Meridian, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

466
FXUS65 KBOI 201638
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
938 AM MST Sat Dec 20 2025

.DISCUSSION...Mostly clear, cool, and dry in our CWA through
this evening, with the next atmospheric river (AR) currently
along 39-41N from 140W in the Pacific to northern NV. The AR
will moisten further in the Pacific today, then inland tonight,
while at the same time an upper trough will dig southward from
the Gulf of Alaska. The digging trough will turn upper level
winds to SW-ly and the AR will shift northward into our CWA
Sunday with a warm front. Whereas the previous AR targeted our
northern zones this one will impact our southern zones, with
latest MOS products indicating a drenching rain at lower
elevations Sunday morning. Pcpn will start as snow in the
pre-dawn in eastern OR, with 1-2 inches accumulation above 4000
feet, before changing to rain up to 5000 feet north to 8000
feet south later Sunday. The transition to rain may include
freezing rain in wind-sheltered valleys in Baker County. Will
address that in the afternoon package. In Idaho, the higher
terrain of the central mountains may allow a heavy accumulation
of snow above 6000 feet Sunday, changing to rain below. Heavy
rain on steep slopes may again bring down rocks and mud so best
to avoid roads below steep terrain. For the Snake Basin, Sunday
morning will bring a downpour for a couple hours until the warm
front passes. Current forecast matches up well with latest
models, although Sunday`s high temps look a little too cold.

&&

.AVIATION...VFR throughout today. Mid-to-high clouds developing
this afternoon. Precipitation late tonight across eastern OR
with MVFR and IFR conditions. Snow levels dropping to 3-5kft
MSL. Surface winds: E-SE 5-10kt. Winds aloft at 10kft MSL: W-NW
40-60kt.

KBOI...VFR. Few clouds late morning/early afternoon, with OVC
coverage late afternoon and after. Surface winds SE 5-10kt.

Sunday Outlook...Widespread rain/snow Sunday and mountain
obscuration. Snow levels 3k-5kft MSL north of KBNO-KONO-KMYL,
7k-8kft MSL to the south. Surface winds: SW-SE 5-10 kt today,
SW-SE 10- 20 kt Sunday, with SW 20-30kt south of the Snake
Basin in ID and south of KREO in OR.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Monday night...Zonal flow continues
with a lull in precipitation today as the next stream of
moisture remains to our south and west today. Dry conditions
expected for most of the day until the next system arrives late
this evening. Precipitation becomes widespread early Sunday
morning. Snow levels will be at the surface in Baker County and
near the Weiser Basin and Ontario rising to around 7000-8000`
from the Snake Basin south. Snow is expected from Burns to
Ontario initially before changing to rain. With accumulations up
to 1-2 inches possible along the I-84 corridor from Ontario to
Baker City and from Burns OR north. Mountain valleys and the
Camas Prairie in ID will see 2 to 4 inches of snow before
changing over to rain below 6000 feet. Moderate snow
accumulations expected over the mountains above 7000 feet again,
with 12 to 20 inches through Monday evening. Wind gusts of
30-40 mph expected south of a line from Steens Mountain to the
Owyhees and southern Twin Falls County.

LONG TERM...Tuesday through Saturday...Mild, active pattern
continues through the long term. A broad upper level trough will
remain over Haida Gwaii, continuing to direct an atmospheric
river over the area on Tuesday. Lower snow levels (4000-5000`)
will remain northwest of a line from Burns OR to McCall ID, with
warmer air south and east (7000-8000`) along the Snake Basin
and areas south. Southwest flow continues into Wednesday with
significant precipitation over the mountains through this time
period. The flow turns southerly and warm on Wednesday with
temperatures warming into the mid 50s again in the Snake Plain.
Mild and unsettled conditions continue Thursday and Friday with
snow levels lowering to 3500-5000`. Slightly cooler temperatures
expected on Thursday and Friday but still well above normal.
Conditions begin to dry out on Saturday.

&&

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

&&

$$

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DISCUSSION...LC
AVIATION.....JY
SHORT TERM...KA
LONG TERM....KA