FXUS66 KLOX 121130
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
430 AM PDT Tue May 12 2026

.SYNOPSIS...12/335 AM.

Several degrees of cooling are expected today and Wednesday as an
upper low moves through northern California. Low clouds and fog
will move into the coastal valleys with clouds lingering at some
coastal areas through today. Gusty winds are expected times
across the mountains and deserts. Slight warming is expected
Thursday and Friday.

&&

.SHORT TERM (TDY-THU)...12/338 AM.

This morning cross sections show deepening of the marine layer,
thus low clouds and fog will likely extend into some of the
coastal valleys. Looking for a slow-to-no clearing day through
this afternoon for portions of the coast.

High pressure will start to weaken and shift east today, with the
upper level flow turning more southeasterly. The lowering heights
and much stronger onshore pressure gradients will bring 5 to 10
degrees of cooling across much of the forecast area, except only
a few degrees of cooling across the Antelope Valley where highs
will still climb into the 90s. In fact, latest forecast pressure
gradients showing the potential for LAX-Daggett and LAX-
Bakersfield gradients to exceed +9 mb which is rather significant
for this time of year. Looking at historical pressure gradient
percentile information, a +9 LAX- Bakersfield gradient would be
near all-time highs for the month of May, and LAX-Daggett would
exceed the 97th percentile. With this in mind, looking for a
significant increase in coverage and strength of onshore winds
across the interior this afternoon/evening, with gusts mostly
ranging in the 30 to 45 mph range. A Wind Advisory is in effect
for this afternoon/evening for the Antelope Valley and adjacent
western foothills where gusts up to 45 mph are expected, and could
locally reach 50 mph in a few of the favored foothill locations.
This will likely generate some blowing dust and sand which could
locally restrict visibilities. Another area of concern for
stronger onshore winds will the interior valley of San Luis Obispo
county where gusts of 30 to 45 mph will be likely, and may also
require a Wind Advisory. The strengthening onshore winds combined
with lingering warm/dry conditions will bring elevated to locally
brief critical fire weather conditions across the interior this
afternoon, thereby increasing the risk of fast-moving and large
grass fires.

Another item to keep an eye on today will be some influx of mid
level moisture and instability as the upper flow turns
southeasterly. Models have been consistent with embedded vorticity
areas sweeping through the interior this afternoon, with some
elevated instability (NAM lifted index values of -4 to
-6 and MUCAPE values of 500 to 700 J/kg). The main limiting factor
will be available mid level moisture, which looks rather minimal
at this point. For now, will keep with a 5-10 percent chance of a
brief shower or thunderstorm across the interior, with the best
chances over the San Gabriel mountains and Ventura county
mountains. If any convection were to develop, forecast model
soundings showing that isolated dry lightning and gusty
downdrafts would be the main concerns, with DCAPE values exceed
1000 J/kg.

An upper low will move through Northern California on Wednesday.
Following the upper low passage northerly flow aloft will
increase across the Santa Ynez Range and western Transverse Range
creating increasing northerly winds in those areas, mainly from
late afternoon through the early morning hours. Forecast ensemble
gradients are still in the -3 to -5 range, which would likely be
strong enough for wind advisories in the Santa Ynez Range. Further
cooling is expected on Wednesday, with little change in
temperatures on Thursday.

.LONG TERM (FRI-MON)...12/429 AM.

In the long term, most temperatures will be within a few degrees
of normal, with a very gradual warming trend each day. 500 mb
heights will likely increase into Saturday, followed by broad
weak troughing over the area. However, weakening onshore to
briefly onshore surface pressure gradients will allow the warming
trend to generally continue, most noticeably at the coasts, where
temperatures will reach a few degrees above normal by Monday.

&&

.AVIATION...12/0752Z.

High confidence in KWJF and KPMD TAFs.

Low to moderate confidence in remainder of TAFs. Timing of flight
category changes may be off by 3 hours and one flight category.

KLAX...Moderate confidence in TAF, with cigs likely to persist
through Tue afternoon. VSBY between 1/2-2SM possible through
16Z-18Z.

KBUR...Moderate confidence in TAF. There is a 30 percent chc of
VFR conditions remaining through period, but latest trends
indicating increasing potential for IFR/LIFR cigs around sunrise.

&&

.MARINE...12/1253 AM.

Winds and seas will remain below Small Craft Advisory (SCA)
levels through Wednesday morning.

Wednesday afternoon through the weekend, winds and seas will
start to strengthen/build, with SCA winds across the outer waters
starting late Wednesday night and Seas reaching steep and choppy
SCA levels around Friday night. There is a 20-40 percent chance of
SCA winds across the inner waters, with the highest chances each
afternoon and evenings. GALE Force winds will be possible across
the outer waters as early as Thursday afternoon, with highest
(30-50 percent) chances on Saturday into Sunday.

As for seas, large SCA level seas of 10-12+ feet will be possible
for the outer and northern waters by this weekend.

Dense fog will be possible through mid morning today.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from 2 PM this afternoon to 10 PM PDT
      this evening for zones 381-383. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Gomberg/Schoenfeld
AVIATION...Schoenfeld
MARINE...Munroe/Lund
SYNOPSIS...MW/RS

weather.gov/losangeles

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