A second winter storm impacted Southwestern California. The heaviest rainfall impacted San Luis Obispo and Santa Barbara counties where rainfall totals ranged from 2 to 4 inches across the coast with 5 to 10 inches across the foothills and mountains.
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 LOX wrote it up.
A second winter storm impacted Southwestern California. The heaviest rainfall impacted San Luis Obispo and Santa Barbara counties where rainfall totals ranged from 2 to 4 inches across the coast with 5 to 10 inches across the foothills and mountains. For Ventura and Los Angeles counties, rainfall totals ranged between 0.50 and 1.50 inches with local amounts up to 3 inches across the foothills. The heavy rainfall produced numerous reports of flooding across San Luis Obispo and Santa Barbara counties. Also, gusty south to southwest winds were reported across many areas.
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 Los Angeles, CA wrote its last area forecast discussion before the first event at Mar 9, 10:09 PM UTC, 4 hours 21 minutes earlier.
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
209 PM PST Thu Mar 9 2023
.SYNOPSIS...09/208 PM.
Rain will spread over the area tonight into Friday, heavy at
times across Santa Barbara and San Luis Obispo Counties. No snow
is expected for the local mountains. Drier weather is expected
Sunday and Monday with the potential for another strong storm
Tuesday into Wednesday.
&&
.SHORT TERM (TDY-SUN)...09/207 PM.
Light rain has been falling across northern SLO County today as
the first rain bands from a warm AR storm approach from the
southwest. Overall, not much change in the forecast as models have
more or less held their ground with timing and rain amounts. The
brunt of the storm is still expected to be north of Pt Conception,
and particularly northwest SLO County where the warm/moist air
mass will combine with strong west to southwest flow aloft to
generate copious amounts of rain over the Santa Lucias. Hi res
models continue to indicate at least 18 hours of moderate to very
heavy rain in that area with rain rates over half an inch per hour
and locally up to 1.25" per hour in thunderstorms. Storm totals
in the Santa Lucias expected to be 5-10" with local amounts of
12-15" in the higher mountains just south of the Monterey County
line. This will likely cause significant and widespread flooding
in that area as creeks and streams overflow their banks. Amounts
will decrease across inland SLO County but runoff from the coastal
mountains will cause rises on the Salinas River, though current
projections only show a 5% chance of reaching flood stage.
Gusty winds expected with this storm as well, especially in SLO
County and in the mountains and Antelope Valley foothills. Gusts
to around 40-50 mph possible at times, which combined with the
saturated ground could lead to a higher number of fallen trees
than in a normal or dry rain year.
As mentioned, rain amounts fall off to the south but there will
still be several hours of moderate to briefly heavy rain
throughout Santa Barbara County and particularly in the mountains.
Rainfall amounts there expected to range from 2-3" for
coast/valleys and 2-4" for the mountains, though there is about a
50% chance of Santa Barbara south coast receiving as much as 3-4"
if the AR sags a little farther to the south than currently
expected.
With little in the way of southerly flow with this system, and
actually some light easterly flow at lower levels, rain amounts
decrease considerably across Ventura County and especially LA
County. Most populated areas of LA County should receive under an
inch of rain while mountains could see around 2 or little more.
These amounts should not pose any significant issues, except in
the mountains where there is the potential for melting snow to
contribute to runoff there. Without the existing snow pack these
rain amounts and rates would likely not be an issue but with
plowed roads and channeling of water there could be a heightened
risk of some minor flooding there.
Rain expected to taper off late Friday night with some lingering
light showers into Saturday morning, possibly into afternoon
across the mountains. Otherwise, still a lot of clouds around with
better chances for clearing across coast/valleys on Sunday.
Temperatures will be warming into the 60s despite the cloud cover
as the air mass remains quite warm and moist.
.LONG TERM (MON-THU)...09/248 AM.
The EC and GFS deterministic are in decent agreement for the
Sun. Both show fairly flat flow across the area. The storm track
is mostly north of the area but cannot rule out a few showers over
nrn SLO county. Max temps will be in the 60s across the csts/vlys
or about 2 to 4 degrees blo normal.
While both EC and GFS deterministic mdls agree that there will be
slight ridging and dry conditions on Monday the ensembles offer a
much wetter opinion with a faster moving trof and an increasing
chc of rain. So not the best confidence in the fcst at this time.
Most ensemble members from the GEFS and EPS do show a second
strong arrive and moving over the area Tue and Wed. As should be
expected for a storm this far out rainfall amount forecasts are
all over the place the current thinking is that this will be a 1
to 3 inch storm but this forecast will very likely change as the
event nears. This looks like another fairly warm storm and snow
levels should remain above 7000 feet through most of the period.
&&
.AVIATION...09/1900Z.
At 17Z at KLAX, there was no inversion or marine layer.
High confidence in many hours of RA over all sites tonight
through Friday. Moderate confidence in ceilings staying MVFR
OVC015-025 for majority of rain period. There is however a 20-40
percent chance of IFR OVC008 during heavier cells, highest over
KPRB KSBP KSMX. Moderate confidence in timing, plus or minus 4
hours.
KLAX...Moderate confidence in the TAF. MVFR ceilings OVC015-025
most likely during rain, with a 20 percent chance of brief IFR
during heavy cells. There is a 60% chance east winds exceeding
10 knots from 11Z Fri to 06Z Sat.
KBUR...Moderate confidence in the TAF. MVFR ceilings OVC015-025
most likely during rain, with a 30 percent chance of brief IFR
during heavy cells.
&&
.MARINE...09/207 PM.
High confidence that SE winds will increase today and reach Gale
Force (35-40 knots) by this evening across the northern two outer
waters zones and the nearshore waters off the Central Coast.
Winds will shift to southwesterly and dropping to Small Craft
Advisory (SCA) level Fri afternoon or evening plus or minus 6
hours from the current noon end time. SCA southeast winds are
likely for the Santa Barbara Channel as well on Friday. Small but
non- zero chance for SCA southeast winds on Friday for the Santa
Monica Basin. Winds will drop below SCA levels Fri evening, then
SCA conds are not expected thru Mon. Much uncertainty still exists
for next week, with a 30 percent chance for a similar storm
Tuesday or Wednesday, and a higher chance for a much weaker storm.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Flood Watch in effect through late Friday night for zones
38-340>353. (See LAXFFALOX).
Wind Advisory in effect from 8 PM this evening to noon PST
Friday for zones 38-346>353-377. (See LAXNPWLOX).
Wind Advisory in effect until noon PST Friday for zones
340>345. (See LAXNPWLOX).
Wind Advisory in effect from midnight tonight to noon PST
Friday for zones 379>382. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 7 PM PST this evening
for zones 645-670-673. (See LAXMWWLOX).
Gale Warning in effect from 7 PM this evening to noon PST
Friday for zones 645-670-673. (See LAXMWWLOX).
Small Craft Advisory in effect from 1 AM to 6 PM PST Friday
for zone 650. (See LAXMWWLOX).
Small Craft Advisory in effect from 7 PM this evening to 6 PM
PST Friday for zone 676. (See LAXMWWLOX).
&&
PUBLIC...MW/Rorke
AVIATION...Schoenfeld/RK
MARINE...DB/RK
SYNOPSIS...MW
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=loxThe Vandenberg AFB radar (KVBX), 61 km away, was scanning. The volume nearest the first event began at 14:05 UTC.
7 flash flood, 6 high wind. Local standard time, as filed.
Strong winds impacted the Santa Lucia Mountains in San Luis Obispo county. The sensor at TV Tower reported wind gusts up to 62 MPH.
Strong winds impacted the interior valleys of San Luis Obispo county. The sensor at Lewis Ranch Road reported wind gusts up to 60 MPH.
Strong winds impacted the western foothills of the Antelope Valley. The RAWS sensor at Lake Palmdale recorded wind gusts up to 68 MPH.
Strong winds impacted the mountains of San Luis Obispo county. The sensor at Mount Lowe reported wind gusts up to 63 MPH.
Strong winds impacted the western range of the San Gabriel Mountains. Some peak wind gusts from the local mesonet include: Magic Mountain Truck Trail (gust 67 MPH) and N3 Highway.
Strong winds impacted the eastern range of the San Gabriel Mountains. The sensor at Ford Observatory reported wind gusts up to 60 MPH.
Heavy rainfall produced flash flooding in Santa Barbara county. Highway 135 was closed from Bell Street to the Harris Grade, due to significant mud and water flowing across the roadway.
California Highway Patrol reported Chimney Rock Road was completely washed out, due to heavy rain and flash flooding.
Heavy rainfall produced flash flooding near the community of Atascadero in San Luis Obispo county. California Highway Patrol reported mud and rocks across Highway 41.
Heavy rainfall produced flash flooding in San Luis Obispo county. California Highway Patrol reported road closures between Avila Beach Drive and San Luis Bay drive, due to flooding.
California Highway Patrol reported significant flooding in the community of Cambria in San Luis Obispo county. At a gas station, water rose to a depth up to half of the gas pumps.
California Highway Patrol reported mud and debris completely blocking York Mountain Road and Shadow Canyon Road.
California Highway Patrol reported mud and debris blocking the offramp of Highway 154.
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: 1090800, 1090799, 1090796, 1090801, 1090795, 1090798, 1090749, 1090774, 1090761, 1090760, 1090789, 1090792, 1090793.