Flash Flooding in California, January 3 to 4, 2026

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
811 AM PST Sat Jan 3 2026

.SYNOPSIS...03/242 AM.

Rain and high elevation snow will develop through tonight as another
storm system continues to move over the region through the
weekend. Gusty southerly winds will continue to develop today across
the higher terrain and for areas north of Point Conception as
pressure difference across the area tightens. Another storm is
expected to move over the region between Monday and Tuesday.
Broader troughing over the West will keep a cooler weather
pattern in place into next week with cool days and cold nights.

&&

.SHORT TERM (TDY-MON)...03/808 AM.

***UPDATE***

The forecast is in good shape this morning with the storm on
track. Made a few minor modifications to the chances of rain to
better reflect the latest guidance.

The area of most concern right now is southern Santa Barbara
County. Cooling cloud tops on satellite and enhancing radar
returns just off the coast is giving credence to the model
consensus that the heaviest rain we will see today is going to
occur this morning there. We have already seen multiple stations
record around 0.75 inch per hour rates around Point Conception.
The HRRR, FV3, and ARW all show rates around 1.25 inches per hour
occuring this morning in that general area, with even the course
GFS 1hr and the RAP with rates of 0.6 inches per hour over the
same area. Thankfully there are no burn scars in that area, but
rates like these will cause a lot of road flooding and heavy flows
in creeks.

Every single model has this band of heavy rain weakening quickly
as it moves through Ventura and Los Angeles Counties. It will rain
everywhere, but the heavy rain and flooding risks will lower
significantly.

***From Previous Discussion***

Rain with the next storm system is moving into the region from the
northwest this morning. Enough instability and moisture moving out
ahead of the system's cold front is producing showers across most
of the area, but the heaviest rainfall is pushing into the Central
Coast early this morning. Orographic lift is enhancing rainfall
totals along the foothills and mountains already this morning.
The trough, now centered near 38N and 131W will continue to
approach the California coast through today. A few lightning
strikes have been observed closer to the trough's center where the
coldest air mass is located. All eyes are on jet streak located
near to the southwest of Point Conception, which is showing some
near computed lifted index values.

With high resolution multi-model forecast ensembles showing rain
developing through today, PoPs have been raised even higher
reflecting the high confidence levels with measurable rainfall
with this system. Moderate to locally heavy rainfall is expected
with this storm. While peak rainfall rates should largely range
between 0.25 and 0.50 inch/hour, there is a likely (60-80 percent)
chance of local rainfall rates in excess of 0.50 inch/hour over
the foothills and mountains. In addition, a slight chance of
thunderstorms has been added as a jet streak near Point
Conception aligns well with a difluent flow pattern pushing across
the area today and into tonight. With any thunderstorms that
develop, higher rainfall rates in excess of 0.50 inch/hour will be
possible. The latest forecast ensembles show a weakening of the
system as it moves into Los Angeles County which should allow for
rainfall rates not reach USGS estimates, but there is a low (20
percent) chance that recent burn scars, such as the Palisades,
Eaton, and Bridge burn scars could see rainfall rates capable of
producing debris flows. A Flash Flood Watch may still be issued
later today if the environment starts to show favorable signals
for heavy rainfall. Storm total rainfall is expected to reach
between one and three inches for the coastal and valley regions,
while the foothills and mountains could see significantly higher
totals ranging from three to six inches. Snow levels are
projected to remain relatively high throughout the event, staying
mostly above 6,500 feet. However, a transition to a rain-snow mix
is possible down to 6,000 feet by Sunday night as colder air moves
in aloft, with temperatures at the 700 mb level dropping as low
as -5 degrees Celsius. Most mountain resorts can expect between
two and six inches of fresh snow, though the highest peaks could
see localized accumulations reaching up to 9 inches.

In addition to the precipitation, a pressure gradient will
continue to tighten as the system's frontal boundary draws closer
the area. The gradient will generate gusty southerly winds. The
most significant wind impacts are expected in the mountains and
for areas north of Point Conception. Wind advisories have been
expanded into the Cuyama Valley and into the Los Angeles County
mountains and the Antelope Valley foothills. Wind advisories
remain in effect for most mountains areas of Ventura County, and
areas north of Point Conception. Given the saturated state of the
soil from previous storms, residents should be prepared for the
possibility of downed trees, particularly in the Santa Lucia range
where the strongest gusts are anticipated today.

The latest forecast ensembles continue to indicate that another
storm system will approach the region between Monday and Tuesday.
While this system is expected to be colder and carry less
moisture than previous storms, it will likely introduce a more
unstable, convective element. Specifically, a shifting wind
pattern aloft and 500 mb temperatures dropping below -25 degrees
Celsius could trigger isolated thunderstorms. These storms may
bring brief but heavy downpours, small hail, and gusty winds,
while also lowering snow levels to around 5,000 feet. Outside of
these localized convective cells, general rainfall is expected to
be light, with most areas receiving between 0.25 and 0.50 inch.

.LONG TERM (TUE-FRI)...03/242 AM.

Following this storm, a significantly colder air mass is
projected to settle into the region for much of next week. High
temperatures for the coastal and valley areas will struggle to
reach the upper 50s and 60s. A northerly flow pattern aloft will
pipe colder air from Canada southward. Overnight low temperatures
will likely drop into the 30s in the colder valleys. This setup
creates a risk for frost or freeze conditions in the valleys and
interior coastal sections. Current ensemble data even suggests
that temperatures in the Antelope Valley could dip into the 20s by
late next week.

&&

.AVIATION...03/1252Z.

At 12Z at KLAX, there was no marine layer and no inversion.

Moderate confidence on prevailing flight categories (+/- one
category). Low confidence in precise timing as there will be
random and unexpected fluctuations up and down in categories as
the storm evolves. This storm will come in two parts, first today
then another round tomorrow, with a generally break tonight.

There are reports of LIFR FG, but with the high clouds around they
are impossible to see from satellite. Very low confidence in FG
evolution as a result.

KLAX...Moderate confidence in prevailing flight categories, but
there will be significant unexpected hour-to-hour fluctuations.
Moderate confidence in east wind forecast, staying east or
southeast through at least 21Z, turning southwest by with a
window of going south to southwest 02-08Z, then going back to the
east by Sunday 16Z. Moderate confidence that winds will stay under
10 knots through the event, except for possible brief wind
enhancements during the peak rain 20-03Z.

KBUR...Moderate confidence in prevailing flight categories, but
there will be significant unexpected hour-to-hour fluctuations.
Brief categories down to IFR/LIFR possible during 21-03Z peak.

&&

.MARINE...03/743 AM.

A storm system will affect the region today into tonight, with
another storm expected on Sunday. This will bring periods of rain,
low visibility, gusty south winds, and a slight risk of
thunderstorms and waterspouts. Although there will be breaks in
the hazardous conditions, mariners should consider staying in safe
harbor through at least the weekend.

The front currently moving through the coastal waters is bringing
20 to 30 knots of south to southeast wind gusts along and ahead of
it. Buoy 46053 in the Santa Barbara Channel has measured gusts to
31 kts as of 7 AM. This activity will continue to move east.
Local gusts to GALE force is possible under heavier bands.
Hazardous, steep seas expected through this afternoon. Another
round of south winds, about 5 to 10 knots weaker, will impact our
coastal waters on Sunday.

Yet another storm system will likely affect the waters Monday
through Tuesday or Wednesday, but low confidence on the details.

Very large tides will affect the area each morning through
Monday. Read BEACHES section below for more information.

&&

.BEACHES...03/1248 AM.

Abnormally large high tides between 7.0 and 7.5 feet MLLW will
occur each morning through Sunday, roughly between 8 am and 11 am.
A mixture of south wind swells and a longer period west swell will
combine with these tides to elevate the risk of coastal flooding.
Similar events in the past suggest that any impacts will be minor,
but folks should plan for some shallow flooding of normally dry
beach areas (including bike paths and walkways) as well as
vulnerable harbor areas. Rain is also expected at this time,
which will enhance the risk for isolated impactful flood due to
the combination of outflow from streams and storm drains. This is
especially the case for areas like Naples Island.

Elevated surf and strong currents are also expected through
Monday. A High Surf Advisory will likely be needed for Sunday for
the Central Coast and Ventura Coast, but will keep the Beach
Hazards Statement going tonight and consider an upgrade tomorrow.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 6 PM PST this evening for zone
      38. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Monday morning for
      zones 87-340-346-349-350-354-362-366. (See LAXCFWLOX).
     Wind Advisory remains in effect until 6 PM PST this evening
      for zones 340>342-344>349-353-376>378. (See LAXNPWLOX).
     Wind Advisory in effect until 10 PM PST this evening for
      zones 379>382. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 4 PM PST this afternoon
      for zones 645-670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 2 PM PST this afternoon
      for zones 650-676. (See LAXMWWLOX).

&&

PUBLIC...Hall/Kittell
AVIATION...Kittell
MARINE...Black/Kittell
BEACHES...Kittell/Ciliberti
SYNOPSIS...Hall

weather.gov/losangeles

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