Valencia, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

958
FXUS66 KLOX 230539
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
939 PM PST Mon Dec 22 2025

.SYNOPSIS...22/159 AM.

Temperatures will remain above normal through Sunday in most
areas except the coast. A cooling trend will begin Monday as a
strong storm approaches with increasing clouds. Rain will begin
Tuesday in most areas with periods of heavy rain Tuesday night and
Wednesday as well as very strong winds. Showers are expected to
continue on Christmas day and through next weekend.

&&

.SHORT TERM (MON-THU)...22/838 PM.

***STRONG ATMOSPHERIC WINTER STORM WITH DANGEROUS FLOODING AND
 ROCK/MUD SLIDES TUESDAY NIGHT THROUGH THURSDAY EVENING***

Taking a look at latest evening model run guidance, forecast
for strong atmospheric storm and associated impacts remains on
track. High resolution model data still pointing to late Tuesday
night into Wednesday as strong upper level southwesterly jet
interacts with a moist tropical air mass (precipitable water
values peaking at around 1.5 inches). Strong moisture transport
during this period, with various atmospheric river models
forecasting IVT values ranging between 750 and 1000 kilograms
per meter per second. The strong jet dynamics combined with
strong warm air advection pattern and strong southerly wind
orographic support setting the stage for prolonged periods of
heavy rainfall, especially across south facing slopes (south
of Point Conception). This matches well with WPC high risk area
for DANGEROUS AND WIDESPREAD FLOODING CONCERNS. Some of the
latest high resolution model data indicating the potential for
rain rates to locally reach up to 1.50 inches per hour (especially
across favored south facing slopes).

RAIN...Light rain will begin across all areas during the day on
Tuesday. The first, and more significant, impulse of the AR will
move across the area late Tuesday night and Wednesday. After a
relatively "lull" Wednesday night, a second impulse will move
across the area on Christmas Day.

RAIN TOTALS THROUGH CHRISTMAS DAY:
North of Point Conception: 2-4 inches coastal/valley areas and
4-7inches for foothills/mountains.

South of Point Conception: 3-6 inches coastal/valley areas and
5-11 inches foothills/mountains.

RAIN RATES: Peak rainfall rates north of Point Conception are
expected to be in the 0.40-1.00 inch/hour range while south of
Point Conception 0.60-1.25 inch/hour rates are expected. There is
a 20-30 percent chance of isolated rates as high as 1.50 inches
per hour across favored south facing slopes (south of Point
Conception).

THUNDERSTORMS: Unstable air, associated with the storm, along with
strong jet dynamics will bring a chance of of embedded
thunderstorms Tuesday night and Wednesday to all areas. Per STORM
PREDICTION CENTER, the area will be under a marginal risk of
severe thunderstorms. So, brief intense rain, small hail, and
locally strong/damaging outflow winds will be significant hazards.
With such strong upper level winds with this system, any
convective element will have a higher risk to bring locally
damaging winds. Additionally, there will be a chance of weak,
short-lived, tornadoes or waterspouts, especially during the
second wave of energy on Thursday when there is colder air aloft
and more instability.

SNOW: Snow levels will remain above the 7500-8000 foot range
through Christmas Eve, but will drop to around 7000 feet on
Christmas Day. So, no winter weather issues are expected through
Christmas Eve, but some decent accumulating snowfall will be
likely at the resort level on Christmas Day.

WIND: Strong and gusty southeast to south winds are expected
Tuesday through Christmas Day. Widespread gusts of 35-55 MPH are
highly likely across all areas. However, there is the potential
for damaging warning level gusts of 60 to 80 MPH across Santa
Barbara and San Luis Obispo counties as well as the mountains and
deserts of Ventura and LA counties. In evening update, have
converted high wind watches to warnings, and added the Santa
Clarita Valley, Santa Monicas, and the islands to the high wind
warning.

IMPACTS: Widespread and significant urban flooding will be likely
along with rock/mudslides and debris flows (with the threat not
just confined to burn areas). The high intensity rainfall and
prolonged duration of heavy rain will bring the threat of debris
flows to the recent burn scars. Streams, rivers, and creeks will
also see rapid flows, thereby increasing the threat of swift water
rescues. A FLOOD WATCH IS IN EFFECT FOR ALL AREAS OF SOUTHWEST
CALIFORNIA DUE TO THESE MAJOR HYDROLOGICAL RISKS. The combination
of increasingly saturated soil and the strong winds will bring the
potential for widespread downed trees and power lines, especially
in areas under a High Wind Warning.

ONCE AGAIN, THIS WILL BE A VERY IMPACTFUL HOLIDAY STORM. ANYONE
TRAVELING ON CHRISTMAS EVE OR CHRISTMAS DAY WILL NEED TO EXERCISE
EXTREME CAUTION. MAKE SURE TO TAKE THE PROPER PROTECTIVE ACTIONS
BEFORE THE STORM HITS.

.LONG TERM (FRI-MON)...22/131 PM.

For Friday and Saturday, models indicate and upper low will drop
across the area. This will keep things unsettled with shower
activity likely to continue across the area. Additional rainfall
totals of 0.25-1.00 inches will be possible. things will be
winding down, but will still remain unsettled. There will continue
to be shower activity across the area with additional rainfall
totals of 0.25 to 1.00 inches through Saturday.

For Sunday and Monday, models have the upper low meander southwest
of the area. This will set up a weak offshore flow pattern across
the area. So, there will be some locally gusty canyon winds.
However, at this time, no widespread advisory-level wind are
expected. Depending on where the upper low sets up, there could be
some wrap around showers across the area late Sunday and Monday.
Confidence in the shower scenario is low, but it will need to be
monitored.

&&

.AVIATION...23/0537Z.

At 2136Z at KLAX, there was a surface based inversion. The top of
the inversion was around 3600 feet with a temperature of 17 C.

High confidence in VFR TAFs for desert airfields (KPMD & KWJF).

Low confidence for remaining TAFs. Timing of CIG/VSBY restrictions
could be off by +/- 3 hours, and off by up to 2 categories at any
point. -DZ could be possible where CIGs are present. Rapidly
deteriorating conds likely Tuesday afternoon to evening as
significant winter storm brings strong south winds and moderate to
heavy rain.

KLAX...Low confidence in TAF. Good confidence that any east wind
component remains below 7 kts through 08Z. 20% chc reaching 7 kts
through 12Z Tuesday, then 40% 12Z-15Z Tuesday, and increasing to
greater than 60% thereafter through end of forecast period. South
cross winds potentially gusting 15-25 kt, MVFR/IFR cigs/vsbys
with -RA/dz at times developing late Tuesday afternoon or evening.

KBUR...Moderate confidence in TAF. Generally expecting VFR
conditions through 03Z Tue. LIFR to IFR CIGs possible from 06Z to
12Z Tue then lifting to IFR to MVFR thereafter.

&&

.MARINE...22/255 AM.

High confidence in the current forecast through Monday night,
then moderate confidence thereafter. Confidence lower due to
timing and seas. Winds and seas will largely remain below SCA
levels through tonight. Patchy dense fog will be possible through
Tuesday morning.

On Tuesday, SE to south winds and seas will are expected to
rapidly increase to dangerous levels as a storm system approaches
the coastal waters. SCA level southerly winds will develop by
Tuesday afternoon with a likely (80-90 percent) chance of
widespread Gale Force Winds through at least Tuesday night with a
50-70 percent chance of STORM FORCE winds 45-55 kt for the waters
north of Point Sal. Large short- period seas are likely to
develop Tuesday night and should linger Wednesday into Thursday.
There is also a 5-15% chance of thunderstorms Tuesday night
through Thursday.

Boaters are urged to monitor the latest weather forecasts. If
marine weather conditions deteriorate as advertised, boaters
should remain in safe harbor during this significant storm.
Unprotected south facing harbors may be especially vulnerable to
the south swell and winds.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Warning in effect from noon Tuesday to 3 PM PST
      Thursday for zones 38-87-88-340>353-369-370-376>383-549-550. (See LAXNPWLOX).
     Flood Watch remains in effect from Tuesday afternoon through
      Thursday evening for zones 38-87-88-340>358-362-366>383-548. (See LAXFFALOX).
     High Surf Advisory in effect from 9 PM Tuesday to 11 AM PST
      Saturday for zones 340-346-349-350. (See LAXCFWLOX).
     Wind Advisory in effect from noon Tuesday to 3 PM PST
      Thursday for zones 354>358-362-366>368-371>375-548. (See LAXNPWLOX).
     High Surf Advisory in effect from 11 PM Tuesday to 11 AM PST
      Saturday for zones 354-362-366. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect from 4 AM to 1 PM PST Tuesday
      for zones 645-670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect from 8 AM to 1 PM PST Tuesday
      for zones 650-655-676. (See LAXMWWLOX).
     Gale Warning in effect from 1 PM Tuesday to 1 PM PST
      Wednesday for zones 650-655-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Gomberg/Thompson
AVIATION...Phillips/Black
MARINE...RM/Phillips/Black
SYNOPSIS...MW

weather.gov/losangeles

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