textproduct: Boise

KEY MESSAGES

- Isolated afternoon thunderstorms today and Thursday, mainly forming over the central Idaho mountains, and southern Twin Falls County.

- Thunderstorms capable of producing gusty erratic outflow winds up to 40 mph.

- Scattered showers and isolated thunderstorms over southwest Idaho on Friday and Saturday capable of producing wetting rains.

SHORT TERM /Through Friday Night/

Issued 220 PM MDT WED AUG 26 2026 An intense anticyclone continues to dominate the weather pattern over the southwestern US, with the northern extent of an associated upper ridge continuing to support well above-normal temperatures across the region. This will also maintain a ribbon of moisture across southern and central Idaho, and continue to favor isolated to scattered thunderstorm development today and Thursday afternoon near the Nevada border into the central Idaho Mountains. Increasing flow aloft ahead of a strengthening upper trough over the Pac NW will bring increased breeziness to eastern Oregon, and eventually into western and central Idaho, with elevated to critical fire weather conditions expected. Isolated morning shower activity is also possible Thursday morning, but will pose limited impacts.

By Friday, a more significant increase in moisture will occur, with precipitable water values exceeding the 90th percentile. This will promote scattered to widespread shower development on Friday. Ensemble guidance continues to support a focused band of shower development, spanning from near the Nevada/Oregon/Idaho border northeastward on Friday. Amounts are likely to remain under a quarter-inch in most locations. Temperatures will also cool significantly - on the order of 10-15 degrees - as more seasonable late-summer temperatures finally take hold.

AVIATION /18Z Wednesday through Thursday/

Issued 1117 AM MDT WED AUG 26 2026 VFR. Isolated showers and virga during in the lower Snake Plain (KBOI-KONO) and w-central ID mtns through early afternoon (20Z). Isolated showers and thunderstorms near KTWF/KJER and over central ID mtns in the afternoon/eve (after 20Z). Outflows 30-45 kt. High density altitude in the afternoon due to heat. Areas of smoke near wildfires degrading visibility. Surface winds: Mainly SW-SE 5-15 kt with gusts 20-30 kt in the afternoon across SE Oregon. Winds aloft at 10kft MSL: SW 15-25 kt.

KBOI...VFR. Isolated showers and virga in vicinity through early afternoon. High density altitude in the afternoon. Light surface winds becoming NW this afternoon.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Red Flag Warning from noon to 9 PM MDT Thursday for IDZ423. OR...Red Flag Warning from 11 AM to 8 PM PDT Thursday for ORZ670>672.