textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Isolated thunderstorms will focus along the Nevada border and western Magic Valley today and central Idaho Mountains Thursday, capable of producing strong, gusty outflow winds.

- A significant pattern change arrives Friday morning as a cold core low pushes a cold front through, bringing widespread showers and cooler temperatures.

- Temperatures around 15 to 20 degrees below normal Saturday and Sunday.

- Significant precipitation and light snow above 7000 feet possible Saturday through Sunday.

SHORT TERM /Through Friday Night/

Issued 210 PM MDT WED JUN 24 2026 A weak shortwave moving across the Pacific Northwest will initiate isolated thunderstorms this afternoon through this evening. The main focus for these storms will be along the Nevada border and western Magic Valley. Given the high-based nature of this activity, strong and gusty outflow winds will be the primary threat with wind gusts up to 50 mph.

On Thursday, the threat of thunderstorm activity shifts into the central Idaho mountains as moisture increases ahead of the next major weather system. Activity could begin early Thursday as the shortwave continues to push east into Montana and Wyoming. Temperatures look to be about 5 degrees cooler than today.

A significant pattern change begins in earnest on Friday as a potent cold core low moves into the Northwest, dragging a strong cold front through southeast Oregon and southwest Idaho Friday morning. This system will usher in widespread showers and thunderstorms across the area through Friday night. Low levels will take some time to saturate, but widespread wetting rains are anticipated particularly along the frontal boundary. There is currently a 60% chance for the valleys to pick up over a tenth of an inch of rain, while the central mountains of Idaho could see higher amounts up to half an inch. The best chance for thunderstorms appears to be behind the front Friday afternoon across Southeast Oregon though the overall coverage remains uncertain. The stronger storms could produce brief heavy rain as PW values peak to the 90th percentile. Temperatures on Friday will drop sharply, landing around 10 degrees below normal.

LONG TERM /Saturday through Wednesday/

Issued 210 PM MDT WED JUN 24 2026 Cool and showery conditions will continue on Saturday and Sunday with a slight chance of thunderstorms as the upper low system slowly moves overhead. Saturday and Sunday will see the highest chances of wetting rains, mainly over higher terrain, with area- wide temperatures 15-20 degrees below normal. Significant weekend precipitation remains possible with this system, depending on its final track. As it stands right now, precipitation amounts of up to 1 to 1.25 inch possible over the central ID mountains, with lesser amounts in eastern OR, where less than 0.25 inch expected. With snow levels expected to drop into the 6500-8000 ft MSL range by Sunday, light snowfall remains likely over the west-central ID mountains, with accumulations up to 2 inches on the highest peaks above 7500 ft through Sunday morning. Conditions dry out with breezy conditions on Monday and Tuesday as the system moves northeast into Manitoba. This system will keep temperatures below normal under cool northwest flow aloft. Long-range guidance indicates a mostly dry Pacific shortwave trough digging over our area on Wednesday, likely continuing a cooler northwest flow with dry conditions.

AVIATION /00Z Thursday through Friday/

Issued 548 PM MDT WED JUN 24 2026

VFR. High density altitude this afternoon due to heat. Isolated showers and thunderstorms this afternoon, mainly near the ID/NV border. Thunderstorms will be capable of outflows of 35 kt. Isolated showers and thunder continuing through Thu/AM over the W-Central Mtns. Surface winds: W-NW 10-15 with gusts to 20-25 kt this afternoon. Then variable 5-10 kt after Thu/06z. Winds aloft at 10kft MSL: SW-NW 5-10 kt.

KBOI...VFR. High density altitude this afternoon due to heat. Isolated virga showers through Thu/AM. Surface winds: NW 8-12 kt with gusts to around 20 kt this afternoon. Becoming W-SW under 8 kt overnight.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.