Tornado and Flash Flooding in California, February 13, 2025

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1019 PM PST Wed Feb 12 2025

.SYNOPSIS...12/122 PM.

A significant storm system is moving into the region.
Precipitation will remain light through this evening. Then
periods of moderate to heavy rain are expected Thursday into
Thursday night, followed by scattered showers into Friday morning.
Gusty southerly winds are likely across most of the area,
especially Thursday and Thursday night. A warming and drying trend
is expected over the weekend into next week.

&&

.SHORT TERM (WED-SAT)...12/857 PM.

***UPDATE***

The little prestorm impulse moved through the area today and
behaved as expected: bringing cloudy skies, light rain, and very
cool temps. Rainfall totals were almost all under a quarter inch
inch except for the SLO county coast where a quarter to a half
inch of rain fell (and up to .71 inches near the Monterey border).
Rainfall rates were very light and created no hazards save for
slick roadways. Max temps came in under the already cool forecast
and ended up in the lower to mid 50s.

Fairly dry conditions with only ocnl rain will continue through at
least midnight. After midnight the main storm will arrive. Warm
frontal rain will develop first across the Central Coast and by
500am or 600 am steady lgt-ocnl mdt warm frontal rain will be
falling across the entire area. This portion of the storm may drop
up to an inch and half of rain over the flatter portions and
double those amounts along the coast facing slopes. The warm
advection within the front will lift snow levels to 7500+ ft.

The cold front now looks more dynamic and unstable with a
favorable jet energy and location. This has increased the
likelihood of TSTM just in front of and with the front. The
forecast has been updated to up the chc of TSTMs to 30 percent
with the front. The jet is now forecast to push the front along a
little faster and this may result in a little less rain than
forecast. Total rainfall, however, is not the worry with this
system. Rainfall rates are the main concern and due to the
increased chance of convective cells there is a higher
probability of rainfall rates in excess of 1 inch per hour.

Will update the forecast to revise the TSTM timing probability
and coverage.

***From Previous Discussion***

The main thrust of the storm though will begin Thursday morning
along the Central Coast and mid afternoon to early evening across
Ventura and LA Counties. This timing is about 3-6 hours faster
than what models had advertised yesterday. As such, the timing of
the flood hazards has been modified and refined to start and end
earlier.

Aside from that, not too many significant adjustments have been
made to the forecast or the overall message. There is a little
more instability during the peak of the storm than models had
shown yesterday, with CAPE values up to around 600j/kg and some of
the hi res models are showing stronger signals for convection. The
most likely time for thunderstorms is noon to 10pm Thursday when
the strongest dynamics and forcing arrive. And the HREF now has a
small area of rain rates just over 1" per hour across portions of
southern Santa Barbara County and western Ventura County. However,
any location is susceptible to rain rates between a half and one
inch per hour, especially during the peak of the event when
convection is most likely.

In addition to the rain, gusty winds are expected just about
everywhere, though strongest in SLO County, the mountains and the
Antelope Valley. And of course strong gusty winds are likely near
any convection.

Have decided not to include any winter hazards at this time as
snow levels will be at or above 8000 feet for much of the event
until the very end, by which time any accumulations below that
will be minimal and not that impactful.

Models still show enough moisture and energy aloft to maintain
scattered showers into Friday, though by that time the low and
mid level flow shifts to the west so showers will quickly taper
off south of the blocking Transverse range from SB to western LA
County. And with the air mass stabilizing by that time most of the
lingering showers should be on the lighter side. Gusty west to
northwest winds are expected Friday afternoon following the system
and wind advisories may be needed in some areas, especially near
the coast.

Dry conditions expected Saturday winds winds aloft shift to the
north. Mountain areas may have some gusty winds as well as
southern Santa Barbara County.

.LONG TERM (SUN-WED)...12/216 PM.

Dry and warmer weather is expected Sunday through next week with
highs warming to the 70s across the valleys and 60s to lower 70s
for the coast. No sign of any additional precipitation through
next week. Possibly some gusty north to northwest winds in the
mountains and southern Santa Barbara County as models indicate an
increasing north to south gradient along with a favorable
northwest flow aloft as a couple of weaker storm systems move into
the Pac NW and far northern California.

&&

.AVIATION...13/0617Z.

Around 06Z, there was no marine layer depth at KLAX.

Low confidence in the current forecast as flight categories could
vary between IFR and VFR categories, especially between times of
heavier rainfall. The timing could be off by up to two to four
hours.

IFR to MVFR conditions are likely at coastal and valley terminals
through the period. The next round of more stronger and more
organized rainis moving into the northern terminals, followed by
Ventura and LA counties after 10Z. There is a moderate chance of
LIFR condition during heavier rainfall. Periods of gusty winds
with moderate to strong low-level wind shear and turbulence are
possible after 12Z, with the highest chances for terminals north
of KSBA.

KLAX...Ceilings at or below 6000 feet are very likely through the
period. Flight categories will vary between IFR to VFR conditions
through at times during breaks in the rain. There is a 60 percent
chance of IFR to MVFR conditions developing in rain, increasing
to 80 percent between 11Z and 14Z. There is a 80 percent of east
winds between 7 and 12 knots through 11Z. Less confidence exists
in winds between 11Z and 18Z, but there is a 30 percent chance of
southerly cross winds with gusts up to 25 knots between 14Z and
18Z. Southerly winds greater than 10 knots for Thursday afternoon
and evening.

KBUR...Ceilings at or below 6000 feet are very likely through the
period. Flight categories will vary between IFR to VFR conditions
at times during breaks in the rain. There is a 60 percent chance
of IFR to MVFR conditions developing in rain, increasing to 80
percent between 11Z and 14Z. There is a chance of southwesterly
cross winds on Thursday evening.

&&

.MARINE...12/1011 PM.

In the Outer Waters, high confidence in current Small Craft
Advisories for the northern two zones (PZZ670/673) tonight. Winds
are likely to increase to GALE force (60-70% chance) Thursday
morning, but may need to move Gales earlier if conditions worsen
faster. Winds will decrease to SCA levels behind the front later
Thursday. Sub advisory winds are likely Fri morning, then there
is a 50-60% chance of winds increasing to SCA levels Friday
afternoon through Sat morning. For the southern zone (PZZ676),
there is a 50% chance winds don't reach SCA levels until later
tonight. Otherwise, SCA winds from the S to SW will spread across
the zone until late Thursday, then W to NW SCA level winds will
arrive and last through Sat. Steep seas nearing 20 feet will
impact the entirety of the Outer Waters through Saturday. Conds
will likely be sub advisory late Sat through Sun, then chances
return late Sunday into the beginning of the week.

In the Inner Waters N of Pt Sal (PZZ645), SCA level SE winds will
persist into the overnight hours, with a potential for local gale
force gusts. SE-S winds increase to GALE force levels Thu morning
(60-70% chance). Winds will then transition to SCA levels in the
afternoon, primarily from the SW. Then winds will become W Thu
night and NW Fri, remaining near or above SCA levels thru late Fri
night. Seas will be well above SCA levels Thu thru Sat. Conds
will be below SCA levels Sat night thru Sun night.

In the Santa Barbara Channel (PZZ650), there is a 40% chance of
SCA level E to SE winds tonight. SCA level SE to S winds are
expected Thu morning thru early Thu night, with local gusts to
gale force before the front passes through. SCA level W to NW
winds and seas are likely Fri afternoon thru late Fri night. Seas
may linger above SCA levels into Sat morning.

In the southern Inner Waters SCA level SW-S winds appear likely
Thu morning through the evening hours. Brief local gusts may near
gale force near the front. There is a 50-60% chance for W to NW
SCA level winds Friday morning into the evening. Steep seas are
also expected late Thurs into Sat morning. Then SCA conds are not
likely through Sunday.

Conditions will become dangerous for boaters as a strong low
system with a cold front moves thorough the region. Please see the
product LAXMWSLOX for details. A period of large and dangerous
seas is expected across the waters Thu afternoon or evening thru
early Sat, peaking in most areas Fri into Fri night. Seas of 15 to
20 feet are expected in the outer waters, 12 to 16 feet in the
inner waters north of Pt. Sal, and 8 to 12 feet in the inner
waters S of Pt Conception.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Flash Flood Watch in effect from 10 AM PST Thursday through
      Thursday evening for zones
      88-348-353-355-358-362-366>375-377>380-548. (See LAXFFALOX).
     Flood Watch now in effect from 4 AM PST Thursday through
      Thursday afternoon for zones 340>345. (See LAXFFALOX).
     High Wind Warning remains in effect from 7 AM to 10 PM PST
      Thursday for zones 340>345-353. (See LAXNPWLOX).
     High Surf Advisory in effect from 3 PM Thursday to 3 PM PST
      Saturday for zones 340-346-354. (See LAXCFWLOX).
     High Surf Advisory in effect from 9 PM Thursday to 9 AM PST
      Saturday for zones 349-350. (See LAXCFWLOX).
     High Surf Advisory in effect from 3 AM Friday to 3 AM PST
      Saturday for zones 362-366. (See LAXCFWLOX).
     High Wind Warning in effect from 6 AM Thursday to 1 AM PST
      Friday for zones 376>382. (See LAXNPWLOX).
     Wind Advisory in effect from 7 AM Thursday to 1 AM PST Friday
      for zone 383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 4 AM PST Thursday for
      zone 645. (See LAXMWWLOX).
     Gale Warning in effect from 4 AM to noon PST Thursday for
      zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 9 AM to 9 PM PST Thursday
      for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PST Thursday for
      zone 670. (See LAXMWWLOX).
     Gale Warning in effect from 3 AM to noon PST Thursday for
      zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 6 AM PST Thursday for
      zone 673. (See LAXMWWLOX).
     Gale Warning in effect from 6 AM to 3 PM PST Thursday for
      zone 673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PST Saturday for
      zone 676. (See LAXMWWLOX).

&&

PUBLIC...MW/Rorke
AVIATION...Hall
MARINE...Phillips/Lewis
SYNOPSIS...MW

weather.gov/losangeles

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