546
FXUS66 KLOX 290323
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
823 PM PDT Fri Jun 28 2024

.SYNOPSIS...28/749 PM.

Temperatures will gradually warm through this weekend, and then
become very warm to hot for next week. Dangerously hot conditions
are expected next week over interior areas, where daily high
temperatures of up to 100 to 105 degrees will be possible, with
high temperatures upwards of 105 to 115 possible over interior
valleys and foothills including the Antelope Valley.

&&

.SHORT TERM (FRI-MON)...28/819 PM.

Upper level trough along the California coast combined with
strengthening onshore flow and a deeper marine layer to provide
some cooling in most areas today. The marine layer depth increased
to 1500-2000 feet this morning. As we go through the weekend,
Southwest California will be sandwiched in between a lingering
upper level trough across northern and central California and an
upper level ridge building westward from the south-central states.
500 mb heights will gradually increase across the weekend,
leading to a warming and drying trend across the interior.

Current satellite imagery showing marine layer low clouds
returning to portions of the Central Coast and LA county coast
this evening. Low clouds and fog are expected to overspread
most coastal areas overnight into Saturday morning, locally
extending into the coastal valleys. The marine layer depth
is expected to gradually decrease through the weekend, resulting
in the potential for some fog, possibly becoming locally dense
by Saturday night/Sunday morning.

*** From previous discussion ***

Midlevel heights will gradually rise over the region this weekend
into early next week, as an upper-level ridge builds westward
from the south-central states. Surface pressure gradients will be
neutral to moderately onshore. This pattern will maintain night
and morning low clouds and fog in the marine layer near the coast
and over coastal valleys, scattering out and clearing during the
afternoon. Otherwise, dry conditions are expected into early next
week. By Sunday, high temperatures are expected to have warmed to
the 90s in most areas, 100-105 over the Antelope Valley, and the
70s near the coast. Another couple of degrees of warming is
expected going into Monday. Gusty southwest to northwest winds are
expected each afternoon over interior areas, and strongest --
upwards of 35-45 mph -- over the Interstate-5 corridor as well as
the Antelope Valley and nearby foothills. However, the issuance of
Wind Advisories is currently unlikely.

.LONG TERM (TUE-FRI)...28/232 PM.

Dangerously hot conditions are expected to develop over the region
next week, as an upper-level anticyclone builds offshore and
expands eastward over California. The latest multi-model consensus
offers increasing confidence for 500-mb heights rising to 596-600
dam just north or northeast of the area by late next week. This
should correspond to daily high temperatures up to 100 to 105
possible in many areas away from the coast, with highs upwards of
105 to 115 possible over interior valleys and foothills including
the Antelope Valley, each day starting Tuesday. Warm overnight low
temperatures, especially late next week, will worsen the effects
of extreme heat. Nighttime temperatures may not fall below 80
degrees late next week over the interior valleys and nearby
foothills. An Excessive Heat Watch has been issued for a large
portion of the interior areas from Tuesday morning through
Saturday, July 6.

In addition, very warm to hot conditions will have the potential
to bring significant heat impacts to the coast, starting on
Wednesday and continuing through the remainder of next week. This
would occur as the marine layer becomes increasingly shallow and
retreats toward the coast provided the rising heights aloft. Heat
headlines may need to be expanded to include a larger portion of
Southern California in later forecasts.

Present indications are that precipitation chances will be
unlikely (below 20%) through late next week. However, given how
hot and strongly mixed the boundary layer will be over interior
sections during latter parts of the week, any low-predictability
monsoonal moisture influx south of the midlevel ridge axis could
introduce chances for showers or thunderstorms over higher
terrain. Chances are too low for mention in the forecast at this
time, though this scenario will continue to be monitored.

&&

.AVIATION...29/0023Z.

At 0000Z at KLAX, the marine layer was 1700 feet deep. The top of
the inversion was at 4200 feet with a temperature of 22 Celsius.

High confidence in VFR conditions for KPRB, KPMD, and KWJF.
Moderate confidence in cigs returning tonight/Sat morning at most
coastal/valley TAF sites, however lower confidence in ceiling
timings at KSBA (30%) and KBUR (30%). High confidence that cigs
will be generally lower than last night, with a 10% chance of
some coastal locations/KBUR entering LIFR conditions.

KLAX...Moderate confidence in VFR conditions through at least
07Z, with a 20% chance of cigs by 03Z. Moderate confidence in IFR
ceilings occurring tonight, with a 10% chance that cigs reach LIFR
conditions. High confidence in any southeast winds staying under
08 knots.

KBUR...High confidence in VFR conditions through at least 11Z.
There is a 60% chance of IFR ceilings forming tonight as early as
11Z and last through 16Z. If cigs occur, there is is 10% chance
of LIFR conditions occuring. High confidence in seasonal winds.

&&

.MARINE...28/748 PM.

The moderate threat of dense fog (visibilities one mile or less)
returning tonight along the Central Coast. Moderate confidence
that visibilities will be up everywhere else.

Moderate to high confidence the Small Craft Advisories (SCA)
winds and/or steep seas will continue through most of tonight from
the Central Coast to San Miguel Island. This will be a low-end
event however, and conditions may stay just under criteria, but it
will still be unpleasant out there. Elsewhere, high confidence in
fairly benign conditions through at least Saturday. High
confidence in northwest winds increasing once again later Saturday
Night and lasting through Monday Night. There is a moderate
threat of Gales for the outer waters from the Central Coast to
Point Conception Sunday through Monday. There is also a low but
present threat of these winds pushing deep enough into the Santa
Barbara Channel to need a Small Craft Advisory.  There is a
potential for winds to be stronger than the most recent event. As
a result of these winds, choppy seas are expected everywhere.

Moderate confidence for significantly and abnormally light winds
Tuesday and Wednesday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Watch in effect from Tuesday morning through
      late Friday night for zones
      38-88-343>345-353-376>379-381>383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Gomberg/Cohen
AVIATION...Lewis/Gomberg
MARINE...RK/Smith
SYNOPSIS...Cohen/Smith

weather.gov/losangeles

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