One last Winter storm impacted Southwestern California in the month of March. Rainfall totals across the area ranged between 1 and 3 inches which produced numerous reports of nuisance urban flooding.
Every event with a place to put it; 1 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.
One last Winter storm impacted Southwestern California in the month of March. Rainfall totals across the area ranged between 1 and 3 inches which produced numerous reports of nuisance urban flooding. In the mountains of Los Angeles county, snowfall totals up to 12 inches, combined with wind gusting to 67 MPH, generated winter storm 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 Los Angeles, CA wrote its last area forecast discussion before the first event at Mar 29, 2:43 AM PST, 47 minutes earlier.
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
343 AM PDT Wed Mar 29 2023
.SYNOPSIS...29/231 AM.
Rain and mountain snow will spread over the region today as a
cold storm system moves across into the region. A showery and
unsettled weather pattern will then move into the area this
evening and last through Thursday. Dry but cool conditions are
expected for Friday through the weekend.
&&
.SHORT TERM (TDY-FRI)...29/319 AM.
A cold front, originating from a cold low west of Humboldt County,
is currently over SBA county and pushing to the east. It is
producing light to locally moderate rain. Rainfall totals, so
far, through early this morning are .5 to 1.5 inches across
SLO and SBA counties (Rocky Butte in far NW SLO county is being
its usual rambunctious self coming in at 2.36 inches) inches
across the foothills of San Luis Obispo county. Ventura county's
rainfall is between .25 and .50 inches. Rainfall has just started
to fall across LA county. Rain rates have mostly been less than
0.25 inches per hour. Rainfall totals from last evening through
this afternoon will likely range from a half inch to an inch and
half with local amounts to 2 inches. Snow levels will start
between 5000 and 6000 ft and will lower to 4000'
The main frontal band will exit LA county late this morning or
early this afternoon. There will be a noticeable break in the
rain behind the front with only a few lingering showers. There may
even be a few peaks of sunshine. Max temps will come in much
cooler than ydy's with highs across the csts/vlys only in the mid
50s to lower 60s.
This evening the upper low will move down the coast with very cold
500 mb temps which will destabilize the atmosphere starting with
SLO county. The left exit region of a 135kt jet will be across LA
County. This along with some PVA embedded in the cyclonic flow
around the low will set the stage for a showery pattern that will
start this evening and last into early Thursday afternoon. A
slight chc of TSTMs will spread over the area. Given the turning
in the atmosphere, the position of the jet and the upper low there
is a risk of waterspouts and/or small tornadoes. Rainfall amounts
from these showers will not be very homogeneous but most areas
will see an additional quarter to half inch of rain with locally
heavier amounts under stronger showers or TSTMs. The upper low
will sweep to the east Thursday morning and by afternoon most of
the area will be dry. The Central Coast will dry out sooner than
that and will likely be much sunnier. High temps there will warm
some. Despite this warming all max temps on Thursday will remain
10 to 15 degrees blo normals.
A dry trof moves across the area on Friday and will keep the hgts
near 563 dam. It will be a sunny day and the extra sunshine will
bring 2 to 4 degrees of warming to most of the area.
.LONG TERM (SAT-TUE)...29/319 AM.
It looks like we are in store for a nice weekend. Both the GFS and
the EC deterministic and ensemble based forecasts agree that hgts
will rise to about 572 dam. Max temps will jump 3 to 6 degrees on
Saturday and perhaps another degree or two Sunday (The ensembles
exhibit a goodly amount of spread on Sunday's max temps)
Not the best agreement between the longer range deterministic mdls
and noticeable increase in the spread across the ensembles for
the Mon/Tue forecast. The GFS and troffier and cooler while the EC
has a warmer slightly anti cyclonic. Some GFS ensembles show
light rain across the Central Coast but odds on it will be dry.
Forecast slightly favors the cooler cloudier GFS but really not a
high confidence fcst.
&&
.AVIATION...29/0002Z.
At 2330Z, the marine inversion at KLAX was based at 700 feet.
The top of the inversion was 1600 feet with a temperature
of 14 degrees Celsius.
Overall, low to moderate confidence in 00Z TAF package. Through
the TAF period, rain will overspread the area this evening through
Wednesday morning. Lower confidence in forecast due to changes in
the CIG/VSBY category changes. Generally, conditions are expected
to drop to MVFR levels, with a 20-30% chance of brief period of
IFR conditions with heavier rain.
KLAX...Moderate confidence in 00Z TAF. High confidence in
development of MVFR conditions, in rain, after 07Z. However, low
confidence in timing of flight category changes with respect to
both CIG and VSBY. No significant easterly wind component is
expected.
KBUR...Moderate confidence in 00Z TAF. High confidence in
development of MVFR conditions, in rain, after 07Z. However, low
confidence in timing of flight category changes with respect to
both CIG and VSBY.
&&
.MARINE...29/341 AM.
At the time of issuance winds and seas in the Outer Waters and
the Inner Waters north of Point Conception are at or approaching
Small Craft Advisory (SCA) levels. Small Craft Advisories are
issued until Thursday afternoon for the Outer Waters, SBA Channel,
and Southern Inner Waters, though there is a 40 percent chance of
SCA conditions extending until Thursday night for all waters
south of Point Conception. Winds may fall briefly below SCA level
early Thursday morning, but are expected to pick back up quickly.
There is a 20 percent chance of SCA level SW-W winds in the SBA
Channel early this morning. Additionally near SCA level SW
shifting to NW winds are expected in the southern Inner Waters
adjacent to LA and Orange County, with the wind shift occuring as
the cold front passes through the region.
There is a slight chance of thunderstorms across the waters today
through Thursday. Some storms could produce small hail, gusty
winds, dangerous lightning, and possibly waterspouts.
&&
.BEACHES...29/343 AM.
Large swell in the coastal waters may bring marginal high surf 7
to 10 feet on Central Coast beaches on Wednesday and Thursday and
4 to 7 feet on Ventura beaches on Thursday. This is a fairly low
confidence forecast with only a 50 percent chance of reaching
criteria. However, there will be a high risk of rip currents on
many beaches Wednesday and Thursday.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 5 AM PDT early this morning for
zones 38-342-344-345. (See LAXNPWLOX).
High Surf Advisory in effect from 11 AM this morning to 8 AM
PDT Thursday for zones 340-346. (See LAXCFWLOX).
Winter Weather Advisory in effect until 10 AM PDT Thursday
for zones 353-376-377. (See LAXWSWLOX).
High Surf Advisory in effect from 8 PM this evening to 8 PM
PDT Thursday for zone 354. (See LAXCFWLOX).
Winter Weather Advisory in effect until 2 PM PDT Thursday for
zones 378-379. (See LAXWSWLOX).
Winter Storm Warning in effect until 2 PM PDT Thursday for
zone 380. (See LAXWSWLOX).
Wind Advisory in effect from noon today to 6 AM PDT Thursday
for zones 381>383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 AM PDT Thursday for
zone 645. (See LAXMWWLOX).
Small Craft Advisory in effect from 11 AM Thursday to 5 AM
PDT Friday for zone 650. (See LAXMWWLOX).
Small Craft Advisory in effect from 11 PM this evening to 5
AM PDT Friday for zone 655. (See LAXMWWLOX).
Small Craft Advisory in effect until 5 PM PDT Thursday for
zones 670-673-676. (See LAXMWWLOX).
&&
PUBLIC...Rorke
AVIATION...RAT
MARINE...Schoenfeld
BEACHES...Sweet/DB
SYNOPSIS...30
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=loxThe national radar mosaic for the moment the first event began.
1 winter storm. Local standard time, as filed.
Winter storm conditions developed across the eastern range of the San Gabriel Mountains. Above 5000 feet, snowfall totals of 6 to 12 inches were reported. Additionally, southerly winds, gusting up to 67 MPH, were reported.
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: 1099514.