textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Slightly warmer today but still cooler than normal.

- Widespread showers and isolated thunderstorms late Sunday through Monday.

- Cooler Monday, then warming through Friday.

SHORT TERM /Through Monday Night/

Issued 228 PM MDT SAT SEP 5 2026 An upper level trough will remain along the Oregon coast over the next day with a weak front stalled out over southwest Idaho. Showers and thunderstorms will generally be confined to western Baker County in OR and northeast of Valley County in ID this afternoon. A weak wave will move across NV late this afternoon and trigger some isolated showers and thunderstorms tonight over southwest Idaho through early Sunday morning. The trough will begin to move inland on Sunday across southern OR Sunday afternoon. Showers and thunderstorms increase late Sunday afternoon across eastern OR, with isolated thunderstorms over the west central ID mountains. The upper level low will track across southern ID early Monday morning, with showers and isolated thunderstorms areawide. The precipitation will quickly taper off across eastern OR and the Snake Basin in southwest ID early Monday morning, with lingering showers over the central ID mountains through Monday afternoon. A convergence zone will set up in wake of the Wallowas late Monday afternoon keeping showers and thunderstorms north of McCall late into the evening.

LONG TERM /Tuesday through Saturday/

Issued 228 PM MDT SAT SEP 5 2026 begins to move east on Tuesday with drier and warmer conditions through Friday under westerly flow aloft. A trough from the Gulf of Alaska will move south along the BC coast into the Pacific NW by Saturday with cooler conditions possible next weekend. Uncertainty remains elevated in the extended period, as tropical activity in the Pacific enhances the jet stream. Models do not handle the energy transfer well in these situations so expect lots of changes in the far extended period over the next week with all these tropical systems across the Pacific.

AVIATION /00Z Sunday through Monday/

Issued 523 PM MDT SAT SEP 5 2026

Mainly VFR. Patchy mountain-valley fog and low stratus in the AM. Scattered showers moving from SW to NE over southwest Idaho late tonight through Sun morning. Then, numerous showers with isolated thunderstorms moving into E Oregon Sunday afternoon, and into SW Idaho by evening. Heavy rain and storm outflows to 30-40 kt possible. Surface winds: variable up to 10 kt, then SW- NW 5-15 kt with gusts 20-25 kt Sun afternoon. Winds aloft at 10kft MSL: S-SW 10-30 kt.

KBOI...VFR with temporary light rain showers between Sun/06Z-09Z. Then, a 60% chance of showers and thunderstorms Sunday late evening. Surface winds: NW 5-10 kt, then variable or light SE overnight and morning.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.