821
FXUS65 KPIH 292342
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
442 PM MST Sat Nov 29 2025

.KEY MESSAGES...

- Snow returns tonight and lasts into early Sunday afternoon.

- Bulk of the precipitation with this round is along the 84/86
  corridor and south into the higher elevations.

- Much colder temperatures remain in place next week with
  another round of snow likely on Tuesday.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 143 PM MST Sat Nov 29 2025

As expected, much colder temps in place this afternoon despite
the ample sunshine for much of the area. Temps are still
running below freezing for most of eastern Idaho with the
exception being parts of the lower Snake Plain and into the
Magic Valley where mid to upper 30s are being observed.
Afternoon satellite shows just some high clouds streaking across
the region but to our northwest across Washington state, seeing
much denser cloud cover in association with an upper level
trough moving into the PacNW and this feature will move over our
area around daybreak tomorrow bringing a quick round of snow to
parts of the region. The biggest change in the forecast appears
to be a slight southward adjustment to the area with best
precip chances and overall snowfall amounts. 12Z HREF and 18Z
HRRR and NAM solutions show the primary area of focus for
snowfall tomorrow has shifted south, generally along and south
of the I-86 corridor and into the far SE corner of the Gem
State. That being said, forecast snow amounts have come down
across much of the I-15 corridor from around Blackfoot north
towards Idaho Falls and into the Rigby and Rexburg areas. Totals
near Pocatello also have come down a touch with only about half
an inch currently in the forecast. As you move from Pocatello
west into the Magic Valley, expecting a solid 1/2 to 1 1/2
inches in the lower elevations with 2-5" likely across the
higher terrain of the South Hills and into the Bear River Range.
This will be a quick moving system with snowfall likely to
begin shortly before sunrise and ending for most during the
early afternoon and should be finished basically everywhere by
the time the sun goes down. Winds are light tomorrow so no
concerns for blowing a drifting snow. Skies should clear out
quickly by Sunday evening and into Monday morning with overnight
lows into the teens for much of eastern Idaho keeping any
freshly fallen snow on the ground for at least a little while.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 143 PM MST Sat Nov 29 2025

The beginning of the extended period begins with a break on
Monday under influence of transitory ridge. The next system
arrives Monday night and lingers through Wednesday morning.
Model means support an additional inch of snowfall at lower
elevations, and 2-4" across the higher elevations south and east
of the interstates. Beyond Wednesday there is still uncertainty
present in the models. Ensemble clusters favor building a ridge
off the coast, with a couple clusters attempting to develop a
rex block over the western states. This should result in a dry
northwest flow over East Idaho. But the deterministic GFS and
ECMWF both flatten the ridge quickly and introduce fast active
flow into the PacNW by the end of the week into the weekend. The
NBM moderates temperatures slightly for Friday and Saturday,
but maintains weakly unsettled flow with continued chances of
showers mainly over higher elevations.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 442 PM MST Sat Nov 29 2025

A shield of BKN high-level clouds is overspreading southeast Idaho
from the northwest as a progressive shortwave trough (weak closed
low at times) approaches the region, but confidence remains high in
VFR conditions and no significant weather impacts to aviation
through 09-11z/2-4am overnight tonight...good news for wrapping up
most of today`s air traffic this evening. Early Sunday morning, have
tweaked/refined timing of a period of snow/snow showers with a re-
review of the HREF suite along with new runs of the NAMNest and
HRRR, with the greatest impacts (MVFR cigs and MVFR to IFR vsbys)
still favoring KBYI and KPIH. KSUN will be right on the edge of the
more organized precipitation but may also see similar conditions. If
organized/persistent -SN materializes for KBYI (as hinted at in some
guidance such as HREF snowfall rates), 1-2SM vsbys will be likely
and we may need to trend that direction in future forecast updates
(when it comes to snow...if it "goes", it really goes as far as
dropping vsbys). Further northeast, confidence is just a touch less
at KPIH (where we continue a PROB30 for similar impacts and at least
predominate -SHSN), and especially drops off at KIDA and KDIJ which
may reside along the northern/eastern edge of ANY snow shower
activity with this system (VCSH and PROB30s here, but it`s possible
cigs/vsbys hold closer to the upper end of MVFR or even VFR if snow
showers avoid the terminals). Precipitation should be done by 19-
20z/noon-1pm Sunday at all TAF terminals (assuming any lingering low
clouds clear out efficiently as advertised by the NBM) with skies
quickly going FEW to SCT, and no further impacts to aviation for the
rest of the afternoon and evening. No guidance favors any winds
exceeding 10kts. Beyond the current TAF period...will need to
further evaluate the potential for at least some nearby fog or low
stratus for KIDA hinted at in HRRR guidance late Sunday night into
Monday morning. Confidence in this is currently very low.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...McKaughan
LONG TERM...DMH
AVIATION...KSmith