388
FXUS66 KLOX 260309
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
809 PM PDT Fri Jul 25 2025

.SYNOPSIS...25/715 PM.

A persistent onshore flow pattern will continue into early next
week as an upper-level trough remains anchored to the north of the
area. Night through morning low clouds and fog will continue to
be a staple of the forecast for most coastal and valley locations
through Monday. Late night and early morning drizzle cannot be
ruled out, especially Saturday morning. Below normal temperatures
will linger through the weekend, then a warming trend will
establish as onshore flow weakens.

&&

.SHORT TERM (FRI-MON)...25/808 PM.

The latest water vapor imagery shows an upper-level trough of low
pressure over the state this evening. The trough, centered near
Modesto, will slowly lift out to the northeast through the
weekend while dampening. The trough will serve to keep a
persistent and strong onshore flow in place that will feed a
deeper marine layer depth. The latest RAOB sounding from KVBG
indicates a 2400 foot deep marine layer depth north of Point
Conception, sloping to about 1100 feet deep south of Point
Conception at KLAX. The latest NAM BUFR time height sections
indicate the marine layer depth deepening some overnight,
especially south of Point Conception as an eddy circulation
regenerates.

Low clouds and fog will push well into the valleys tonight and
into Saturday, likely reaching some of the coastal slopes by
Saturday morning. The deepening marine layer depth will interact
with the upper-level dynamics with the trough overnight tonight
and into Saturday morning to squeeze out some drizzle. Late night
through early morning drizzle cannot be ruled out across many
coastal and valley locations, but the most favorable chances for
heavy drizzle or light rain will likely occur for areas north of
Point Conception. NAM BUFR time height sections indicate a few
hundredth of precipitation for KSBP and KSMX late tonight and
early Saturday morning, while multi-model high resolution
ensemble members favor a slight probability of precipitation
along the Central Coast. PoPs were increased above the previous
and current NBM values and a mention of drizzle was added to the
forecast overnight and Saturday morning.

A cooler than normal weather pattern is likely to persist through
the weekend with persistence being the best forecast, especially
along the beaches and immediate coastal locales. Temperatures well
below seasonal normals will linger through the weekend and into
early next week.

A tighter northwesterly surface pressure gradient across Santa
Barbara County will continue, but Sundowner winds should be weaker
than last night across the southwestern portion. KSBA-KSMX surface
pressure gradients were running a little stronger than this time
last night an hour ago but have since backed off. The latest
model solutions and ensemble member gradients suggest the pattern
weakening through the night. At this point, the best approach is
to monitor surface pressure gradients and wind observations for
further development.

***From Previous Discussion***

Overall, forecast guidance is in good synoptic agreement through
the short term period. The upper-level pattern features a low over
Central California that is expected to weaken Saturday. As the
ridge over the eastern CONUS retrogrades/builds, the H5 flow will
become more cyclonic over our area. Therefore, moderate onshore
gradients will persist, meanwhile northerly offshore gradients
will weaken.

Forecast-wise, fairly benign weather with cooler than normal
temperatures expected through the weekend. Concerning the Marine
Layer, it is expected to deepen a few hundred feet overnight and
will likely reach the Santa Clarita Valley. Patchy drizzle is
likely. Thereafter, H5 heights will begin to increase, compressing
the MABL (marine atmospheric boundary layer) and reducing
coverage and extent inland. Elsewhere, skies are expected to
remain mostly clear other than some high clouds.

Sundowners are expected to remain sub-advisory and confined to
the western half of the Santa Ynez Range, with a gradual decrease
in wind speeds through the weekend. The Antelope Valley and
adjacent foothills will have gusty winds each afternoon and
evening but will remain sub-advisory. Overall, no wind issues are
expected.

Below normal temperatures with minor day-to-day temperatures
fluctuations are expected through Saturday. Due to an increase in
H5 heights and less MABL influence, expect a few degrees of
warming each day through Monday.

.LONG TERM (TUE-FRI)...25/223 PM.

High confidence in calm and warmer weather in the long term, with
few impacts for the general public. A warm up is expected,
however daytime highs are not favored to exceed normal by more
than a few degrees. There is little-to-no risk for extreme heat
through at least next Saturday (August 2).

Forecast models are in agreement that 500 mb heights will
gradually trend upwards into late next week, as high pressure over
the southern central US affects the region. However, a strong low
pressure system off the coast of British Columbia and associated
shortwave troughs, will dampen the westward extend of the ridge
into SoCal. Thus temperatures Tuesday through Friday will be
warmer than this week, but will remain near normal for much the
region.

Near the surface, moderate onshore gradients will continue to the
east, with weak northerly offshore gradients. This will maintain
cooling sea breezes, overnight to morning clouds for the coasts
and some valleys (although inland extend will become less
extensive). Sundowner winds across southwest Santa Barbara County
and southwest onshore breezes for the interior (especially the
Antelope Valley and foothills) will continue to be common in the
afternoons and evenings.

&&

.AVIATION...25/1711Z.

At 1629Z at KLAX, the marine layer was 2000 ft deep. The top of
the inversion was 4000 feet with a temperature of 17 C.

High confidence in VFR TAFs for KWJF and KPMD.

Moderate confidence for remaining TAFs. There is a 40% chance of
IFR CIGs at KPRB from 10Z to 16Z Sat. Flight cat changes may be
off +/- 2 hours and minimums by one category.

KLAX...Moderate confidence in 18Z TAF. Arrival and departure of
CIGs may be off by +/- 2 hours. Good confidence in MVFR CIGs
010-015. No significant easterly wind component expected.

KBUR...Moderate confidence in 18Z TAF. Arrival and departure of
CIGs may be off by +/- 2 hours. CIGs may scatter out at end of
forecast period (15Z-18Z Sat).

&&

.MARINE...25/757 PM.

For the Outer Waters, SCA winds are expected south of Point Sal
through Saturday, with a 30% chance of SCA level winds north of
Point Sal. Areas of SCA winds across the outer waters will
continue through as least Tuesday and likely through Wednesday.

For the Inner Waters north of Point Sal, there is a 30-40%
chance of SCA level winds in the afternoon and evening hours each
day except for a 40-50% chance Sunday afternoon and evening.

For the Inner Waters south of Point Conception, Small Craft
Advisory (SCA) level winds are expected across the western half of
the Santa Barbara Channel during the late afternoon and evening
hours, with a 20% chance of SCA level wind elsewhere across the
Southern Inner Waters. Winds will likely remain below SCA level
Monday and Tuesday except for a 30% across the Western Santa
Barbara Channel. Winds are then expected to increase Wednesday
with a 30-50% chance of SCA speeds Wednesday afternoon through
Wednesday night.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zones 650-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall/Black
AVIATION...Black
MARINE...Black/Schoenfeld/Ciliberti
SYNOPSIS...Hall

weather.gov/losangeles

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