Tornado and Flash Flood in California, March 12 to 15, 2025

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
212 PM PDT Wed Mar 12 2025

.SYNOPSIS...12/135 PM.

A strong storm will move through the area tonight with periods of
heavy rain, mountain snow, and gusty winds. Thursday will be a
mixed bag of weather with showers and thunderstorms and periods of
heavy rain and lower elevation snow, but some sunny breaks as
well. Light showers expected Friday then dry and warmer over the
weekend.

&&

.SHORT TERM (TDY-SAT)...12/203 PM.

Light warm frontal rain showers continue mainly south of Pt
Conception where amounts up to a third of an inch have been
observed. The main event will be overnight tonight with a strong
and fast moving cold front traversing the area from northwest to
southeast. This storm will pack quite a wallop despite it's short
duration as a strong southerly low level jet will interact with a
narrow but potent frontal band with PW's projected to be close to
1.2". So the necessary ingredients will be in place to generate a
3 to 6 hour period of very heavy rain tonight, especially near and
on the south facing mountain slopes from Santa Barbara to LA
County. Hi res ensembles have been consistent showing a 60-80%
chance of rain rates reaching a half inch per hour somewhere in
those upslope areas and a 10-20% chance of hourly rates close to
an inch per hour. Sub-hourly rain rates may be just as or perhaps
even more important to monitor as it's likely those will be
exceeded as well. Strong winds at times are expected, especially
interior SLO County.

Thunderstorms are possible as well, though the best chances for
those will likely be following the frontal passage Thursday as the
colder and more unstable air moves in. PW's drop about 50% during
this phase of the storm but with the colder and more unstable air
present periods of very heavy rain, along with small hail, gusty
winds, and possibly even a waterspout or small tornado are all
possible through the day so the threat of flooding and debris
flows will continue through at least Thursday afternoon.

Snow levels will stay at or above 6000 feet for most of the night
but then will fall rapidly Thursday down to around 3000 feet.
There may be some light accumulations on some of the lower
mountain passes including the Grapevine on Interstate 5, highway
14 and 33, as well as possibly Highway 154 over San Marcos Pass,
and some of the Santa Lucias. Up to 1 to 2 feet of snow expected
above 6000 feet with lighter amounts below that.

Showers are expected to decrease late in the day and evening
Thursday. However, another area of showers is expected to move
through Friday into early Saturday. Additional amounts are
expected to from around a half inch north of Pt Conception to
around a quarter inch or less south.

.LONG TERM (SUN-WED)...12/211 PM.

A weak high pressure ridge will bring a return to dry and warmer
weather late Saturday into Sunday. Another system will arrive late
Sunday night into Monday with another round of mostly light
showers with little to no impacts. Still some uncertainty with
this one as some of the ensemble solutions keep most of the
precipitation north of Pt Conception. The rest of the week looks
dry and slightly warmer. Some gusty northerly winds possible
Tuesday and Wednesday, with small chances of a weak Santa Ana.

&&

.AVIATION...12/1847Z.

At around 17Z at KLAX, there was no marine layer or inversion.

Overall, low confidence in 18Z TAF Package. Showers will be spotty
ahead of the main frontal precipitation band with mostly temporary
periods of IFR conds. Expect gusty SW to SE winds ahead of the
front. Expect RA to +RA as the main precip band moves in from
west to east. Thereafter, winds will shift rapidly to the NW-W
with diminishing precip intensity and coverage.

Cigs and vsbys will vary frequently, especially during rainfall.
Expect mostly MVFR/IFR, with a chance for even VLIFR under the
worst conditions.

There is a 10-20% chance for thunderstorms after 00Z. Any
thunderstorm may produce gusty, erratic winds, small hail, and
lightning.

KLAX...Low confidence in 18Z TAF. IFR to MVFR conds
are possible at any point during rainfall. RA to +RA will begin
impacting the terminal after 06Z as the frontal precipitation band
moves through, and conds could be as low as VLIFR. Winds will
remain generally from the south. Gusts up to 25 kt are possible,
especially after 03Z. Then, a rapid shift to west winds will occur
around 10Z, with gusts up to 25 kt possible. West winds and
spotty showers with thunder potential expected through the
remainder of the period.

KBUR...Low confidence in 18Z TAF. IFR to MVFR conds are possible
at any point during rainfall. RA to +RA will begin shortly after
06Z and conds may be as low as VLIFR during this time. Winds will
shift more westerly upon the passage of the front towards the end
of the period.

&&

.MARINE...12/1157 AM.

Hazardous sea conditions through Friday. Stay in safe harbor.
Wait for the weekend with improved conditions.

Very confused seas will continue through Thursday, with a combo
long period northwest to west swell and short period southwest
swell along with southerly wind waves.

A moderate to strong cold front will move through the area from
northwest to southeast beginning this afternoon through the
overnight hours. All areas will see at least a few hours of high
end Small Craft Advisory (SCA) level south winds today, with low
end Gale Force winds expected north of Point Conception. For the
waters south of Point Conception, there is a 40-50% chance of
brief Gale Force winds as the front passes through the region, but
winds will be localized and short lived, thus a Gale Warning will
not be issued at the moment. Rain will be heavy at times, with a
chance of thunderstorms (through Thursday afternoon) and
associated hazards like locally strong winds, lightning, and
waterspouts.

Post-frontal west to northwest winds will quickly form tonight
into Thursday, with a 40-60% chance of reaching Gale Force south
of Point Conception. Best chances in zones PZZ650/655 especially
for the nearshore waters from Point Mugu to Santa Monica, and the
San Pedro Channel.

Another storm will move through the area on Friday, with another
round of gusty south winds and post frontal west to northwest
winds. Winds should be weaker than today/Thursday, but SCA-levels
are likely over most waters.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory remains in effect until 10 PM PDT this evening
      for zones 38-340>343-346>349-351. (See LAXNPWLOX).
     Flood Watch remains in effect from 6 PM PDT this evening
      through Thursday afternoon for zones
      87-88-349>352-354>358-362-366>375-378>380-548. (See LAXFFALOX).
     High Surf Advisory in effect from 9 PM this evening to 9 PM
      PDT Friday for zones 340-346. (See LAXCFWLOX).
     High Wind Warning remains in effect until 2 AM PDT Thursday
      for zones 344-345. (See LAXNPWLOX).
     Winter Storm Warning remains in effect until 5 AM PDT
      Saturday for zones 353-376>382. (See LAXWSWLOX).
     High Surf Advisory in effect from 9 AM Thursday to 3 PM PDT
      Friday for zones 354-362-366. (See LAXCFWLOX).
     Wind Advisory remains in effect from 10 PM this evening to 6
      AM PDT Thursday for zones 369-370-375. (See LAXNPWLOX).
     Wind Advisory now in effect until midnight PDT tonight for
      zone 383. (See LAXNPWLOX).
     Wind Advisory now in effect from midnight tonight to 6 AM PDT
      Thursday for zone 383. (See LAXNPWLOX).
PZ...Gale Warning in effect until 9 PM PDT this evening for zones
      645-670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until noon PDT Thursday for
      zones 650-655. (See LAXMWWLOX).
     Gale Watch in effect from Thursday afternoon through Thursday
      evening for zones 650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Thursday for
      zone 676. (See LAXMWWLOX).
     Gale Watch in effect from Thursday morning through Thursday
      afternoon for zone 676. (See LAXMWWLOX).

&&

PUBLIC...MW
AVIATION...Lewis/Black
MARINE...Phillips/Lewis/Black
SYNOPSIS...MW

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox