Wind Advisory 5, NWS Boise, ID

Area Forecast Discussion
National Weather Service Boise ID
911 PM MDT Mon Mar 13 2023

.DISCUSSION...Showers continue to move northeast across the area
this evening, and the showers will last overnight and most of the
day tomorrow. Winds are expected to increase Tue afternoon across
the southern portion of the CWA (generally from the Boise area
south to the NV border both in Oregon and Idaho). The wet pattern
will extend into Wed before we dry out Wed night and then
experience a dry Thu and Fri. All this is handled well by the
current forecast and no changes will be made at this time.

&&

.AVIATION...Mostly VFR. Periods of valley rain and mountain snow
will produce local MVFR in the valleys and MFR/IFR in the mountains.
Mountains obscured. Snow levels around 5500-6500 feet MSL, except
3000-4000 feet MSL in Baker County, OR. Surface winds: SW-SE 10-20
kt with gusts to 30 kt becoming variable less than 10 kt overnight.
Winds aloft near 10k ft MSL: W-SW 35-50 kt becoming SW 20-30 kt
after 14/15Z.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Wednesday night...Active weather
will continue through Wednesday under the influence of an
atmospheric river stationed in the Pacific. Shower activity will
continue through the evening tonight as a weak disturbance crosses
the area. Snow levels will remain near 5500-6000 ft MSL through
the evening, posing localized minor flooding concerns as rain
falls over the snowpack in mountain valleys. Instability will
increase this afternoon, which may generate a lightning strike or
two in stronger showers. Precipitation will slowly decrease in
coverage through the evening, with the mountains accumulating an
additional 2 to 5 inches of snowfall before the next system moves
in.

Heavier precipitation will move in overnight as a cold front
swings through the region. Precipitation will become widespread
Tuesday morning, though high resolution models show some rain
shadowing over portions of the Treasure Valley. Snow levels will
briefly drop across the north to 3000-4000 ft MSL ahead of an
advancing warm front. The warm front will surge northward mid-
morning Tuesday, filling in most areas with rain or snow. Winds
will increase Tuesday afternoon, most notably along the Nevada
border, with gusts up to 35-40 mph. Precipitation will shift to
the north of the Snake River Plain by mid-evening Tuesday before
another cold front slides across the region from west to east
overnight into Wednesday morning. Though the cold front will push
precipitation out of the region by Wednesday afternoon, winds will
become gusty along the I-84 corridor behind the front with gusts
up to 40-50 mph possible. Conditions will dry out by Wednesday
evening, with lower elevations seeing up to half an inch of
rainfall, mountain valleys seeing up to 2 inches of snow, and the
higher peaks accumulating up to 2 feet of snow through the short-
term forecast period. A Backcountry Avalanche Watch issued by the
Sawtooth Avalanche Center remains in effect for portions of the
Boise Mountains, including Banner Summit, through Tuesday, where
additional stress on the weak snowpack may pose dangerous travel
and recreation conditions.

LONG TERM...Thursday through Monday...An upper level ridge will
build over the area on Thursday and continue through Friday bringing
dry weather, mostly clear skies and light winds to southwestern
Idaho and southeastern Oregon. Forecast models have slowed down the
progression of the next Pacific storm system which may allow the
ridge and associated fair weather to last into the upcoming weekend.
About half of the models hold onto the ridge through Saturday and
about half give way to the next storm system.  The ridge will almost
certainly be gone by late Sunday...which will allow Pacific moisture
to come streaming back into the area. Our official forecast accounts
for this uncertainty and shows an increasing chance of precipitation
each day beginning on Saturday at about a 20 percent chance to
around a 30 percent chance on Sunday and as high 50 to 60 percent
chance by Monday. Snow levels will be above valley floors Saturday
through Monday.

&&

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

&&

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DISCUSSION...SP
AVIATION.....SA
PREV SHORT TERM...AL
PREV LONG TERM....JB