819
FXUS65 KPIH 292340
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
440 PM MST Mon Dec 29 2025

.KEY MESSAGES...

- High pressure rebuilds across the western U.S.

- Dry conditions and warmer conditions through New Year`s Eve

- Rain and snow rings in 2026

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 1257 PM MST Mon Dec 29 2025

Afternoon satellite imagery is generally void of clouds across
eastern Idaho aside from some occasional high cirrus moving from
north to south. High pressure will remain in firm control in the
short term, in fact, becoming amplified further into mid week. This
will keep the area free of precip with light winds continuing.
Temperature inversions will be the only forecast challenge with some
locations potentially far off their forecast highs or lows depending
on localized circumstances and ones elevation. Temperatures are
generally running around seasonal norms today but will rise to above
normal levels as early as tomorrow as the upper flow becomes more
NW as opposed to north. This will become more westerly by Wednesday
which should usher in some seasonably mild air for mid/late week.
More on that below.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 1257 PM MST Mon Dec 29 2025

Wed (NYE) through next Mon. Latest cluster analysis was from 12Z
yesterday. Upper level ridging remains strong enough with a tilt
that keeps the upper level flow zonal, which should end the
constant influx of cold air from the north. So temperatures will
continue to warm on Wed, and even New Year`s Day still has
positive height anomalies with troughing attempting to break
down this ridge coming up from California; By 2/00Z it is still
offshore of California in 50 percent of the solutions. For Fri/3
Jan only around 30 percent of the solutions have a cluster with
a flattened upper level flow over the Gem State. About half the
solutions have set up a pattern close to a Atmospheric River
event. The remaining 20 percent have the low still farther west
and less likely for precipitation reaching Idaho. All of this
indicates warmer than normal temperatures and a threat of rain
and snow by the 2nd. Afternoon highs in the NBM are running 6 to
13 deg F above normal, and once cloud cover arrives on New
Year`s Day mild overnight lows9 to 15 deg F above normal for the
time of year. Wind appears slightly elevated but not even to
the "windy" category of 20 to 30 mph wind, more like "breezy" at
best, starting Fri afternoon.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 439 PM MST Mon Dec 29 2025

VFR conditions forecast at all terminals under high pressure with
light and variable winds. Mid to high level FEW to SCT high
clouds will return tonight into Tuesday morning, but skies will
clear again during the afternoon. Low chances for low stratus or
fog again.

&&

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

&&

$$

SHORT TERM...McKaughan
LONG TERM...Messick
AVIATION...Cropp