textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Cooler than normal temperatures, 10 to 15 degrees below normal through Monday.

- Unsettled conditions through early Tuesday, mainly on the Idaho side, with widespread rainfall over Magic Valley and Boise Mountains.

- Snow levels near 6000-7000 feet in the west central ID mountains through Monday with light accumulations.

- Warm and dry conditions Wednesday through next weekend.

SHORT TERM /Through Tuesday Night/

Issued 320 AM MDT SUN OCT 11 2026 The closed upper low will slowly dig southward right into our area today through Monday, with the center hanging over east-central OR. This pattern will continue temperatures 10 to 15 degrees below normal today and Monday. The system will steer abundant tropical moisture over east/central ID through late Monday, continuing the onset of widespread precipitation along the eastern portions of our CWA. The Magic Valley and Boise Mountains will still see the highest potential for heavy rainfall today through Monday, with total amounts of 0.5 to 1.0 possible generally from Twin Falls and areas further east, with up to 0.25 possible over the rest of SW Idaho. Southeast OR will be very limited in precipitation, but will see some breezy northwest winds this afternoon from the low passage.

With snow levels expected to drop in a west-to-east gradient at 4000- 6000 ft MSL in eastern OR to 6000-8000 ft MSL in southwest ID, mountain snow/wintry mix showers are expected in the central ID mountains through Monday, but with light accumulations limited to high peaks. By late Monday, the upper low will dig further down into the upper Great Basin as it steers out east, but with a weakening moisture load. Precipitation chances over the Magic Valley and Boise Mountains will gradually diminish late Monday and early Tuesday, but the extent of the low's remaining moisture continuing rainfall over south-central ID remains slightly uncertain. Tuesday will see the low move completely out of our area as a sharp Pacific ridge builds in, returning drier conditions and near-normal temperatures.

LONG TERM /Wednesday through Sunday/

Issued 320 AM MDT SUN OCT 11 2026 A warming and drying trend will set in Wednesday through the end of the week as a strong Pacific ridge builds in behind the upper low pushing out east. This ridging will bring mostly clear skies throughout the week, with some overnight/morning fog possible in mountain valleys each day. Temperatures will take on a slow warming trend Wednesday through Sunday. Temperatures 5 to 10 degrees above normal remain possible Friday through Sunday as the area comes under peak ridging from the Pacific high.

AVIATION /12Z Sunday through Monday/

Issued 608 AM MDT SUN OCT 11 2026 Generally VFR. Isolated showers through the morning, mainly over SW Idaho. Then, broad area of precip expanding from SE to NW in the afternoon, mainly east of KBOI-KMYL line. Low VFR to MVFR conditions in heavier showers. Mountains becoming obscured, with IFR-LIFR likely in high mtn snow in central ID. Snow levels in SW Idaho ranging 5-8kft MSL Sun/AM, then 6-9kft Sun/PM. Surface winds: W-NW 5-15 kt with gusts 20-30 kt this afternoon, mainly over southeast OR. Winds aloft at 10 kft MSL: SW-W 10-25 kt, then variable 5-15 kt by 15Z.

KBOI...VFR. A 30% chance of light rain after Sun/21Z. Surface winds: NW 6-14 kt through the period, with gusts up to 20 kt returning after 18Z this afternoon.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.