textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Isolated to scattered showers and thunderstorms this afternoon and evening, mainly across the higher terrain of far southern Oregon and Idaho. Storms may produce gusty outflow winds, possibly moving through the Treasure and Magic valleys.

- Isolated to scattered thunderstorms Wednesday across the higher terrain of central and southern Idaho. - Hot temperatures through the week and into the weekend. - Breezy winds each afternoon, especially Wednesday and Thursday.

SHORT TERM /Through Thursday Night/

Issued 350 AM MDT TUE JUL 7 2026 Southwest flow aloft will bring additional mid-level moisture into southern areas today. Daytime heating will increase instability, with showers and thunderstorms developing over the higher terrain near the Nevada border this afternoon. With dry lower levels, thunderstorms may produce outflow wind gusts 40-60 mph. The strongest storms may also produce brief heavy rain and small hail. Storms will lift northeast off the higher terrain south of the Snake River and weaken as they enter the Snake River Valley. However, gusty outflow winds are possible as storms dissipate in both the Treasure and Magic valleys late this afternoon and evening, with around a 20% chance of storms holding together into the valleys. Otherwise today, expect a 3-6 degree rise in temperatures from yesterday, except a bigger warmup in portions of eastern Oregon and the west-central Idaho mountains where clouds and showers held temperatures down. Lower elevations should reach the mid to upper 90s, with 80s to lower 90s in mountain valleys. Outside of storms, winds will be relatively light.

An upper level trough moving into British Columbia on Wednesday will begin to push moisture to the east. This will limit the chance for afternoon and evening showers and thunderstorms to the higher terrain of southern and central Idaho, although thunderstorms and outflow gusts may also drift north into the Magic Valley. A weak, dry cold front will move through Wednesday night and Thursday. Temperatures will remain steady on Wednesday, then cool a few degrees Thursday behind the front. The front will bring gusty winds to the area Wednesday night, continuing into Thursday across southern Idaho with gusts 20-35 mph. Low humidity with gusty winds will increase fire weather concerns.

LONG TERM /Friday through Tuesday/

Issued 350 AM MDT TUE JUL 7 2026 A strong ridge of high pressure will build north across the Great Basin on Friday, then expand across the Rocky Mountains and Northern Plains over the weekend into early next week. This will bring hotter temperatures with lower elevations reaching the upper 90s to around 100 degrees each day. The hottest temperatures are expected to remain to our east as an upper trough sits off the Pacific Northwest coast. However, even a slight shift west of the ridge would bring even hotter temperatures with highs above 100 degrees at lower elevations. Southwest flow aloft will bring breezy afternoon and evening winds to higher elevations each day. Monsoonal moisture will begin to work its way north around the periphery of the ridge Monday and Tuesday, reintroducing a threat of showers and thunderstorms.

AVIATION /12Z Tuesday through Wednesday/

Issued 541 AM MDT TUE JUL 7 2026 Mainly VFR. Isolated to scattered showers and thunderstorms this afternoon and evening developing over the higher terrain near the Nevada border and drifting northeast. Gusty and erratic winds 30-50 kt near storms, producing localized blowing dust reducing visibility. High density altitude this afternoon due to heat. Terrain locally obscured near wildfire smoke. Surface winds outside of storms: variable less than 10 kt. Winds aloft at 10kft MSL: SW-W 5-15 kt.

KBOI...Mainly VFR. Foothills obscured by wildfire smoke. A 30% chance of gusty outflow winds 30-40 kt late this afternoon and evening from dissipating showers/storms, with brief blowing dust possible. High density altitude this afternoon due to heat. Smoke from nearby fires may reduce visibility at the terminal tonight. Surface winds: SE around 5 kt this morning, becoming NW 5-10 kt late morning into the afternoon, then SE 5-10 kt tonight.

BOI WATCHES/WARNINGS/ADVISORIES

ID...OR...None.