textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- High pressure will bring above normal temperatures and dry conditions through the weekend and into early next week.

- Cooler temperatures and chances for precipitation return by the middle of next week.

SHORT TERM /Through Monday Night/

Issued 207 PM MDT SAT APR 4 2026 Warm and dry through Sunday as the axis of the upper level ridge shifts eastward over our area. Clear skies and light winds will promote efficient radiational cooling tonight. While the airmass is moderating, it remains dry enough for temperatures to dip into the 30s across most valleys, while higher mountain basins will see teens and 20s. Some residual low level moisture trapped in the deeper valleys of the West Central and Boise Mountains may support patchy fog development once again toward sunrise Sunday.

Sunday and Monday will see the peak of the warming trend. High pressure centered over the Great Basin will keep conditions dry and mostly sunny, though some thin cirrus may spill over the ridge top at times. High temperatures on Sunday will reach the upper 60s to low 70s in the lower valleys. By Monday afternoon, the airmass warms further, with high temperatures reaching the mid 70s in the Treasure Valley and parts of southeast Oregon. These values are nearly 15 degrees above the seasonal average for early April. Surface winds will remain generally light and terrain driven, although a slight increase in southerly breezes is expected across the high desert of southeast Oregon Monday afternoon as the ridge begins to shift east and the next system approaches the coast. Overnight lows Sunday night and Monday night will be much milder than previous nights, staying well above freezing in the lower elevations.

LONG TERM /Tuesday through Saturday/

Issued 207 PM MDT SAT APR 4 2026 A cooler and unsettled pattern will return for the long-term period with multiple shortwaves. As the ridging that dominated the short-term period moves east, flow aloft over our area will become more zonal ahead of a shortwave moving just to our north. This shortwave will allow for a slight chance (10-20% of shower) across higher terrain, mainly to our north; as well as increasing winds as a result of a tighter pressure gradient. Come Tuesday afternoon, winds will gust to 35-45 mph across higher terrain and south/west of the Snake Plain with the passage of a cold front. Temperatures will also drop to near normal come Wednesday

Forecast uncertainty increases beyond Tuesday; more specifically, the evolution of a closed low that will set up off the coast of California and it's interaction with the polar jet. Guidance continues to favor the slower evolution of the low. This would favor drier and warmer (temps 5-10 degrees above normal) conditions, at least initially. The best chance of precipitation will come Thursday afternoon with moisture and warm air advection in southwesterly flow. Precipitation chances come Thursday afternoon will range from 15-55%, highest south and east. However, given the uncertainty in pattern evolution, am maintaining a 10-40% chance of precipitation each afternoon Wednesday through Saturday (highest south and east).

AVIATION /00Z Sunday through Monday/

Issued 538 PM MDT SAT APR 4 2026

VFR, except patches of fog in w-central ID mtn valleys in the AM. Surface winds: variable up to 10 kt, then NE-SE 5-15 kt on Sunday. Winds aloft at 10kft MSL: southerly 5-10 kt.

KBOI...VFR. Light NW surface winds through sunset, becoming SE 5-12 kt tonight through Sunday.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.