textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Warm and dry conditions through the weekend, with high temperatures 5 to 10 degrees above normal.

- Active pattern returning cooler conditions and precipitation chances Wednesday through Friday.

SHORT TERM /Through Monday Night/

Issued 353 AM MDT SAT OCT 17 2026 The upper-level ridge that has been in place over the past few days is breaking down this morning as an upper-level shortwave trough moves into the Pacific NW / BC, Canada. Today is forecast to be the warmest day in the short term, with temperatures around 10 degrees above normal, or solidly in the 70s across lower elevations. A weak cold front will give the area a passing blow late tonight and overnight, bringing a cooler Sunday. Wind speeds are expected to remain weak, with an increase of high clouds being the only tangible evidence of the front. On Monday, southwesterly flow aloft will strengthen ahead of an upper- level low pressure system diving south along the U.S. west coast. Wind gusts in higher elevations will strengthen to 20-30 mph, with the western Snake Plain expected to warm a couple degrees from Sunday as southeasterly flow at the surface increases. An overlap of stronger wind speeds and low minimum relative humidities will exist in southern Harney and Malheur counties Monday afternoon.

LONG TERM /Tuesday through Saturday/

Issued 353 AM MDT SAT OCT 17 2026 Through much of the work week, the upper-level low pressure system will move from just off the California coast to lingering in the Great Basin. Temperatures will cool off Tuesday as another weak front moves into the region along with increasing cloud cover during the day. Models are split on fully moving the front through the area or having it stall out in southwest ID. Regardless, temperatures will cool down to near- normal in southeast OR and around 5 degrees above normal in southwest ID. Flow aloft through much of the week will be out of the south, gradually increasing PWATs through at least Thursday. This, along with favorable topographic effects, will introduce widespread precipitation chances Wednesday afternoon into Thursday.

Ensemble guidance largely favors another cold front late Thursday into Friday as another upper-level trough moves into the Pacific NW and BC, Canada. This feature will have the low rejoin the broader flow and move east through the day Friday. This will lead to even colder temperatures going into next weekend. The synoptic pattern with the next trough is too uncertain to discuss Saturday any further at this time.

AVIATION /12Z Saturday through Sunday/

Issued 525 AM MDT SAT OCT 17 2026

VFR with high clouds. Smoke from prescribed burns will locally reduce visibility. Patchy fog in SE Oregon Sunday morning. Surface winds: E-S 5-15 kt through Sat/AM, then SE-SW Sat/PM. Winds aloft at 10kft MSL: SW 10-25 kt.

KBOI...VFR with surface winds E-S 5-15 kt through Saturday afternoon.

Sunday Outlook...VFR conditions, with periods of high cloud cover. Patchy morning fog in SE Oregon. Surface winds become variable 5-12 kt Sunday. Winds aloft will remain out of the SW.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.