647
FXUS66 KLOX 040411
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
911 PM PDT Wed Jul 3 2024

.SYNOPSIS...03/127 PM.

A significant heatwave will affect the region this week and will
continue through much of next week, with dangerously hot
temperatures across much of the area. High temperatures will reach
95 to 105 degrees in many areas away from the coast, with highs
upwards of 105 to 115 over interior valleys and foothills,
including the Antelope Valley. Very warm to hot conditions could
extend closer to the coast by late this week. Patchy night to
morning dense fog will affect the coasts through at least
Thursday morning.

&&

.SHORT TERM (WED-SAT)...03/203 PM.

Temperatures are heating up today with many interior areas already
over 100 degrees and several over 105. No significant changes to
the pattern and forecast except just some fine tuning of the high
temperatures. Synoptically, high pressure continues to slowly move
towards the West Coast. The strong subsidence aloft and warming
air mass is squashing the marine layer well under 1000 feet,
meaning there will be lots of dense fog across coastal areas
during the night and morning hours, at least through Thursday.
After Thursday there are increasing signals that the coastal
marine inversion will be too shallow to support a stratus layer,
especially south of Pt Conception.

Temperatures will rise another 3-6 degrees tomorrow and a few more
degrees still on Friday, bringing warmer coastal valleys close to
110 and inland coastal areas in the 80s to low 90s. Deserts and
other far interior areas will be approaching or even locally
exceeding 115. This is the start of what likely will be an
unprecedented stretch of high temperatures over 110 degrees there.
The record for consecutive days at or above 110 is three for
Palmdale and Lancaster and five for Paso Robles. The desert streak
will almost certainly be crushed with the current forecast showing
highs well over 110 for the next seven days. Paso Robles will be
a little more difficult as there is a chance of some cooling sea
breezes to get in there later in the weekend. Some daily
individual records are likely as well, though a heat wave during
this period in 2018 pushed records over 110 in the valleys and
over 100 for Downtown LA for coastal and valley areas. Santa
Barbara has a special situation there later this week with some
northerly flow developing over the Santa Ynez Ranging pushing very
hot air down towards the coast with highs in the high 80s and 90s
possible. It will be quite warm on the Central Coast as well with
highs in the 80s and 90s through Saturday.

.LONG TERM (SUN-WED)...03/214 PM.

Unfortunately, for many areas the extreme heat will continue well
into next week. Most of the ensemble solutions maintain a strong
high over the area at least through the middle of next week.
However, models are also indicating an increase in onshore flow
starting Sunday. While this should bring a few degrees of cooling
to coast and coastal valleys, with strong high pressure aloft it`s
unlikely this cooling will reach the interior. However, increasing
winds with the onshore push will reach the deserts, increasing
fire danger there with the continued extreme heat and hot and dry
air mass. The Excessive heat warning for the interior areas
(mountains, deserts, interior SLO/SB County) has been extended to
Wednesday and may need additional day beyond that. Coastal and
valley areas will be "cooler" but still 6-12 degrees above normal.

&&

.AVIATION...04/0022Z.

At 00Z at KLAX, the marine layer was 800 feet deep. The top of
the inversion was at 3600 feet with a temperature of 31 Celsius.

High confidence in CAVU TAFs for KPRB, KBUR, KVNY, KPMD, and
KWJF.

Moderate confidence in remainder of TAFs. For coastal locations,
expecting IFR-VLIFR cigs/vsbys due to fog and low clouds returning
tonight. Cig/vsby restrictions dissipating from late to early
afternoon Thursday. Timing of flight category changes may vary by
+/- 2-3 hours of current forecasts, and there is up to a 30%
chance for minimum flight categories to be off by at least one
category.

KLAX...Moderate confidence in TAF. VLIFR conditions due to fog,
with a 30% chance cigs/vsbys will be 1-2 hours off in arrival and
clearing times. No significant easterly wind component is
expected.

KBUR...High confidence in TAF.

&&

.MARINE...03/910 PM.

For the Outer Waters, Small Craft Advisory (SCA) conditions are
not expected through Thursday morning. Areas of SCA winds are
forecast to develop over PZZ673 and PZZ676 Thursday afternoon,
with SCA winds continuing into Saturday morning for PZZ676, and
continuing into Saturday night for PZZ673. There is a 60% chance
for SCA winds to occur across PZZ670 from Friday afternoon through
Sunday morning. There is also a 10-15% chance of local Gale Force
wind gusts for Friday afternoon and evening during the periods of
SCA winds across the Outer Waters.

For the Inner Waters north of Point Sal, SCA conditions are
generally unlikely through early next week, though there is a 30%
chance for SCA winds for Friday afternoon and evening.

For the Inner Waters south of Point Conception, SCA winds are
anticipated from Thursday afternoon through Thursday night across
a portion of the western Santa Barbara Channel. The area of
anticipated SCA-level NW-N winds is from Santa Cruz Island to the
Santa Barbara County coast from Point Conception to Gaviota to
Refugio State Beach. Within this area, there is also 10-15% chance
of local Gale Force wind gusts just offshore from the immediate
coast Thursday afternoon through Thursday night. There is also a
70% chance for SCA-level winds to reoccur in the Western portions
of the Santa Barbara Channel for Friday afternoon through Friday
night.

Dense fog is expected over the coastal waters for the remainder
of this week during the overnight to morning hours, with a
gradual decrease in the coverage of fog as the week progresses.
Please reference the Marine Weather Statement for additional
information.

&&

.BEACHES...03/133 PM.

A southerly swell front will overspread the Southern California
coastal waters Thursday into Friday, followed by 15-17-second
southerly swell persisting from late this week into the weekend.
While surf is not expected to be particularly high, surf heights
upwards of around 5 feet are anticipated at beaches exposed to
southerly swell -- especially the LA and Ventura County beaches.
Moreover, significant wave energy with the long-period swell will
combine with the elevated surf to create dangerous conditions at
area beaches, with powerful and dangerous rip currents expected.
This is especially the case for the beaches of LA and Ventura
Counties. A Beach Hazards Statement is in effect from Thursday
mid-day through the weekend to address these concerns.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning now in effect until 6 PM PDT Wednesday
      for zones 38-343>345-353-376>379-381>383. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect until 6 PM PDT
      Monday for zones 88-342-348-351-352-356>358-369>375-380. (See LAXNPWLOX).
     Heat Advisory remains in effect from 11 AM Thursday to 6 PM
      PDT Sunday for zones 341-347-355-368. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect from 11 AM Thursday
      to 6 PM PDT Saturday for zones 349-350. (See LAXNPWLOX).
     Beach Hazards Statement in effect from Thursday morning
      through Sunday evening for zones 354-362-366. (See LAXCFWLOX).
     Heat Advisory remains in effect until 6 PM PDT Sunday for
      zone 548. (See LAXNPWLOX).
     Fire Weather Watch in effect from Friday morning through late
      Friday night for zones 342>345. (See LAXRFWLOX).
     Red Flag Warning in effect from 6 PM Thursday to 6 AM PDT
      Saturday for zones 349-351>353-376>378-381. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect from 2 PM Thursday to 2 AM PDT
      Friday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 PM Thursday to 5 AM PDT
      Sunday for zone 673. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 PM Thursday to 8 AM PDT
      Saturday for zone 676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW
AVIATION...Lewis/Phillips/Cohen
MARINE...Smith/Lewis/Cohen
BEACHES...Cohen
SYNOPSIS...Cohen/Smith/MW

weather.gov/losangeles

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