Bruneau, Idaho Weather Forecast Discussion

312
FXUS65 KBOI 031002
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
402 AM MDT Fri Oct 3 2025
.SHORT TERM...Today through Sunday night...Have seen steady
precipitation with embedded thunderstorms overnight focused
along the leading edge of an upper trough. Through 3AM MDT the
heavier precipitation ran a line from the Owyhee Mtns to
McCall, intersecting the Snake Plain in the vicinity of
Caldwell/Boise. The upper trough will shift eastward today with
a closed low over central CA becoming the dominant feature for
precipitation development by this afternoon. This will result in
the gradual weakening the band of moderate to heavy rain
through late morning. That said, leaving the Flash Flood Watch
as is for now as a chance of heavier showers and thunderstorms
remains for this afternoon across the w-central ID mtns. The
HRRR could be heavy handed but is showing localized 0.50"
amounts with an area of showers/storms. Another area of
potentially heavier precipitation will be southern Harney and
Malheur counties which will be positioned along the northern
periphery of the upper low. Showers and possible thunderstorms
will regenerate in this area through the day resulting in broad
rainfall amounts between 0.15" and 0.30" with the potential for
up to 0.75" through this evening.
For the weekend, the region remains on the backside of a
broader trough. This will feed a 20-40% chance of showers will
across the mtns of Baker County and SW Idaho while low
elevations are dry. Snow levels will drop to between 6-7.5kft
MSL by Sunday so higher mtns would see snow showers, but little
if any accumulation. Northwest winds will become gusty Friday
night into Saturday reaching 15-30 mph across open terrain of
with sites along the Snake River (south and east of Boise)
seeing gusts of 40-45 mph. Temperatures will hold steady,
averaging 5-10 degrees below normal.
.LONG TERM...Monday through Friday...The beginning of the long
term will provide some relief from precipitation as flow aloft
will be from the north. This is the case thanks to a broad,
positively tilted shortwave trough spanning over the Great Basin
area (south of the CWA) that will slowly move east through
Thursday. With this in place, and a blocking pattern over the
southern U.S. and Gulf states, upper-level flow will be nebulous
and volatile. Long range models vary between westerly flow,
southwesterly flow, or varying flow around a weak upper-level
low pressure centered near the ID/NV border. Regardless, a
gradual warming trend from temperatures below normal Monday to
slightly above normal Friday. Beginning Wednesday into Thursday,
a Gulf of Alaska low will begin to slowly move onshore. This
will bring southerly/southwesterly flow and moisture transport
back into the region, with precipitation chances returning once
again.
&&
.AVIATION...Widespread precip with embedded thunderstorms continuing
through Fri morning, becoming scattered by Fri afternoon. MVFR/IFR
and localized LIFR in heavier precip and low clouds. Mtns obscured.
Surface winds: variable up to 10kt. Gusts between KBOI-KTWF to
decrease through morning from NW-W 25-35 to 15-20 kts. Winds aloft
at 10kft MSL: NW-NE 5-15 kt.
KBOI...Periods of MVFR/IFR in rain and low ceilings, mainly between
03/10z-15z. Rain coverage and intensity will decrease by 03/12z, but
scattered showers expected through Fri evening. Foothills obscured.
Surface winds: W to NW 5-12 kt.
Weekend Outlook: Patchy AM fog for sheltered mtn valleys and basins.
Showers continuing in central Idaho mtns and around KTWF/KJER
Saturday. Then, isolated showers over central Idaho mtns Sunday.
MVFR/IFR in heavier rain showers, IFR/LIFR in snow.
Snow levels 7000-9000 ft MSL Saturday, decreasing to 6000-7500 ft
MSL Sunday. Mountains obscured in precip. Surface winds: N-NW 10-20
kt gusting to 20-30 kt Saturday, with localized gusts to 40 kt in
the Snake Plain. Then, NW-NE 5-10 kt Sunday.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Flash Flood Watch through this afternoon IDZ011-013.
OR...None.
&&
$$
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SHORT TERM...DG
LONG TERM....CH
AVIATION.....CH

NWS BOI Office Area Forecast Discussion