601
FXUS65 KBOI 260937
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
237 AM MST Sun Jan 26 2025

.SHORT TERM...Today through Tuesday night...Cold, dry air has
settled in our CWA and will continue through at least Tuesday,
while higher elevations begin warming Monday as high pressure
aloft moves inland from the Pacific. Skies will stay clear.
The Cold Weather Advisory in the Camas Prairie has been
extended until Tuesday morning, with only gradual warming
foreseen after that. Northeast winds near the OR/NV border
will diminish to 10-15 mph today, then generally light and
variable tonight through Tuesday. An exception will be
continuing northeast winds to 20 mph from the very cold
Camas Prairie into the Jerome/ID area.

.LONG TERM...Wednesday through Sunday...High pressure aloft
will persist over the northwestern US through early Friday
then flatten and shift south. Moist westerly flow from the
mid-Pacific will then have a clear path eastward to the Oregon
coast, depicted most clearly by the GFS model, and then inland
Friday through Sunday. Snow will likely overspread our CWA as
the moist, warmer air overruns cold surface air already in
place. Meanwhile, another upper trough will dig south along the
BC coast this weekend. ECM and GFS differ on what happens next.
GFS continues to bring milder air inland, finally changing snow
to rain at lower elevations. But ECMWF allows the colder BC
trough to come in first, keeping pcpn in the form of snow.
There is no clear consensus just yet but at least all models
bring pcpn to our CWA next weekend after 2-3 weeks of dry
weather.

&&

.AVIATION...VFR and SKC. Surface winds: variable less than 10 kt,
except NE 5-15 kt across SE Oregon and near the Nevada border in
Idaho. Winds aloft at 10kft MSL: ENE 15-30 kt.

KBOI...VFR and SKC. Surface winds: less than 8 kt, NE after 17Z
then back to SE after 02Z.

&&

.AIR STAGNATION...High pressure aloft will move inland from the
Pacific Ocean this week, resulting in lower mixing heights and
calm winds through Friday. These conditions will lead to
stagnant air in the valleys, although the lack of recent
moisture will make it difficult for persistent fog and low
stratus clouds to form. The main anticipated impacts from the
stagnant air will be the potential for deteriorating air
quality, along with haze and continued below normal temperatures
in the valleys.  The stagnation should end later Friday or
Friday night as a Pacific trough moves inland.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Air Stagnation Advisory from 11 AM this morning to 9 AM MST
     Friday IDZ011>016-029-030-033.
     Cold Weather Advisory until 8 AM MST Tuesday IDZ028.
OR...Air Stagnation Advisory from 11 AM MST /10 AM PST/ this
     morning to 9 AM MST /8 AM PST/ Friday ORZ061>064.

&&

$$

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SHORT TERM...LC
LONG TERM....LC
AVIATION.....MC
AIR STAGNATION...LC/SP