957
FXUS66 KLOX 250508
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1008 PM PDT Mon Jun 24 2024

.SYNOPSIS...24/919 PM.

Remnant sub-tropical moisture will remain over the area into
Tuesday. A gradual cooling trend will continue through midweek as
high pressure weakens over the area and onshore flow strengthens.
Night through morning low clouds and fog could return to the
coastal areas as soon as Tuesday morning, but there is a better
chance for Wednesday and Thursday. Temperatures could potentially
rebound over the upcoming weekend and into early next week as high
pressure aloft builds back into the region.

&&

.SHORT TERM (MON-THU)...24/1007 PM.

An upper-level ridge of high pressure is currently centered over
southern New Mexico this evening. Above normal temperatures will
continue across the region over the coming days as enough of the
high`s influence will remain despite strengthening onshore flow.
Remnant sub-tropical moisture continues to stream over the region
this evening. A few showers remain over areas north of Point
Conception this evening from a vorticity maximum that moved over
the region. Some clouds are billowing out ahead another vorticity
maximum off the coast of Baja California, but the latest models
suggest convective parameters be not as favorable for development.
A non-zero chance of showers and thunderstorms will continue into
Tuesday evening as the moisture will remain in place.

The low cloud field is marginally in place this evening as the
convective cloudiness plays tricks with the marine layer deck. The
latest NAM-WRF solutions continue to suggest an eddy circulation
developing through Tuesday morning. Night through morning low
clouds and fog have been added to the forecast, but low-to-
moderate confidence exists at this time. With onshore flow and
low clouds returning, a cooling trend should continue into
midweek.

Outside of the marine layer across the interior portions of the
area, a hot air mass will remain in place into Tuesday. Heat
advisories have been extended across the interior portion of San
Luis Obispo and Santa Barbara Counties into Tuesday evening,
while an excessive heat warning remains in effect for the Antelope
Valley and adjacent eastern foothills.

***From Previous Discussion***

Excessive heat products with moderate to high heat impacts
continue through this evening for portions of the interior, except
through Tuesday evening for the Antelope Valley. We have high
confidence that cooling trends initiated today across the interior
will continue through Wednesday, decreasing heat impact to much
lower levels than weve experienced now for many areas for at
least several days. As such, we do not anticipate extending any of
the heat products.

The moisture associated with the mid cloud deck continues to
support a 5-15 percent chance (highest across the interior
Mountains and deserts) of a thunderstorm across the region today
with afternoon cumulus and a shower or two already showing up
along the high terrain. Dangerous cloud-to-ground lightning and
damaging wind would be the main concerns should a stronger
thunderstorm or two form with climatologically favored areas for
this being the eastern San Gabriel mountains into the Antelope
Valley and Ventura mountains west to the Santa Barbara mountains
(excluding the Santa Ynez Range). Generally weak flow aloft would
likely support slow storm movement towards the north or northeast
around 10 mph with anchoring or back building along the high
terrain possible. Any stalled thunderstorms may also produce
localized flash flooding.

Generally light onshore winds today will likely become stronger
with a west to northwest orientation Wednesday and Thursday,
potentially approaching advisory levels for southwest Santa
Barbara County and the mountains near the I-5 corridor.

Low confidence in low cloud and fog forecast as the marine layer
may struggle to reform as mid level moisture may stick around
until Tuesday or so. Sufficient moisture sticks around until at
least Tuesday afternoon to warrant a 5-10 percent chance of a
shower or thunderstorm across southwest California and the
adjacent waters.

.LONG TERM (FRI-MON)...24/208 PM.

Low confidence in the extended period. There is now a 60-70
percent chance that weak troughing will remain in place through
the weekend with building heat early next week. That does leave a
20-30 percent chance that heat builds as early as this weekend. If
the higher heat scenario plays out, there may be a monsoon push
into at least Los Angeles County early next week. Breezy west to
northwest winds will continue, peaking each afternoon and evening,
potentially nearing advisory levels for southwest Santa Barbara
County at times.

&&

.AVIATION...25/0223Z.

At 23Z over KLAX, the marine layer depth was 800 feet deep at KLAX.
The top of the inversion was near 2400 feet with a temperature
near 27 degrees Celsius.

Moderate confidence in the current forecast. VFR conditions are
expected through the period, except for a moderate-to-high chance
of LIFR to IFR conditions between 08Z and 16Z for coastal
terminals. There is a very slight to slight chance of showers and
thunderstorms, highest for terminals north of Point Conception.

KLAX...There is a less than 10 percent chance of thunderstorms
through 12Z. There is a 60 percent chance of IFR conditions
as early as 09Z, or as late as 16Z. Otherwise, VFR conditions are
expected.

KBUR...There is a less than 10 percent chance of thunderstorms
through 12Z. Otherwise, VFR conditions are expected.

&&

.MARINE...24/950 PM.

Dense fog with visibilities under one mile will remain a concern,
and while the coverage and shrunk a lot, expect some random
patches tonight into Tuesday.

There is a 30 percent chance of Small Craft Advisory (SCA) level
wind gusts Tuesday evening/night for the Outer Waters (offshore
waters of the Central Coast to San Nicolas Island). Northwest
winds will increase Wednesday afternoon through Thursday night.
High confidence in SCA level winds and steep seas for the Outer
Waters, with a 20 percent chance of reaching low-end Gale Force.
50 percent chance for SCA winds and seas for the nearshore Central
Coast waters, and a 20 percent chance for the western Santa
Barbara Channel. Winds start to decrease to SCA levels for Friday
into the weekend.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 8 PM PDT Tuesday for zones
      38-344-345-353. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect until 8 PM PDT
      Tuesday for zones 382-383. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Hall/Munroe
AVIATION...Hall
MARINE...Phillips/RK
SYNOPSIS...Hall

weather.gov/losangeles

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