185
FXUS65 KPIH 180539
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1039 PM MST Wed Dec 17 2025

.KEY MESSAGES...

- Moderate to heavy mountain snow Thursday and Friday

- Weather pattern to remain active into the week of Christmas

&&

.UPDATE...
Issued at 808 PM MST Wed Dec 17 2025

Have gone ahead and cancelled the High Wind Warning and Wind
Advisory as wind gusts continue to diminish tonight. Also issued
a Winter Weather Advisory for portions of the Eastern Highlands
where snow totals from Thursday midday to Saturday morning are
expected to range from 5 to 9 inches below 7000 feet and 10 to
14 inches above 7000 feet with some higher amounts on mountain
tops.

&&

.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 /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1030 PM MST Wed Dec 17 2025

Winds have backed off for all sites except BYI where there are
still gusts of 15 to 20 kts. Winds will continue to drop off.
Expect mostly clear skies with mostly upper-level clouds
overnight. Northwest flow aloft sets up over the area overnight
and continues into tomorrow, Thursday. Models continue to show a
wave of moisture moving 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
and rain for BYI. 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
and then just rain later in the day. Winds will get slightly
gusty tomorrow with gusts of 20 to 25 kts likely for PIH, IDA,
BYI and DIJ. Winds at the surface will be from the south.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 11 AM Thursday to 5 AM MST
Saturday for IDZ060-063-064-066.
Winter Storm Warning from 5 AM Thursday to 5 AM MST Saturday
for IDZ071>074.

&&

$$

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