Emmett Weather

971
FXUS65 KBOI 102045
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
145 PM MST Sat Jan 10 2026

.SHORT TERM...Tonight through Monday night...A high amplitude
upper level ridge remains the dominant weather feature over the
Intermountain West. This pattern will maintain dry and stable
conditions across southeast Oregon and southwest Idaho through
the short term period. High pressure is firmly situated along
the West Coast and will continue to build into the region,
further stabilizing the atmosphere. Higher than anticipated
southeasterly wind has helped temperatures across much of the
Treasure Valley reach the low 40s this afternoon. With high
clouds clearing tonight though temperatures will drop below
freezing again. Mostly clear skies and light winds aloft, should
allow cold air to continue to pool in the lower valleys. This
setup is highly conducive to persistent surface inversions and
the formation of patchy fog and low stratus, particularly in the
Long Valley and other sheltered mountain basins. While mountain
locations will enjoy abundant sunshine and temperatures above
seasonal normals, some valley locations will remain cooler due
to limited daytime mixing. No significant precipitation is
expected through early next week.

.LONG TERM...Tuesday through Saturday...More of the same
through the long term, with high pressure and stagnant
conditions dominating through the extended. Come Thursday,
guidance is hinting at a shortwave swinging northeast of our
area. While no precip is expected (better forcing remain
northeast of our area), a more westerly track could work to
increase transport winds to help mix valley inversions and bring
cooler temperatures into our area. However, out of the Grand
Ensemble, only 21% of members favor a more westerly track
(mostly out of the GFS Suite). The EC-AI, EC, and GFS- AI keep
it east which would do little to help mix out our valleys.
Beyond Friday, the blocking pattern sets back in the high
pressure setting up over the Pacific Northwest, maintaining the
dry and stagnant conditions.

&&

.AVIATION...VFR under high clouds. Areas of fog/low stratus
will develop in sheltered valleys overnight, MVFR/LIFR with mtn
obscuration in fog/low stratus. Surface winds: Variable up to 10 kt.
Locally higher (gusts up to 20 kt) near KJER and portions of the
Snake Basin overnight. Winds aloft at 10kft MSL: Variable 5-20 kt.

KBOI...VFR. Surface winds: SE 5-10 kt.

&&

.AIR STAGNATION...A strong upper level ridge will remain
centered over the region through the end of the week. This
pattern supports the development of steep low level inversions
and very weak transport winds. Forecast mixing heights are
expected to remain well below 1500 feet AGL for extended
periods. These conditions will severely limit ventilation,
leading to the accumulation of pollutants in valley locations.
Because of the persistent nature of this ridge, the Air
Stagnation Advisory has been extended until 5 am MST Friday for
all valley zones in southeast Oregon and southwest Idaho.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Air Stagnation Advisory until 5 AM MST Friday
     IDZ011>014-016-028-033.
OR...Air Stagnation Advisory until 5 AM MST /4 AM PST/ Friday
     ORZ061>064.

&&

$$

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SHORT TERM...JDS
LONG TERM....NF
AVIATION.....NF
AIR STAGNATION...JDS