textproduct: Pocatello

KEY MESSAGES

- Red Flag Warning & Scattered Storms Today: Overnight showers over the Snake Plain and Eastern Highlands will clear this morning, followed by an afternoon flare-up of showers and thunderstorms. A **Red Flag Warning** remains in effect for Fire Zone 422 due to scattered thunderstorm coverage.

- Breezy to Windy Mid-Week: A tight pressure gradient will produce widespread breezy to windy conditions Wednesday through Friday, with some valley corridors flirting with Wind Advisory criteria.

- Below-Normal Temperatures: Afternoon highs will remain suppressed in the mid-to-upper 70s across lower valleys and 60s to low 70s in the mountains, though a brief recovery into the lower 80s is expected today and possible again on Saturday.

- Unsettled Labor Day Weekend Outlook: Unsettled conditions and rain chances increase late in the holiday weekend, with high confidence in cool, below-normal temperatures persisting into the first week of September.

DISCUSSION

Issued at 155 AM MDT Tue Sep 1 2026

Overnight rain showers continue to stream across the Snake Plain and Eastern Highlands early this morning. High-resolution convective-allowing models (CAMs) show this initial wave exiting by mid-morning, yielding a brief lull in precipitation. However, incoming upper-level shortwave energy and lingering atmospheric moisture will spark a secondary round of showers and thunderstorms by early-to-mid afternoon. While forcing and QPF will focus heavily over the Central Mountains and along the Continental Divide, latest model trends indicate an isolated shower or storm is possible nearly anywhere across eastern Idaho. Given the scattered nature of lightning strikes on dry fuels, a Red Flag Warning remains active for Fire Zone 422 today. Convective activity will taper off late this evening, with most showers diminishing by midnight.

Broad upper-level troughing anchored over the Pacific Northwest will dictate regional weather through the remainder of the workweek. Embedded impulses rotating around the parent low will track through the flow, with one prominent lobe crossing the region on Wednesday. Because the core energy will remain shunted to our north and west, shower and thunderstorm chances Wednesday and Thursday will be largely restricted to the Central Mountains. The more widespread operational impact mid-week will be strong afternoon winds driven by a tight regional pressure gradient. Several wind-prone valley corridors will flirt with Wind Advisory thresholds each afternoon. Fortunately, unseasonably cool air will hold minimum relative humidity values above critical thresholds. Afternoon highs Wednesday through Friday will top out in the mid-to-upper 70s in lower elevations and mid-60s to lower 70s across mountain zones.

Lower elevations may see a brief temperature recovery into the lower 80s on Saturday before the next weather system approaches. Guidance indicates a potentially unsettled pattern taking hold for the latter half of the Labor Day holiday weekend, with rain chances trending upward Sunday into Monday. While global models continue to struggle with the exact synoptic placement of the upper low and deepest moisture plumes, confidence remains high that below-normal temperatures will persist through much of the first week of September.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 911 PM MDT Mon Aug 31 2026

A few thunderstorms are on the leading band of moisture working northward. Most of the thunderstorms should diminish by 06z. Showers will pass through east Idaho overnight into Tuesday morning. Gusty winds are likely during the overnight hours but should relax Tuesday morning. Another round of convection is expected Tuesday afternoon.

FIRE WEATHER

Issued at 155 AM MDT Tue Sep 1 2026

The primary operational fire hazard today is scattered thunderstorm activity across south-central Idaho, where a Red Flag Warning remains active for Fire Zone 422. While wetting rain will accompany stronger cores, lightning ignitions outside rain shafts remain a concern. Wednesday through Friday will bring strong, breezy west-to-southwest wind gusts across all zones as pressure gradients tighten. However, unseasonably cool temperatures holding in the 60s and 70s will keep daytime relative humidity recoveries elevated above critical thresholds.

PIH WATCHES/WARNINGS/ADVISORIES

Red Flag Warning from 1 PM this afternoon to 9 PM MDT this evening for IDZ422.