textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Showers and thunderstorms increase area-wide tonight and Tuesday, then chances remaining over higher terrain Wednesday through next weekend.

- Locally heavy rainfall could affect burn scars across southeast Oregon.

- Hot temperatures continue this week and coming weekend.

SHORT TERM /Through Wednesday Night/

Issued 220 PM MDT MON JUL 13 2026 The large scale pattern remains locked in place with a broad high over the interior West and upper trough off the Pac NW coast. Southerly flow aloft, continue to transport deep monsoon moisture into the region. Cloud cover is limiting heating this afternoon, which will limit thunderstorm development. Showers and storms that develop could bring outflow gusts to 40 mph. A weak upper disturbance will bring another chance of showers and possible thunderstorms starting Tuesday morning, with instability caring the threat into the evening. As precipitable water values climb well over an inch, heavy rain will be possible from storms that develop. Expect this threat to be focused across SE Oregon and along the ID/NV border where the best heating and instability sets up. Gusty outflow winds to 40 mph will also be in play. Otherwise the cloud cover will again keep temperatures in check. Wednesday clearing skies and hotter conditions as drier air moves in aloft. A minimal shower/storm threat will reside over the mtns of Baker County and west- central Idaho. High temperatures will warm back above normal, reaching the mid-upper 90s at lower elevations.

LONG TERM /Thursday through Monday/

Issued 220 PM MDT MON JUL 13 2026 Hot south-southwesterly flow persists through early next week, with consistent afternoon shower and thunderstorm chances over high terrain in central and south-central Idaho. With the main moisture band east of the area as a Pacific low moves over the Puget sound, the primary precipitation mode will be spotty, sporadic, showers and thunderstorms. Lightning and gusty outflow winds will be possible. For the rest of the area, temperatures heat back up. The Snake Plain and adjacent lowlands will see regular afternoon max temps around the 100 degree mark, and the forecast for these days has continued to trend warmer. The heat could become hazardous if the trend continues, especially in the weekend. By Monday, the Puget Sound low has de-amplified, and the core synoptic driver becomes the four-corners high of the North American Monsoon. This would shift storm activity from the mountains down to the Nevada border across Oregon and Idaho.&&

AVIATION /06Z Tuesday through Wednesday/

Issued 1141 PM MDT MON JUL 13 2026

VFR. Isolated showers continue overnight, but increase in coverage after 09z/Tue to numerous. By early afternoon, coverage is back to isolated/scattered, with thunderstorms possible (15-30% chance) in Eastern Oregon, the West-Central ID mountains, and Southern Idaho. Surface winds: variable under 10 kt, except becoming W-NW 10-20 kt with gusts to 20-30 kt from KBOI to KJER by late morning. Both showers and thunderstorms will bring outflow wind gusts to 25-40 kt. Winds aloft at 10kft MSL: SW-S 5-20 kt.

KBOI...VFR. Virga and rain showers remain in the area through Tuesday afternoon. Surface winds: variable under 10 kt overnight, then NW 10-15 kt with gusts to 20-25 kt by early/mid morning.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.