A large long period northwest swell impacted the coastline on Sunday January 10th, prompting a High Surf Warning. Large breaking waves near 30 feet were forecast.
Every event with a place to put it; 6 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 MTR wrote it up.
A large long period northwest swell impacted the coastline on Sunday January 10th, prompting a High Surf Warning. Large breaking waves near 30 feet were forecast. Multiple water rescues occurred up and down the coast with two fatalities.
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 San Francisco Bay Area, CA wrote its last area forecast discussion before the first event at Jan 10, 3:37 AM PST, 3 hours 23 minutes earlier.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
337 AM PST Sun Jan 10 2021
.SYNOPSIS...High pressure will remain over California through
next week. As a result, dry conditions will prevail each day,
except for a slight chance of rain in northern Sonoma County on
Tuesday. Daytime temperatures are forecast to be near or above
normal for the week ahead. Near record temperatures are possible
on Thursday and Friday of next week. Otherwise, expect patchy
valley and delta fog each night and morning, which may be locally
dense at times.
&&
.DISCUSSION...As of 02:49 AM PST Sunday...Water vapor imagery
shows a weak shortwave trough moving into far NorCal overnight.
Additionally a wound up low pressure system in the Gulf of Alaska
has its cold front extending down the West Coast. The tail end of
the front and passing shortwave will result in light rain north of
the Bay Area and possibly a few showers into the far North Bay.
KBHX radar to the north does show light rain moving through
Eureka, but only a few showers southward to Mendocino. Latest HRRR
and WRF models do show a few echoes may reach Northern Sonoma by
sunrise, but not much in the way of accumulation.
Skies will clear this afternoon giving way to some afternoon
sunshine. Temperatures today will be a few cooler in the North Bay
due to the passing front, but southern areas will actually be a
tad warmer. Regardless, temperatures in the 50s and 60s are close
to or slightly above seasonal averages.
High pressure will briefly rebuild on Monday leading to slightly
warmer temperatures and dry conditions.
Another cold front is still on track to impact the West Coast by
Monday night into Tuesday. This front looks to have a little more
moisture associated with it bringing more rain to NorCal and
possibly the Bay Area. The tail of this front will also bring a
chance of light rain to the North Bay. Not expecting a lot of
precip, but some showers nonetheless. South of the Golden Gate
will be mainly dry and mild.
High pressure rebuilds Tuesday and Wednesday kicking off a marked
warming trend. Dry weather will also accompany the building high
pressure. No change from previous forecast as temperatures are
expected to soar to well above normal values. The warmest
temperatures are still expected Thursday and Friday with highs in
the upper 60s to mid 70s for the SF Bay Area and upper 70s to
lower 80s in the Monterey Bay Area.
&&
.AVIATION...as of 3:36 AM PST Sunday...For the 12Z TAFs. Mostly
VFR, but patchy fog VLIFR/IFR possible, particularly in the North
Bay this morning. Higher clouds move in as a weak system moves
into Northern California, but no precip is expected at Bay Area
terminals. Despite the increase in higher cloud cover, VFR is
expected through the day, with breezy onshore winds in the
afternoon. Models are trending toward an increase of midlevel
clouds Sunday night for the possibility of MVFR conditions with
isolated patchy fog in traditional sheltered areas.
Vicinity of KSFO...VFR. Winds are light as high clouds increase.
Possible brief low clouds development before 16z, but there is low
confidence in it. Breezy onshore winds in the afternoon as the
VFR conditions continue. Increasing chances for low to mid level
clouds Sunday night as winds weaken for the MVFR conditions
possible.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR with light winds despite an
occasional low cloud. Breezy onshore winds Sunday afternoon,
before weakening Sunday night. There is a sight chance at patchy
low clouds developing overnight into Monday morning, particularly
closer to the coast.
&&
.BEACHES...as of 3:30 AM PST Sunday...A new northwest swell
arrives Sunday and will build, impacting the coast. Large
breaking waves of 23 to 28 feet, locally in excess of 30 feet at
favored breakpoints especially at west to northwest facing
beaches. A High Surf Warning is in effect from 7 AM to 9 PM PST
Sunday. Additionally, sea surface temperatures remain cold, down
in the lower to mid 50s. Cold water drownings occur each year with
these events but are avoidable by remaining a safe distance from
the coastline.
While the swell and associated waves begin to subside late Sunday
into Monday, high astronomical tides will coincide with continued
larger than normal waves resulting in an increased risk of minor
coastal flooding. A Coastal Flood Advisory has been issued from 3
AM PST on Monday through 3 PM PST Monday.
&&
.MARINE...as of 02:34 AM PST Sunday...North to northwest winds
are light to moderate with an occasional stronger gust. A large,
long period northwest swell arrives Sunday providing enhanced
waves near harbor entrances through the evening. This swell will
make for hazardous seas, particularly for smaller vessels through
Monday. The next weak system moves over the coastal waters on
Tuesday night with a chance for light showers in the northern
outers waters.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...High Surf Warning...CAZ006-505-509-529-530
SCA...Pt Reyes to Pigeon Pt 0-10 nm from 9 AM
SCA...Pigeon Pt to Pt Pinos 0-10 nm from 9 AM
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...Mry Bay from 2 PM
&&
PUBLIC FORECAST: MM
AVIATION: DK
MARINE: DK
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www.youtube.com/nwsbayareaThe national radar mosaic for the moment the first event began.
6 high surf. Local standard time, as filed.
Santa Cruz Harbor Patrol rescued several people Sunday morning. Exact timing unknown https://www.ksbw.com/article/1500-santa-cruz-county-teachers-to-be-vaccinated-this-week/35485139.
Half Moon Bay Buoy reported waves between 16 to 20 feet at 17 to 20 seconds.
The Pacific Grove Police Department responded to around seven water rescues in a 30 minute span on Sunday due to large waves. Exact time of rescues unknown https://kion546.com/news/2021/01/10/pacific-grove-pd-rescues-several-people-caught-in-high-surf/.
A man and some friends were along the bluffs at Point Bonita when high surf swept three people into the ocean. Two were able to escape but one was not. Rescue crews searched but were unable to rescue him https://sanfrancisco.cbslocal.com/2021/01/11/update-woman-still-missing-after-being-swept-into-the-ocean-at-pescadero-beach/.
Sunday afternoon a man and woman were searching for mussels at Pescadero State Beach in San Mateo County when large waves swept them off the rocks. The man was rescued and taken to the hospital, but crews were unable to rescue the woman.
Large swell capsized several small boats near the Santa Cruz Harbor in the Monterey Bay Sunday afternoon. Twelve children part of a sail school needed to be rescued after sailboats were capsized. Patrols were already posted in the water and everyone was quickly rescued https://sanfrancisco.cbslocal.com/2021/01/10/massive-swells-capsize-sailboats-at-mouth-of-santa-cruz-harbor-12-children-rescued-from-turbulent-seas/.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| High Surf, Coastal North Bay Including Point Reyes National Seashore | 2021-01-10 | Male | In Water | Direct | |
| High Surf, San Francisco Peninsula Coast | 2021-01-10 | Female | In Water | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, 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: 932619, 932623, 932617, 932615, 932614, 932616.