St. Anthony, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

649
FXUS65 KPIH 200528
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1028 PM MST Fri Dec 19 2025

.KEY MESSAGES...

- Moderate to heavy mountain snow continues through tonight,
  along with valley rain.

- Weather pattern remains active through Christmas week.

- Continued well above normal temperatures through Christmas.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 117 PM MST Fri Dec 19 2025

Satellite and radar imagery shows frontal boundary beginning to
approach western Idaho early this afternoon. Precipitation
continues ahead of the front with snow levels remaining
6500-7500 ft this afternoon. Winds remain gusty especially at
higher elevations and throughout the upper portions of the Snake
Plain. As the front sags through this evening, we should see
precipitation gradually shift focus to the southern through the
night. Winds are expected to diminish this evening. Believe that
the Winter Storm Warning across the central mountains could be
removed early when the Wind Advisory expires. Otherwise the
Winter Weather Advisory, or at least the southern portions of
it, will continue while snow is still ongoing in those areas.
HREF short-term ensembles look reasonable in drastically
decreasing the precipitation even Saturday morning across the
southern highlands. Saturday should provide a break in the
precipitation and some brief sun, with temperatures still above,
but closer to normal. The next system begins to encroach from
the south as the upper trough off the Pacific coast starts to
amplify, shifting flow aloft more southwest. There are some
hints that a few light showers could begin as early as Saturday
evening, but the consensus holds off the onset of precipitation
until after midnight Sunday night. Overnight temperatures are
expected to be cold enough to support snow down to valley floors
late Saturday night, but accumulations are expected to be
minimal at best.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 117 PM MST Fri Dec 19 2025

Our wet and breezy pattern continues to begin next
week. We have another round of moderate to heavy precipitation moves
in during the day Sunday, with the bulk of this round falling
through Sunday night/early Monday morning. Some subtle differences
will determine where heavier precipitation across the Snake Plain,
Magic Valley and the South Hills/Albion Mountains. The slam dunk
areas will be portions of the eastern and southeast highlands, and
across the central mountains. The GFS favors the Magic Valley,
southern end of the Snake Plain, and South Hills/Albion Mountains.
The NAM shifts north to encompass the Lava Beds through the INL/Arco
Desert into Idaho Falls northward. The ECMWF favors both depending
on the time period you look at in the model. No matter where the
band sets up, we are seeing signals for downslope along and south of
the Snake River...and upslope into the central mountains and along
the Montana border. In fact, this pattern is shaping up to provide
the Wood River Valley and surrounding areas with a lot of moisture.
The question will be snow levels. The official snow level forecast
pushes them to 6000-7000ft across the central mountains and eastern
highlands. Snow levels elsewhere push 7500-9000ft due to southerly
flow and downslope effects. If you look at the low end range for
snow levels...meaning how low they COULD be, we are seeing them 500-
1500 ft lower at times. While that shouldn`t make a difference with
snowfall in the lowest valleys, this could easily mean some spots
getting a few inches or getting dumped on with a lot of wet, sloppy
snow. Our latest forecast combining the Blend of Models and
precipitation amounts from WPC, favored areas of precipitation, are
looking at 0.50-1.5" of moisture. Higher elevations of the Big
Holes/Bear River Range, Sawtooths and mountains surrounding
Hailey/Ketchum are looking at 1.50-2.0". There is a 10-20% chance of
exceeding 2" around Galena Summit. Even if we see a northward shift
of the band across the Magic Valley and Snake Plain, there should be
a "shadow" across portions of the Snake Plain with 0.10-0.50" worth
of moisture falling. Looking at snowfall, where snow levels remain
much higher across the Snake Plain and Magic Valley, we are seeing
little to no snow. Where we can get snow to fall there, look for a
couple of inches. Little to snow, for now, is forecast across the
southern mountain valleys, Teton Valley, and the Challis/Pahsimeroi
Valleys. Up to 5" is possible across Island Park and Stanley Basin.
We have similar amounts for the Wood River Valley, BUT if snow
levels end up 500ft or so lower...we could several more inches of
wet snow falling. The current forecast puts most of the accumulating
snow at/above 7000ft and in the 10-20" range for portions of the
central mountains, Bear River Range, Big Holes and higher elevations
surrounding Island Park. There is room for this forecast swing
wildly in the next 24 hours, so please stay tuned to any changes
coming even though most people may be out and about shopping or
traveling to get an early holiday start. We need to let the current
round of headlines expire before deciding on when and where we might
need something for this round.

The moisture train continues into next week. Trends show things
letting up on Monday and another band developing, but quickly
shifting north on Tuesday. Christmas Eve, Christmas Day and the day
after look wet. The chances for a white Christmas for lower
elevations isn`t good at all. IF we see snow for Christmas morning,
it would be early and with this warm pattern continuing...it would
melt pretty quickly. For a guaranteed white Christmas, you likely
need to head well up into the mountains to find it. Lower elevation
temperatures remain well above average throughout the extended
forecast period with highs in the 40s and 50s...and places like
Stanley, Copper Basin and Island Park above freezing in the
afternoon. We aren`t talking too much about wind, but this pattern
really isn`t giving a break at all from a lot of wind. Does that
mean it will blowing every day at every location? No. The overall
pattern though is indicative that a lot of places will see the wind
off and on throughout next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1028 PM MST Fri Dec 19 2025

Precipitation continues to shift southeastward with VCSH at both
KBYI and KDIJ for a couple more hours. Winds will remain breezy
overnight into the first half of tomorrow. The next round of
moisture will begin working into the central mountains around
Midnight Saturday night/Sunday morning. Have included VCSH at KSUN
at 08z Sun to indicate this next round`s arrival. Precipitation
reaching the other terminals will fall just outside of this period,
after 06z Sunday.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 AM MST Saturday for IDZ060-063-
064-066.

&&

$$

SHORT TERM...DMH
LONG TERM...Keyes
AVIATION...Cropp