864
FXUS66 KLOX 071640
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
940 AM PDT Sun Jul 7 2024

.SYNOPSIS...07/929 AM.

A long-lasting and extreme heatwave will continue across the
mountains and interior areas through much of the coming week with
a high risk for dangerous heat illness and fast-growing fires.
Temperatures across coast and valleys have returned to normal
levels for now, however a warming trend is expected there through
the week with increasing risk of heat issues in the valleys.

&&

.SHORT TERM (TDY-TUE)...07/939 AM.

***UPDATE***

An even stronger onshore flow than expected brought a return of
low clouds and significant cooling to coast and valley areas
yesterday and this trend will continue today. The 24 hour
temperature change map shows widespread cooling of 5-10 degrees
from just a few miles inland and throughout much of the valleys
and Santa Monica mountains and as much as 15-20 degrees of cooling
in and around the Santa Clarita Valley. This is a result of a
3-5mb onshore trend that started yesterday and continues this
morning. So while it will still be quite warm across the valleys
today temperatures will be much closer to normal for this time of
year and the heat hazards there have been cancelled for now.

***From Previous Discussion***

Monday should again be very similar to today, if not a little bit
warmer as the onshore flow starts to weaken. Tuesday will once
again warm up as the gradients will weaken even more, allowing the
valleys to warm up - possibly to heat advisory levels.

Sundowners across the Santa Barbara South coast will start Monday
night resulting in winds close to, but likely just sub- advisory
levels. However, Tuesday night the offshore gradients will
increase and likely result in advisory level winds across the SBA
South Coast.

.LONG TERM (WED-SAT)...07/517 AM.

The upper level high will slowly move eastward through the
workweek and by Saturday, a weak upper level trough will start to
push into the California Coast. Onshore gradients will continue to
weaken through midweek, allowing Wednesday and Thursday to be
extremely similar to Tuesday in terms of temperatures and cloud
coverage. Thus, the excessive heat will continue across the the
interior valleys, mountains, and deserts, and possible heat
advisories or even warnings across the valleys of Ventura and Los
Angeles Counties, and a less, but still present, chance across the
far interior coastal plains.

The Central Coast is expected to have night and morning low
clouds and fog through the period, with varying amounts of low
clouds and fog South of Point Conception, primarily on the
L.A. and Ventura County coast at times. However, the (likely
advisory level) Sundowner winds across Southern Santa Barbara
County Wednesday and Thursday nights should keep the southern
coast free of low clouds.

Temperatures should cool down enough Friday and Saturday due to
stronger onshore flow to the N and E, that the only locations that
may need heat products would be the L.A. County interior mountains
and deserts. However, even with cooler temps for the coast and
valleys, it will still be several degrees above normal each day.

&&

.AVIATION...07/1318Z.

At 12Z at KLAX, the marine layer was 1500 feet deep. The top of
the inversion was at 500 feet with a temperature of 33 deg C.

Very high confidence in CAVU TAFs for KPRB, KPMD, and KWJF.

Elsewhere, low clouds were widespread in all coastal areas, and
lower portions of the Santa Ynez and San Gabriel Valleys. Conds
were mostly LIFR to VLIFR, except IFR to even low MVFR in coastal
sections of L.A. County. Local MVFR vsbys were observed in the
San Fernando Valley. Expect skies to clear by mid morning in the
valleys, by late morning across interior sections of the coastal
plain, and early this afternoon near the coast. Clouds may linger
thru the day on beaches south of Pt Conception.

Expect widespread low clouds and fog tonight in all coastal
areas, and in portions of the Santa Ynez and San Gabriel
Valleys with mostly LIFR to VLIFR conds expected.

Fires may lead to periods of smoke at some terminals today,
especially KSBA and north.

KLAX...Moderate confidence in the 12Z TAF. There is a 20-30%
chance that cigs could linger thru 21Z or 22Z. There is a 20%
chance that cigs will not arrive tonight until 06Z or later.
Good confidence in any east wind component remaining under 5 kts.

KBUR...High confidence in the 12Z TAF. There is a 20% chance of
MVFR vsbys thru mid morning, and a 10% chance of IFR cigs after
10Z tonight.

&&

.MARINE...07/835 AM.

In the Outer Waters, winds are expected to remain below SCA
levels thru Mon morning. In the northern zone (PZZ670), SCA conds
are likely (70% chance) Mon afternoon/evening, with a 40% chance
of SCA conds at times Tue thru Thu night. In the southern two
zones (PZZ673/676), SCA conds are not expected through Tue
morning. There is a 40% chance of SCA levels winds Tue afternoon
thru Thu night, mainly during the late afternoon thru late night
hours.

In the inner waters N of Pt. Sal, there is a 30% chance of SCA
level winds during the afternoon/evening hours Mon and Tue,
otherwise SCA conds are not expected thru Thu night.

In the inner waters S of Pt Conception, SCA conditions are not
expected thru Thu night. The possible exception is in western
portions from Santa Cruz Island to the SBA County south coast from
Pt. Conception to Refugio State Beach, where there is a 30%
chance of SCA level winds during the late afternoon thru late
evening hours Tue thru Thu.

Areas of dense fog will affect the coastal waters thru mid
morning. Please reference the Marine Weather Statement for
additional information.

&&

.BEACHES...07/836 AM.

A moderately sized south swell with a 14 to 15 second period will
continue to affect the coastal waters thru this evening. This
will produce elevated surf of 4 to 6 ft on beaches exposed to
southerly swell, especially the L.A./VTU County beaches.
Significant wave energy and elevated surf will bring at threat of
powerful and dangerous rip currents. This is especially the case
for the south-facing beaches of L.A./VTU Counties, where a Beach
Hazards Statement is in effect.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning remains in effect until 9 PM PDT
      Wednesday for zones 38-343>345-353-376>379-381>383. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect until 9 PM PDT this
      evening for zones 351-352-380. (See LAXNPWLOX).
     Beach Hazards Statement in effect through this evening for
      zones 354-362-366. (See LAXCFWLOX).
     Red Flag Warning in effect until 6 AM PDT Monday for zones
      378-381. (See LAXRFWLOX).
PZ...NONE.

&&

$$

PUBLIC...MW/Lund/DB
AVIATION...DB
MARINE...DB/Sirard
BEACHES...DB
SYNOPSIS...MW

weather.gov/losangeles

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