textproduct: Pocatello

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 SUNDAY/

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 /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 958 AM MST Mon Dec 29 2025

Strong high pressure will keep skies nearly clear with no CIGs, and even SCT decks occur above FL160. No concern with radiation BR or FG noted at this time. Wind is extremely light with only KBYI expected to exceed 10KT occasionally. Favored wind direction in the Snake River plain is north to east, while KSUN will struggle to get a southeast upslope wind today, mainly staying northwest at night and becoming VRB for the afternoon.

PIH WATCHES/WARNINGS/ADVISORIES

None.