306
FXUS66 KLOX 300504
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1004 PM PDT Mon Apr 29 2024

.SYNOPSIS...29/225 PM.

Mostly clear skies and warmer temperatures will prevail across
the region through this week, although some night through morning
coastal low clouds and fog can be expected at times through
Wednesday. Gusty northwest to north winds will prevail over the
mountains and deserts through Wednesday, then turn NE and gusty
over portions of Ventura and Los Angeles Counties Wednesday night
into Thursday. There is a slight chance of rain with cooler
temperatures later in the upcoming weekend.

&&

.SHORT TERM (MON-THU)...29/805 PM.

***UPDATE***

Skies were clear this evening with gusty northerly winds across
many interior mountains and deserts to southwest Santa Barbara
County. A small fire was ongoing across the northern Antelope
Valley.

Low confidence forecast for low cloud and fog formation this
evening focused across the LA Basin near sunrise tomorrow as the
closest low clouds are focused near San Diego. However, a -1.5
Santa Barbara to San Diego gradient should support at least a
moderate eddy, which may support the low clouds developing as is
currently forecasted (50-60 percent chance of occuring).

Forecast on track with no adjustments scheduled.

***From Previous Discussion***

There were some low clouds right along the L.A. County beaches
early this afternoon which may persist thu late afternoon.
Otherwise sunny skies covered the forecast area with little
change expected thru sunset.

Northerly pressure gradients helped to keep gusty NW to N winds
over portions of the SW SBA County mtns and coast, VTU County
mtns, L.A. County mtns along the I-5 Corridor, and the western
Antelope Vly foothills into the Antelope Vly. Advisory level wind
gusts to 40 to 50 mph at times can be expected in these areas this
afternoon and Wind Advisories will continue. Breezy to gusty W-NW
winds will also affect much of the coast and adjacent vlys thru
this afternoon, strongest on the Central Coast where winds could
approach Advisory levels at times.

A flat upper level pattern with H5 heights around 576 dam will
persist over the area, helping to keep temps near normal to a few
degrees above normal. Highs this afternoon for the inland coast,
vlys and lower mtns should reach the 70s to low 80s, with the
warmest temps in the western San Fernando Vly.

Flat upper level ridging with H5 heights around 576 dam will
persist over the area tonight thru Tue, then very weak upper level
troffiness should move in by Wed with H5 heights falling slightly
to around 572-573 dam. The weak upper level troffiness should
linger Wed night and Thu as well.

Low clouds should affect the L.A. County coast tonight into Tue
morning, and for the L.A./VTU County coast Tue night into Wed
morning. There should also be more low clouds late tonight into
Tue morning for the Salinas River Vly. Otherwise and elsewhere
across SW CA, mostly clear skies will prevail thru Thu.

Strong and gusty NW to N winds are expected to continue tonight
thru early Wed afternoon for the VTU County mtns, L.A. County
mtns around the I-5 corridor and along the Hwy 14 corridor, and
the western Antelope Vly foothills into the Antelope Vly. Gusty
northerly winds are also expected for the SBA County mtns
including Santa Ynez Range, and the SBA County S coast especially
below the favored passes and canyons. Gusts to 40 to 55 mph will
be possible at times. Wind Advisories are be in effect or will be
issued for these areas thru Wed afternoon. Please see the latest
Non-Precipitation Weather Message (LAXNPWLOX) for further details
on the Wind Advisories.

For the coast and vlys, breezy to gusty sub-Advisory level W to
NW winds can be expected each afternoon, strongest along the
Central Coast.

As pressure gradients turn sharply offshore to the E Wed night,
winds are expected to turn more to the NE Wed night into Thu, with
gusty winds possibly to Advisory levels expected by Thu morning
for the favored portions of VTU/L.A. Counties.

Temps are forecast to be near normal to a several degrees above
normal Tue thru Thu, altho Thu should be the warmest day overall
thanks to the offshore flow. Highs for the inland coast, vlys and
lower mtns should reach generally into the 70s to lower 80s each
day.

.LONG TERM (FRI-MON)...29/222 PM.

The GFS and EC deterministic and mean ensembles are in generally
good agreement Fri, but then diverge Sat and Sun as the GFS
continued to dig a significant (for early May) upper level trof
into CA late Sat thru Sun along with a surface cold front,
bringing the potential for measurable rain across the region. The
EC is weaker with the upper trof and just brushes a dissipating
cold front across the region Sun with a small chance of measurable
rain. As far as the GFS mean ensembles, there were 18 members out
of 30 showing precipitation across the fcst area this weekend,
while yesterday`s run had only 4 members with any rain. The NBM,
meanwhile, is keeping POPs very low and less than 10 percent.

Given that the EC now has some rainfall possibilities, have opted
to go against the NBM and introduce mostly slight POPs to the fcst
Sat night into Sun. Due to lingering uncertainties it is too
early to tell how much rain we may receive from this system, but
up to 0.10 inch may fall for many areas. However, the potential
exists for as much as one quarter to one half inch of rainfall
from Sat night thru Sun. We will know more as additional model
runs come in over the next few days.

Dry weather is expected Fri into Sat, with a slight chance of
rain for northern SLO County late in the day. The front is
expected to move across the forecast area Sat night and Sun with a
band of mainly light rainfall, then dry weather should return on
Mon. Temps will be near normal to slightly above normal Fri, then
should cool to a few degrees below normal by Sun before rebounding
some on Mon.

&&

.AVIATION...29/1739Z.

At 1719Z at KLAX, the marine layer was 500 ft deep with an
inversion top at 2300 ft with a maximum temperature of 17 C.

High confidence in TAFs, except for KLAX and KLGB (30% chc of no
cigs), KSMO (40% chance of IFR cigs from 12Z-16Z Tue), and KOXR
(15% chance of IFR cigs after 14Z Tue).

KLAX...Moderate confidence in TAF. There is a 30% chance of no
cigs developing tonight. No significant easterly wind component is
expected.

KBUR...Moderate to high confidence in TAF, some uncertainty in
wind direction after 04Z Tue.

&&

.MARINE...29/1003 PM.

For the outer waters, current Gale Warnings look on track with
gusty NW gales expected to continue thru at least Tue night.
Could see winds fall below Gale strength Tuesday morning/early
afternoon before strengthening again. Swell will continue to be
steep and choppy, a significant hazard to small vessels in
particular. SCA conds are expected for the outer waters, Wed thru
Fri, with a 30% chance of gales persisting into Wed night.

In the inner waters N of Pt. Sal, there is a 25% chance of gale
force winds tonight, and SCA level winds are likely thru Tue
night. Then, there is a 50% chance of SCA conds late Wed thru Fri.
Seas are expected to be above SCA level through Wed.

In the SBA Channel, SCA level W-NW winds are expected, particular
across western portions, during the afternoon thru late night
hours thru Wed. Winds will likely remain below SCA levels for
eastern portions of the channel, most of the time through the
period.

In the southern inner waters, there is a 20% chance of SCA level
W to NW winds across northwestern portions, near Anacapa Island
during the late afternoon thru late evening hours through
Wednesday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 2 AM PDT Wednesday for
      zones 340-346. (See LAXCFWLOX).
     Wind Advisory now in effect until 3 PM PDT Wednesday for
      zones 349-351>353-376>378-381-383. (See LAXNPWLOX).
     Wind Advisory in effect until 3 PM PDT Wednesday for zone
      379. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Tuesday for
      zone 650. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Wednesday for zones
      670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Munroe/Sirard
AVIATION...Schoenfeld
MARINE...Phillips/RM
SYNOPSIS...Sirard

weather.gov/losangeles

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