031
FXUS66 KLOX 010529
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1029 PM PDT Tue Apr 30 2024

.SYNOPSIS...30/731 PM.

Mostly clear skies and warmer temperatures will continue through
this week, with some night through morning coastal low clouds and
fog at times. Locally breezy winds will affect the mountains and
deserts through Wednesday, then turn NE over interior Ventura
and Los Angeles Counties Wednesday night into Thursday. Cooling is
expected Friday through the weekend with a slight chance of rain.

&&

.SHORT TERM (TUE-FRI)...30/823 PM.

***UPDATE***

A slightly higher marine layer coverage is expected for coastal
and some valley areas tonight into Wednesday morning, compared to
previous nights. But that said, cloud cover will be fairly limited
north of Ventura County, with portions of Santa Barbara seeing low
clouds, including the eastern South Coast and near Santa Maria.
Further south, better coverage is expected for the Ventura and
L.A. coast and coastal valleys. A Catalina Eddy along with good
onshore gradients will help to move the layer inland over these
areas.

Meanwhile, north winds are just below Advisory levels along the
western Santa Barbara South Coast, with gusts up to 40 mph. Expect
there will be some isolated gusts up to 45 mph through 10 PM
before winds begin to subside there. However, in the western
Antelope Valley and foothills and the I-5 Corridor, winds will
increase this evening, with gusts of 45 to 50 mph expected by 11
PM. Have issued a Wind Advisory for these areas, in effect through
9 AM Wednesday.

Otherwise expect a mostly clear day Wednesday after the morning
low clouds scatter out. Temperatures will be similar to, or
slightly cooler than, today`s highs.

***From Previous Discussion***

The biggest adjustment to the forecast today was to cut back on
the offshore winds for Thursday as models (particularly the NAM)
have really reversed course on that. Onshore flow will be lighter
but any northeast winds should be confined to the interior and be
well below advisory levels. High temperatures will only go up a
few degrees at most for Thursday, mainly mid 80s for the valleys
and low to mid 70s for coastal zones. Then turning cooler again
Friday as a trough approaches from the northwest and gradients
shift back to onshore again marine layer coverage expands.

.LONG TERM (SAT-TUE)...30/221 PM.

Still a lot of uncertainty this weekend with the approaching upper
low. The deterministic models are still split with the GFS
favoring an inside slider low dropping through interior California
while the EC keep the low mainly north of Lake Tahoe. The grand
ensemble mean solution is much closer to the farther north EC
solution and not surprisingly NBM pops are extremely low. This may
ultimately prove to be an accurate assessment of the rain chances
at this point there are still enough solutions with at least some
light rain or drizzle to have some mention of precip in the
forecast by later Saturday into Sunday. For what it`s worth all
the higher precip solutions from the earlier GEFS solutions were
gone on the 12z run and only 30-40% of the remaining solutions had
even light rain, perhaps indicating models are starting to move
towards a drier scenario for the weekend.

In any case, rain chances are mostly confined to late Saturday
and early Sunday so the majority of the daytime periods are
expected to be dry. The cooling trend that will have begun Friday
will continue through the weekend with highs 4-8 degrees below
normal, coolest on Sunday.

There will be slightly warming Monday but most models maintain
cooler than normal temperatures well into next week.

&&

.AVIATION...01/0527Z.

At 0400Z at KLAX, the marine layer was 1000 ft deep with an
inversion top at 3000 ft with a temperature of 17 C.

Overall low to moderate confidence in the 06Z TAFs for coastal
sites and the LA Valley sites, with high confidence elsewhere.
For KSMX, KSBA, KOXR and KCMA, low confidence in whether CIGs
will form, with a 20-30 percent chance they remain clear
overnight. Otherwise, moderate confidence in the LA County sites,
although the timing of CIGs arrival and clearing may be off by +/-
2 hours.

KLAX...Moderate confidence in the 06Z TAF. Timing of cig
arrival/clearing may be off by +/- 2 hours. There is a 30% chance
of an east wind component reaching 8 kts from 10Z-18Z Wed.

KBUR...Low to moderate confidence in the 06Z TAF. Timing of cig
arrival/clearing may be off by +/- 2 hours, with a 20% chance of
CIGs lowering to IFR. 20 percent chance of no CIGs.

&&

.MARINE...30/932 PM.

For the outer waters, current Gale Warnings are on track with
gusty NW gales expected to continue until late tonight. Swell
will continue to be steep and choppy. After gales subside, Small
Craft Advisory (SCA) conds are expected for the outer waters,
Wednesday through Sunday. However, there is a 30% chance of winds
to increase to gale force Wednesday night and a 40-50% chance
Thursday afternoon and evening.

For the inner waters N of Pt. Sal, SCA level winds are likely
through tonight. Then, there is a 60% chance of SCA winds during
the afternoon and evening hours Wednesday through Friday. Seas
are expected to be above SCA level through Wednesday.

For the Santa Barbara Channel, SCA level W-NW winds are expected
across the western portion through late night hours tonight and
again Wednesday afternoon/evening. Then, there is a 20-30% chance
of SCA winds each afternoon/evening Thursday and Friday across
the extreme western portion. Winds will likely remain below SCA
levels for eastern portions of the channel through Friday night.
Saturday afternoon through Sunday, there is a 30-40% chance of
widespread W to NW SCA level winds across the entire inner waters.

For the southern inner waters, there is a 20% chance of SCA level
W to NW winds near Anacapa Island Wednesday evening. Otherwise,
good confidence in conds remaining below SCA levels through Friday
night. Saturday afternoon through Sunday, there is a 30-40%
chance of widespread W to NW SCA level winds across the entire
inner waters.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 2 PM PDT Wednesday for
      zones 340-346-354. (See LAXCFWLOX).
     Wind Advisory in effect until 9 AM PDT Wednesday for zones
      378-381-383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
      zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zone 650. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Wednesday for zones
      670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Smith
AVIATION...Smith
MARINE...Phillips/Schoenfeld
SYNOPSIS...Smith

weather.gov/losangeles

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