Nampa, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

707
FXUS65 KBOI 221047
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
347 AM MST Sun Dec 22 2024

.SHORT TERM...Today through Tuesday night...Progressive pattern
with rapid day to day changes as upper troughs and ridges come
in from the north Pacific. Ridge this morning over our CWA with
mostly cloudy skies and little if any pcpn. Patchy fog also
observed in the valleys. Next trough just off the northwest
coast will bring more valley rain and mountain snow tonight,
especially to central and northern areas before exiting east
Monday. Next ridge and relative drying later Monday and Monday
evening, then heavier pcpn with the next Pacific trough Tuesday,
followed by clearing Tuesday night into Christmas morning as
the next ridge comes in. Temperatures continuing 5 to 10
degrees above normal. Snow level generally near 5000 feet north
to 7000 feet along the NV border. Total (liquid equivalent)
pcpn through 5 AM MST Christmas morning should be 0.75 to 1.25
inch in the northern third of our CWA, and generally .25 to .75
inch in central and southern areas. Total snowfall 8 to 14
inches in higher northern mountains, 1-3 inches at 5000 feet,
and little or none below 5000 feet. No significant winds through
Christmas Eve.

.LONG TERM...Wednesday through Sunday...An upper level ridge will
briefly move overhead on Christmas Day, bringing dry conditions.
Temperatures will be several degrees cooler than Tuesday but still
around 5 degrees above normal. Breezy winds in the Magic Valley
will subside through the day as a trough moves east. A very
active period will then develop Thursday through Sunday as an
upper low in the Gulf of Alaska brings abundant moisture and a
series of shortwave troughs into the Pacific Northwest. The
first trough will arrive Thursday with widespread rain and snow.
Ensembles disagree on how much cold air will remain entrenched
as moisture moves into the area, with the GEFS indicating enough
cold air for a chance of valley snow while the ENS generally
pushes the cold air out and allows snow levels to rise to
3500-4500 feet. The NBM depicts this uncertainty with about a
30% chance of measurable snow in the Treasure Valley. The
forecast currently leans closer to the ENS solution with snow
levels just above lowest valley floors, but this trend will be
monitored as the event draws closer. Moderate precipitation
amounts are expected with this system.

Another trough will move through on Friday, with ensembles in
agreement that snow levels will be high enough for rain in the
Treasure Valley with a rain/snow mix possible in the Magic Valley.
Moderate precipitation amounts are once again expected with this
system. Additional troughs will move through Saturday and Sunday
with more rain and snow. Snow levels are expected to rise to
5000-7000 feet over the weekend as the flow aloft becomes more
southwesterly and transports warmer air into our area.
Temperatures will climb to 5-15 degrees above normal.

The active pattern Thursday through the weekend will result
in heavy precipitation totals, with the mountains above 6000
feet likely to see several feet of snow, and lesser but
potentially still heavy amounts in mountain valleys. Lower
valley precipitation (mostly rain) totals of 0.5 to 1 inch
are forecast.

&&

.AVIATION...Areas of LIFR fog this morning in valleys. Very
light valley rain/mountain snow today, resulting in areas of
MVFR/IFR conditions in the mountains. Tonight, widespread valley
rain/mountain snow resulting in MVFR/IFR conditions will move
across the area. Snow levels 4000-5500 ft MSL today, rising to
5500-7000 ft tonight. Mountains frequently obscured. Surface
winds: SE-SW 5-15 kt. Winds aloft at 10kft MSL: SW 20-30 kt.

KBOI...MVFR conditions this morning from mist. Fog is expected
to remain west of the terminal near KMAN/KEUL. Low VFR cigs
today with a 10% chance of rain showers at the terminal.
Rain will increase tonight, mainly after 06Z/Mon, with cigs
lowering to MVFR. Surface winds light this morning, becoming
SE 4-8 kt this afternoon.

&&

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

&&

$$

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SHORT TERM...LC
LONG TERM....ST
AVIATION.....ST