An approaching strong upper level low brought widespread damaging winds to the Bay Area and Central Coast on February 21. A Wind Advisory was issued for the entire region in advance of the event, and was upgraded to a High Wind Warning along the coast and in the higher elevations of the Central Coast.
Every event with a place to put it; 13 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 approaching strong upper level low brought widespread damaging winds to the Bay Area and Central Coast on February 21. A Wind Advisory was issued for the entire region in advance of the event, and was upgraded to a High Wind Warning along the coast and in the higher elevations of the Central Coast.
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 Feb 21, 10:33 AM PST, 2 hours 37 minutes earlier.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
1033 AM PST Tue Feb 21 2023
.SYNOPSIS...Strong wind gusts will impact the Bay Area and Central
Coast Tuesday through Wednesday. A cold weather system arrives on
Wednesday providing frigid temperatures, the chances for rain
showers and thunder, as well as winter weather impacts for the
highest peaks and ridge tops.
&&
.DISCUSSION...as of 03:52 AM PST Tuesday...A busy week of weather
is in store for the Bay Area and the Central Coast.
Key messages----
* Strong winds arrive Tuesday impacting the area through
Wednesday. A Wind Advisory has been issued for winds 25-35 mph
with strong wind gusts expected, strongest gusts over the higher
terrain in excess of 55 mph.
* Cold temperatures arrive Wednesday morning and will last through
Sunday. Frost advisories and Freeze Watches have been issued for
Thursday morning.
* Rain showers arrive impacting coastal areas on Wednesday,
becoming more widespread Thursday night into Friday.
* A few thunderstorms are possible on Friday and Saturday with
lightning, heavy rain, and small hail as the primary impacts.
* Snow is expected at elevations above 1,500 feet, with the
highest confidence over the Santa Lucia Range. A Winter Storm
Watch has been issued for the Higher elevations of the Central
Coast.
* Rain chances return early next week.
Satellite night fog products are displaying thinly veiled stratus
hugging the San Mateo coastline, stretching down to the Monterey
Bay. Widespread fog is not forecast through the early morning
hours, but that patch of stratus heading for the Monterey Bay is
drifting southward and could impact KMRY before the morning is
over. Temperatures are still running on the warm side, relatively
speaking, in the 40 degree range and isolated low 50s. Isolated
areas in interior valley locations have the opportunity to reach
the upper 30s, but this morning remains the last remnants before
the weather changes on Tuesday. While afternoon temperatures will
reach the 50s and isolated low 60s, cold temperatures will arrive
later in the week.
An anomalously deep upper level low will drop down the Great Basin
Tuesday and settle over Central California this week. This storm
system will provide multiple impacts starting Tuesday and remain
through Saturday morning.
Strong north-northwest winds will arrive out in front of the system
late Thursday morning, featuring stronger wind gusts. While the
strongest wind gusts will be at the highest peaks and ridge tops,
these winds gusts will mix down and impact the entire CWA from
Sonoma County down to Monterey County. A Wind Advisory will go into
effect at 1 PM PST and remain valid through 1 PM PST on Wednesday.
Wind gusts at the lower elevations will likely be 35 mph to 45 mph,
with higher elevations receiving gusts stronger than 55 mph.
However higher resolution models have increased the confidence for
stronger winds over the highest elevations of the Santa Lucias and
the Gabilan Range that it was decided to upgrade those areas to a
High Wind Warning.
Temperatures will drop as the system slowly arrives on Wednesday.
Morning low temperatures will drop into the 30s and low 40s
Wednesday morning. Patchy frost may develop in the interior valley
locations. However, the coldest morning low temperatures of the week
will be feature Thursday, Friday and even Saturday morning.
Temperatures in the interior locations have over a 70 percent
probability of dropping below freezing. While the ocean will help
limit the drop in temperatures for coastal ranges, these areas will
still have temperatures that range from 33 to 38 degrees Fahrenheit.
A Freeze Watch has been issued for all interior locations, valleys
and hilltops, and a Frost Advisory has been issued for the coastal
and bay shoreline areas. The Freeze/Frost product was issued for
Thursday morning due to the high confidence in the near term, but
additional freeze products will likely be issued through the
weekend. Now is the time to prepare for the cold temperatures by
protecting sensitive plans and precautionary measures for pipes. The
unsheltered community will be especially impacted by these cold
temperatures through the weekend.
As the low tracks southward on Wednesday, the increase for scattered
showers accompanies it. Precipitation likely be light to moderate;
however, localized heavier rainfall is possible during more
convective periods. Instability will be present late Tuesday through
Thursday with steeper lapse rates which means that the chance for a
few thunderstorms is in the forecast and the chance for small hail
is plausible. The Storm Prediction Center has placed the coastline
from Sonoma County down to Monterey County, where the risk is
greatest in their General Thunder risk zones. As this system will be
a prolonged event, there will be periods of breaks in the rain. Rain
will likely be confined to the coastline Tuesday night through
Thursday morning, then become more widespread as it moves inland.
Total rainfall between Tuesday to Saturday has been bumped up
slightly. Interior valley areas are likely to get between 0.50
inches to an inch, with isolated areas receiving around 1.25 inches.
Higher elevations are forecast to receive an inch to 1.50 inches.
The Santa Cruz Mountains and the Santa Lucia range has the best
probability to receive over two inches of liquid precipitation.
That liquid is an important term, because mesoscale models are
continuing the trend that the air mass at 850 mb has a high
likelihood of being lower than 32 Fahrenheit. Snow levels have been
in the forecast to be between 1,000 and 1,500 feet for several days
now, with parts of the North Bay Mountains down to 500 feet.
Monterey County will feel the initial impact of the storm as the
relatively warmer ocean waters and the cold air mass aloft is
forecast to produce snow over the higher peaks of the Santa Lucia
range as early as overnight tonight, through Wednesday, and into
Thursday morning. As the showery activity becomes more spread out on
Wednesday, the Santa Cruz Mountains and the Diablo Range of Santa
Clara County and the Gabilan range will also see snowfall on
Wednesday through Thursday morning. A Winter Weather Watch has been
issued for all four of these areas through Thursday morning.
However, again, this system will not be going anywhere on Thursday.
A secondary pulse on Thursday night into Friday will bring
additional snowfall to the area. Additional products will be issued
as that time frame comes into the range of mesoscale models. But for
now, higher elevations could see 8 to 12 inches of snow, with the
highest peaks of the Santa Lucia range with the probability of
getting around two feet of snow when all is said and done by
Saturday morning.
To recap: wind, cold, rain, thunder, and snow, all over the span
of four days. Truly a dynamic system with all these hazards
impacting the area for a prolonged period of time.
Most ensemble models are suggesting that there will a brief break
over the weekend from the rain; however, scattered showers may
linger into Saturday. The cold temperatures are not forecast to go
away so quickly. Morning low temperatures are not currently forecast
to climb out of the 30s until Monday of next week. However, cluster
analysis of the ensemble models has a high likelihood of another
upper level trough approaching the Bay Area early next week with
ensemble models showing another shot of rain chances for the area. I
suppose the positive spin on that is that at least the temperatures
are expected to rebound enough so that snow is not in the forecast
early next week.
&&
.AVIATION...as of 10:30 AM PST Tuesday...For the 18Z TAFs. VFR
through the TAF period. Winds gain strength through the afternoon
becoming gusty across the region. Scattered showers will enter the
area into the late afternoon and spread south into the evening
and night. Winds at the surface will reduce in some areas into the
late evening while winds aloft remain strong leading to LLWS
concerns that will last beyond the TAF period.
Vicinity of KSFO...VFR through the TAF period. Strong and gusty
Northwesterly winds build into the afternoon, peaking around 30 kts
with gusts above 40 kts. Expect these winds to last through the
night before reducing into Wednesday morning. While winds will
reduce into Wednesday, they will still be on the strong side, around
20 kts with 32 kt gusts.
KSFO Bridge Approach...Similar to SFO.
Monterey Bay...VFR through the TAF period. The afternoon offers
gusty westerly winds that remain strong well into the evening. Winds
will reduce but will stay gusty in the late evening with scattered
showers moving into the area. Winds aloft will keep their strength,
leading to LLWS concerns through the remainder of the TAF period.
Shower chances increase into Wednesday morning.
&&
.CLIMATE...
Minimum Temperature Records
02/22 02/23 02/24 02/25
San Francisco D'town...38, 1890...38, 1890...40, 1891...38, 1887
SFO Airport............34, 1951...35, 1955...35, 1955...35, 1953
Oakland D'town.........38, 2019...36, 1974...34, 1987...36, 1987
Santa Rosa.............24, 1920...28, 2022...26, 2022...24, 1915
Kentfield..............27, 1920...26, 1955...29, 1955...29, 1920
Napa...................29, 1955...28, 1949...25, 2022...28, 2022
Livermore..............29, 1976...21, 1942...26, 2022...26, 2022
Redwood City...........30, 1939...32, 1975...30, 2022...31, 2022
Half Moon Bay..........30, 2006...30, 2022...28, 2018...29, 2022
San Jose...............27, 1897...24, 1897...26, 1897...28, 1894
Salinas Airport........30, 1975...30, 2018...30, 2018...25, 1935
King City..............24, 1953...24, 1984...24, 2022...23, 1974
&&
.MARINE...as of 10:32 AM PST Tuesday...The strong weather system
is arriving. Expect widespread strong winds with gale force gusts
expected. Hazardous and steep seas will also develop as a large
northwest swell arrives. Hazardous marine conditions will likely
persist through the week. Rain showers and perhaps a thunderstorm
are possible into Wednesday with gradually diminishing winds
thereafter.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...Wind Advisory...CAZ006-502>506-508>510-512>516-528>530
High Surf Advisory...CAZ006-505-509-530
High Wind Warning...CAZ517-518
GLW...SF Bay
GLW...Mry Bay
GLW...Pt Arena to Pt Reyes 0-10 nm
GLW...Pt Reyes to Pigeon Pt 0-10 nm
GLW...Pigeon Pt to Pt Pinos 0-10 nm
GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm
GLW...Pt Arena to Pigeon Pt 10-60 nm
GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm
&&
PUBLIC FORECAST: DK
AVIATION: Murdock
MARINE: Murdock
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www.youtube.com/nwsbayareaThe national radar mosaic for the moment the first event began.
7 high wind, 6 strong wind. Local standard time, as filed.
Multiple trees were falling onto the roadway on Interstate 280 west of Millbrae between Larkspur Drive and Trousdale Drive.
A spotter at the Healdsburg Municipal Airport reported port-a-potties being blown down the road and large trash dumpsters blown out onto the roadway.
The Oakland International Airport ASOS measured a gust of 63 mph.
A tree blocked the offramp from Southbound US Highway 101 to Embarcadero Rd in Palo Alto.
A tree fell on both lanes of California Highway 68 near the SFB Morse Gate in Pacific Grove.
The Wolfpack Ridge weather station operated by PGE reported a wind gust of 66 mph.
The San Francisco International Airport ASOS reported a wind gust of 68 mph.
The San Jose International Airport ASOS reported a wind gust of 61 mph.
The Black Diamond Mine station operated by PGE reported a wind gust of 62 mph.
The Las Aquilas station operated by PGE reported a gust of 66 mph.
A tree fell onto power lines between Gurneville and Forestville, starting a fire.
The Sweeney Ridge weather station operated by PGE reported a wind gust of 64 mph.
A redwood tree fell onto a home on the west side of Boulder Creek, injuring a 1-year old child.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2023Every state in 2023This day in weather historyWarnings in California, February 2023
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: 1085840, 1085835, 1085829, 1085834, 1085842, 1085830, 1085833, 1085841, 1085838, 1085831, 1085837, 1085843, 1085825.