Sepulveda, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

073
FXUS66 KLOX 211047
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
347 AM PDT Wed May 21 2025

Updated aviation and marine sections

.SYNOPSIS...21/213 AM.

Hot conditions with an increased risk of heat illness will
continue through Thursday before cooling to near normal by the
holiday weekend. Breezy and dry conditions focused across the
interior will lead to heightened fire weather concerns.

&&

.SHORT TERM (TDY-FRI)...21/258 AM.

Today will be the hottest day of the next 7 with only a little
cooling slated for Thursday.

Weak ridging will bring hgts up to 584 dam today. At the sfc there
will be weak onshore flow to the east and weak offshore flow from
the north. Skies are clear save for a finger of low clouds across
the southern LA county beaches. The rising hgts, weak gradients
and late May sun angles will all combine to bring 3 to 6 locally
8 degrees of warming to most of the areas. Weak offshore flow
across the Central Coast will warm that area 10 to 12 degrees. The
trickiest temperature forecast will be along the beaches where sea
breezes may keep temps on the cooler side. It will, however,
sizzle away from the beaches. Look for 80s across most of the
coasts and 90s in the vlys. There is a 30 percent chc that the
warmest vly locations will reach 100 or 101 degrees. These Max
temps will be about 8 degrees above normals for the csts while the
rest of the area will be 12 to 18 degrees above normal. Heat
advisories cover most areas away from the beaches through 9pm
tomorrow evening, please see the product LAXNPWLOX for all of the
details.

An eddy is forecast to spin up tonight and this will likely bring
low clouds to most of the beaches south of Pt Conception. The lift
from the eddy should lift the marine layer just enough to preclude
the threat of dense fog (although there is about a 30 percent chc
that the lift will not be strong enough and there will be dense
fog up and down the csts). Min temps at the inversion level
(around 1000 ft) will be well above normal offering little
recovery from the afternoon heat.

Onshore flow increases on Thursday and hgts lower a few dam. These
things along with the deeper and more expansive marine layer will
bring 1 to 3 degrees of cooling to most of the area. Max temps
will remain well above normal and coupled with the warm overnight
lows will continue the heat danger and the heat advisories will
continue into the evenings. Increasing N to S flow across SBA
county will lead to gusty sundowner winds later in the afternoon
and into the evening.

The very warm conditions and locally gusty winds will bring
increased fire danger in grassy areas which have already dried
out.

A decent sized trof will move across the state on Friday and lower
hgts to 576 dam. Onshore flow will increase to about 7 mb to the
east and the offshore flow in the N/S direction will switch to
onshore. Look for a pretty robust morning marine layer cover much
of the cst and even extending into the vlys. Max temps will fall 3
to 6 degrees across VTA/LA counties and 4 to 8 degrees across
SLO/SBA counties. Max temps will remain 4 to 8 locally 10 degrees
above normal everywhere except for the Central Coast which will
fall to a few degrees blo normal as a strong sea breeze roars in.
The cooling will be enough, however, to eliminate the heat danger.

.LONG TERM (SAT-TUE)...21/309 AM.

Big cooling slated for Saturday with lower hgts, a deep marine
layer and strong onshore flow (esp to the east). LA/VTA counties
will cool 5 to 10 degrees and SLO/SBA counties will end up 3 to 5
degrees cooler. This cooling will bring most cst/vly areas down to
a few degrees blo normal. The strong onshore flow will bring gusty
winds to the mtns, the Central Coast and the western Antelope Vly
and foothills.

A little ridge will pop up Sunday and max temps will rise a degree
or two. The gusty afternoon winds will continue.

Not the best mdl agreement for the Mon/Tue period. The EC brings a
weak trof to the area while the GFS creates a full blown cut off
low. The ensembles favor the more normal looking EC solution. Look
for fairly typical May weather with morning low clouds, near
normal temperatures and gusty afternoon winds in the mtns and
deserts.

&&

.AVIATION...21/1046Z.

Around 0730Z, the marine layer depth was around 500 feet deep at
KLAX. The top of the inversion was 1900 feet with a temperature
near 24 degrees Celsius.

Moderate confidence in the current forecast for coastal terminals,
otherwise high confidence exists in the forecast for valley and
desert terminals. There is a moderate to high chance of LIFR to
IFR conditions at coastal terminals through 16Z, and again after
04Z Thursday. The highest chance will be for Los Angeles County
coastal terminals.

KLAX...There is a 40 percent chance of LIFR to IFR conditions
through 16Z, otherwise VFR conditions are expected through at
least 04Z Thursday. After 04Z Thursday, there is a 30 percent
chance of LIFR to IFR conditions. Any easterly winds should
remain less than 7 knots.

KBUR...VFR conditions are expected through the period. No winds
impacts are expected at this time.

&&

.MARINE...21/323 AM.

Moderate to high confidence in the current forecast. Higher
confidence exists in the forecast for seas relative to the
forecast for winds.

For the Outer Waters and the nearshore waters along the Central
Coast, there is a 70-90 percent chance of Small Craft Advisory
(SCA) conditions through Saturday night. There will be some for
lulls in the winds nearshore along the Central Coast during late
night and early morning hours, but it is likely that hazardous
seas will linger across the western portion. There is a 40-60
percent chance of GALE Force winds from tonight through early
Thursday morning, and again for Thursday evening and Friday
evening.

Across the Santa Barbara Channel, winds are expected to remain
below SCA levels through Thursday afternoon, but there is a
moderate-to-high (30-50 percent) chance of SCA wind gusts across
the far western portions tonight. There is a high (30-50 percent)
chance of SCA winds, mixing with hazardous seas during the
evenings, Thursday through Friday evening.

South of Point Mugu, into the Santa Monica Bay, and the San Pedro
Channel, winds and seas are expected to remain below SCA levels
through the weekend. There is a moderate (30-40 percent) chance
of SCA level winds on Friday evening.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory remains in effect from 11 AM this morning to 9
      PM PDT Thursday for zones
      88-343-348-351>353-356>358-368-374-375-548. (See LAXNPWLOX).
     Heat Advisory remains in effect until 9 PM PDT Thursday for
      zones 369>373. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 645-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 PM PDT this evening
      for zone 670. (See LAXMWWLOX).
     Gale Watch in effect from this evening through late Friday
      night for zone 670. (See LAXMWWLOX).
     Gale Watch in effect from late tonight through Saturday
      morning for zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Hall
MARINE...Hall
SYNOPSIS...Munroe

weather.gov/losangeles

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