953
FXUS66 KLOX 251655
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
955 AM PDT Tue Jun 25 2024

.SYNOPSIS...25/227 AM.

A gradual cooling trend will continue through midweek as high
pressure weakens over the area and onshore flow strengthens. Night
through morning low clouds and fog will slowly return to the
coastal areas. Temperatures will likely rebound next weekend as
high pressure builds back into the region.

&&

.SHORT TERM (TDY-THU)...25/951 AM.

***UPDATE***

No significant updates with the morning forecast update. With
lingering mid level moisture, there is less than a 10 percent
chance of a shower or thunderstorm across the higher terrain in
eastern Los Angeles County, the northern Ventura County mountains,
and northern San Luis Obispo County.

Modest cooling and moistening trends were evident just about
everywhere, but most significant towards the coast where
moderate onshore trends is a reverse of trends of previous days,
asserting the greater natural cooling effects a recovering marine
layer. Heat products for the interior seem well placed for today
and seems reasonable for most if not all to expire without
extension this evening as cooling trends (especially for morning
low temperatures) continue into midweek.

The low cloud forecast continues to be a challenge for tonight,
as it typically is with a recovering marine layer.

***From Previous Discussion***

Three fairly unexciting weather days on tap for the southland
starting today. The area will be under the western edge of a large
upper high over srn NM. An upper low will scoot through the PAC NW
Wed and Thu its energy will push the upper high to the SE while
turning the anti-cyclonic flow to a weakly cyclonic one. Hgts will
be the highest today around 592 dam. By Thursday hgts will be down
to about 590 dam. Strong onshore flow to the east and moderate
onshore flow to the north (peaking in the afternoon) will continue
for all three days.

Residual humidity and partly cloudy skies wrapping around the
upper high this morning have prevented the formation of any marine
layer clouds. The partly cloudy skies will advect away to the
north in the morning leaving sunny skies for the afternoon. The
flow does not turn to the SW fast enough to totally eliminate the
threat of mtn convection in the afternoon but the chc is less than
10 percent which is too low to mention in the fcst. The onshore
flow will bring 4 to 8 degrees of cooling to the coasts and vlys.
The interior will see little or no cooling and heat
advisories/warnings are in place for the interior of SLO/SBA
counties as well as the Antelope Vly. See the product LAXNPWLOX
for details. This will be the last day of the heat products as
there will be enough cooling tomorrow to bring temperatures down
to below advisory thresholds.

Look for two days of cooling with an gradual increase in the night
through morning low clouds. Since hgts are still quite high the
marine layer will be smooshed to below 1000 feet and will only
cover the coasts and the lowest vlys. Lowering hgts and a better
developed marine layer along with the strong onshore flow will
bring 2 to 4 degrees of cooling each day. By Thursday the coasts
and vlys will be 1 to 3 degrees blo normal (vly highs from 80-90)
and the interior will be near normal.

.LONG TERM (FRI-MON)...25/321 AM.

The cooling trend peaks on Friday especially across SLO and SBA
counties. Max temps will end up 3-6 degrees blo normal. The marine
layer stratus will be well developed and may push further into the
vlys. Some beaches may not clear at all. The strong onshore flow
will bring near advisory level west winds the Antelope Vly and its
foothills. In addition strong NW winds across the outer waters
will filter through SW SBA and may produce advisory level gusts
across the western portion of the SBA south coast.

High pressure begins to reassert itself over the weekend. Max
temps will rise 1 to 3 degrees Sat and 2 to 5 degree on Sunday.
The marine layer will shrink a little. Breezy west to northwest
winds will continue, peaking each afternoon and evening,
potentially nearing advisory levels for southwest Santa Barbara
County at times.

Not much mdl agreement on the fcst for next Monday. About 50
percent of the ensembles favor further warming with a growing
upper high while the other half bring in troffing and cooler
temps. No threat of monsoon convection so no real impacts no
matter the outcome.

&&

.AVIATION...25/1636Z.

At 16Z over KLAX, the marine layer was 600 feet deep. The top of
the inversion was 3000 feet and 25 degrees Celsius.

High confidence in VFR conditions with lighter than usual winds.
There is a 5-10% chance of afternoon thunderstorms over the
mountains and over KWJF KPMD. Moderate confidence in more low
cloud coverage over the region tonight into Wednesday, but
generally low confidence in exact coverage and timing. There is a
chance for LIFR ceilings and visibility at KSBP (30%) KSMX (50%)
KSBA (10%). There is a chance for IFR conditions at KOXR (30%)
KCMA (20%) KSMO (40%) KLAX (40%) KLGB (50%). Otherwise, VFR
conditions expected.

KLAX...High confidence in VFR conditions through 04Z. There is a
50% chance of ceilings tonight, forming as early as 06Z or as
late as 12Z. Moderate confidence in IFR conditions if ceilings
form. SE winds are likely 09-15Z, but high confidence in winds
staying under 8 knots.

KBUR...High confidence in VFR conditions through Wednesday with
seasonal winds.

&&

.MARINE...25/846 AM.

Patchy dense fog with visibilities under one mile will affect
portions of the waters today, including nearshore. Fog will cover
more of the area tonight and Wednesday, with a possibility of
being dense especially off the Central Coast.

There is a 20% chance of Small Craft Advisory (SCA) level wind
gusts this tonight in the Outer Waters (offshore waters of the
Central Coast to San Nicolas Island). Otherwise high confidence in
quieter than usual conditions into Wednesday.

Northwest winds will increase Wednesday and Thursday. High
confidence in SCA conditions for the outer waters, with a 20-40%
chance of low-end gale force winds (highest chances well off the
Central Coast). For the nearshore waters, the is a 40-60% chance
of SCA winds along the Central Coast (afternoon and evening hours)
and a 20% chance for the western Santa Barbara Channel. Higher
chances on Thursday.

Winds will gradually weaken Friday and Saturday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory remains in effect until 8 PM PDT this evening
      for zones 38-344-345-353. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect until 8 PM PDT this
      evening for zones 382-383. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Munroe/Rorke
AVIATION...RK
MARINE...RK
SYNOPSIS...30

weather.gov/losangeles

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