941
FXUS65 KBOI 211703
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1003 AM MST Fri Feb 21 2025

.DISCUSSION...Locally dense fog is lingering along the ID/OR
border, Weiser Basin and mtn valleys this morning. Expect much
of it to burn off by noon under mostly clear skies. Otherwise
dry across the region today with lighter winds. High
temperatures will be similar to yesterday, though with less
wind/mixing, sheltered lower valleys could be slower to warm
today and even a few degrees cooler than yesterday. Have touched
up fog forecast for this morning, otherwise no other updates.

&&

.AVIATION...Mostly VFR, except in patchy MVFR/IFR valley fog and
low stratus mainly near KMYL, KONO, and KBKE through Fri/21Z.
Lowering ceilings tonight ahead of next system arriving
Saturday. Surface winds: variable 10 kt or less except SW-SE
5-10 kt this morning in the Snake River Valley. Winds aloft at
10kft MSL: NW-N 5-10 kt, becoming W 10-20 kt this afternoon.

KBOI...Generally VFR. Lowering ceilings in nearby light
precipitation tomorrow afternoon. Surface winds: SE 4-12 kt.

Weekend Outlook...Mostly VFR Saturday, except MVFR/IFR in
isolated snow showers north of the KBNO-KEUL-KSUN line during
the morning. Then, all flight categories expected Sat
night/Sunday as widespread precip arrives. High snow levels
favor rain at all terminals, except rain/snow mix at KMYL.
Mountains becoming obscured. Surface winds: E- S 5-15 kt
Saturday, then SE-SW SE 5-15 kt with 20-30 kt gusts Sunday.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Sunday night...
Another dry day is in store as transient high pressure
persists across the region. Some localized fog is present
across lower elevation and mountain valleys in western Idaho and
eastern Oregon this morning, and will persist across parts of
the Camas Prairies into the late morning or early afternoon, but
should burn off elsewhere after sunrise. Otherwise, a rather
uneventful weather day is in store today with light winds and
scattered clouds.

Westerly flow becomes re-established on Saturday, with an
initial weak impulse moving across east-central Oregon and
west-central Idaho in the morning. This will bring a dusting
of snow above 2500 feet in those areas, with accumulations
generally below one inch. A more significant system and
associated rich IVT plume will become oriented across the
southern half of Oregon and Idaho on Sunday, bringing widespread
rainfall and warming temperatures. The most significant liquid
precipitation totals will be focused over the Boise, southern
Wallowa, and West-Central Idaho mountains. ECMWF EFI output
suggests totals in the Idaho mountains will be around the 90th
percentile of climatology. Also somewhat problematic will be the
rising snow levels during the initial portion of the event,
reaching 7000-8000 feet in many areas, which will lead to rain
over existing snowpack immediately below those elevations.
Forecast hydrographs show the Weiser River approaching (but
remaining just shy of) action stage on Monday in response.
Significant snowfall is also expected at the higher mountain
peaks. High temperatures in the 50s across the Treasure Valley
and western Magic Valley will keep those areas solidly in rain.

LONG TERM...Monday through Friday...
Precipitation over the area is expected to taper down through
the later hours of Monday. Another cold front bring bring
another round of precipitation through Tuesday. Snow levels will
fall to 4000-5000 ft throughout the day, favoring snowfall over
the mountains and rain over the lower valleys. Peak daytime
temperatures are expected to stay on the warmer end in the low
to mid 50s from Monday through Friday. From Wednesday through
Friday, a large-scale high pressure will build across the entire
Pacific NW region and sustain drier conditions across SE Oregon
and SW Idaho.


&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.

&&

$$

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DISCUSSION...DG
AVIATION.....SA
SHORT TERM...JR
LONG TERM....JY/JR