982
FXUS66 KLOX 101258
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
558 AM PDT Sun Aug 10 2025

.SYNOPSIS...10/433 AM.

A very warm to hot weather pattern will continue across many
valley, mountain, and desert locations into Tuesday as high
pressure aloft lingers over the region. Temperatures will remain
above seasonal normals through midweek, except along the coast
where persistent onshore flow and a marine intrusion wedged in
place will keep temperatures cooler. Areas of night through
morning low clouds and fog will remain a staple of the forecast
along the coast and into some coastal valleys through the period.
Cooler temperatures are expected for late week.

&&

.SHORT TERM (TDY-TUE)...10/435 AM.

A broad ridge of high pressure remains over the West Coast and the
eastern Pacific Ocean this morning. Mostly clear skies prevail
outside of the typical night through morning low clouds and fog
early this morning. A marine intrusion remains wedged in as an
onshore flow regime continues. The low cloud field along the
Central Coast of California continues to remain well-entrenched,
and it is likely that low clouds and fog will continue to struggle
to clear each afternoon. South of Point Conception and into the
southern California bight, low cloud formation has gotten a
little later start in some areas, but low clouds and fog are
rapidly filling in across the bight and the Santa Barbara Channel
and starting to form a more aggressive advance toward the Los
Angeles County coast and San Gabriel Valley. Multiple eddy
circulations, seen inside the southern California bight on fog
product imagery, should aid development through the early morning
hours. The latest AMDAR soundings from KLAX indicate a marine
layer depth around 1250 feet deep, about 400 feet deeper than last
night, but north of Point Conception, the marine layer depth is
likely a little thinner due to the influence of the ridge center.
The best chance for any dense fog will be for the coastal
foothills and lower valleys south of Point Conception, and the
Central Coast and into the Santa Ynez Valley this morning.

With an upper-level ridge of high pressure lingering, a hot to
very warm air mass will remain outside the marine influence. The
upper-level ridge center nosing into the northern California will
likely bring near dangerous levels of heat to the mountains and
interior valleys the next several days. Some warming expected
over the interior portions of the area has nudged the mountains
into advisory level heat criteria. Currently, some lower
elevations of the mountains are seeing overnight low temperatures
dipping only into the upper 70s to lower 80s, so far. The warm
overnight low temperatures in combination with the warming lower-
levels of the atmosphere has ticked up heat risk values. A heat
advisory was added to the Cuyama Valley and the Transverse Ranges
farther from the coast, including the San Gabriel Mountains and
the Ventura and Santa Barbara County mountains. Each day through
Monday evening, daytime temperatures in the lower elevations of
the mountains and the interior valleys will likely soar to between
the 90s to around 105 degrees, while the higher elevations of the
mountains will see temperatures between in the mid 80s and mid
90s. Overnight low temperatures will offer little reprieve from
the heat.

Closer to the coast and into the marine influence, an onshore flow
regime will keep the coastal and lower valley below to near
normal. Persistence will likely be the best forecast for these
areas at least through Monday or Tuesday. Night through morning
low clouds and fog will likely continue to be a staple of the
forecast for the period.

Some cooling with start to develop on Tuesday as high pressure
aloft starts to break down and be replaced by a trough to the
north, but above normal temperatures away from the coast should
be expected into midweek.

As the upper-level pattern starts to transition between Monday
and Tuesday, gusty Sundowner winds will likely develop as the
northwesterly gradient starts to tighten. Marginally gusty
Sundowner winds could develop as soon as this evening, but Monday
and Tuesday evenings look like to be higher chance. A wind
advisory may be needed for southwestern Santa Barbara County as
soon as more confidence arrives for wind speeds and the exact
timing. As the Sundowner winds develop, downsloping into the south
coast of Santa Barbara County will likely warm the air mass
during the evening. The forecast accounts for localized
compressional heating, pushing temperatures above forecast
guidance, but with 950 mb temperatures progged to be near 32
degrees Celsius, high temperatures soaring into the 80s and lower
90s each evening cannot be ruled out.

Northerly winds could also develop through the Interstate 5
Corridor on Monday night and/or Tuesday night. EPS ensemble
members continue to indicate the possibility of advisory level
winds at KSDB each night, but deterministic solutions and
forecast guidance leans toward stronger winds on Monday night and
into Tuesday morning.

.LONG TERM (WED-SAT)...10/416 AM.

A cooling trend should persist into the weekend as all the
cluster analysis panels suggest an upper-level trough along the
Pacific Northwest. The majority of the panels favor a deepening
trough with the strongest onshore flow along the Central Coast.
Temperatures below seasonal normals with continued night through
morning low clouds and fog should be expected. Low clouds and fog
may return to the valleys each night and clouds may struggle to
clear from some beaches each day.

&&

.AVIATION...10/1257Z.

At 0636Z at KLAX, the marine layer was 1400 ft deep. The top of
the inversion was at 3700 ft with a temperature of 28 C.

Smoke from nearby wildfires may cause reduced vis at times,
especially for KSBP, KSBA, and KPRB.

Otherwise, high confidence in VFR TAFs at KPRB, KBUR, KVNY, KPMD,
and KWJF.

Low to moderate confidence in forecast for the remaining
airfields, with reduced confidence due to timing of flight
category changes potentially being off by +/- 2 hours. Expecting
LIFR-IFR cigs/vsbys through this morning for the coastal
airfields. CIGs could linger at the immediate coastal sites south
of Point Conception through the afternoon, with a 30% chance of
no VFR transitions.

KLAX...Moderate confidence in TAF through 01Z Monday, then low
confidence. Timing of flight cat changes could be off by +/- 2
hours. There is a 30% chance of no VFR transitions through the
period. If CIGs do clear, rearrival of low clouds could occur as
early as 02Z Monday or as late as 12Z Mon. Any east wind
component should remain below 7 kts.

KBUR...High confidence in TAF.

&&

.MARINE...10/236 AM.

For the outer waters, generally high confidence in the current
forecast. In the northern zone (PZZ670), there is a 30-40% chance
of SCA level wind gusts during the afternoon and evening hours
each day starting Monday. For the outer waters south of Point Sal,
there is a 50-60% chance of SCA wind gusts this afternoon through
Thursday night, with brief lulls possible during the late night
through morning hours.

For the inner waters north of Point Sal, generally high
confidence in the current forecast with winds and seas expected
to remain below SCA levels through Thursday night. However, there
is a 30% chance of SCA level winds during the afternoon and
evening hours on Monday and Tuesday.

For the inner waters south of Point Conception, generally moderate
confidence. Across the SBA Channel, there is a 40-50% chance of
SCA wind gusts at at times, mainly during the afternoon and
evening hours today through Thursday especially across the
western portions. Over the southern inner waters (PZZ655), there
is a 20-30% chance of SCA wind gusts late this afternoon into
this evening around Point Dume and into the San Pedro Channel,
otherwise conds are expected to be below SCA levels through
Thursday night.

In addition, night to morning dense fog may continue at times
into early next week.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect from 9 AM this morning to 9 PM PDT
      Monday for zones 38-351>353-376>380. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 2 PM this afternoon to 3
      AM PDT Monday for zones 650-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall
AVIATION...Lund
MARINE...Sirard/Ciliberti/Lund
SYNOPSIS...Hall

weather.gov/losangeles

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