textproduct: Boise

KEY MESSAGES

- Light rain and mountain snow Monday afternoon through Tuesday morning, mainly in northern areas.

- Windy Monday afternoon in open southern areas.

- Continuing chance of light rain and snow showers in northern areas through Wednesday.

- Next best chance of widespread precipitation this weekend.

SHORT TERM /Through Wednesday Night/

The upper-level low which will act as our next weather maker can be seen on water vapor imagery spinning off the Washington coast. With a cold front making its way through Oregon. This front should make it into our western zones before noon before moving across the area from west to east. Breezy south to southwest winds will set in this morning ahead of the front, with gusts to 20-30 mph. Behind the front, winds will become southwest to northwest. The windiest areas will generally be south and west of the Snake River Plain, and in the typical windy portions of the Snake River Plain. Winds will decrease behind the front this evening and overnight. Showers will increase along and behind the front as it moves from west to east, with coverage most widespread in the Central Idaho Mountains. While temperatures will be cool, cooling aloft as the upper low moves inland will support for weak instability to build in over the Central Idaho Mountains, supporting a slight chance (15-20%) of thunderstorms this afternoon. Following the passage of the front and upper-low, a trailing shortwave will prolong showers over our northern zones through Wednesday.

Over the course of today through Tuesday, higher terrain in our northern zones are forecast to receive generally 0.20-0.40 inches of liquid, with 0.10-0.20 in northern valleys and higher terrain south; elsewhere will be under 0.10 inches or dry. Lowering snow-levels behind the front will make for a transition to snow showers for elevations above 6kft MSL, with accumulations ranging from a dusting to around 2 inches (up to 4-5 inches on the highest peaks above 8kft MSL). Tuesday will be the coolest day of the short-term period, with lower elevation temps in the 50s and mountain valleys in the 40s (roughly 5 degrees cooler than today). Clearing Skies will allow for slightly cooler overnight lows Wednesday morning and slightly warmer daytime highs Wednesday afternoon, but seasonable temperatures for the time of year.

LONG TERM /Thursday through Monday/

Increasing southwesterly flow on Thursday will allow for another few degrees of warmup, with dry conditions as brief shortwave ridging builds in ahead of the next system. Guidance seems to be backing off of the southern split solution mentioned in last nights discussion (if you read that one :) ), with ensembles now favoring a more northern track. With this, the best chances of precipitation will come over the weekend in southwest Idaho, after increasing late Friday in the Central Idaho Mountains. Snow levels for this system will range from 4-6kft MSL, increasing from west to east. Temperatures will continue to be seasonable for the time of year through the period.

AVIATION /06Z Monday through Tuesday/

Issued 1111 PM MDT SUN OCT 25 2026

VFR tonight with high/mid clouds. A 10% chance of fog/low stratus in sheltered mtn valleys, limited by high clouds. Showers arriving from W to E with cold front after Mon/14Z in E Oregon, after Mon/17Z in SW Idaho. Low VFR to MVFR in rain, IFR in mountain snow. Snow levels: 5.5-6.5kft MSL. Mtns becoming obscured. Surface winds: E-S 5- 15 kt, shifting to SW-NW 10-20 kt with 20-30 kt gusts Mon/PM. LLWS overnight near KONO/KBNO. Winds aloft at 10kft MSL: SW-W 15-30 kt.

KBOI...VFR with high/mid clouds. Showers arriving after Mon/19Z through Tue/00Z with cold front, with brief MVFR possible. A 10% chance of lightning during shower onset. Surface winds: SE 5-12 kt, gusts 15-20 kt late Mon AM. Shifting to W-NW 8-15 kt around Mon/19Z with cold front. Period of gusts to 20-30 kt with arrival of showers/cold front Monday afternoon.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.