802
FXUS65 KPIH 160533
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1033 PM MST Sat Nov 15 2025

.KEY MESSAGES...

- More active pattern returns with more widespread precipitation
  Sunday into Monday.

- Unsettled pattern continues into midweek with more systems
  likely.

- Warm temperatures in the short-term with cooler temperatures
  arriving for midweek and beyond.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 128 PM MST Sat Nov 15 2025

WV satellite imagery shows closed low off California coast
beginning to shift northeast in response to incoming Pacific
trough currently located near 150W. Warm frontal feature
associated with approaching low shifts north through East Idaho
tonight, bringing leading band of isolated weak showers. Light
precipitation is mainly focused along the leading edge of the
central mountains through Blaine and southern Custer counties
into early Sunday morning. Southerly flow increases during the
day Sunday, especially across the southern highlands and
adjacent portions of the Snake Plain. Showers become more
prevalent through the day as the low opens into a trough and
approaches the region. Southerly downslope flow may limit
rainfall in the southern portions of the Snake Plain, at least
initially. The downslope flow appears to weaken during the
afternoon with a slight wind shift to the southwest, which would
diminish precipitation inhibition in these areas and allowing
some rainfall to occur.

The upper low continues to open and track northeast across the
region Sunday night. Models have diverged somewhat on the track
of the 5H center, with some solutions tracking the feature
further south across northern Utah. This uncertainty impacts the
development of wrap-around moisture and showers overnight, as
well as how the cold air wraps into the region. NBM brings snow
levels and accumulating snow down to about 6500-7000 feet, and
rain/snow mix down to about 6000 feet. Meanwhile the heaviest
precipitation overnight Sunday night should be relegated to the
highlands east of I-15. Snowfall totals through 5AM Monday at
the higher elevations generally remain 1-3" above 7000 ft, with
minor impacts at pass level. Above 8500 feet, 3-5" will be
possible.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 128 PM MST Sat Nov 15 2025

Lingering showers continue into Monday mainly across higher
elevations as low shifts east of the state. Temperatures cool
off about 10 degrees from highs on Sunday, with snow levels
6500-7000 ft. Models have shifted yet again in the long term,
with a split trough of varying amplitude Tuesday into Wednesday.
Some ensemble clusters favor a more clear split vs a highly
amplified trough. Either way, this could be the best chance for
precipitation in the extended. For Thursday and beyond, there is
very little agreement in the models other than a broad sense of
developing a deep trough over the western states by the end of
the week. How that trough develops differs significantly among
ensemble clusters, but it should lead to some ridging over Idaho
late in the period for drier conditions. Temperatures for
Wednesday and beyond are typically in the 40s for lower
elevation daytime highs.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1033 PM MST Sat Nov 15 2025

Only a few minor tweaks were required with the fresh 06z TAF
package...either because changes weren`t needed, or confidence is
too low for big nudges yet given some lack of agreement in our
various models. Multiple large shields of clouds in the mid- and
upper-levels will continue to build northward across southeast Idaho
this evening and tonight, as a warm front also lifts north (now
approaching KBYI and KPIH from the south). As expected, a few
showers are likely reaching the ground along the front, but with not
quite enough coverage to include VCSH beyond KBYI (where so far
echoes on radar have manifested as increased/lowering clouds only),
with a continued better chance of increasing showers kicking off
later. Thus, have generally held off until 07z/12am at KSUN, and 10-
12z/3-5 am at KPIH/KIDA/KDIJ, for initiating VCSH (just slight
tweaks to previously forecast timing there), followed by an
increasing trend in shower coverage thereafter during the day Sunday
with -SHRA for all terminals. Agreement is unfortunately not great
among the 00z HREF suite on timing and placement of the most
persistent showers, but we don`t yet have enough confidence to back
off from -SHRA for any organized period at any of the TAF terminals.
Cigs are generally expected to remain VFR through late afternoon
Sunday with the showers. Dry air at the sfc will take some time to
overcome, and southerly downslope winds are expected especially at
KPIH, so it`s possible VCSH and -SHRA groups may begin an hour or
two too early at KBYI and KPIH in the current forecast. Have also
maintained winds slightly above guidance after 19z/noon at KPIH due
to that southerly downslope expectation with gusts to 20kts
possible. As low pressure approaches our area Sunday evening from
the southwest, many guidance sources are advertising a more
significant drop in cigs to MVFR along with a continued trend into
more widespread showers or rain after sunset, affecting especially
KPIH, KIDA, and KDIJ. Interestingly, while the signal remains
ominous in the HRRR and eventually MOS guidance, the NBM has backed
off...or at least trended later...on increasing impacts especially
with cigs. Will continue to monitor trends.

&&

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

&&

$$

SHORT TERM...DMH
LONG TERM...DMH
AVIATION...01