516
FXUS66 KLOX 102103
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
203 PM PDT Thu Jul 10 2025

.SYNOPSIS...10/1250 PM.

Above normal temperatures will linger into the weekend, but a
cooling trend will establish into early next week. The best
cooling will occur across the coast and valleys. Night through
morning low clouds and fog will become a staple of the forecast,
expanding in coverage over the weekend. Monsoon moisture could
spread into the region during the middle to later half of next
week.

&&

.SHORT TERM (TDY-SUN)...10/152 PM.

Another hot day is occurring across the valleys, mountains, and
desert as strong high pressure aloft remains in place today.
Several sites away from the coast are closing in on the 100 degree
mark in the Southland. A heat advisory (issued earlier this
morning) remains in effect until 8 pm PDT this evening due to air
mass approaching critically hot criteria for people sensitive to
the heat.

Onshore flow, keeping temperatures moderated along the coast the
past several days, will strengthen through early next week. The
marine layer depth will deepen over the coming days and through
the weekend as strong onshore flow establishes. With 500 mb
heights not changing by much and model solutions continuing to
suggest KLAX-KDAG surface pressure gradients exceeding 9 mb, there
is some concern that low clouds and fog may sock in the beaches
similar to a May Gray or June Gloom day. Outside the marine layer
depth, the air mass will remain and above normal for this time of
year. The latest NAM BUFR time height sections suggest the marine
layer depth deepening to near 1500 feet deep at KLAX by Saturday,
so it is same to assume the foothills, mountains and desert will
remain above seasonal normals. Despite strong onshore flow
exceeding 5 to 6 mb along the Central Coast, dense fog issues
should linger over the next several nights and mornings.

With the strong onshore flow developing and surface pressure
gradient above the 97th percentile for this time of year, gusty
onshore winds are likely to develop across the interior valleys,
such as the San Luis Obispo County interior valleys and the
Antelope Valley. While confidence higher for advisory level winds
each afternoon and evening in the adjacent foothills of the
Antelope Valley, advisory level winds cannot be ruled out in the
Shandon and Cholame Valleys and the Antelope Valley floor. Wind
advisory headlines could be needed as soon as Friday afternoon
and evening, but there is always some uncertainty with the actual
surface pressure gradient values as the transition takes place.
Confidence is a bit higher for stronger gradient values over the
weekend as the onshore flow will likely strengthen into the
forecast range. With the gusty winds across the interior and
warmer than normal conditions lingering, elevated to brief
critical fire weather conditions are likely to persist.

.LONG TERM (MON-THU)...10/201 PM.

Strong onshore flow will remain in place through at least Monday,
and possibly into Tuesday. EPS solutions suggest a brief pop-up in
the 500 mb heights on Sunday, which will likely thin the marine
layer slightly, but strong onshore flow in place will likely drive
the forecast for most coastal and valley areas. Night through
morning low clouds and fog will continue to be a staple of the
forecast, struggling to clear from the beaches and immediate
coast each afternoon. Gusty onshore winds will continue to flirt
with advisory levels across the interior portions of the area.

Currently, the latest forecast ensembles suggest a weakening of
the onshore flow pattern on Wednesday, then hint at the
possibilty of the window opening up for monsoonal moisture to slip
into the region.

&&

.AVIATION...10/1805Z.

At 1730Z, there was a 700 foot marine layer at KLAX. The top of
the inversion was near 3900 feet with a max temperature of 27 C.

High confidence in VFR TAF for KPMD, KWJF, KBUR, and KVNY. Lower
confidence in winds for KVNY, where there is a 40% chance of a W
wind 8-12 kts surfacing from 22Z to 04Z.

High confidence in return of cigs at KSMX tonight and moderate
confidence in KSBP (+/- 2 hours timing). Moderate confidence in
vsbys. There is a chance for less than 1/2SM at KSBP (20%) and
KSMX (30%).

Low confidence in remaining TAFs. There is a 40% chance for brief
cigs 004-010 at KLAX and KSMO through 21Z, but low confidence in
minimum cig height and there is a 15% chance VFR conds prevail
through the period after that. There is a 30% chance for IFR cigs
after 08Z at KCMA (30%) and KSBA (20%). For KOXR there is a 30%
chance for no cigs. If cigs arrive, timing may be off +/- 3
hours and minimum flight cat may be off by one cat.

KLAX...Moderate confidence in TAF. A patch of low clouds developed off
the west coast of the LA Basin. There is a 40% chance for brief
cigs 004-010 through 21Z, but low confidence in minimum cig
height. Vsbys may be as low as 1SM if clouds make it to KLAX. For
tonight, arrival of low clouds may be off +/- 3 hours and minimum
cig height may be off +/- 400 feet. There is a 15% chance for VFR
conds to prevail tonight. Moderate confidence in any east wind
component remaining under 8 kts.

KBUR...High confidence in VFR TAF.

&&

.MARINE...10/133 PM.

Small Craft Advisory (SCA) level winds will continue across the
outer waters south of Point Conception through late tonight and
into early Friday morning. Local Gale Force wind gust are possible
through this evening from Point Conception south to San Nicolas
Island.

SCA level winds will continue across the inner waters north of
Point Sal and the Santa Barbara Channel this afternoon and
evening. Local gusts to 21 kts may occur nearshore along the
Ventura coast and off the coast of Los Angeles and Orange
Counties, particularly across the San Pedro Channel and near Point
Dume through this evening. Steep and choppy seas are likely
across most of the inner waters through late tonight.

Patchy dense fog focused across the waters adjacent to the central
coast and west of the Channel Island will likely occur tonight and
into morning hours tomorrow.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 8 PM PDT this evening for zones
      88-342>345-369>372-374-375-379-380. (See LAXNPWLOX).
     Wind Advisory remains in effect until 3 AM PDT Friday for
      zones 349-351. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 650-670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Friday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall
AVIATION...Lewis
MARINE...Lewis
SYNOPSIS...Hall

weather.gov/losangeles

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