textproduct: Boise

KEY MESSAGES

- Afternoon and evening showers/thunderstorms today and Friday, mainly across southwest/central Idaho and far east Oregon.

- Some thunderstorms may become strong to severe today, capable of gusty outflow winds up to 60 mph, heavy rain, and hail.

- A marginal risk for excessive rainfall is forecast for Friday afternoon across central and south-central Idaho.

- Hot temperatures continue into early next week, with valley highs around 100 degrees; Hottest today.

SHORT TERM /Through Saturday Night/

The return of monsoon moisture today will ignite a new round of showers and thunderstorms this afternoon and evening, this time mainly across southwest and central Idaho and far east Oregon. Storms will be capable of strong to severe outflow winds to 40-60 mph, brief heavy rainfall, and small hail. Higher terrain will be the most susceptible to impacts from rainfall, especially if the rain shafts pass over steep terrain and/or newer burn scars. In addition to storms, the strong upper high to the east will build further into the area today, leading to several degrees of warming across the area. Temperatures will peak in the upper 90s to 103 for the Treasure Valley and Weiser Basin, and a Heat Advisory is in effect due to moderate/major Heat Risk. Shower and thunderstorm chances will re-develop Friday afternoon, heavily focused on central and south-central Idaho terrain. A marginal risk of excessive rainfall is forecast over this area, once again yielding a threat to steep terrain and newer burn scars.

Heat will continue over the weekend, with slightly drier conditions expected as the bulk of the moisture shifts east. A slight chance of storm activity remains across portions of central/south-central Idaho Saturday afternoon, with the majority of the activity remaining east of the forecast area.

LONG TERM /Sunday through Thursday/

Continued hot and mostly dry conditions are anticipated Sunday, with shower/thunderstorm chances limited to south- central Idaho. The influence of the central U.S. high pressure will stay prevalent, keeping temperatures 5-10 degrees above normal Sunday and into next week. Shower and thunderstorm chances will increase once again Monday through Thursday with continual pulses of monsoon moisture. Precipitable water values will exceed 1.00" by early next week, allowing storms to become heavy rain producers. Outflow winds will also remain a concern as rain-induced cold pools will drive surface density gradients due to surrounding heat. A pattern change is unlikely through the week, with forecast probabilities maintaining hotter and wetter than normal conditions.

AVIATION /06Z Thursday through Friday/

Issued 1227 AM MDT THU JUL 16 2026

Mainly VFR. Isolated to scattered showers and thunderstorms returning over southwest/central ID and far east OR this afternoon. Stronger storms capable of outflow winds to 35-50 kt, heavy rain with vis reductions, and small hail. Mtn obscuration in storms. High density altitude due to heat in the afternoon. Surface winds outside of storms: variable 5-15 kt through morning. Then, SW-SE 5-15 kt in the afternoon, with gusts to 20-25 kt in SE Oregon. Winds aloft at 10kft MSL: southerly 10 to 20 kt.

KBOI...Mainly VFR. Isolated showers/thunderstorms in the area this afternoon, with best chance at terminal between Thu/21Z and Fri/02Z. Stronger storms capable of outflow winds to 30-45 kt, brief heavy rain with vis reductions, and small hail. High density altitude due to heat in afternoon. Surface winds outside of storms: SE-S 5-12 kt, with gusts up to 20 kt in the afternoon.

Weekend Outlook...Mainly VFR. Showers/thunderstorms developing Fri afternoon over central/south-central Idaho, capable of strong outflow winds, heavy rain with vis reductions, and small hail. Mtns obscured in precip. Slight chance of showers/thunderstorms over same areas Saturday afternoon, then limited to south- central ID Sunday afternoon. High density altitude due to heat. Surface winds outside of storms: SW-NW 5-15 kt, afternoon gusts 15-25 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Red Flag Warning from noon today to 9 PM MDT this evening for IDZ420-423-424-426. Heat Advisory from noon today to 9 PM MDT this evening for IDZ012-014-033. OR...Heat Advisory from noon MDT /11 AM PDT/ today to 9 PM MDT /8 PM PDT/ this evening for ORZ064.