National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KLOX 260559
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1059 PM PDT Thu Apr 25 2024

.SYNOPSIS...25/213 PM.

Strong onshore flow and a deep moist layer will keep temperatures
cooler than normal across Southwest California through Friday.
There should be some showers on the north mountain slopes Friday
into Saturday morning, otherwise dry weather can be expected
along with gradually warmer temperatures this weekend into the
middle of next week.

&&

.SHORT TERM (THU-SUN)...25/827 PM.

***UPDATE***

Latest satellite/surface observations indicate a chaotic cloud
pattern, ranging from clear to cloudy with most clouds across
Ventura/LA counties. Deep, but weak, inversion caps a moist layer
around 5000 feet deep. Some breezy west to northwest winds, gusts
25-40 MPH, are currently observed with the strongest gusts across
the Antelope Valley foothills and the western Santa Ynez Range.

Overall for the immediate short term, main issue will be the
winds. Overnight, expect northwesterly winds to increase in
coverage and intensity across the area. Strongest winds are likely
through the I-5 Corridor, but gusty winds will impact the rest of
the mountains and the Antelope Valley. Current spate of wind
products (warnings and advisories) across the the mountains and
Antelope Valley look on track. See LAXNPWLOX for the latest
details on the various wind products. Along with the wind, the
northwesterly flow will bank up moisture across the northern
mountain slopes. So, there is a chance of some light showers in
these areas overnight. Snow levels look to remain rather high,
above 6500 feet overnight, so no issues are anticipated for the
Grapevine area.

Overall, current forecast has good handle on the immediate short
term. So, no significant updates are anticipated at this time.

***From Previous Discussion***

A deep moist layer continued into early this afternoon over the
forecast area, with plenty of lingering stratocu altho there were
some breaks here and there. The clouds are expected to scatter
out a bit more thru the afternoon for much of the coast and a few
adjacent vlys, but overall should linger for much of the coastal
slopes and inland vlys.

Gusty mainly sub-Advisory level NW to N winds are expected to
affect the Central Coast, the southwestern SBA County mtns and
coast, the Antelope Vly including foothills, and the L.A. County
mtns along the I-5 Corridor thru the afternoon hours. Otherwise,
breezy onshore winds can be expected this afternoon.

A cool air mass from a departing upper level trof will result in
afternoon temps being about 6-12 deg below seasonal norms. Highs
should only be in the 60s for much of the coast, vlys and deserts.

Weak upper level ridging thru this evening will be replaced by
upper level troffiness later tonight, with a stronger upper level
trof moving in from the6/00 +8.3 +9.8 -1.5 -1.9 +2.4 -2 +1.4 + 2
-0.5 +4.2 +3.4 +12.9 N on Fri. This upper level trof will linger
over SW CA Fri night before exiting to the E on Sat. Upper level
ridging should then start to build into the area Sat night and
Sun, with H5 heights increasing to around 576-577 dam Sun
afternoon.

The main story of the upper level trof will be the winds. Strong
and gusty NW to N winds will cover much of the interior areas
tonight thru Fri night or Sat morning, as well as the SW SBA
County coast and mtns, where a series of Wind Advisories and High
Wind Warnings/High Wind Watches will be in effect. Gusts of 40 to
65 mph will be possible, strongest in the mtns. Gusty Advisory
level winds will also be possible for the Santa Clarita Vly and
along the Central Coast Fri afternoon into Fri night, where Wind
Advisories may be needed. Please see the latest Non-Precipitation
Weather Message (LAXNPWLOX) for further details.

Partly to mostly cloudy skies will persist tonight into Friday,
then be mainly on the N slopes Fri night into Sat morning, with a
slight chance to chance of showers and snow showers mainly on the
N mtn slopes. Mostly sunny skies can then be expected in all areas
Sat afternoon.6/00 +8.3 +9.8 -1.5 -1.9 +2.4 -2 +1.4 + 2 -0.5 +4.2
+3.4 +12.9

Marine layer low clouds and fog are expected to develop along
many coastal areas into some adjacent vlys Sat night into Sun
morning, otherwise mostly clear skies can be expected for the
second half of the upcoming weekend.

Temps are forecast to be several degrees below normal on Fri then
warm to near or slightly above normal by Sun. Temps over the
inland coast and vlys should reach the upper 60s to low 70s Fri,
the 70s on Sat, and in the 70s to around 80 on Sun.

.LONG TERM (MON-THU)...25/209 PM.

The EC and GFS deterministic and mean ensembles are in generally
good agreement during the extended period. Weak and mostly flat
upper level ridging will prevail over the region Mon and Tue,
followed by weak upper level troffiness Wed and especially Thu.

Dry weather will prevail over the forecast area Mon thru Thu. The
marine layer pattern is expected to continue thru the period,
with varying amounts of night and morning low clouds and fog along
portions of the coast Mon and Tue, then expand along the coast
and extend inland to the adjacent vlys Wed and Thu. Otherwise,
skies will be mostly clear.

Temps are expected to be near normal to a few degrees above
normal on Mon, then increase to several degrees above normal for
many areas away from the immediate coast Tue and Wed. It should
turn cooler in all areas Thu with temps slightly below normal for
most areas, and a few degrees above normal for some interior
areas.

&&

.AVIATION...26/0156Z.

At 0019Z at KLAX, the marine layer was up to 4900 ft under an
inversion with a top around 6800 ft and a temperature of 7 C.

Moderate confidence in TAFs. Expecting MVFR to VFR cigs with a
very deep marine layer. Lower confidence in timing of MVFR
conditions, but they will be most likely overnight into the early
morning hours. Gusty N to NW winds will affect the higher terrain
of the southern SBA County eastward to the Antelope Valley. LLWS
and turbulence, with mdt UDDF near the mtns.

KLAX...Moderate confidence in TAF, with uncertainty in OVC015 cig
arrival and clearing times. There is a 20% chance that conds will
be BKN035 or higher tonight. There is a 30% chance of east winds
reaching 8 kts from 07Z-14Z.

KBUR...Moderate confidence in TAF, with uncertainty in OVC015 cig
arrival and clearing times.

&&

.MARINE...25/1058 PM.

In the Outer Waters, the Gale Watches have been converted to Gale
Warnings. The Gale Warnings for the southern two zones
(PZZ673/676) have been moved up to begin at 11PM tonight, as winds
are already gusting to 30 kt. The Small Craft Advisory for the
waters north of Point Sal look on track, and expecting gales to
start Friday afternoon. May need to extend the Gale Warnings for
all outer waters out through Tuesday night. Expecting at least SCA
level winds and/or seas are to continue thru Tuesday night.

For the Inner Waters N of Pt. Sal, SCA level winds/seas are
occuring and will likely continue much of the time thru Tue,
particularly during the afternoons and evenings. There is a 50-70%
chance of gales Fri afternoon/evening, with a 30% chance of gales
returning Sat afternoon/evening.

In the Inner Waters S Pt Conception, winds may occasionally drop
below SCA levels late tonight. The Gale Watches have been
converted to Gale Warnings and look on track, with SCA winds
leading up to Gales on Friday. The strongest winds should move
further to the west on Saturday as they turn more northerly but
there is a with a 40-50% chance of gales Sat afternoon into Sat
night. Sunday and Monday SCA winds will linger for the SBA
Channel and the western portions of the southern inner waters.

Friday, seas are expected to build to around 8-12 feet,
especially for the waters south of the Channel Islands. Widespread
gale force winds and gale force nearshore winds will create
dangerous ocean conditions with short-period, steep, choppy waves
and could create breaking waves at west-facing harbors. Mariners
should remain in safe harbor until conditions improve.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory now in effect until 3 AM PDT Sunday for zones
      349-351. (See LAXNPWLOX).
     Wind Advisory in effect until 3 AM PDT Saturday for zones
      353-379-380. (See LAXNPWLOX).
     High Surf Advisory in effect from 2 PM Friday to 10 AM PDT
      Saturday for zones 354-362-366. (See LAXCFWLOX).
     Wind Advisory in effect until 6 PM PDT Friday for zones
      376-377. (See LAXNPWLOX).
     High Wind Watch in effect from Friday evening through late
      Friday night for zones 376-377. (See LAXNPWLOX).
     High Wind Warning in effect until 3 AM PDT Saturday for zones
      378-381. (See LAXNPWLOX).
     Wind Advisory in effect until 3 AM PDT Friday for zone 383. (See LAXNPWLOX).
     High Wind Watch in effect from 3 AM PDT Friday through late
      Friday night for zone 383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PDT Friday for
      zones 645-670. (See LAXMWWLOX).
     Gale Warning in effect from 3 PM to 9 PM PDT Friday for zones
      645-670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Friday for zone
      650. (See LAXMWWLOX).
     Gale Warning in effect from 9 AM Friday to 3 AM PDT Saturday
      for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 2 PM PDT Friday for zone
      655. (See LAXMWWLOX).
     Gale Warning in effect from 2 PM Friday to 3 AM PDT Saturday
      for zone 655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 11 PM PDT this evening
      for zones 673-676. (See LAXMWWLOX).
     Gale Warning in effect until 8 AM PDT Sunday for zone 673. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Sunday for zone 676. (See LAXMWWLOX).

&&

$$

PUBLIC...Sirard/Thompson
AVIATION...Phillips/Schoenfeld
MARINE...Phillips/DB
SYNOPSIS...Sirard

weather.gov/losangeles

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