154
FXUS66 KLOX 132119
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
219 PM PDT Sat Sep 13 2025

.SYNOPSIS...13/129 PM.

A warming trend will continue, with temperatures increasing a
couple degrees from day to day through next week. Night through
morning low clouds and fog will cover many coasts and coastal
valleys through at least Tuesday, and some of the fog could
become dense. The heat peaks during the middle of next week, and
will be replaced by a slow cooling trend and chances for showers
and thunderstorms Wednesday.

&&

.SHORT TERM (TDY-TUE)...13/207 PM.

No significant weather issues expected through Tuesday. A weak
trough will move through Oregon later tonight and Sunday but that
will have little to no impact this far south. The marine layer was
still around 3000 feet this morning south of Pt Conception and it
should still be somewhere between 2000 and 3000 feet tonight as
well so expecting most coast and valley areas to fill in with
stratus overnight. Some lowering of the marine layer is expected
along the Central Coast tonight and Sunday morning as the trough
passage. In addition, a light northeast flow is expected to
develop that should lead to several degrees of warming there,
especially along the coast due to the downsloping effects there.

Heights will start rising following the trough passage Monday and
Tuesday. This is expected to bring down the marine layer depth
and lead to warming for areas south of Pt Conception. By Tuesday
some of the warmer valleys are expected to reach low end triple
digits while inland coastal areas will be in the 80s to around 90.

One possible caveat for Tuesday is that the 12z NAM was much more
aggressive with the return of monsoon flow and was hinting at an
earlier start to the convection with CAPE values over 1000J/kg,
mainly over the coastal waters. This could be a potential dry
lightning risk since the deeper monsoon moisture will still be
south of the area. While a few of the ensemble solutions showed
showers as early as Tuesday across our area, most were were still
favoring Wed or Thu as the more likely start to possible
convection locally.

.LONG TERM (WED-SAT)...13/218 PM.

Still looking like a potentially active monsoon pattern for the
middle and end of next week. Ensembles have been very consistent
with increasing PW`s next week, peaking on Thursday between 1.5
and 2" across LA County and as high as an inch across the Central
Coast. The threat of thunderstorms will cover the entire forecast
area and not just the mountains and deserts. Showers and storms
could develop at any time of day or night given the ample moisture
and instability. There will be a risk of flash flooding,
particularly in the mountains and deserts, but even lower
elevations will be at risk for brief periods of heavy rain.

At the same time the air mass will be warming up and with
increasing humidity the concern will be for increasing heat risk
factors across region-wide. Confidence remains rather low right
now due to the uncertainty of the cloud and possible rain/storm
coverage. The most likely days for heat hazards would probably be
Tue and Wed before the deeper moisture and higher rain/storm
chances arrive.

&&

.AVIATION...13/1717Z.

At 1600Z at KLAX, the marine layer was 2600 ft deep. The top of
the inversion was at 4800 ft with a temperature of 18 C.

High confidence in TAFs for desert airfields (KPMD and KWJF).

Moderate confidence in all coastal and valley TAFs.

Timing of CIG/VSBY restrictions may be off by 2 hours & flight
categories may be off by one at times when CIGs are present.
There is a chc for no low clouds at KPRB (30%), KBUR (15%), and
KVNY (15%).

KLAX...Moderate confidence in 18Z TAF. Arrival and clearing times
may be off by +/- 3 hours. There is a 10% chance of a southeast
wind component reaching 8 kt 10Z-17Z Sun.

KBUR...Moderate confidence in 18Z TAF. Arrival and clearing times
may be off by +/- 2 hours. However, there is a 15% chance for no
low clouds tonight.

&&

.MARINE...13/207 PM.

Small Craft Advisory (SCA) level NW winds (20-30 kts) will impact
the outer waters and the nearshore waters along the Central Coast
through late Sunday night, peaking in the afternoon and evening
hours, with relative lulls each morning. There is a 50% chance for
Gale Force winds (34-38 kts) Sunday afternoon through evening for
the northern Outer Waters beyond 20 NM from shore. Chances for
Gales nearshore to 20 NM away from shore are 25%. Will let the
afternoon or overnight shift determine whether or not a GALE
warning is needed for PZZ670. Seas are expected to become small
early next week, before building to 6 to 8 feet Thursday into
Friday. Conditions are expected to stay below advisory levels on
Monday and Tuesday.

For the inner waters south of Point Conception, SCA level wind
gusts are likely across the western portion of the Santa Barbara
Channel through Midnight. Thereafter, conditions are generally
expected to remain sub-advisory thru at least Tuesday. Local SCA
level wind gusts cannot be ruled out.

An upper-level low will draw sub-tropical moisture northward
across the coastal waters mid-week, bringing chances for showers
and thunderstorms. Will continue to monitor the situation, and
iron out the details as we get closer.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT Sunday for zone
      670. (See LAXMWWLOX).
     Gale Watch in effect from Sunday afternoon through late
      Sunday night for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Monday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW
AVIATION...Black
MARINE...Black
SYNOPSIS...MW/Cohen

weather.gov/losangeles

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