Acton Weather

231
FXUS66 KLOX 090638
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1138 PM PDT Thu May 8 2025

.SYNOPSIS...08/143 PM.

A warming trend will continue through Saturday as high pressure
aloft will be in place over California. However, continued
onshore flow will keep temperatures cooler near the coast.
Onshore flow will strengthen next week and bring much cooler
conditions with low clouds and fog pushing back into the valleys.

&&

.SHORT TERM (THU-SUN)...08/857 PM.

***UPDATE***

Latest satellite and surface observations indicate clear skies
across most of the area, except for the immediate Central Coast
and adjacent coastal waters. Current sounding data indicates
marine inversion around 500 feet in depth. As for winds, some west
to northwest gusts, 20-30 MPH, across the Antelope Valley as well
as the western Santa Ynez Range.

Forecast-wise for the immediate short term, only issue will be the
marine layer stratus overnight. Marine inversion will remain very
shallow overnight, keeping any stratus confined to the immediate
coastal plain. Also with the shallow inversion, dense fog will be
a potential issue overnight. Given the uncertainty in marine layer
coverage overnight, will not issue any dense fog advisories this
evening. However, it may need to be a consideration for the night
shift. Other than marine layer issues, no significant issues are
expected overnight.

Overall, forecast has great handle on the immediate short term.
So, no significant updates are planned.

***From Previous Discussion***

High pressure building over the region will bring much warmer
weather through the weekend, peaking Friday and Saturday with
highs approaching 100 in the warmest valleys and even low to mid
80s across inland portions of the coastal plain. Highs will be
very close to daily records in the valleys and heat advisories
have been posted across the valleys and Santa Monica mountains.
The marine layer depth has lowered to 1000 feet or less, meaning
stratus will be confined to the coastal areas at best with some
dense fog during the overnight and morning hours. Onshore flow
will remain weak the next few days, but weakest Friday, then
slowly increasing Saturday and Sunday.

The high pressure ridge will shift east late Saturday into Sunday
allowing cooler air from the ocean to surge inland. The timing of
this surge will determine how much temperatures drop on Sunday.
There are still quite a few model solutions keeping highs in the
valleys in the 90s Sunday, especially the eastern San Fernando and
Santa Clarita valleys.

.LONG TERM (MON-THU)...08/218 PM.

Much cooler temperatures are expected next week as troughing
replaces the high pressure ridge. The trough is deepest late
Tuesday into Wednesday and slightly more than half of the ensemble
solutions are showing some drizzle or light rain along the Central
Coast. There are far fewer solutions showing any precip south of
Pt Conception but would not be surprised to see a return of a
3000` or higher marine layer with areas of drizzle or light rain
across coast and valley areas, especially those areas adjacent to
the south facing mountains. Rapidly increasing onshore flow will
mean a return of gusty afternoon and evening winds to the interior
areas, especially the Antelope Valley.

That system is expected to shift east of the area later Wednesday
but general troughing will continue through the remainder of the
week, maintaining cooler than normal temperatures.

&&

.AVIATION...09/0624Z.

At 05Z at KLAX, the marine layer was based near the surface. The
top of the inversion was 1600 ft with a temp of 25 degrees C.

High confidence in VFR conds prevailing for KPMD KWJF KPRB KBUR
KVNY through the period.

Low to moderate confidence elsewhere with a 20 percent chance of
VFR conds prevailing for KCMA, KSMO, KLAX, and KLGB. There is a
20-30 percent chance of IFR or lower cigs/vsbys between 09-16Z for
coastal sites. Timing of low cigs/vsbys may be off by 2-3 hours.

KLAX...Low confidence in TAF. Cigs most likely in the 400-800
range with a 20 percent chance that VFR conds prevail. Arrival
tonight may be 2-3 hours later than forecast. No significant east
wind component is expected.

KBUR...High confidence in TAF. There is a 10% chance for 4SM to
5SM BR/HZ 12-16Z.

&&

.MARINE...08/1050 PM.

Current Small Craft Advisories look on track, ending tonight.

Expecting more SCA level winds for the outer waters north of the
Channel Islands, and the inner waters north of Point Sal Friday.
There is also a 30-40% chance for shorter lived, localized SCA
level winds for portions of the inner waters south of Point
Conception Friday evening. High confidence in at least SCA conds
focused across the outer waters lasting through Saturday,
becoming widespread by Sunday and potentially continuing into
early next week. There is a 20-40 percent chance of Gales in the
Saturday evening through Monday time frame, with the lowest
potential focused across the inner waters, especially south of the
Channel Islands.

Dense fog focused in the night to morning hours may become more
common through Friday or Saturday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect from 10 AM Friday to 9 PM PDT
      Saturday for zones 88-343-356>358-369>375-548. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Thompson
AVIATION...Phillips/Lund
MARINE...Phillips
SYNOPSIS...MW

weather.gov/losangeles

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