A deep low off the coast of Oregon spread heavy snow across Southeast Oregon and Southwest Idaho over a 2 day period.
Every event with a place to put it; 4 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 low off the coast of Oregon spread heavy snow across Southeast Oregon and Southwest Idaho over a 2 day period.
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 Feb 11, 2:08 PM MST, 5 hours 52 minutes earlier.
Area Forecast Discussion
National Weather Service Boise ID
208 PM MST Thu Feb 11 2021
.SHORT TERM...Tonight through Saturday night...Flurries or
sprinkles this afternoon will become steadier precipitation this
evening, then all snow late tonight through Friday as the first of
three Pacific storms moves inland. Winter Weather Advisories will
continue in effect for this first storm tonight through Friday in
Baker County, the West Central Idaho Mountains, Boise Mountains,
and Upper Weiser River area. Southern valleys will have little if
any snow accumulation tonight, but will get up to an inch Friday
morning as temperatures lower to freezing. Roads at lowest
elevations should stay wet, but may become icy around sunrise
Friday. After a short break, the second Pacific storm will bring
more snow late Friday night through Saturday, this time targeting
southeast Oregon and southern Idaho, although northern areas,
especially northern mountains, will also get several inches. The
second storm will be colder and wetter than the first, and snow is
expected to accumulate 2 to 4 inches across the Snake Basin in
addition to the rest of southeast Oregon and southwest Idaho
through Saturday. Snow will decrease from west to east Saturday
afternoon and evening. Partial clearing Saturday night will allow
low temperatures Sunday morning to drop to the single digits in
the mountains and 10 to 20 in the valleys. The third Pacific storm
will reach eastern Oregon late Sunday.
.LONG TERM...Sunday through Thursday...Northwest flow aloft will
continue. Models continue to indicate another strong surge of
moisture moving into eastern Oregon late Sunday night, with
snow spreading into the Idaho zones early Monday morning. Early
to mid-morning snowfall remains possible across the Treasure
Valley for Monday. The biggest question for early next week will
be how warm we get considering we potentially will have snow on
the ground, which would tend to keep the region cooler and
therefore allow precipitation to remain as snow vs a rain/snow
mix. The afternoon package does keep snowfall across the Upper and
Lower Treasure Valleys Monday. Lingering snow is possible Tuesday
as the northwest flow aloft continues over the region. A brief
upper ridge axis will move over the area Wednesday night and
Thursday morning but another upper low will push into the Pac NW
Thursday afternoon. This system will have southwest flow aloft
out ahead of it. Therefore, the lower valleys should see a threat
of rain with the mountains remaining as snow. Temperatures will
generally be 5 to 10 degrees below normal through the forecast
period.
&&
.AVIATION...MVFR to IFR conditions are expected to prevail
through the evening due to low clouds and snow ahead of a wintry
system. Mountain obscurations expected. Some improvement in
conditions is expected across Eastern Oregon potentially after
midnight tonight and into Idaho by sunrise. Flight restrictions
are still possible Friday. Surface winds: Variable generally less
than 10 kts...except southwest 10 to 15 kts near the NV border.
Winds becoming westerly 10 to 15 kts Friday afternoon. Winds
aloft at 10kft MSL: West-northwest 25 to 40 kts.
Weekend Outlook...MVFR to IFR conditions with gusty surface winds
Saturday under the influence of another wintry system. A lull in
activity anticipated for Sunday, with a return of snowfall on
Sunday night. Periods of mountain obscuration will continue.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until 5 PM MST Friday IDZ011-013-033.
Winter Weather Advisory from 11 PM Friday to 11 PM MST Saturday
IDZ012-014>016-029-030-033.
OR...Winter Weather Advisory until 4 PM PST Friday ORZ062.
Winter Weather Advisory from 11 PM MST /10 PM PST/ Friday to 11
PM MST /10 PM PST/ Saturday ORZ062>064.
Winter Weather Advisory from 10 PM Friday to 10 AM PST Saturday
ORZ061.
&&
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SHORT TERM...LC
LONG TERM....CR
AVIATION.....CRThe national radar mosaic for the moment the first event began.
4 heavy snow. Local standard time, as filed.
The National Weather Service measured over 10 inches of snow during a two day period and received reports of 8 to 12 inches throughout the Treasure valley.
The COOP observer at Cambridge reported 12 inches of new snow with reports of 9 to 14 inches of snow around the Council area.
The observer near Placerville reported 14 inches of new snow with reports of 9 to 12 inches of snow around the Idaho City area.
Numerous reports were received from the public of 8 to 12 inches of snow across the Lower Treasure Valley.
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, February 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: 944608, 945794, 945793, 945778.