303
FXUS65 KBOI 180353
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
853 PM MST Wed Dec 17 2025

.DISCUSSION...Strong winds have subsided across the region, with
mostly clear skies allowing for some rapid cooling to occur
across the region. Several stations exceeded high wind warning
criteria (prolonged gusts greater than 58 mph) with several
reports of damage and road closures from the high winds today. A
public information statement has been issued along with several
local storm reports on the area wide impacts.

A warm front will move in from the southwest tomorrow
morning, bringing a brief wet snow to elevations above 4000
feet MSL by early tomorrow morning. A quick rain-snow mix is
still anticipated at elevations between 2000-4000 feet MSL
tomorrow morning, with potential for slick roadways during the
morning commute. The latest hi-res models show a swift
transition to rain below 7000 feet MSL as the warm air pushes in
by mid-morning, however the Treasure Valley will likely be
rain-shadowed thanks to the southwest flow orientation aloft
and breezy southeast winds. Lingering cold air in the Camas
Prairie and sheltered mountain valleys increases the threat of
freezing rain tomorrow evening. With the rising confidence in
rain shadowing and warm temperatures, have lowered probability
of precipitation and slightly increased snow levels.

&&

.AVIATION...VFR this evening. Precipitation returns early Thu
morning, starting out as snow across much of the area before
transitioning to rain through Thursday afternoon. VFR/MVFR in
rain, MVFR/LIFR in snow. Mountains obscured. Snow levels:
2.5-3.5 kft MSL Thu AM, rising to 6-8kft MSL Thu PM. Surface
winds: Variable up to 12 kt overnight, then SW-SE 10-20 kt with
gusts of 20-40 kt Thu PM. Strongest across highlands. Winds
aloft at 10kft MSL: W-NW 20-40 kt.

KBOI...VFR under increasing clouds overnight. Precipitation
beginning around Thu/17z. A 30% chance of initial rain snow mix,
before all rain after Thu/19z. MVFR ceilngs/visibility in precip.
Surface winds: Becoming SE under 10 kt overnight, then SE 8-12 kt
with gusts up to 24 kt Thursday afternoon.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Friday night...The cold front
exited the forecast area before noon today, ending the
thunderstorm and precipitation threat, though strong winds with
gusts up to 60 mph will persist across southwest Idaho through
the afternoon before diminishing near sunset. Numerous reports
of downed trees and power lines have been received across
southern Idaho due to the earlier frontal passage, and a full
summary of these reports will be compiled later this evening.
Attention then turns to the next system, which arrives late
Thursday morning as a warm front, bringing widespread
precipitation that will initially fall as snow before
transitioning to rain below 8,000 feet MSL by the afternoon.
Cold air will likely linger longer in the Wallowas, Hells
Canyon, the Camas Prairie, and the McCall area, keeping snow
levels lower until late evening before they eventually rise to
between 6,000 and 7,000 feet MSL. Snow accumulations of 6 to 10
inches are possible above 6,500 feet MSL, while mountain valleys
in the West Central and Boise Mountains can expect 1 to 3
inches; the Snake River Basin and Treasure Valley may see a
brief rain/snow mix with no accumulation before switching to all
rain. By Thursday evening, the warm front will lift north,
leaving the valleys dry while precipitation continues in the
West Central Mountains.

On Friday, a west-to-east oriented cold front over northern
Oregon and central Idaho will slowly sag southward, refocusing
precipitation over the mountains and leaving the Snake Basin
largely dry due to rain-shadowing. Snow levels will range from
7,000 to 8,000 feet MSL south of Boise to around 5,500 feet MSL
near Baker and McCall, eventually falling to valley floors in
the northern zones by Friday night. Because of the heavy
subtropical moisture, snow-to-liquid ratios will be low,
resulting in a dense, heavy snow where one inch of liquid
equivalent translates to only 5 to 8 inches of snow. While
additional wind headlines may be necessary on Friday, winter
weather headlines are not currently expected as significant snow
accumulations will be confined to the highest peaks.

LONG TERM...Saturday through Wednesday...A very active and wet
pattern will continue through the long term. Precipitation will
briefly taper off on Saturday as a cold front stalls along the
Nevada border and weakens. Temperatures will be 5-10 degrees cooler
than Friday, but still slightly above normal. On Sunday and Monday,
southwest flow aloft ahead of a deep trough off the coast will bring
a plume of subtropical moisture into our area. The initial push of
moisture is expected to arrive Sunday into Sunday night as a warm
front lifts north through the area, bringing widespread
precipitation. Snow levels will rise through the day, reaching 5500-
7500 feet MSL by Sunday night. Moderate to heavy precipitation
totals are likely with this event, but significant snowfall will be
limited to the peaks. Strong southwest flow aloft will continue on
Monday, bringing additional moisture especially to the mountains.
Snow levels are somewhat uncertain due to the trough moving slowly
inland. On Tuesday and Wednesday, the flow aloft is expected to
become more southerly as the trough deepens off the coast. This will
keep our area mild with a 30-60% chance of rain and high elevation
snow on Tuesday, increasing to a 50-80% chance on Wednesday.
However, slight adjustments in the position of the trough could
adjust temperatures higher or lower.

&&

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

&&

$$

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DISCUSSION...SA
AVIATION.....NF
SHORT TERM...JDS
LONG TERM....ST