An amplifying ridge over the Pacific and a deep upper trough over the Great Basin provided the set up for strong northerly flow over most of central and northern California. Winds gusted as high as 78 mph up on Mt Saint Helena with widespread gusts of 40 to 60 mph reported.
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.
An amplifying ridge over the Pacific and a deep upper trough over the Great Basin provided the set up for strong northerly flow over most of central and northern California. Winds gusted as high as 78 mph up on Mt Saint Helena with widespread gusts of 40 to 60 mph reported. These winds prompted both Wind Advisory and Gale Warnings across much of the region. Numerous downed trees were reported and a fatality occurred on the San Francisco Bay as a result of these conditions.
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 Dec 31, 3:34 AM PST, 2 hours 26 minutes earlier.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
334 AM PST Mon Dec 31 2018
.SYNOPSIS...Dry conditions with seasonable highs and cold overnight
lows will prevail through the majority of the work week ahead.
Gusty north winds will impact the higher elevations as well as
the San Francisco Bay Shoreline through the day. Temperatures may
fall below freezing in the colder valleys late Monday night into
early Tuesday and again late Tuesday night into early Wednesday. A
chance of rain finally returns to the forecast next weekend.
&&
.DISCUSSION...As of 2:40 AM PST Monday...The main story for today
will be the moderate to strong northerly winds that will impact
portions of the San Francisco Bay Area and Central California
Coast. At this time, we remain between an amplifying ridge to the
west over the Pacific and a digging upper trough over the Great
Basin. This synoptic setup is providing the resultant northerly
flow over most of central and northern California, and with that
the breezy conditions expected for a good portion of the region
for the final day of the calendar year. Winds in the higher
elevations of the North Bay are already gusting above 40 mph with
the PG/E weather station on the west side of Mount Saint Helena
reporting a peak gust of least 67 mph. As a result, a Wind
Advisory went into effect as of midnight Monday for the North Bay
Mountains, the East Bay Hills, and the Santa Cruz Mountains. Winds
will gradually diminish late Monday night and into Tuesday
morning across the higher elevations.
As the morning progresses, these stronger north to northeast
winds that have thus far been generally confined to the higher
elevations are expected to mix down to the surface, and eventually
to sea level. This will result in an uptick in wind speeds across
much of the Bay Area by mid-morning or lunchtime, including
populated areas such as San Francisco, Oakland, and Fremont. North
to northeast winds of 15 to 25 mph with gusts of 35 to 45 mph
will have the potential to knock down tree limbs and may make
driving difficult, particularly along west/east-oriented
roads/bridges -- including (but not limited to) the Bay Bridge,
San Mateo Bridge, and Dumbarton Bridge. A Wind Advisory will go
into effect at 9 am PST Monday for the San Francisco Bay Shoreline
and Delta area, and continue into the evening hours.
With New Year's Eve events taking place all over the region
tonight, we urge folks to bundle up as temperatures are forecast
to drop to the middle 30s to middle 40s by the stroke of midnight
January 1st. These temperatures combined with lingering breezes
will produce wind chills in the 20s and 30s. If your New Year's
Eve plans take you outdoors for prolonged periods, dressing in
layers and wearing a hat and gloves will help protect yourself
from these cold conditions. The coldest temperatures for the
morning of January 1 are forecast to be in parts of San Benito
County and southern Monterey County where winds will be light or
calm. If confidence continues to increase, may have to consider
issuing freeze headlines.
On New Year's Day the upper level ridge over the Pacific will
build over the West Coast and will allow any lingering breezes to
subside through the day. Plentiful sunshine is expected across the
region for the first day of 2019, but with the cold airmass in
place, temperatures will hold in the 50s for the Bay Area and
Central Coast. Temperatures will drop again on Tuesday night with
widespread 30s to low 40s likely region-wide, largely due to the
absence of mixing winds. More frost/freeze headlines may be
required, perhaps beyond just San Benito and southern Monterey
Counties.
Models are keeping the northern half of California under the
ridge's influence through much of the week. This will result in a
gradual day-to-day and night-to-night warming trend by a degree or
two for the region through the week, allowing many locations to
return to early January climatological normals by Friday. For next
weekend, models break the ridge down and bring in California's
first system of 2019. Details on the timing and strength remain a
bit unclear due to model differences, but will continue watching
over the days to come.
&&
.AVIATION....As of 03:34 AM PST Monday...For 12Z TAFs. VFR with
passing high clouds this morning before clearing later today.
Pushed back the arrival of gusty offshore winds a couple of hours,
but still expect low level gusts 25-30 kt with winds aloft around
35 kt starting this morning. Expecting winds to remain gusty into
this evening before gradually diminishing overnight.
Vicinity of KSFO...VFR through the period with passing high clouds
this morning. Winds to become gusty this morning potentially
reaching 30-35 kt in the afternoon. Will closely monitor winds
this afternoon to see if an AWW will be needed. Winds will slowly
ease tonight but will remain breezy into early tomorrow morning.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR through the period. Stronger winds
still not expected to affect the terminals aside from possible
15-20 kt gusts into this afternoon at KMRY.
&&
.MARINE...as of 02:45 AM PST Monday...An upper low over the Great
Basin will allow for gusty northerly winds to continue across the
waters, along the coast, and over the bays. Gale force gusts will
be possible across the outer waters and over the San Francisco
Bays into the afternoon and evening. Winds will gradually diminish
over the bays late tonight and over the coastal waters tomorrow as
the low moves further inland. Moderate to long period northwest
swell will continue through mid-week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...Wind Advisory...CAZ006-508-510
Wind Advisory...CAZ507-511-512
SCA...Mry Bay
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pigeon Pt to Pt Pinos 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
GLW...Pt Arena to Pigeon Pt 10-60 nm until 3 PM
GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 PM
GLW...Pt Reyes to Pigeon Pt 0-10 nm
SCA...SF Bay until 7 AM
GLW...SF Bay from 7 AM
&&
PUBLIC FORECAST: Rowe
AVIATION: AS
MARINE: AS
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www.youtube.com/nwsbayareaThe national radar mosaic for the moment the first event began.
10 strong wind. Local standard time, as filed.
PGE station at Highland Peak measured wind gusts around 45 mph peaking at 58 mph.
Middle Peak RAWS measured gust.
SFO ASOS reported sustained winds of around 35 mph with gust to 40 mph.
Tree down on Liberty Street between Walnut Ave and Sundale Dr.
Hawkeye RAWS measured gust.
A large pine tree blew over and smashed into a car in Niles Community Park. No injuries reported. Multiple other locations reported downed trees as well. Time is estimated https://sanfrancisco.cbslocal.com/2018/12/31/blustery-winds-batter-entire-bay-area/.
Media reported a downed tree in Santa Cruz that damaged a car, breaking the back window and damaging the bumper https://www.kron4.com/news/bay-area/police-warning-of-high-winds-downed-trees-in-santa-cruz/1681307091.
Winds gusting to above 40 mph at Pittsburg Marina.
Two people in their 40s were on a row boat on Richardson Bay during a gale warning when both fell out of the boat, possibly from waves. They were both brought to the hospital where the woman suffered from hypothermia but survived and the man was pronounced dead at the hospital. Neither were wearing a life jacket https://www.sfchronicle.com/bayarea/article/One-man-dead-in-Richardson-Bay-boat-accident-13501280.php.
Wind gusts around 50 mph at Grizzly Peak.
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 |
|---|---|---|---|---|---|
| Strong Wind, Coastal North Bay Including Point Reyes National Seashore | 2018-12-31 | Male | Boating | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2018Every state in 2018This day in weather historyWarnings in California, December 2018
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: 792340, 792177, 792181, 792169, 792175, 792168, 792167, 792337, 792166, 792342.