textproduct: Pocatello

KEY MESSAGES

- Unseasonably Warm Through Friday: High pressure will maintain dry weather with passing mid-to-high clouds and highs 7 to 12 degrees above normal (50s and 60s), with potential downslope warming pushing portions of the Snake Plain, Magic Valley, and bench areas above the low-to-mid 60s.

- Splitting Storm & Mountain Snow (Friday NightSaturday): A splitting Pacific system will deliver its main moisture push from after midnight Friday through late Saturday afternoon, focusing 0.25" to 0.50" of liquid (locally 0.50"0.70" on high peaks) across the Wood River Valley, Sawtooths, South Hills/Albion Mountains, and Southeast Highlands. Snow levels near 7,000 feet will yield up to 3 inches of snow (locally 45 inches), with light accumulations in high valleys like the Stanley Basin as Saturday highs drop into the 30s and 40s.

- Next Week Colder Pattern Shift: Another split-flow trough moves inland Monday bringing renewed temperature drops, daily rain and mountain snow chances, and potential overnight/early morning valley snow by mid-week.

DISCUSSION

Issued at 248 AM MST Thu Nov 12 2026

The weather pattern across eastern Idaho will remain benign today with high pressure remaining in control for one more day. Early morning satellite imagery shows mostly clear skies currently although some patchy overnight fog could transpire in a few localized spots over the next few hours. Strong atmospheric subsidence and rising 500 mb heights will keep conditions dry and promote unseasonably mild afternoons, with daytime highs running 7 to 12 degrees above seasonal averages in the 50s and 60s. Forecasters will monitor boundary-layer mixing closely to see if downslope flow pushes temperatures above the low-to-mid 60s across portions of the Snake River Plain, Magic Valley, and adjacent bench areas.

The tranquil synoptic pattern breaks down heading into the weekend as an upper-level trough over the Gulf of Alaska taps into Pacific moisture and ejects energy across the Pacific Northwest. Light precipitation will begin across the Wood River Valley and Sawtooths later Friday evening, with the bulk of the moisture falling from after midnight through late Saturday afternoon and early evening. Because the storm system splitssending the primary low southeastward toward the Four Cornersprecipitation will be heavily concentrated across the Wood River Valley, the Sawtooths and surrounding mountains, the South Hills/Albion Mountains, and the Southeast Highlands, while other locations see only light amounts, a tenth or two at most.

Favored terrain and adjacent valleys are projected to receive 0.25 to 0.50 inches of liquid or melted snow equivalent, with a few spots across the highest elevations near Ketchum and the South Hills/Albion Mountains pushing 0.50 to 0.70 inches. QPF amounts are well-aligned across deterministic and ensemble versions of the GFS and ECMWF aside from minor differences near the Utah border. Snow levels will sit generally around 7,000 feet, though elevated valleys such as the Stanley Basin will see light accumulations. Overall snowfall totals will run up to 3 inches, with an additional 1 to 2 inches possible within localized heavier pockets. Thick cloud cover, precipitation, and cold advection will drop Saturday daytime highs sharply into the 40s. Eastern Idaho will reside in a brief lull between moisture surges during the second half of the weekend. Aside from a few isolated showers lingering early in the day, conditions will remain mostly dry under partly cloudy skies until the next Pacific low shifts inland. This break in precipitation will allow afternoon temperatures to rebound 5 degrees or so compared to Saturday's highs.

A more pronounced and prolonged pattern shift takes hold to start next week as broad upper-level troughing anchors over the western United States. While the National Blend of Models (NBM) introduces precipitation as early as Sunday night, overall model trends have favored holding off the bulk of Idaho's moisture arrival until Monday. Synoptically, this incoming storm mirrors the weekend system, featuring split flow with the main energy passing to our south. Once the low moves inland, temperatures will drop sharply once again, ushering in below-normal readings and daily chances for scattered rain and mountain snow. Depending on the depth of cold air advection, snow levels could reach valley floors during overnight and early morning hours toward the tail end of the forecast period, though considerable ensemble spread remains regarding exact amounts and timing at that range. Bottom line is next week continues to look much cooler and unsettled.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 248 AM MST Thu Nov 12 2026

VFR likely to prevail through the period with mostly clear skies through the day and light winds. Clouds will be on the increase late in the period as mid/high level moisture increases ahead of our next weather system. Winds will stay light through the current period but will become breezy and gusty just beyond this forecast cycle. There will be some very localized fog potential this morning, mainly around KPIH will could cause some localized MVFR/IFR conditions if it transpires. For now, will handle with a TEMPO group and monitor trends through the overnight.

PIH WATCHES/WARNINGS/ADVISORIES

None.