textproduct: Boise

KEY MESSAGES

-Dry and warm conditions, with areas of gusty west winds, will continue through Sunday.

-Cold front will bring cooling trend Monday through Tuesday, with gusty northwest winds and chance of rain showers over valleys and snow showers over mountains.

-Gulf of Alaska low will bring widespread precipitation Wednesday and Thursday, with rain showers over valleys and moderate to heavy snowfall over mountains.

SHORT TERM /Through Monday Night/

Upper level ridging will remain the dominant feature through Sunday, maintaining dry conditions and unseasonably warm temperatures across southeast Oregon and southwest Idaho. Highs on Sunday will once again reach the 70s for most valley locations, which is roughly 15 degrees above seasonal normals. However, a significant pattern shift is on the horizon as an upper level trough currently over the Gulf of Alaska moves inland.

The associated cold front is expected to reach southeast Oregon early Monday morning, pushing through the Treasure Valley by midday and exiting into the Magic Valley by Monday evening. This front will bring a sharp drop in temperatures, with Monday highs occurring early in the day for western zones. In addition to the cooling, expect breezy to gusty northwest winds behind the front, with gusts of 25 to 35 mph possible.

Precipitation chances will increase significantly with the frontal passage, especially for the mountains. Models have been trending drier for the lower valleys with the frontal passage with little to no measurable precipitation expected. While the mountains will see rain and snow showers, cold air advection behind the front will cause snow levels to fall. By late Monday night and early Tuesday morning, snow levels are forecast to reach mountain valley floors, particularly in the north-central portions of the forecast area. While moisture is somewhat limited, light mountain snow accumulations of up to 2 inches are possible through early Tuesday.

LONG TERM /Tuesday through Saturday/

Following the cold frontal passage in the short-term, precipitation chances will begin to taper down. However, a shortwave will move across the Great Basin and will allow for elevated precipitation chances (25-60%, highest south) across the southern 2/3rds of our area. Southwesterly return flow ahead of this shortwave, and then ahead of the larger Gulf of Alaska low will result in temperatures being near normal come Tuesday and Wednesday (if not leaning above normal Wednesday). Another consequence of this will be snow levels rising to 5-7.5kft MSL Tuesday/Wednesday. Over the course of early Tuesday through early Wednesday, QPF totals will be primarily south and west of the Snake Basin with liquid amounts generally 0.05 to 0.25 inches (although locally higher amounts up to 0.5 inches on higher peaks).

Confidence continues to be high on a Gulf of Alaska low impacting our area come midweek next week. Precipitation chances will increase throughout the day Wednesday as this system approaches, reaching 60- 95% by late Wednesday night. Late Wednesday night into Thursday morning will be the time frame of heaviest precipitation. Precipitation chances will begin to decrease Thursday evening into Friday and take on more of a showery nature with cold air aloft. Over the course of Wednesday morning through Friday morning, the central Idaho mountains have a 75+ percent chance of receiving at least 0.75 inches of liquid. Elsewhere, amounts of 0.25-0.5 inches of liquid are likely. Following the cold front temperatures will drop to below normal, with snow levels following the trend lowering to 2.5-4 kft MSL through Friday. These cooler temps and lower snow levels will result in late season snow across higher elevations. Mountain valleys above 4.5 kft MSL could pick up a few inches of snow over the course of the week (50-70% chance), elevations above 6kft MSL have a 60-80% chance of receiving at least 8 inches of snow, with localized amounts near a foot along the highest peaks.

Come this weekend, conditions will dry out with a warming trend as the trough exits our area to the east and ridging begins to build back in.

AVIATION /18Z Saturday through Sunday/

Issued 1141 AM MDT SAT MAR 28 2026

VFR with periods of mid to high ceilings. Surface winds: Becoming W-NW 5-15 kt with gusts up to 25 kt across higher terrain and south/west of the Snake Basin, becoming variable up to 10 kt overnight. Winds aloft at 10kft MSL: 10-25 kt.

KBOI...VFR. Surface winds less than 10kt, northwest this afternoon then variable overnight.

Sunday Outlook...VFR under mid to high ceilings. Lower clouds with light showers across mountains north of KBKE-KMYL in the afternoon and evening. Showers may temporarily obscure mountains with snow levels 7-8kft MSL. Breezy SW-W winds with gusts 20-35 kt in the afternoon across higher terrain, otherwise SW-NW 5-15 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.