National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KLOX 132159
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
259 PM PDT Sat Apr 13 2024

.SYNOPSIS...13/210 PM.

Much cooler weather is expected through Sunday as another late
season storm affects the region. Rain will turn to showers tonight
and Sunday, with a slight chance of thunderstorms especially on
Sunday. Accumulating snow and wintry conditions is expected at
higher elevations. A warming trend will then begin Monday with
dry and warm weather expected through the end of the week.

&&

.SHORT TERM (TDY-TUE)...13/208 PM.

Early this afternoon, a cold 540 dam H5 upper level low was about
160 miles W of San Francisco. A 1007 mb surface low was in this
general area with a cold front extending S of the low into SLO and
SBA Counties with a band of rain along the front. This front is
forecast to move slowly E into VTU/L.A. Counties from about mid
afternoon thru early this evening. Pre-frontal rain associated
with a warm front has already developed over VTU County. The rain
coverage will increase with rain spreading across all areas thru
this afternoon into this evening. Mainly light to moderate
intensities are expected, altho heavy rain at times cannot be
ruled out especially on south-facing slopes. There is also enough
cold air aloft along the Central Coast to warrant a slight chance
of thunderstorms there during the late afternoon and evening.

The main front will move E of L.A. county later this evening with
the widespread rain ending and turning more showery. Showers will
increase in coverage over SLO/SBA Counties later tonight as the
cold upper level low approaches, and the slight chance of
thunderstorms will continue.

Strong and gusty S to SE winds will accompany this storm system
as well, especially over the foothills and mtns of SBA/VTU/L.A.
Counties, and for the Antelope Vly including the foothills. The
strongest winds to Advisory levels will be thru this evening for
much of the area. Wind Advisories are in effect and more details
can be found in the latest Non-Precipitation Weather Message
(LAXNPWLOX).

Snow is expected to move into the higher mountains of
SBA/VTU/L.A. Counties as well this afternoon and tonight with
hazardous wintry driving conditions especially at the higher
elevations. Snow levels thru sunset will be around 6000 to 6500
feet or so then drop to 4000 to 5000 feet tonight, altho much of
the widespread steady snow will end this evening. The snow and
gusty winds have resulted in a Winter Weather Advisory for these
areas. Please see the latest Winter Weather Message (LAXWSWLOX)
for further details.

The upper level low is forecast to move over the forecast area
from mid morning Sun thru the afternoon. The very cold air aloft
(-23 to -28 deg C at 500 mb) combined with the cyclonic flow and
strong April sunshine will significantly destabilize the
atmosphere, resulting in numerous showers and a slight chance of
thunderstorms. Any heavier showers and thunderstorms could produce
heavy rain, small hail and gusty winds. Dangerous cloud-to-ground
lightning can be expected with any thunderstorms as well. There
is also a very small non-zero chance that a weak tornado could
develop.

Rain totals thru Sun are expected to be highest across
SLO/SBA/VTU Counties, mainly south facing mountains where 1-3
inches of rain are expected. Across LA County, amounts drop off to
around a half to one inch, though locally higher amounts possible
where thunderstorms develop. In the mountains, 5-10 inches or
more of snow are possible at higher elevations and 2-5 inches down
to around 5000 feet.

The storm is expected to exit Sunday evening with some leftover
north slope showers Sunday night. Otherwise, dry and warmer
weather is expected across the forecast area Monday through
Tuesday. Mostly clear skies should develop in all areas by Mon
afternoon, altho some marine layer low clouds could affect the
L.A. County coast later Mon night into Tue morning. Some breezy to
gusty northerly winds are possible Mon as well.

High temps by Tue are expected to reach the 70s to around 80 from
the inland coast to the lower mtns and deserts.

.LONG TERM (WED-SAT)...13/208 PM.

The EC and GFS mean ensembles and deterministic are in generally
good agreement thru the extended period. Upper level ridging will
build into the forecast area Wed then weaken and flatten Thu and
Fri before weak upper level ridging moves back in for Sat.

Skies are expected to be mostly clear Wed thru Sat, altho some hi
clouds could move in between Wed and Thu for partly cloudy skies
at times. There is also a good chance the marine layer could
redevelop with night and morning low clouds and fog affecting
several coastal areas thru Thu then expand along the coast and
inland some Fri and Sat.

Temps are expected to increase to about 5-10 deg above normal for
many areas Wed and Thu before cooling some Fri and Sat,
especially for the coast and vlys. High temps for the warmest
inland coast, vlys and lower mtns should reach the 70s to mid 80s
Wed and Thu, then drop to the 70s to around 80 Fri and Sat. For
the Antelope Vly, highs each day are expected to be in the low to
mid 80s.

&&

.AVIATION...13/1820Z.

At 1706Z at KLAX, there was a deep moist layer up to about 7000
feet, but no real marine inversion.

Low confidence in TAFs. There is a multi-layered cloud deck, so
cigs will bounce between categories through the period,
especially during rain. Conds will deteriorate this afternoon,
with increasingly widespread MVFR to IFR cigs, and local LIFR to
VLIFR conds in the foothills/mtns. Conds may improve to low VFR or
high MVFR in coastal/vly areas tonight, but IFR to VLIFR conds
are still likely in the foothills/mtns. Another area of rain will
likely push into SLO/SBA Counties late tonight.

Gusty SE-S winds will diminish by early afternoon in most areas.
In the mtns and Antelope Valley, gusty S-SW winds are likely thru
this evening. There will be areas of LLWS, mdt turbulence and UDDF.

KLAX...Low confidence in TAF. There will likely be frequent
changes in cig heights, especially during rain. SE winds 10 -15
kt expected through 19-20Z, then shifting to the S-SW.

KBUR...Low confidence in TAF. There will likely be frequent
changes in cig heights, especially during rain.

&&

.MARINE...13/252 PM.

Complex forecast through Monday afternoon, as conds will be
marginally close to thresholds for Small Craft Advisory (SCA)
level winds and seas.

For all the Outer Waters and the inner waters N of Point Sal, SCA
level SE to S winds will shift to the W to NW this
afternoon/evening. For the outer waters, conditions are expected
to be at or near SCA level much the time through at least Wed. In
the near future, there may be some lulls in the winds this
evening and Sunday mid-day, particularly for the southern Outer
Waters and the inner waters N of Point Sal. By Monday afternoon,
SCA winds will strengthen somewhat with a 20% chance of Gale Force
winds. SCA winds may last though Thursday, strongest in the
afternoon and evenings.

In the SBA Channel, after S to SE winds subside this evening,
there is a 40-50% chance of SCA level W winds Sun eve into Monday
morning, mainly in western sections. SCA level W-NW winds are
likely Mon afternoon into Mon night.

In the southern inner waters, after SE winds subside today, there
is a 40% chance of SCA level W winds Sun into Sunday night, and
again Mon evening with NW winds.

There is a slight chance of thunderstorms for all the coastal
waters waters tonight and Sun.

&&

.BEACHES...13/157 PM.

A low-end high surf event is expected tonight through Sunday with
strong rip current activity. On the Central Coast, surf of 6-10
ft, with local sets to 12 feet, is expected tonight/Sun, highest
on W and NW facing beaches. S of Pt Conception, surf of 5-8 ft is
expected Sun, highest on W facing beaches.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect from 9 PM this evening to 9 PM
      PDT Sunday for zones 340-346. (See LAXCFWLOX).
     Winter Weather Advisory in effect until 5 PM PDT Sunday for
      zones 353-376-377-379-380. (See LAXWSWLOX).
     High Surf Advisory in effect from 9 AM to 9 PM PDT Sunday for
      zones 354-362-366. (See LAXCFWLOX).
     Wind Advisory in effect until 9 PM PDT this evening for zones
      378-381>383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 9 PM this evening to 9 AM
      PDT Sunday for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 6 PM PDT this evening
      for zones 650-655-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 PM PDT Sunday for zone
      670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Monday for zone
      673. (See LAXMWWLOX).
     Small Craft Advisory in effect from 9 AM Sunday to 9 AM PDT
      Monday for zone 676. (See LAXMWWLOX).

&&

$$

PUBLIC...Sirard
AVIATION...Schoenfeld
MARINE...DB/Schoenfeld
BEACHES...DB
SYNOPSIS...Sirard

weather.gov/losangeles

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