A deep upper level trough brought cold air and with several embedded short wave troughs that brought a few rounds of snow for southwest Idaho and southeast Oregon through December 26th, 2021.
Every event with a place to put it; 8 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS BOI wrote it up.
A deep upper level trough brought cold air and with several embedded short wave troughs that brought a few rounds of snow for southwest Idaho and southeast Oregon through December 26th, 2021.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Boise, ID wrote its last area forecast discussion before the first event at Dec 23, 2:41 PM MST, 2 hours 11 minutes earlier.
Area Forecast Discussion
National Weather Service Boise ID
241 PM MST Thu Dec 23 2021
.SHORT TERM...Tonight through Saturday night...No significant forecast
changes through Christmas morning. Cold front will come in from
the west tonight through Friday morning with increasing snow above
5000 feet, and rain below that will change to snow behind the
front. Heavy snow will fall at higher elevations, especially north
of the Snake Basin where a Winter Storm Warning will continue
through 5 PM MST Christmas Day. The warning may be extended beyond
that time by later shifts. In the Treasure Valley rain should
change to wet snow around 5 AM and may accumulate an inch by
sunrise, but roads should stay wet, or at worst slushy. The Wind
Advisory in Owyhee and southern Twin Falls Counties will continue
until 5 PM MST this afternoon. Temperatures will gradually become
colder Friday and Christmas Day with snow, heavy at times,
continuing in the West Central Idaho Mountains and Boise Mountains,
and lighter snow showers elsewhere with an inch or two accumulations.
.LONG TERM...Sunday through Thursday...Good model agreement
continues into the extended period indicating an active, unsettled
pattern. A series of disturbances and lingering moisture will keep
snow falling across much of the forecast period, with brief lulls
anticipated between systems. Near normal temperatures will start
off the extended period, but an arctic air mass will drop into
the Pacific Northwest behind the trough on Monday lowering
afternoon high temperatures to about 15 degrees below normal
Tuesday through Thursday. Frigid overnight lows are expected,
ranging from single digits and teens to as low as 10 below zero
in the mountain valleys. Periods of gusty conditions can be
expected between systems. Additional snow accumulations will
continue in the mountains with lighter snow showers elsewhere as
an upper trough remains over the area.
&&
.AVIATION...VFR conditions expected with lingering MVFR/IFR
conditions across Idaho's Central Mountains southward toward KTWF
due to low clouds and lingering showers. Mountains will be
obscured the next several days. Next system will move in
overnight bringing widespread MVFR/IFR conditions. Snow levels
will lower to near the valley floors by morning.
Surface winds: Southeast to southwest 10 to 15kt with local gusts
20 to 25kt generally south of a KTWF-KBOI-KBNO line. Winds near
10kft MSL: West to Southwest 30 to 50 kt.
Weekend Outlook...Periods of snow will continue MVFR to IFR
conditions. Mountains will remain obscured. Gusty south or
southwest winds will continue, especially south and west of the
Snake Plain.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until 5 PM MST Saturday IDZ011-013.
Wind Advisory until 5 PM MST this afternoon IDZ015-030.
Winter Weather Advisory until 5 PM MST Saturday IDZ029.
OR...None.
&&
www.weather.gov/Boise
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www.twitter.com/NWSBoise
SHORT TERM...LC
LONG TERM....CR
AVIATION.....CRThe national radar mosaic for the moment the first event began.
8 heavy snow. Local standard time, as filed.
The McCall town snow stake measured 2.0 inches at 5,030 feet.
A CO-OP Observer in Murphy Hot Springs reported 10.5 inches of total snowfall.
A CoCoRaHS observer measured 6.5 inches of snow about three miles southeast of Filer.
A CoCoRaHS station measured 3.3 inches two miles northwest of New Meadows, ID.
A member of the public reported 7.0 inches of snow about five miles south of Hazleton, ID.
Total snowfall of 5.0 inches in the last twelve hours and 9.0 inches in 48 hours in Kimberly, ID.
A CoCoRaHS observer measured 3.0 inches of snow in Yellow Pine, ID.
A spotter measured 14.5 inches of snow one mile south of Featherville, ID.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2021Every state in 2021This day in weather historyWarnings in Idaho, December 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 999185, 997741, 997752, 999160, 999189, 997740, 999187, 997754.