textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Dry today, with near normal temperatures.

- Precipitation chances increasing across higher terrain Friday afternoon. Becoming widespread Saturday afternoon into Sunday.

- A drying and warming trend will set in Monday, through at least midweek.

SHORT TERM /Through Saturday Night/

Issued 120 AM MDT THU OCT 29 2026 This afternoon will feature warmer temps and increasing high- clouds in southwesterly flow aloft. Temperatures this afternoon will be around 60 degrees in lower elevations of SW-Idaho and in the 50s in the Oregon high desert and higher Idaho basins. A weak shortwave will move northeast over the area this evening. While moisture availability remains somewhat limited, sufficient moisture will advect northward to south-central Idaho to support isolated to scattered showers late Thursday night through Friday. As this shortwave departs, a brief dry period will occur Friday night, barring a continued 20-50% chance of precipitation in the far eastern portions of our CWA.

Come Halloween, a closed low with an elongated southern trough will begin encroaching upon our area. Ahead of this trough, a good pull of Pacific moisture will overspread our area, allowing for precipitable water values to reach around the 90th percentile in southwest Idaho. This moisture will allow for increasing precipitation chances across the area through Saturday, peaking Saturday evening and night (60-90% chance, highest in SW-Idaho) as the greatest forcing for ascent overspreads our area. The day shift made a good argument for a Mary Poppins costume, as an umbrella would make a good addition to any costume for evening festivities. Over the course of Saturday evening through Sunday, liquid precipitation totals are generally 0.5-1 inch in northern mountains, 0.20-0.50 inches in lower elevations and southern mountains, and then 0.01 to 0.20 in eastern Oregon.

The southwesterly flow aloft will keep snow-levels elevated to 6.5- 8.5 kft MSL with the bulk of the precipitation, limiting snow accumulations across the area. While they will eventually lower to 3.5-5kft MSL behind the cold front, which passes through the area Sunday, this will coincide with as precipitation tapers off behind the departing system. This will keep much of the snow above 6.5kft MSL, with totals trending down with the snow levels trending higher. Over the course of the same period above, elevations above 6.5kft MSL would see a dusting to a few inches of snow (although the highest peaks in the Sawtooths could see several).

LONG TERM /Sunday through Thursday/

Issued 120 AM MDT THU OCT 29 2026 Showers will continue through Sunday, tapering off throughout the day as the system departs, with QPF details in the short-term. Snow levels Sunday will have lowered to 4.5-6.5kft MSL (increasing from west to east), allowing for a chance of snow/wintry mix down to around 4.5 kft MSL Sunday in E-Oregon, with little to no accumulation expected that low. Sunday afternoon and evening will feature gusty winds following the cold frontal passage, with west to northwest gusts of 20-40 mph (strongest in the typical windy portions of the Snake River Plain.

Beginning Monday, the area will be dry with a warming trend through Thursday, although seasonable temperatures are anticipated throughout. While there will be multiple opportunities for weak shortwaves to pass over the area, moisture will be limited and the shortwaves will just result in periods of increased high clouds.

AVIATION /12Z Thursday through Friday/

Issued 457 AM MDT THU OCT 29 2026

Generally VFR with increasing clouds throughout the period. A low (<10%) chance of localized IFR/LIFR conditions in high elevation valley fog/low stratus early this morning. Surface winds: Variable less than 10 kt this morning, then NE-SE 5-15 kt by early PM. Winds aloft at 10kft MSL: SW 20-30 kt.

KBOI...VFR. Increasing high cloud cover through the day. Surface winds: E-SE 5-10 kt, with gusts up to 20 kt by late morning.

Weekend Outlook...Isolated to scattered showers Saturday morning, becoming widespread Sat/PM. Precipitation continuing through Sunday, tapering off from W-E through the afternoon. VFR-MVFR in rain showers, IFR-LIFR in mountain snow. Mountain obscuration this weekend. Snow levels: 6.5-8.5 kft MSL Saturday, lowering to 4.5-6.5 kft MSL Sunday. Surface winds: SW-SE 5-15 kt Saturday, then W-NW 10-20 kt with gusts to 20-30 kt behind a cold front Sunday.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.