textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Fire weather concerns increase due to threat of thunderstorms this afternoon into Friday.

- Thunderstorms with heavy rain may also increase the risk for flash flooding especially for recent burn scars on Friday and Saturday.

- Temperatures cooling to around 5 degrees below normal come Friday.

SHORT TERM /Through Saturday Night/

Issued 253 AM MDT THU AUG 13 2026 A more active pattern will kick off today, continuing into Saturday. Current water vapor imagery shows a deepening trough over the west coast, with an embedded shortwave out ahead of it. This shortwave will continue to eject around the trough through the day, leading to scattered showers and thunderstorms this afternoon into Friday morning. Storms will initially take on more of a dry posture, leading to elevated fire weather concerns when combined with the lightning potential. Thunderstorms this afternoon will also be capable of wind gusts to 40-45 mph.

With a more saturated atmosphere come Friday, the threat associated with thunderstorms will transition from dry lightning and gusty winds to heavy rain. Heavy rain will increase the risk for flash floods and debris flows, especially across steep/rocky areas and recently burned areas (including the Wapiti burn scar). The better dynamical forcing at this point will be over southwest Idaho, with the highest chances of precipitation (60-95%) over the Central ID Mountains, with scattered thunderstorms continuing. With moisture remaining elevated (80-90th percentile PWATs) in the southwest flow aloft come Saturday, hazards similar to that of Friday will present themselves yet again over the same area. Temperatures come Friday will be around 5 degrees below normal.

LONG TERM /Sunday through Thursday/

Issued 253 AM MDT THU AUG 13 2026 Ridging will build back in over the Great Basin come Sunday, leading to near normal temperatures and generally dry conditions through Monday. Barring a slight chance (10-20%) of afternoon showers and thunderstorms over the Central ID Mountains. Come Tuesday, a quick short-wave looks to approach from the northwest, reintroducing breezy conditions and precipitation chances. Moisture looks to be more limited this time around, with the best chances of precipitation (15-35%) over higher terrain. Beyond Wednesday, guidance hints at a ridge building back in over the great basin, support another warming and drying trend.

AVIATION /12Z Thursday through Friday/

Issued 541 AM MDT THU AUG 13 2026

Generally VFR. Showers increasing in the morning in south- central Idaho, with isolated to scattered thunderstorms developing across the area late afternoon and evening. Outflow gusts up to around 40 kt near thunderstorms. Surface winds: SW- NW 5-15 kt. Variable and gusty winds to 25 kt near showers. Winds aloft at 10kft MSL: W-SW 5- 15 kt.

KBOI...VFR with reduction in visibility due to wildfire smoke at times. Foothills obscured by smoke. Smoke improving this afternoon. A 20% chance of showers and thunderstorms by late Thursday evening, continuing overnight. Surface winds: variable less than 10 kt overnight, becoming SE 10-20 kt Thursday afternoon from distant showers.

Weekend Outlook...Isolated to scattered showers and thunderstorms continuing Saturday. Storms Saturday capable of heavy rain, gusty outflows, and MVFR conditions. Showers taper off come Sunday with clearing skies. Surface winds: SW-SE 5-15 kt Saturday, then SW-NW 5-10 kt Sunday. Light and variable overnight.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Red Flag Warning from 3 PM this afternoon to 6 AM MDT Friday for IDZ400>403-420-421-423-424-426. OR...Red Flag Warning from 2 PM this afternoon to 5 AM PDT Friday for ORZ670>672. Air Quality Alert until 1 PM MDT /noon PDT/ Friday for ORZ061- 063-064. Red Flag Warning from 3 PM MDT /2 PM PDT/ this afternoon to 9 AM MDT /8 AM PDT/ Friday for ORZ673>675.