Garden City, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

793
FXUS65 KBOI 070441
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
941 PM MST Thu Feb 6 2025

.DISCUSSION...Potent shortwave now entering the northern CA
coast this evening. This will track northeastward across
southeast OR overnight and into SW Idaho by morning. The center
of the trough is forecast to pass right over Boise by Friday
morning, which will increase snow amounts in the Treasure
Valley, with highest amounts near Ontario OR, ramping down
toward Boise. Generally 1 to 3 inches in the lower Treasure
Valley, with an inch or less across Boise and Meridian (with
around a 25% chance of receiving more than an inch), with a
dusting from Mountain Home to the Magic Valley. Forecast has
been updated for slightly cooler temperatures tonight, which
will adjust the snow accumulation forecast in the lower Treasure
Valley. As the system moves east of the area, strong west to
northwest winds expected on Friday afternoon, and the current
wind forecast reflects that well. Minor updates coming out
shortly.

&&

.AVIATION...Widespread MVFR to LIFR in snow for KBNO/KBKE/KONO areas
spreading into SW Idaho this evening, especially across the
mountains north of Interstate 84. Terrain shadowing will limit Snake
Plain precipitation rates/accumulations. SE of a KMYL-KREO line snow
levels will rise to around 4-5 kft MSL. In that same region,
precipitation may be more convective and showery, suggesting graupel
may be possible with a very slim chance of lightning. Areas of 20-30
kt LLWS including KMUO/KJER/and KTWF, primarily Fri/08z to Fri/18z.
Surface winds: S-SE 5-15kt, becoming SW-W 10-20kt with gusts to 25kt
Friday morning, increasing to 20-30kt with gusts up to 45kt in
highlands near the ID-NV border and Magic Valley. Winds aloft at
10kft MSL: SW 35-55kt tonight becoming W-NW 25-45kt Friday morning.

.KBOI...VFR and overcast with periods of MVFR in light snow
showers. Terrain shadowing should limit IFR conditions, but brief
periods early tonight are possible due to showery precipitation.
Becoming mixed precipitation early Friday morning. Winds SE 5-15kt,
becoming W-NW 10-20 kt Friday around noon.

.WEEKEND OUTLOOK...Generally VFR, with brief MVFR/IFR in mountains
due to isolated snow showers. Surface winds: NW 5-15 kt. 10kft MSL:
NW 5-15 kt.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Saturday night...Satellite
imagery at 1:30 PM MST shows the next Pacific storm system
moving east-northeast over northern California. This system is
expected to bring moderate snowfall and gusty winds to parts of
the region tonight through Friday, impacting road conditions for
the Friday morning commute.

Precipitation will increase this evening ahead of a warm
frontal boundary, initially affecting southeast Oregon before
expanding into southwest Idaho early Friday morning. A strong
band of moderate snowfall is expected to develop along the warm
front as a surface low tracks northeast. The heaviest snowfall
is forecast along and north of a Burns to Ontario to Lowman
line, where lower valleys could receive 2 to 4 inches of snow by
Friday morning, while mountain valleys may see 4 to 8 inches by
Friday afternoon. Snow-covered roads could create hazardous
travel conditions.

Further south, the remaining Treasure Valley (from Caldwell
through Glenns Ferry) and the Western Magic Valley will receive
far less precipitation due to downsloping from strong
southwesterly winds aloft (40-60 kts) and warmer surface
temperatures. Ensemble guidance indicates an 80% chance of
snowfall exceeding 1 inch for Ontario, while Caldwell, Boise,
and Mountain Home have a much lower probability (around 20%)
further supporting the influence of downslope winds. Snowfall
accumulations of less than half an inch are expected early
Friday morning in these areas, potentially creating slushy
conditions for the Boise Metro commute.

As the cold front with the surface low moves east-northeast
late Friday morning, it will bring convective showers and gusty
winds. Some high-resolution models indicate a 5% chance of
lightning and a 60% chance of a rain/snow/graupel mix with
strongest showers. The strongest winds will develop behind the
front Friday afternoon, affecting the southern highlands, Owyhee
Mountains, southern Twin Falls County, and the Western Magic
Valley. No changes to the current Winter Weather Advisories or
Wind Advisories.

Colder, drier conditions will follow on Saturday under northerly
flow. Areas with snow cover will experience single-digit
temperatures in the lower valleys, while regions with little to
no snow cover will drop into the teens. High temperatures will
remain cold, with snow-covered valley areas struggling to rise
above freezing.

LONG TERM...Sunday through Thursday...Colder N/NW flow dominates
through Thursday morning, favoring a cooling trend with just enough
moisture for a 15% chance of snow showers over mountains each day.
The Camas Prairie, and potentially other basins, is very likely to
end up much colder than the forecast, so a manual adjustment was
made to keep it below model solutions. The coldness reaches it`s
peak (or nadir?) Wednesday morning, after a very strongly positively
tilted passes Tuesday afternoon. It will briefly bring in much
colder air Wednesday and Thursday mornings, so expect an algid
commute in the middle of next week. The good news is that Thursday
afternoon the flow aloft becomes much more zonal as our next system
approaches, allowing temperatures to rise quickly. Models seem to be
doing a better job on agreeing on the forecast after Thursday.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until 5 PM MST Friday
     IDZ011-013-028-033.
     Wind Advisory from 8 AM to 5 PM MST Friday IDZ015-016-029-030.
OR...Winter Weather Advisory until 5 PM MST /4 PM PST/ Friday
     ORZ061>064.

&&

$$

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DISCUSSION...KA
AVIATION.....TL
SHORT TERM...JDS
LONG TERM....JM