000
FXUS65 KBOI 250250
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
850 PM MDT Wed Apr 24 2024

.DISCUSSION...This evening, scattered showers persist in the
Southwest Highlands and Southern Twin Falls County, though much
of the activity has tapered off. Earlier, a few outflow
boundaries were observed from stronger storms, but there haven`t
been any additional boundaries sighted in the past hour.

A dry cold front is advancing southeastward this evening,
accompanied by brief gusty winds. As of 8:30 PM MDT, the front
was positioned south of a Burns-Baker City line and will
continue its southeastward trajectory. It`s expected to reach
Ontario by approximately 9:30 PM MDT, Boise by 10:30 PM, and
eventually Twin Falls and Jerome around 4 AM MDT. Wind gusts of
up to 30 MPH are anticipated with the passage of this front.

Dry conditions are forecasted to persist through early Thursday
afternoon until the arrival of the next cold frontal system,
which will bring widespread showers Thursday night into Friday
morning. The current forecast appears comprehensive, requiring
no updates at this time.

&&

.AVIATION...Generally VFR. Isolated rain showers in south-central
Idaho. Gusty outflow winds up to 30 kt. Surface winds: SW to NW
5-15 kt, with gusts to 20-30 kt from KBKE/KONO to KMUO with
cold front overnight. Winds aloft at 10kft MSL: W-NW 10-20 kt.

KBOI...VFR under mid to high level clouds. Surface winds: NW
5-15 kt. Cold front arrives around Thu/04-05Z, with the
potential to bring gusts to around 20 kt overnight. Light rain
showers arrive Thursday night after Fri/03Z, lowering ceilings
to 5000-7000 ft AGL. Thunderstorm chances less than 15%
Thursday night.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Friday night...A broad upper low
lifting out of the Desert SW will keep a chance of showers over
far southern zones overnight, mostly along the ID/NV border.
The thunderstorm potential with this activity will diminish
with sunset. As that system moves eastward a cold front will
push through the region tonight in advance of the next upper
wave. The frontal passage will be dry, bringing gusty winds to
SE Oregon and portions of the Snake Plain in Idaho. Thursday
will see breezy, dry and cooler conditions to start, with
showers developing over higher terrain in the afternoon.
Precipitation fills in Thursday night as an upper low provides
dynamical support. Valleys will see a 30-50% chance of
measurable precipitation with a 70-90% chance of rain and high
elevation snow in the mountains through the day Friday.
Afternoon instability will support a 15-20% chance of
thunderstorms Friday across SE Oregon and higher terrain of SW
Idaho. Snow levels will range between 5500-6500 feet Thursday
night into Friday with 3-6 inches possible above 6500 feet.
Breezy northwest winds will be strongest across open terrain,
especially through the Snake Plain east of Boise where gusts of
40 mph are possible each afternoon/evening. The gusty winds will
carry into Friday morning as the low begins to exit eastward.
Temperatures will trend 5-8 degrees cooler each day through
Friday.



LONG TERM...Saturday through Wednesday...As an upper level
trough exits our area to the east on Saturday, surface gradient
forcing will support very windy conditions in the Snake Plain.
Winds gusts of up to 40-50 mph in the Middle Snake Plain meet
Wind Advisory criteria, although it is still too far in the
future for a product at this time. Gusts in the Lower Snake
Plain will generally be 30-40 mph. Some lingering precipitation
potential exists on Saturday, 20- 50% chances, mostly along our
eastern boundary and in the Central Mtns of Idaho. At the same
time our next upper low pressure system begins tracking south
from the Gulf of Alaska, putting us under southwest flow from
Monday morning through at least Tuesday. Models are split on
where the low sets up exactly, which is resulting is some pretty
varied forecasts as all of them show the low slowing down. Most
of the ensembles keep the low offshore, with a cold front
stalled over our area, and it is the position of the front that
is resulting in the uncertainty. Temps may be 10 degrees above
normal if we remain east of the front, or 10 degrees below
normal if we are west of the front. The range of precipitation
chances is roughly 10- 50%, with best chances over higher
terrain. There is a slight warming trend, a degree or two each
day, through the period and winds are set to be somewhat breezy
each afternoon.

&&

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

&&

$$

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DISCUSSION...JDS
AVIATION.....SH
SHORT TERM...DG
LONG TERM....JM