The period from January 10 to 16 continued a pattern of a strong and persistent Aleutian Low pressure system in the eastern Pacific that began December 29, 2020 and which directed the jet stream and primary storm track at Washington State. This resulted in a series of atmospheric rivers and wind storms that battered Washington State.
Every event with a place to put it. 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 SEW wrote it up.
The period from January 10 to 16 continued a pattern of a strong and persistent Aleutian Low pressure system in the eastern Pacific that began December 29, 2020 and which directed the jet stream and primary storm track at Washington State. This resulted in a series of atmospheric rivers and wind storms that battered Washington State. Water vapor transport into Washington State averaged 160-200% of normal during the period from December 29 through January 16. Numerous periods of heavy rain occurred during this period, which in turn resulted in widespread and sustained river flooding, urban and small stream flooding, mudslides, and landslides in addition to the significant and widespread impacts from high winds, pounding surf, and coastal flooding.
During the wettest portion of this 19-day period, Washington State experienced widespread precipitation totals between 200% and 350% of normal. The prolonged bouts of moderate to heavy rain between January 10 and 16, 2021, resulted in 12 major rivers exceeding flood stage, 3 of them exceeded moderate flood.
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 Seattle, WA wrote its last area forecast discussion before the first event at Jan 12, 1:45 AM PST, 6 hours 15 minutes earlier.
Area Forecast Discussion
National Weather Service Seattle WA
145 AM PST Tue Jan 12 2021
.SYNOPSIS...It is going to be wet out there. With yet another
atmospheric river, Western Washington will experience an onslaught
of wet weather. Expect persistent rain even at higher elevations,
river and urban flooding, an increased risk of landslides as well
as strong winds for Tuesday. Wednesday will be more of the same
but with added mountain snow. Things should quiet down from
Thursday and into the weekend.
&&
.SHORT TERM /TODAY THROUGH THURSDAY/...With an atmospheric river
funneling moisture right towards Western Washington the next
couple of days are going to be rather wet throughout the region.
The rain that began yesterday will continue through today. As of
midnight the Cascade passes are still experiencing snow. Previous
model guidance really underestimated the persistent surface
easterly winds and moved the warm air into the region much too
soon. We do expect that that these snow showers to change over to
rain as the surface winds veer more south/southwesterly. This wind
shift will continue through the night and we expect the snow at
the passes to be fully changed over to rain at by 10 AM. With
steady south/southwesterly flow aloft and at the surface snow
levels are expected to rise above 7000 feet.
With the high snow levels, a steady flow of moisture as well as
terrain enhancement 2-4 inches of rain is likely in the Cascades
as well as the Olympics. With this much rain falling at high
elevations as well as on average another 1-2 inches in the
lowlands, we anticipate flooding from both rivers rising above
banks as well as urban flooding. See the hydrology discussion
below for more details.
Alongside the flooding potential we also have an increase risk of
landslides occuring throughout the area. With already saturated
soils and rain continuing slopes are unstable and will remain so
for the next few days.
Due to the timing of the system moving through the area, the King
Tides, as well as higher winds we anticipate some coastal flooding
to occur at shorelines for all the area waters. At the coast
specifically we also expect large waves greater than 20 ft to run
up on shore creating for dangerous beach conditions. Alongside of
the the large waves sneaker waves are also likely to occur so
remember to not turn your back on the ocean.
The final portion of the Tuesday forecast is the area winds. Winds
are expected to remain sub advisory level for the Western
Washington area. The highest winds today will come in two
batches, one in the morning and one later tonight. Power outages
and downed trees may occur as a result of these higher gusts.
Wednesday will be a bit of a repeat but a little less intense.
Additionally, snow levels are expected to drop back down to
2000-3000 feet which will create for wintery conditions along the
passes.
Thursday will be the start to some relief from these atmospheric
river systems, as ridge will be moving through the area during the
day. So that should give us time to dry out just a little bit
before some more weather heads our way.
Butwin
.LONG TERM /FRIDAY THROUGH MONDAY/...Friday will be a return to
wet weather but it will not be as intense as what we are
experiencing now here at the beginning of the week. A ridge will
be exiting the area Thursday night and behind it are a series of
shortwave disturbances that will bring some light rain and
mountain snow to the area. These weak disturbances will continue
through the weekend.
Butwin
&&
.AVIATION...Rain will continue across Western Washington into early
Wednesday as an atmospheric river impacts the area. In addition to
widespread rain, southwest winds will be gusty through early this
morning and again tonight into Wednesday morning, particularly at
coastal terminals and in the North Interior. Mostly MVFR conditions
through the period with periods of IFR to LIFR in heavier rain.
KSEA...MVFR conditions with rain likely through the period though
could see brief periods of IFR ceilings during heavier rain.
Southerly winds through the period 10 to 15 kts with gusts up to 25
kts this morning and again this afternoon into tonight.
Carpenter
&&
.MARINE...A frontal system will stall over the area through
today with small craft advisory strength winds at times for most
waters. Gale force southerly winds will continue through this
morning for the Coastal Waters, East Entrance Strait of Juan de
Fuca, and Northern Inland Waters. In addition to the wind, seas will
build across the coastal waters with seas of 18-22 feet. Another
push of gusty winds is likely tonight into Wednesday. Portions of
the coastal waters and Strait may push gale criteria again. Current
forecast has winds just shy of this criteria so have put out small
craft advisories but trends will need to be monitored by next shift
for possible upgrade. Winds will ease Wednesday night with a break
in the action until later Thursday into Friday.
Carpenter
&&
.HYDROLOGY...Atmospheric river event is underway. Rainfall totals
over the past 24 hours are between 2 to 4 inches on the Olympic
Peninsula, 0.3 to around an inch in the lowlands, and around an inch
in the Cascades. As heavy rain continues, expect an additional 1 to
4 inches in the Olympic Peninsula, 0.25 to 1.5 inches in the
lowlands, and 2 to 4 inches in the Cascades. Easterly flow has won
out a bit at the Cascade passes but snow levels are on the rise
everywhere and should rise to 6000 to 8000 feet today.
National Water Model shows deep ground saturation across the area
and streamflows running above average in most basins. Rainfall for
the past 7-14 days is running some 150-300% of normal across the
area. All this combined with additional heavy rainfall will create
renewed concern for landslide threat as well as localized urban and
small stream flooding. Area rivers have begun to respond with rapid
rises expected today into Wednesday. Given latest precipitation and
snow level forecasts, the potential for river flooding remains
pretty much area-wide over the next 24 to 48 hours. The greatest
flooding threat remains on rivers flowing out of the Olympics and
the interior from King County southward. The Skokomish River near
Potlatch is already approaching moderate flood stage. River
forecasts can change frequently so those with interest should keep a
close eye on things.
Carpenter
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch through Wednesday evening for Admiralty Inlet Area-
Bellevue and Vicinity-Bremerton and Vicinity-Cascades of
Pierce and Lewis Counties-Cascades of Snohomish and King
Counties-Cascades of Whatcom and Skagit Counties-Central
Coast-East Puget Sound Lowlands-Eastern Strait of Juan de
Fuca-Everett and Vicinity-Hood Canal Area-Lower Chehalis
Valley Area-North Coast-Olympics-San Juan County-Seattle
and Vicinity-Southwest Interior-Tacoma Area-Western Skagit
County-Western Strait of Juan De Fuca-Western Whatcom
County.
Coastal Flood Advisory until 8 AM PST this morning for Admiralty
Inlet Area-Bremerton and Vicinity-Everett and Vicinity-Hood
Canal Area-San Juan County-Seattle and Vicinity-Tacoma Area-
Western Skagit County-Western Whatcom County.
Winter Storm Warning until 4 PM PST this afternoon for Cascades
of Snohomish and King Counties-Cascades of Whatcom and
Skagit Counties.
Coastal Flood Advisory from 9 AM this morning to 3 PM PST this
afternoon for Central Coast-Eastern Strait of Juan de Fuca-
North Coast-Western Strait of Juan De Fuca.
PZ...Small Craft Advisory until 4 PM PST this afternoon for Grays
Harbor Bar.
Gale Warning until 7 AM PST this morning for Coastal Waters From
Cape Flattery To James Island 10 To 60 Nm-Coastal Waters
From Cape Flattery To James Island Out 10 Nm-Coastal Waters
From James Island To Point Grenville 10 To 60 Nm-Coastal
Waters From James Island To Point Grenville Out 10 Nm-
Coastal Waters From Point Grenville To Cape Shoalwater 10
To 60 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater Out 10 Nm.
Gale Warning until 6 AM PST early this morning for East Entrance
U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters
Including The San Juan Islands.
Small Craft Advisory until 4 AM PST Wednesday for Admiralty
Inlet-Puget Sound and Hood Canal-West Entrance U.S. Waters
Strait Of Juan De Fuca.
Small Craft Advisory until 7 AM PST this morning for Central
U.S. Waters Strait Of Juan De Fuca.
&&
www.weather.gov/seattleThe national radar mosaic for the moment the first event began.
7 flood. Local standard time, as filed.
The Snoqualmie and White Rivers exceeded flood stage. Urban and small stream flooding occurred as well. Heavy rain caused some landslides.
The Snohomish, Skykomish, and Stillaguamish Rivers exceeded flood stage. Urban and small stream flooding also occurred. Heavy rain caused some landslides.
Heavy rain caused surface runoff, landslides, and urban and small stream flooding. One to three inches of rain fell during the day.
The Satsop River near Satsop and Chehalis River at Porter exceeded flood stage. Urban and small stream flooding also occurred.
The Chehalis River near Grand Mound and Skookumchuck River near Bucoda crested above moderate flood. Urban and small stream flooding occurred as well.
The Skokomish River exceeded moderate flood stage. Urban and small stream flooding occurred as well.
The Cowlitz River at Randle and Newaukum River near Chehalis exceeded flood stage. Urban and small stream flooding occurred also.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2021Every state in 2021This day in weather historyWarnings in Washington, January 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: 994294, 994295, 994296, 994292, 994275, 994293, 994291.