841
FXUS66 KLOX 042357
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
457 PM PDT Wed Jun 4 2025

.SYNOPSIS...04/203 AM.

Broad troughing and strong onshore flow will bring night through
morning low clouds and fog and cooler than normal temperatures
through the end of the week. A warming trend will develop for the
weekend especially away from the beaches.

&&

.SHORT TERM (TDY-SAT)...04/215 PM.

Overall, 12Z models in good synoptic agreement through the short
term period. At upper levels, trough will linger over the area
through Friday then will become a cutoff low that develops west of
Point Conception. Near the surface, moderate to strong onshore
flow will continue.

Forecast-wise, two main issues in the short term will be
convection and the marine layer stratus. With respect to
convection, still looks good (as mentioned in the morning
discussion) for a slight chance of showers/thunderstorms over the
eastern San Gabriel Mountains and adjacent desert foothills this
afternoon. For Thursday, instability parameters (CAPE, K-Indices,
etc.) decrease a bit over the eastern San Gabriel Mountains, but
increase a bit over the Ventura county mountains. Additionally,
PWATs increase over the northern Ventura county mountains and
remain similar to today over the eastern San Gabriel Mountains.
So, still think there is enough moisture and instability to
warrant inclusion of a slight chance of showers/thunderstorms
Thursday afternoon over the eastern San Gabriel Mountains and the
northern Ventura county mountains. Any storms that develop will
likely be a mix of wet and dry. So, both brief heavy rain and dry
lightning strikes will be possible.

The second issue, marine layer stratus, H5 heights remain
virtually unchanged tonight. So, with continued onshore gradients,
inversion will be deep enough for stratus to push into the coastal
slopes tonight. Clearing should be better on Thursday afternoon.
For Thursday night through Saturday, rising H5 heights will
increase, resulting in more shallow inversion and lesser areal
extent of stratus/fog.

As for winds, the onshore gradients will generate the usual gusty
southwesterly winds across interior sections through Saturday.
However, outside of Lake Palmdale, expect winds to remain below
advisory levels.

Finally with respect to temperatures, will expect a gradual
increase in temperatures from day-to-day with lessening marine
influence and rising H5 heights.

.LONG TERM (SUN-WED)...04/215 PM.

For the extended period, 12Z models are not in the best synoptic
agreement. The ECMWF and its ensembles indicate more upper level
ridging than the GFS family. However, near the surface, both
models indicate a continued onshore flow.

Forecast-wise, the differences between the models are not expected
to produce any significant issues. Through the period, dry
conditions are expected. As for clouds, marine layer stratus/fog
should remain mostly confined to the coastal plain, before making
a bit further inland Tuesday/Wednesday as H5 heights decrease a
bit. Other than the marine layer stratus, skies are expected to
remain mostly clear through the period. Temperatures will follow
the same trend, with a warming trend Sunday/Monday then some
slight cooling Tuesday and Wednesday. As for winds, will expect
continued onshore breezes each afternoon, but nothing worrisome.

&&

.AVIATION...04/2353Z.

At 2305Z at KLAX, the marine layer was 1600 feet deep. The top of
the inversion was at 4400 feet with a temperature of 19 C.

High confidence in VFR TAFs for KPMD and KWJF.

Moderate confidence in all remaining TAFs. There is a 20% chance
of IFR/MVFR cigs materializing at KPRB from 08Z to 16Z Thu. There
is a 20% chance of intermittent LIFR cigs at KSMX and KSBP from
08Z to 16Z Thu. There is around a 30% chance of no clearing for
coastal terminals south of Point Conception through the fcst pd.

KLAX...Moderate confidence in 00Z TAF. Arrival and departure of
MVFR (010-015) cigs could be off +/- 2 hours. Intermittent IFR
cigs (007-009) possible to likely from 08Z to 18Z Thu. Cigs likely
to return by 03Z Fri, with a 25% chance of no clearing through
fcst pd. No significant east wind component expected.

KBUR...Moderate confidence in 00Z TAF. Arrival and departure of
cigs may be off +/- 2 hours, with a 30% chance of LIFR cigs from
08Z to 16Z Thu.

&&

.MARINE...04/206 PM.

High confidence in unseasonably quiet conditions through Friday
with no Small Craft Advisories (SCA) needed. The thunderstorm risk
is zero today. More seasonally typical northwest to west winds
will form by Saturday or Sunday, with high confidence SCA winds
and seas over the Central Coast to San Nicolas Island waters. This
will bring short period choppy seas to the nearshore waters as
well.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...Thompson
AVIATION...Black
MARINE...Kittell/Lewis
SYNOPSIS...30

weather.gov/losangeles

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