718
FXUS65 KBOI 100946
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
246 AM MST Fri Jan 10 2025

.SHORT TERM...Today through Sunday night...The inversion is
expected to break down today as a cold front moves in from the
NW associated with an upper trough. Widespread light snow and
valley rain beginning Friday afternoon through early Saturday
morning. Snow levels begin at 3-4 kft MSL and drop to valley
floors Friday night. Valley locations will likely see flurries,
and a dusting over colder surfaces, but surface temperatures
just over freezing means measurable accumulation is unlikely
below 3 kft MSL. Valleys 3-4 kft are more likely to see
accumulation, up to half an inch. Generally 1-4 inches of snow
accumulation above 4kft MSL, with up to 6 inches along ridges.
Liquid equivalent of 0.1-0.3 inches in mountains, and below 0.1
inches in lower valleys. Post-frontal winds increase Friday
night through Saturday to 20-30 mph with gusts to 30-40 mph in
highlands and the Magic Valley. Gusty winds will help ensure any
remaining stagnant air is mixed out. Winds die down and
conditions improve Sunday, though some isolated snow showers
will continue over mountains.

.LONG TERM...Monday through Friday...Early next week, a closed
low west of SoCal will allow a high pressure system to build
directly over the area for a few days. This set up will support
inversion development and morning fog/stratus in valleys. As the
closed low moves slightly NE-ward on Thursday, the high center
moves east and the flow becomes northwesterly. This flow may
support a few mountain snow showers late Friday, though without
decent dynamic support there`s only a 20-30% chance of precip
over ridges.

&&

.AVIATION...Mostly VFR. IFR/LIFR in low stratus/fog over
sheltered valleys and the upper Snake Plain. Snow with valley
rain below 3-4k feet moving in from the NW to SE OR by Fri/22Z
and the lower Snake Plain by Sat/00Z. Areas of LLWS over Snake
Plain from Sat/00Z-Sat/12Z. Surface winds: variable 10 kt or
less, shifting to W-NW 10-15 kt with gusts to 25 kt this
evening. Winds aloft at 10kft MSL: N to NW 10-15 kt shifting to
W-NW 30-40 kt this afternoon.

KBOI...VFR with high-mid level clouds. MVFR and local IFR
conditions this evening as a cold front brings mixed precip and
lower ceilings. Little to no snow accumulation as surface temps
remain a few degrees above freezing. Surface winds SE 5-12 kt
becoming NW 5-10 kt this evening.

Weekend Outlook...Low stratus, fog, and isolated snow continue
Saturday. Snow levels at valley floors through the weekend.
Gusty west to northwest winds Sat afternoon. Improving
conditions for most areas on Sunday, except in isolated snow
showers over the mountains with continued mountain obscuration.

&&

.AIR STAGNATION...The Air Stagnation Advisory continues through
this morning but mixing should improve this afternoon as a
north Pacific cold front approaches. The front will break the
inversion and gusty post-frontal west winds will fully scour the
valleys.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Air Stagnation Advisory until 11 AM MST this morning
     IDZ011>015-028-029-033.
OR...Air Stagnation Advisory until 11 AM MST /10 AM PST/ this
     morning ORZ061>064.

&&

$$

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SHORT TERM...JM
LONG TERM....JM
AVIATION.....JM
AIR STAGNATION...JM