Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 270956
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
356 AM MDT Wed Mar 27 2024

.SHORT TERM...Today through Friday night...A warm frontal
passage this morning will open up into moist southwest aloft
this afternoon. Precipitation will initiate over southeast
Oregon early in the afternoon, spreading into southwest Idaho by
early evening. While the thunderstorm threat today is less than
15% an overlap in daytime heating and increasing instability
aloft could support a strike/flash over portions of SE Oregon,
mainly Harney/Malheur counties. The increased flow aloft and
deep Pacific low will bring breezy conditions today, the
strongest winds across southeast Oregon. Wednesday night is wet
across the region as a broad upper low approaches the Pac NW
coast. The mountains of e-central Oregon and w-central Idaho see
the focus of heaviest precipitation through Thursday morning
where liquid totals of 0.50 to 1.00 inch are expected. Snow
levels through Wednesday night will run 5000 to 6000 kft
dropping to 3500 to 5000 ft Thursday. Total accumulation of 5 to
10 inches is expected above 6000 ft with up to 2 inches in
mountain valleys above 4500 feet. Lower elevations that stay dry
into Wednesday evening will see precipitation fill in overnight
with the passage of a cold front. Lower valleys are likely to
see 0.10 to 0.20 inch of rain. The main low will reach the WA
coast on Thursday, the accompanying colder air aloft and daytime
heating supporting a continued chance of showers and slight
chance of thunderstorms. The shower threat retreats to the
mountains Thursday night, expanding again on Friday with a 20%
chance in the valleys and 40 to 70 percent chance in the
mountains.

.LONG TERM...Saturday through Wednesday...The closed upper level
low will move to our southwest on Saturday, becoming a
positively tilted upper level trough that will keep temperatures
cool through the weekend. 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 Saturday
and 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 by Sunday night. 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 Wednesday. Tuesday looks
to be the warmest day, with temperatures in the valleys
reaching the upper 60s and low 70s.

Good model agreement exists with this pattern through next week,
with only slight variation in the deterministic model`s
evolution of the closed low. This accounts for the forecast
uncertainty in precipitation this weekend, although all
ensembles and deterministic solutions show light precipitation
in the region.

&&

.AVIATION...Mostly VFR tonight. Localized LIFR/IFR in patchy
mountain valley fog near KMYL through the mid morning. A line of
mountain snow and valley rain will bring MVFR/IFR conditions by
Wed/20Z to SE OR, then Wed/22Z to SW ID. Widespread
precipitation will continue throughout the region through
Thursday morning. Snow levels 3500-4500 feet. Mountains obscured
in precipitation and low clouds. Patchy valley fog and low
stratus will redevelop tomorrow night mainly in mountain
valleys.

Surface winds: variable 5-15 kt, then SW to SE 10-20 kt after
Wed/16z. Afternoon gusts to 25-30 kt in SE Oregon. Winds aloft
at 10kft MSL: W 15-25 kt, then SW 25-40 kt around Wed/18z.


&&

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

&&

$$

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SHORT TERM...DG
LONG TERM....SA
AVIATION.....SA


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