Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 281605
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1005 AM MDT Thu Mar 28 2024

.DISCUSSION...A cold front has moved through the area this
morning and delivered more precipitation than forecast, with up
to 0.50 to 0.75 inch of precipitation over the area. The cold
front also brought thunderstorms to southern Twin Falls County
this morning. With the cold air aloft combined with partial
clearing this afternoon, that will help destabilize the
atmosphere, aiding in shower and thunderstorm development. Some
showers may produce brief heavy rain, small hail, graupel and
gusty winds up to 40 mph this afternoon. Slightly warmer air
aloft will move into the region on Friday, lowering the chances
of precipitation on Saturday. Will update the forecast to
include all of southeast OR and southwest ID this afternoon for
isolated thunderstorms.

&&

.AVIATION...Fog behind this morning`s precip is set to clear by
Thu/17z, otherwise mostly VFR. Scattered showers and isolated
thunderstorms developing Thursday afternoon. Snow levels
4000-5000 feet MSL, but graupel may fall below the snow level.
Mountains obscured. Surface winds: S-SW 10-20 kt, gusts 25-30
kt. Winds aloft at 10kft MSL: WSW 15-25kt.

Weekend Outlook...MVFR/local IFR in isolated showers through
the weekend, mainly over the Central ID Mountains and near the
Nevada border/Magic Valley. Snow levels will be around 5000-6000
feet. Surface winds will be NE-NW 5-15 kt, with breezy
afternoon winds NW 10-20kt with gusts to 30 kt.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Saturday night...A broad area of
light to moderate precipitation over SW Idaho early this
morning will exit to the east by afternoon. Any brief clearing
is shortlived as instability showers and isolated thunderstorms
fill in across the region this afternoon. The environment for
thunderstorms will be marginal and have kept isolated coverage
across e-central Oregon and SW Idaho from the Snake Plain into
the w-central ID mtns. Graupel and wind gusts to 40 mph are
possible from heavier showers and thunderstorms. Snow levels
fall through this morning behind a cold frontal passage,
bringing accumulating snow down to 4500 feet. Mountain valleys
could see up to 2 inches of additional snowfall today with an
additional 2 to 4 inches above 6000 feet. While the low center
remains along the coast, broad troughing will keep a 10-30%
chance of showers in the valleys with a 30-60% chance in the
mountains. Warming aloft will diminish the threat for deeper
convective development so have kept thunderstorms out of the
forecast on Friday. Conditions trend drier for Saturday as the
low center tracks south along the coast. Coverage of afternoon
instability showers will decrease with most valley sites staying
dry while mountains keep a low chance (20-40%). Today is the
coldest day of the period with temperatures warming back to near
normal on Saturday.

LONG TERM...Sunday through Thursday...The positively tilted
upper level trough will keep temperatures cool through the
Sunday. Lingering moisture with this trough will also allow for
a slight chance of precipitation (20-30% chance) over high
terrain and near the Nevada border on Sunday. Temperatures will
be slightly below normal, with snow levels right around
4000-5000 feet. Any snow accumulations will be minimal, with
higher elevations in the mountains seeing anywhere from 1-3
inches on Sunday night into Monday morning. This low will begin
to move out on Monday, with a deep ridge building in over the
region late Monday into Tuesday, bringing above normal
temperatures and dry conditions through Thursday. Tuesday looks
to be the warmest day, with temperatures in the valleys reaching
the upper 60s and low 70s. However, models have trended warmer
the last couple of days, so there is a low chance (10% chance)
we could even see 80F in the Lower Treasure Valley on Tuesday.

Good model agreement exists with this pattern through next week,
with only slight variation in the deterministic model`s
evolution of the closed low and upper level ridge. This
accounts for the forecast uncertainty in precipitation and high
temperatures through the long term period. All ensembles and
deterministic solutions are in agreement that wherever the
precipitation falls, it will be light.

&&

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

&&

$$

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DISCUSSION...KA
AVIATION.....JM
SHORT TERM...DG
LONG TERM....SA


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