730
FXUS65 KBOI 212134
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
234 PM MST Thu Nov 21 2024

.SHORT TERM...Tonight through Saturday night...A slow moving deep
trough off the Pac NW coast will continue to funnel moisture
into the region on a southwest flow. The focus of precipitation
will stay across SE Oregon and portions of SW Idaho through
tonight while remaining north of the western Magic Valley. This
will continue to be a mostly orographic event with the bulk of
precipitation falling across higher terrain while lower
elevations see periods of light rain. As warmer air builds, snow
levels will push above 7000 across the east-central Oregon and
w-central Idaho mtns, and to above 8000 feet along the NV
border. A ripple in the flow on Friday will bring warmer
southerly winds into the region. Most areas will see a break in
the precipitation with possibly some breaks in the clouds across
lower elevations. Temperatures will warm to 10-15 degrees above
normal. The western Magic Valley will be the warmest spot,
seeing a 40% chance of reaching 60 or warmer.

The trough moves onto the coast Friday night, bringing a return
of rain and high mountain snow. A frontal passage early
Saturday will bring a wind shift and initiate a drop in snow
levels while also cutting off the main moisture tap. So while
mtn valleys will likely see a changeover to snow, accumulations
will be light as precipitation intensity decreases. Instability
Saturday afternoon will support showers and possibly a
thunderstorm mostly across the central and northern portions.
Temperatures are 5-10 degrees cooler on Saturday, though still
slightly above normal. Snow accumulation will be heaviest at
7kft MSL and above, where 1-2` of additional snow is expected
through Saturday. This will translate to 1-2" of rain or liquid
equivalent in the mountains while lower elevations could see up
to 0.75".


.LONG TERM...Sunday through Thursday...After a weak ridge briefly
passes over the region Sunday, SW flow aloft will redevelop
ahead of an upper level low off the coast. The low is forecast
to open up and move east, moving over our CWA Tue or Tue night.
Relatively dry NW flow will then dominate our weather Wed and
Thanksgiving Day. Overall, this keeps a mention of precipitation
in the forecast through most of the long term, with snow levels
3500-4500 ft AGL Sunday through Tuesday, falling to 2500-3500
Wed and Thanksgiving Day. Although it will be cold enough for
snow on most valley floors Wed and Thu, very little if any
precipitation is forecast in the valleys. Precipitation will
even be light in the mountains, especially compared to what they
are experiencing with the current atmospheric river event. Only
1 to 3 inches of new snow are forecast for the mountains in the
long term period, with only a trace currently forecast for
lower elevations.

&&

.AVIATION...Mostly VFR. Widespread rain/snow creating MVFR/IFR
at times, especially in the mountains. Mountain obscuration.
Snow levels initially 5500-7500 ft MSL, rising to 7500-8500 ft
AGL tonight. Surface winds: SW to SE 10-20 kt, gusts 25-35 kt,
decreasing overnight but continuing still stronger than normal.
Winds aloft at 10kft MSL: SW 35-50 kt, decreasing to 25 to 40
overnight.

.KBOI...Mainly VFR, with frequent periods of rain. MVFR
ceilings possible in heavier rain. Surface winds: S to E 7-17 kt
with gusts up to 20-30 kt, continuing through the night.

WEEKEND OUTLOOK...Periods of MVFR/IFR in precipitation Friday, with
best chance from KBNO-KBOI-KSUN and north. Mountains obscured. Snow
levels around 7000ft MSL. Surface winds SE-SW 10-20 kt, with gusts
25-40 kt. Cold front Fri night thru Sat, bringing widespread
rain/snow and MVFR to LIFR conditions at times. Lowering snow levels
to 4500-5500ft MSL Saturday. Surface winds becoming SW-NW 5-15 kt,
gusts to 20-30 kt. Drier and VFR Sunday, except in patchy fog.

&&

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

&&

$$

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SHORT TERM...DG
LONG TERM....SP
AVIATION.....SP