148
FXUS66 KLOX 190320
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
820 PM PDT Fri Jul 18 2025

.SYNOPSIS...18/1235 PM.

Showers and thunderstorms will be possible through Saturday for
portions of Los Angeles and Ventura Counties, with the best chance
today across Antelope Valley and the San Gabriel Mountains and
Valley. Night through morning low clouds and fog will continue for
most coasts and valleys. Below normal temperatures are expected,
with a possible warming trend late next week.

&&

.SHORT TERM (FRI-MON)...18/816 PM.

***UPDATE***

Current satellite and radar indicate earlier convective activity
across eastern LA county has diminished. Rainfall totals across
the eastern San Gabriel Mountains generally around 0.25 inches or
less also some isolated areas received around 0.75 inches.
Elsewhere, sprinkles or a couple hundredths of an inch were
reported across eastern LA county.

With the convective activity ending, it should be a very quiet
through the overnight hours. Main issue will be how the marine
layer stratus redevelops overnight. North of Point Conception,
good confidence in stratus returning to the coastal plain and into
the Santa Ynez Valley. South of Point Conception, confidence in
the redevelopment of the stratus is noticeably lower. Current
forecast indicates stratus developing across the LA coastal plain
overnight, but not anywhere else. Given the uncertainty, do not
have a good reason to change the areal coverage at this time.

Overall, other than some minor updates to the immediate sky cover
grids, no updates are anticipated this evening.

***From Previous Discussion***

Thunderstorms are currently developing over the eastern San
Gabriel Mountains and are drifting southwest, with associated
cumulus cloud development over much of eastern Los Angeles County.
The San Gabriel Valley, eastern San Gabriel Mountains, and the
eastern Antelope Valley are at high risk of thunderstorms (or
showers) into this evening. A slight chance of storms also extends
to the Ventura County mountains, and much of LA County. Hazards
with any storms include lighting and dry lighting new fire starts,
damaging wind gusts, and areas of flash flooding, especially for
the higher elevation areas of LA County. At present, there is a
20-30 percent chance of rain rates reaching debris flow thresholds
along the Bridge Burn Scar, with lower but non-zero chances for
the Eaton Burn Scar. Please stay alert to the weather conditions
and have multiple way to receive emergency alerts (such as cell
phone, NOAA Weather Radio, or our website). As always, when
Thunder Roars --> Go Indoors!

A low pressure system to the south has shuttled moisture into the
area, and PWATs of 1.0 to 1.4 inches are widespread across the
Los Angeles Basin. Daytime heating and the expansion of the deep
mixed layer across the interior is interfacing with marine layer
moisture in the San Gabriel Valley. Pockets of surface CAPE of up
to 3000 J/kg are possible along this boundary, and likely are not
resolved in the high resolution CAMs. These factors will continue
to fuel convection into this evening. Saturday, continual
monsoonal moisture will result in linger chances of afternoon into
evening thunderstorms centered around the eastern San Gabriel
mountains and extending into the nearby foothills. By Sunday,
chances for any storms will subside as the low exits the areas and
shuts off the mositure source.

Due to the higher heat capacity of moist air, temperatures will
be a touch cooler across the normally very dry inland areas.
Temperatures will remain a few degrees below normal over the next
several days, as a result of general upper level troughing over
the region.

.LONG TERM (TUE-FRI)...18/117 PM.

High confidence in quiet weather is expected next week with
limited if any impacts. Below normal temperatures are expected,
though a gradual warming trend is possible starting on Thursday.
The cooler temperatures will be caused by a period of weak
troughing for the region as a low pressure system drifts south
from the Pacific Northwest to off the coast of far northern
California. Onshore surface pressure gradients will maintain
marine layer overnight clouds and fog across the coasts and some
valleys, as well on gusty southwest to west winds across interior
areas. Winds will be the strongest across the Antelope Valley and
adjacent foothills, and the Highway 14 corridor. Weak Sundowner
winds may also return for southwest Santa Barbara County midweek.
however all winds are likely to remain below Advisory level.

&&

.AVIATION...18/2338Z.

At 2230Z at KLAX, the marine layer depth was around 1000 feet. The
top of the inversion was 4100 feet with a temperature of 25C.

For 00Z TAF package, high confidence in KWJF, KPMD, KPRB, KBUR and
KVNY.

For coastal TAFs, only moderate confidence in 00Z TAFs. Lower
confidence due to uncertainties with how the marine layer stratus
will behave tonight with mid-level moisture moving in. Timing of
return of CIG/VSBY restrictions tonight could be +/- 3 hours of
current forecasts.

Thunderstorms over the far eastern deserts and San Gabriel
Mountains could generate gusty outflow winds through the
mountains.

KLAX...Moderate confidence in 00Z TAF. Timing of return of IFR
CIGs could be +/- 3 hours of current 06Z forecast with a 40%
chance that CIG restrictions do not develop. No significant
easterly wind component is expected.

KBUR...High confidence in 00Z TAF.

&&

.MARINE...18/720 PM.

Overall, moderate to high confidence in the current forecast.

For the outer waters, Small Craft Advisory (SCA) winds are
expected much of the time through Wednesday. There will likely be
a lull in winds below SCA levels during the morning hours each
day. Seas are expected to remain well below SCA levels through
this timeframe.

For the inner waters north of Point Sal, SCA NW winds are likely
(60% chance) across PZZ645 Saturday afternoon into the evening
hours. There will be a lull in winds on Sunday, before moderate
chances return for the afternoon/eve hours Monday thru Wednesday.
Seas are expected to remain well below SCA levels through this
timeframe.

For the inner waters south of Point Conception, SCA W winds are
likely (60% chance) across western and southern portions of the
Santa Barbara Channel late Saturday afternoon into the evening
hours. There will be a lull in winds on Sunday, before moderate
chances return for the afternoon/eve hours Monday thru Wednesday.
Elsewhere, conditions are expected to remain below SCA levels
through this time frame.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 1 PM to 9 PM PDT Saturday
      for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 5 PM to 11 PM PDT
      Saturday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Sunday for zone
      670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Monday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Schoenfeld/Thompson
AVIATION...RAT
MARINE...Black
SYNOPSIS...Schoenfeld

weather.gov/losangeles

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