Acton Weather

000
FXUS66 KLOX 041158
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
458 AM PDT Wed Aug 4 2021

updated aviation discussion

.SYNOPSIS...03/808 PM.

Warm and mostly clear weather will continue through the week,
with temperatures six to twelve degrees above normal for many
areas through midweek. Night through morning low clouds and dense
fog may affect some coastal areas during this time. Gusty
afternoon and evening winds and low humidities will elevate the
fire risk, mainly across the mountains, Antelope Valley and the
Santa Barbara South Coast and adjacent foothills through late
week.

&&

.SHORT TERM (TDY-FRI)...04/258 AM.

Not much change in the forecast and SoCal is still set to sizzle
(at least away from the coast).

Today will be the peak of the heat for many areas as 595 dam hgts
and only weak onshore flow combine with copious sunshine to bring
widespread triple digit heat to the vlys and interior. A shallow
marine layer and seabreeze will keep the beaches in the 70s. Heat
warnings and advisories cover much of the vly/interior sections of
LA/VTA/SBA counties - please see the product LAXNPWLOX for
details. Away from heat a shallow sub 1000 ft marine layer has
produced abundant stratus across the Central Coast but also some
patchy low clouds across some LA/VTA beaches.

The evening sundowners will continue across the SBA south coast
where a decent northerly push will set up again this evening.
There will be enough upper level support to produce advisory wind
gusts across the western half of the SBA south coast.

4 to 8 degrees of cooling on tap for the entire area on Thursday
as a fairly strong trof moves through the northern half of the
state and pushes the upper high away to the south and the east. In
addition the onshore flow will increase which will aid in
developing a more extensive morning low cloud pattern. The lower
hgts, deeper marine layer and earlier arriving seabreeze will all
combine to knock 4 to 8 degrees off of the max temps. While max
temps away from the coast will not reach advisory level they will
still be 3 to 6 degrees above normal.

The high sinks a little more to the south on Friday. It will be a
sunny day save for the morning marine layer stratus across
beaches. There will be a little more cooling south of Pt
Conception but some offshore trends and slight hgt rises will
bring a little warming to the Central Coast

.LONG TERM (SAT-TUE)...04/309 AM.

The EC and the GFS agree that SoCal will not have much upper
level flow overhead. An upper low will be well the north and an
upper high will be well to the east. By Tuesday the upper low will
push far enough to the south to introduce weak cyclonic flow to
the southern half of the state. More importantly the onshore flow
will increase both to the north and the east and will generate a
persistent night through morning low cloud pattern. The onshore
push will likely be strong enough to keep a few beaches across the
Central Coast cloudy all day.

The cooling trend will continue and by Sunday most areas will
experience max temps a few degrees blo normal.

The flow pattern does not look conducive to monsoon flow /
afternoon convection.

&&

.AVIATION...04/1157Z.

At 0527Z at KLAX, the marine layer was 900 feet deep. The top of
the inversion was at 2300 feet with a temperature of 30 C.

Very good confidence in inland and vly TAFs.

Moderate confidence in coastal TAFs south of Point Conception with
a 30% chance of IFR cigs through 16Z.

KLAX...Moderate confidence in TAF through 16Z then good confidence.
There is a 30% chance of 2SM BR OVC006 through 16Z. Any east wind
component will be less than 5 kt.

KBUR...High confidence in CAVU TAF.

&&

.MARINE...04/136 AM.

High confidence in Small Craft Advisory (SCA) level NW winds
continuing through this afternoon from the outer waters along the
Central Coast to San Nicolas Island. There is a 60-70% chance of
Gale force winds from Point Conception to San Nicolas Island late
this afternoon through Thursday night. As such, have decided to
convert the Gale Watch to a Gale Warning. For the portion of the
outer waters north of Point Conception, good confidence in winds
remaining below Gale force today, but there is a 40-50% chance
that Gales could develop. For Thursday, winds look a bit stronger
so there is a 50-60% chance that this portion will exceed Gale
force. Winds look to quickly diminish on Friday, so moderate
confidence in continued SCA level winds through Friday night. For
the nearshore waters along the Central Coast, high confidence in
SCA level winds during the afternoon and evening hours through
Thursday, with a 30-40% chance of Gales. For the Santa Barbara
Channel, moderate to high confidence in SCA level winds across the
western portion during the afternoon and evening hours through
Thursday. There is a 40% chance of SCA gusts from Anacapa Island
to the Santa Monica Bay as well.

High confidence in very short period and choppy seas continuing
over much of the coastal waters through late in the week, with
seas building some through this time. A noticeable long period
but small (2-3 ft) south swell will continue to build in through
Thursday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 8 PM PDT this evening for zones
      38-46-52>54-88-547. (See LAXNPWLOX).
     Wind Advisory in effect from 3 PM this afternoon to 3 AM PDT
      Thursday for zones 39-52. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 8 PM PDT this evening
      for zone 59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Thursday for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Thursday for
      zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT this afternoon
      for zones 673-676. (See LAXMWWLOX).
     Gale Warning in effect from 3 PM this afternoon to 3 AM PDT
      Friday for zones 673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (FRI-TUE).

No significant hazards expected.

&&

$$

PUBLIC...Rorke
AVIATION...Stewart
MARINE...Stewart
SYNOPSIS...CK/Sirard/Smith

weather.gov/losangeles