A cold front and associated upper level low came through the Bay Area and Central Coast March 28 and 29. The front brought steady precipitation to the region, while the upper level low gave the area convective showers.
Every event with a place to put it; 8 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 cold front and associated upper level low came through the Bay Area and Central Coast March 28 and 29. The front brought steady precipitation to the region, while the upper level low gave the area convective showers. Pea sized hail was reported across portions of the region.
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 Mar 28, 12:21 PM UTC, 3 hours 19 minutes earlier.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
521 AM PDT Tue Mar 28 2023
.SYNOPSIS...A cold front will bring rain and gusty winds this
morning into this afternoon. Rain showers linger into tomorrow
as low pressure remains nearby. Drier conditions are forecast
Thursday into Friday morning, but a cool and unsettled weather
pattern will prevail next weekend.
&&
...Wind and rain impacts through Wednesday...
.DISCUSSION...as of 02:25 AM PDT Tuesday...showers continued to
increase in coverage over the Sonoma, Marin, and Napa County
areas, and were about to start impacting the San Francisco
Peninsula. The powerful upper low headed slowly toward the region
could be seen spinning west of the Oregon coast, with embedded
shortwaves circulating around the parent low. Temperatures had
cooled generally into the mid 40s to lower 50s. Winds were
beginning to pick up out of the south, with the surface pressure
gradient associated with the surface low beginning to tighten up
along the coast and over northern California. Rainfall rates were
averaging less than a tenth per hour for the most part, but a few
areas influenced by terrain had picked up around 1/2 inch already
as of early this morning. The upper low is expected to move
generally southward along the California coast, eventually moving
onshore over our central and southern counties Wednesday night,
then open up into a wave while moving east across the western
CONUS.
As the upper level low moves south today, a cold front will also
move into the area. The combination of lift from the low and from
the cold front will continue to bring precipitation into the area
today into tonight. As has been mentioned previously, snow levels
will initially start fairly low in the 2-3 thousand foot range, but
rise into the 4 thousand foot and higher range today. Significant
snowfall totals are expected in these higher elevations where
impacts will be limited. Amounts of 2 to 7 inches can be expected in
the higher elevations of the Santa Lucia Range, while the Diablo
Ranges may also see accumulations of up to 4 inches at higher
elevations. The cold front will move into the coastline throughout
the day today, reaching Bodega Bay late this morning, the San
Francisco peninsula around Noon, the Santa Cruz area by early
afternoon, and then through Monterey by late afternoon. Ahead of
the front, south/southwesterly winds will increase, resulting in
windy conditions across the area, especially along the coast, and
in higher elevations. Will expand the Wind Advisory across the
entire area, with wind gusts of 40+ mph possible in most if not
all locations. In addition, 50+ mph gusts are not out of the
question in the highest elevations, especially in the coastal
ranges. With the already saturated ground, additional rainfall,
and gusty winds, trees could be downed as winds increase. In
addition, urban and small stream flooding will be likely,
especially within any downpours that occur, potentially impacting
morning traffic. Storm total precipitation is expected to
generally range from 1/2 to 1 inch in most valley areas, with 1 to
2 inches expected in the terrain enhanced mountain ranges.
Behind the front, there may be a relative lull in precipitation, or
at least a change from widespread coverage to a more
isolated/scattered coverage of precipitation from late this
afternoon through late tonight. As colder air aloft continues to
move in over the region, the coverage of showers is expected to
increase from after midnight through Wednesday afternoon. Some of
these showers could produce some lightning and possibly even small
hail. In addition to those concerns, brief heavy downpours may also
result in additional localized flooding, especially in urban areas,
and small streams.
As the low moves south of us Wednesday night into Thursday,
precipitation chances drop off quickly, with only isolated chances
for southern mountain ranges expected by Thursday. Although another
weak trough will move by the region to our south, dry and generally
warmer conditions are expected by Friday.
The forecast remains uncertain from the weekend into early next
week, but another system could impact the region from Sunday night
into Tuesday, bringing another chance for precipitation.
&&
.AVIATION...as of 5:21 AM PDT Monday....For the 12Z TAFs. Still
prevailing VFR across terminals but conditions are starting to
deteriorate in North Bay as more steady rain enters the area. The
cold front that will bring heavier rain and stronger winds is
still offshore of NorCal and looks to reach North Bay by 15z, SF
Bay Area terminals near 18z, then Monterey Bay around 21z.
Southerly winds have been picking up along the coast but still
light to moderate inland. Winds at most terminals will ramp up by
mid morning with gusts 25-35 kt and locally up to 40 kt. Expect a
rapid weakening of winds following the frontal passage along with
a transient shift to SW flow, with uncertainty of +/- 2hrs with
regard to TAF timing.
Scattered showers follow the cold front in the afternoon, with
more breaks in activity by late afternoon. Cigs will generally
remain MVFR, with improvement to VFR by evening. Another round of
showers will arrive late night into Wednesday bringing lower cigs
and brief lower vsby.
Vicinity of SFO...VFR with light showers observed on radar but no
reports of rain at area terminals yet. Expect light rain to begin
reaching the surface within the hour with heavier rain towards
15z-16z. Deteriorating conditions to MVFR and periods of IFR as
the front pushes through. Potential remains high (80% per HREF)
for gusts exceeding 35 kt at SFO, primarily between 15-19Z. Winds
shift to SW behind the front by early- to mid- afternoon and will
diminish substantially. Showers continue in the afternoon, but
diminish in coverage by evening with conditions improving to VFR.
More shower activity near the end of the TAF period with VFR/MVFR
conditions.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR with cigs near 9000 ft. Light rain
arriving around 16z with steadier rain late morning into the
afternoon as the front moves through. Light SE winds increasing
through the morning, then becoming strong and gusty as the front
approaches. Gusts reaching 25-35 kt. MVFR with periods of IFR from
late morning through the afternoon and potentially through the
evening. Another round of showers arrives near the end of the TAF
period with the potential for IFR/MVFR.
&&
.MARINE...as of 03:01 AM PDT Tuesday...Southerly winds have begun
in the far northern and central waters, with the southern water
winds to turn more southerly later tonight. Gale force gusts
through the day as a strong low pressure system moves across the
waters. This system brings rain and strong winds to the coastal
waters and bays today, with a slight chance of thunderstorms
tonight and through Wednesday. Northwest swell continues to decay
but a larger northwest swell builds into the waters late Tuesday
into Wednesday, bringing steep and hazardous seas.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...Wind Advisory...CAZ006-508>510-512>518-528>530
Wind Advisory...CAZ502>506
GLW...SF Bay until 3 PM
GLW...Mry Bay until 3 PM
GLW...Pt Reyes to Pigeon Pt 0-10 nm until 3 PM
GLW...Pigeon Pt to Pt Pinos 0-10 nm until 3 PM
GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 PM
GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 PM
GLW...Pt Arena to Pt Reyes 0-10 nm until 9 AM
GLW...Pt Arena to Pigeon Pt 10-60 nm until 9 AM
&&
PUBLIC FORECAST: SN
AVIATION: Lorber
MARINE: DialH
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayareaPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
814 AM PDT TUE MAR 28 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0756 AM FLOOD 18 WNW MONTE RIO 38.57N 123.32W
03/28/2023 SONOMA CA DEPT OF HIGHWAYS
ROCKSLIDE IN NORTHBOUND LANES OF STATE
HIGHWAY 1 IN THE SALT POINT STATE PARK AREA.
&&
CMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
840 AM PDT TUE MAR 28 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0817 AM NON-TSTM WND DMG 3 WSW UNION CITY 37.58N 122.07W
03/28/2023 ALAMEDA CA DEPT OF HIGHWAYS
OCCUPIED SCHOOL BUS HIT BY DOWNED TREE LIMB.
NO INJURIES REPORTED.
&&
CMSThe Sacramento radar (KDAX), 106 km away, was scanning. The volume nearest the first event began at 21:23 UTC.
7 high wind, 3 flood, 3 hail, 1 strong wind. Local standard time, as filed.
The Bigrock Ridge station operated by PGE recorded a wind gust of 73 mph.
The Point Potrero station operated by NOS-PORTS reported a gust of 62 mph.
The Road to Ranches station operated by PGE recorded a wind gust of 73 mph.
Falling glass from high rises was reported along Mission Street in San Francisco.
The Mines Tower weather station operated by PGE reported a wind gust of 81 mph.
The Lake Drive station operated by PGE reported a gust of 66 mph.
The Wolf back Ridge station operated by PGE reported a wind gust of 62 mph.
The Los Gatos RAWS reported a wind gust of 67 mph.
Street flooding was reported on California Highway 92 in Spanishtown near Half Moon Bay. One way traffic controls were in effect as firefighters dealt with the flooding.
Social media reported pea-sized hail near Van Ness Ave and Lombard St.
Roadway flooding was reported at the intersection of Blanco Road and Davis Road in Salinas.
Social media report of accumulating pea-sized hail in Scotts Valley.
Roadway flooding on the connector from Westbound Interstate 80 to Southbound Interstate 880 near Oakland due to a storm drain being plugged.
Pea sized hail was reported at the National Weather Service office in Monterey.
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, March 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: 1090907, 1090912, 1090906, 1087104, 1087122, 1090909, 1090911, 1090910, 1087111, 1087106, 1087113, 1087928, 1087109, 1087929.