textproduct: Boise

LONG TERM...Thursday through Monday

I am running out of ways to re-word these discussions, with high pressure continuing to dominate the long term period. Air stagnation is likely to stick around through at least Monday. With the inversion remaining in place, valley location temperatures will be cooler and near normal, with the higher elevations warmer and above normal. Have adjusted NBM temps up in higher elevations to better reflect the inverted conditions. Valley fog/low stratus will be in play each morning under the inversion. Guidance has come into better agreement of the previously advertised cold front/shortwave Thursday, with most guidance keeping it east of our area. While 700mb windspeeds will see a slight uptick (20-30kt), it will likely be decoupled from the surface with a small chance of it helping increase mixing. The latest NBM probability of gusts greater the 20 mph Thursday are generally 25% or less throughout the Snake River Plain. Guidance is continuing to hint at a pattern breakdown come the middle of next week...but uncertainty remains high that far out.

AVIATION

VFR. Areas of fog/low stratus will redevelop overnight, mainly in sheltered mtn valleys and lower basins. MVFR-LIFR and mtn obscuration in fog/low stratus. Surface winds: Variable up to 8 kt. Winds aloft at 10kft MSL: SW-NW 5-30 kt, highest north.

KBOI...VFR this evening. Mist/fog and low stratus develop near the terminal overnight after Tue/10z, with a 35% chance of LIFR conditions. Surface winds: light and variable.

AIR STAGNATION

The strong ridge of high pressure will keep a stout inversion in place across the region. Transport winds will remain light with very low mixing heights (below 1500 ft AGL), leading to poor ventilation and the accumulation of pollutants in valley locations. The Air Stagnation Advisory remains in effect for all valley zones in southeast Oregon and southwest Idaho and has been extended through Monday 5 AM.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Air Stagnation Advisory until 5 AM MST Monday IDZ011>014-016-028-033. OR...Air Stagnation Advisory until 5 AM MST /4 AM PST/ Monday ORZ061>064.