The first major winter storm of the season dumped over a foot of snow in the Cascades and the highest elevations of the Coast Range. Much of the snow fell on the 11th in the higher elevations, then snow levels lowered enough to produce significant accumulations in many areas above 2500 feet.
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 PQR wrote it up.
The first major winter storm of the season dumped over a foot of snow in the Cascades and the highest elevations of the Coast Range. Much of the snow fell on the 11th in the higher elevations, then snow levels lowered enough to produce significant accumulations in many areas above 2500 feet.
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 Portland, OR wrote its last area forecast discussion before the first event at Dec 10, 8:30 PM PST, 6 hours 30 minutes earlier.
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
830 PM PST Fri Dec 10 2021
Updated Aviation and Marine Sections
.SYNOPSIS...A strong front will move through the region tonight and
Saturday accompanied by strong southerly winds, rain, and heavy snow
in the Cascades. Cool and wet weather continues into next week.
&&
.SHORT TERM...TONIGHT THROUGH MONDAY...Water vapor satellite imagery
shows a deep upper level trough across the Gulf of Alaska driving a
long fetch of moisture toward Vancouver Island. A strong frontal
system in the NE Pacific will impact the region later tonight
through Saturday. A warm front pushing inland this evening will
increase light precipitation and southerly winds. Winds will
gradually increase as the cold front approaches the coast tonight.
The High Winds Warning along the coastline looks on track with gusts
in the 60-70 mph range, mainly along beaches and headlands late
tonight through Saturday morning. A wind advisory is also in place
for the Willamette Valley during the same timeframe with gusts as
high as 45-50 mph appearing likely. Rain will also be heavy at times
as the front slides south, beginning early Saturday morning across
the northern forecast area and continuing into Saturday evening. A
strong upper level jet with 130 kt core will support the heavy
precipitation with IVT values indicating weak to moderate
atmospheric river conditions. Expecting upwards of 2-3 inches of
rainfall along the coast, and locally higher amounts in the higher
terrain of the Coast Range. Models and ensembles have been
consistent with rainfall amounts around 1.5 inches in the valley.
Still not expecting widespread hydro concerns, but will have to
monitor some of the more responsive river basins over the weekend.
The combination of forcing and modest instability could be enough
for another round of low topped thunderstorms near the coast from
Saturday morning through much of the day Sunday as the upper trough
remains offshore.
Confidence remains high for heavy snow in the Cascades, generally
above 3000 ft. The Winter Storm Warning remains on track with storm
total amounts of 1 to 2 feet expected by Sunday morning. A warm
tongue of air ahead of the front will cause snow levels over the
Coast Range to climb to around 4000 feet, so minimal winter concerns
there. Snow levels along the Cascades will start out somewhat high
initially around 3500-4000 ft Saturday morning, but expected to
lower to around 2500-3000 ft by Saturday night. Snow levels will
continue to fall behind the front to around 1500 ft Sunday morning.
Expect more showery conditions with lower QPF values on Sunday as
southwesterly onshore flow continues ahead of an amplifying trough.
By Monday, the upper trough will be digging south off the coast of
California. A vorticity max may split off and spin up a weak surface
low off the Oregon coast. Expect cool, showery weather pattern to
continue into early next week with snow levels generally around 2000-
2500 ft. /DH
&&
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...A generally cool and wet
pattern will linger through much of next week. WPC 500 mb cluster
analysis, along with the majority of models and their ensembles,
show upper level troughing persisting over the Pacific Northwest
through Thursday. At the surface weak low pressure and onshore flow
will likely maintain a showery weather pattern. Ensemble and NBM
guidance suggest Wednesday could be the wettest day in the long term
period, but not expecting any strong fronts to impact the region at
this time. Snow levels will generally hover around 1000 ft through
Tuesday night as the colder air filters into the region. Also expect
chilly mornings with temperatures falling to near freezing Tue and
Wed mornings. NBM guidance along with some ensemble members show
around a 30% chance of a trace amount of snow in the lowlands, but
do not expect any accumulation. Toward the end of the week models
are split between continued troughing or weak ridging over the
region. /DH
&&
.AVIATION...06Z TAFs: Shortly after 04Z water vapor satellite
imagery showed a strengthening cold front developing offshore
while the warm frontal portion continued to move across
Washington and northern Oregon. Conditions at 04Z were generally
a mix of MVFR and VFR, with cigs 025-035. Coastal conditions will
become predominant VFR between 06Z and 09Z Sat and then become a
mix of IFR and MVFR by 12Z. Expect coastal frontal passage
between 12Z and 14Z along the south Washington and north Oregon
coast and closer to 16Z for the central coast of Oregon. Coastal
conditions improve to at least MVFR by early afternoon and
possibly VFR mid to late afternoon. Inland areas should be
primarily MVFR overnight. There is the possibility of localized
IFR between 12Z and 18Z Sat, especially in the southwest
Washington and far northwest Oregon interior lowlands.
Wind speeds will continue to strengthen ahead of the front
overnight into the early morning hours. Gusts to 50 kt likely for
the coastal areas and 30-40 kt for the interior lowlands. Model
soundings for Willamette Valley TAF sites suggest 35-40 kt of
wind shear overnight through about 17Z. Soundings for KPDX and
KSLE show surface wind speeds of 10-15 kt, but 45-55 kt at FL
020. Soundings also show southwest wind speeds to 65 kt between
FL030 and 060. Thus, will indicate LLWS for all inland TAF sites,
except KEUG.
For detailed regional Pac NW aviation weather information, go
online to: https://weather.gov/zse
KPDX AND APPROACHES...Cigs 025-035 at the terminal and vicinity
as of 0430Z. Expect conditions to become predominant MVFR
overnight and remain that way well into Sat afternoon. Strong
cold front reaches the terminal around 18Z. Gusty south wind is
expected through 18Z Sat, with the strongest wind speeds
occurring around 12Z-17Z. The highest gusts are expected to be
around 35 kt. The 00Z HREF 10m AGL ensemble mean max gust
guidance shows gusts to 45 kt shortly before frontal passage.
The ensemble mean for the same time frame is generally 30-35 kt.
Wind speeds quickly diminish Sat afternoon. Will include LLWS
10Z-17Z Sat. Model soundings show south surface wind 10-15 kt,
but SSW 45-55 kt at FL020. This translates to nearly 40 kt of
overall shear. Weishaar
&&
.MARINE...No changes to marine forecast. The forecast is on
track as the broad low pressure system and strengthening cold
front drop down from the Gulf of Alaska through Saturday.
Expecting widespread gale force winds and building seas.
Southerly winds have increased this evening and are expected to
be in the 30 to 35 kt range with gusts up to 40 kt by early
Saturday morning. Likely will see gusts up to 45 kt, and there is
a chance the waters could see isolated gusts up to 50 kt.
Confidence of those 50 kt winds is low, and if they do occur,
they are more likely near the shore within the coastal jet that
is likely to form. With the increase in winds, the associated
wind wave will amplify greatly. Looking at a 4 ft southerly wind
wave increasing to around 7 to 9 ft in the central waters. In the
post frontal environment, winds will ease to small craft
advisory levels (20 to 25 kt with gusts up to 30 kt) by late
Saturday night, and remain around 15 to 20 kt with gusts around
25 kt through much of early next week.
As the front passes, the fresh westerly swell will move in
which, in combination with wind waves, will cause general seas to
build on Sunday. Expecting seas around 16 to 18 ft at 14
seconds, with the significant wave heights around 20 ft. Those 20
ft seas likely will just be isolated and are not expected to be
widespread. However, it is something to take note of. The highest
seas likely will occur around late morning Sunday through the
early evening. Seas will slowly subside on Monday afternoon.
-Muessle/Weishaar
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning from 8 AM Saturday to 8 AM PST Sunday for
Cascades in Lane County-Northern Oregon Cascades.
High Wind Warning from 1 AM to 1 PM PST Saturday for Central
Oregon Coast.
Wind Advisory until 10 AM PST Saturday for Central Willamette
Valley-Greater Portland Metro Area-South Willamette Valley.
High Wind Warning until 10 AM PST Saturday for North Oregon
Coast.
WA...Winter Storm Warning until 8 AM PST Sunday for South Washington
Cascades.
High Wind Warning until 7 AM PST Saturday for South Washington
Coast.
PZ...Gale Warning until 9 AM PST Saturday for coastal waters from
Cape Shoalwater WA to Cascade Head OR out 60 nm.
Gale Warning until 3 PM PST Saturday for coastal waters from
Cascade Head OR to Florence OR out 60 nm.
Small Craft Advisory until 4 PM PST Saturday for Columbia River
Bar.
&&2 heavy snow. Local standard time, as filed.
A range of 15 to 30 inches of snow fell between December 10-13. Rates were generally advisory level, but there was a 12 hour period where 10 to 14 inches of snow fell early on the 11th.
Generally 12 to 24 inches of snow fell between December 10-13. Summit Lake SNOTEL recorded 33 inches. Rates were mostly advisory level, but 10 to 16 inches of snow fell over a 12 hour period on the 11th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2021Every state in 2021This day in weather historyWarnings in Oregon, 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: 997788, 997791.