or wind advisory until
  late evening.

- Moderate to heavy mountain snow Thursday and Friday

- Weather pattern to remain active into the week of Christmas

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 210 PM MST Wed Dec 17 2025

Saying that it`s been an eventful mid-December day across
eastern Idaho would be a bit of an understatement. Widespread
wind gusts of 50-70 mph were observed just about everywhere this
morning and afternoon in addition to a few 80+ mph gusts along
the I-86 corridor near Coldwater and Pocatello. Winds remain
quite gusty across the region and have decided to extend the
existing High Wind Warnings and Wind Advisories until the late
evening as it seems like the gusts will linger a bit longer than
initially expected. They`ll likely drop below High Wind
Criteria around 5 as initially expected but will probably remain
in the 30-40 mph range into the late evening.

Afternoon satellite imagery shows gradually clearing skies
across the region post-FROPA with colder air expected to filter
in over the next few hours. As such, all of eastern Idaho will
drop below the freezing mark tonight, although not by much
across the Snake Plain and Magic Valley. The clearing skies will
be short-lived as our next system will be here by mid- morning
across the western half of the forecast area and overspread the
rest of the area by early to mid afternoon. Precip type is
expected to be all snow, initially, with snow levels quickly
rising to well above 6000-7000 ft by late evening. That being
said, lower valleys will have a brief period of snow before
transitioning to a mix and then eventually all rain. This short
duration should lead to very little, if any, accumulations
across the lower elevations. Higher elevations however are a
different story. Winter Storm Watches have been upgraded to
Warnings across the Central Mountains where snowfall totals will
be measured in feet above 7000 feet. A few feet of snow appear
likely on Galena Summit. Around Stanley and Sun Valley, event
totals will be closer to the 4-8 inch range however with the
snow levels and temperatures being a bit more marginal in these
areas. Areas around Island Park and into the Big Holes are
expected to see some snow accumulations throughout the day
tomorrow nearing Winter Weather Advisory levels. Held off for
now but a short-fused one may be needed on the next forecast
package. The active weather looks to continue into the weekend
and early next week. More on that below.

&&

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
Issued at 210 PM MST Wed Dec 17 2025

The unsettled pattern continues Friday as bulk of next system
works through the region. Another windy day is expected Friday.
Current NBM means carry another round of at least Advisory
level sustained winds over 30 mph. 90th percentile winds touch
back into lower end High Wind Warning thresholds. NAM and GFS
both hold 700mb winds around or just below 60kts, whereas the
mid level support for today exceeded 70kts over a widespread
area. Temperatures remain mild, keeping snow levels 6500-7000 ft
across the region, so this event once again is keeping snow at
higher elevations, though small amounts may be possible at lower
elevations during overnight hours Friday night into Saturday
morning. Additional accumulations Friday morning through early
Saturday look to be highest across portions of the central
mountains, mainly higher elevations surrounding the Wood River
Valley and Stanley Basin. The probability of 24-hr snow
accumulations exceeding 1 ft Friday morning through Friday night
exceeds 60% for most of the Sawtooth Recreation Area in the
area of greatest snowfall totals. Thus the Winter Storm Warning
continues into early Saturday. Precipitation tails off during
the day Saturday along with the wind.

We are seeing amplification of the Pacific trough along or off
the coast beginning Sunday, resulting in increasing southwest
flow into Idaho. Ensembles and clusters are in relative
agreement in continuing precipitation chances through some of
the heaviest travel days of the season. Given the southwest flow
aloft, temperatures remain in the very mild pattern, and snow
levels remain high. Thus lower elevations are expected to see
all rain, with snow levels around/above 6000 ft. It`s not great
news for anyone at lower elevations hoping for a White
Christmas, but the mountains will stand to see additions to the
snow pack. Those traveling for the holidays will want to keep an
eye on upcoming forecasts, as fluctuating snow levels could
provide potential impacts for travel routes over higher
elevation passes.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 452 PM MST Wed Dec 17 2025

Still have strong winds behind an exiting cold front with gusts
of 20 to 40 kts for all TAF sites. Lowest winds currently are at
SUN and BYI. Winds will continue to drop into the early evening
becoming below 10 to 15 kts by 10 pm to around midnight. High
pressure builds in overnight. Expect mostly clear skies with
mostly upper-level clouds. Northwest flow aloft sets up over
the area overnight and continues into tomorrow, Thursday.
Models continue to show a wave of moisture dropping into the
area by late tomorrow morning/early afternoon through the
northwest flow aloft. Expect snow showers at SUN and DIJ and a
rain/snow mix for PIH and IDA. Temperatures look to warm up
tomorrow afternoon into the early evening. SUN and DIJ should
remain snow with IFR conditions. Precipitation at IDA and PIH
will likely turn to rain with mostly just MVFR conditions.
Though with the onset of precipitation, IFR conditions could
occur at IDA and PIH before conditions improve as snow turns to
a rain/snow mix or just rain later in the day. Winds will get
slightly gusty tomorrow as well with gusts of 20 kts likely for
PIH, IDA and DIJ.


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 11 PM MST this evening for IDZ051>058-
062-064>075.
Wind Advisory until 11 PM MST this evening for IDZ059>061-063.
Winter Storm Warning from 5 AM Thursday to 5 AM MST Saturday
for IDZ071>074.

&&

$$

SHORT TERM...McKaughan
LONG TERM...DMH
AVIATION...TW