-- Discussion containing changed information from previous version are highlighted. --
949
FXUS66 KLOX 080658
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1158 PM PDT Fri Jun 7 2024

.SYNOPSIS...07/951 PM.

An upper-level trough, developing along the West Coast, will
continue a cooling trend and a strong onshore push each afternoon
through the weekend. A deep marine layer depth will keep night
through morning Low clouds and fog with areas of drizzle across
coast and valleys into next week. A warming trend will develop
after Tuesday.

&&

.SHORT TERM (FRI-MON)...07/951 PM.

The latest fog product imagery shows low clouds and fog already
well-entrenched along the southern and central California coast
this evening. A broad upper-level trough of low pressure over the
West Coast is producing strong onshore flow across the area. A
cooling trend, establishing today, will continue each day through
the weekend. The marine intrusion will filter more inland each day
through Sunday, while the marine layer depth will deepen. The
latest AMDAR soundings from KLAX indicate a marine layer depth
currently around 1800 feet deep, agreeing well with local 3-km
WRF solutions. If local 3-km WRF solutions play out, the marine
layer depth should deepen to near 3300 feet deep by Saturday
morning and 3700 feet deep by Sunday morning. To the north and
earlier this evening, KVBG soundings indicated a marine layer
depth close to 2000 feet deep. With the marine layer depth
already sitting the near the coastal slopes, low clouds and fog
should push into the coastal slopes of the mountains overnight.
Clouds will continue to struggle to clear from the land mass each
day as strong onshore flow will make for a slow clearing each
day.

Gusty onshore winds will develop across the Antelope Valley and
adjacent foothills each afternoon and evening. A wind advisory
remains in effect for these areas through 3 am PDT tonight. While
surface pressure gradients are progged to diminish some, low
confidence exists in it actually happening. Given the upper-level
pattern, one would expected surface pressure gradients to continue
to strengthen through the weekend as the trough axis approaches
the California coast. As there is some discontinuity, any
extension of the wind headlines will delay for more data at this
time. The next shift will be briefed about the possibility.

An update to the forecast will be issued shortly to expand low
cloud coverage and add some clouds into the coastal slopes of the
mountains and into the San Luis Obispo County valleys.

*** FROM PREVIOUS DISCUSSION ***

Gradients continue to trend onshore this afternoon, now up to
9.3mb (LAX-DAG). South to north gradients also slightly stronger
which is kept clouds pretty well entrenched over the south facing
beaches. Not seeing too much change in this pattern over the
weekend and into early next week as yet another trough moves
onshore along the West Coast. Daytime temperatures will continue
to trend down across the inland areas, meaning valley highs will
mainly top out in the mid to upper 70s and far interior valleys in
the mid 80s to low 90s. This puts highs around 5 degrees below
normal for coast/valleys and around 5 degrees above normal for the
interior. As the trough gets closer the chances for morning
drizzle will increase and some areas could see light measurable
precip, especially near the coastal slopes. Clearing will be slow,
even across the valleys. Gusty afternoon west to southwest winds
expected each day across the interior valleys and through the
mountain passes.

The NBM is showing a couple degrees of warming early next week
However, models have been consistent showing a weak upper low
settling just west of southern California so probably minimal
changes Monday.

.LONG TERM (TUE-FRI)...07/230 PM.

Models have been consistent showing the upper low hanging around
through most of next week and actually deepening and moving
overhead Wednesday into Thursday. So, expect more of the same
pattern with cooler than normal temperatures across coast/valleys
with slow clearing marine layer and gusty onshore winds across
the interior. There is a potential for warming with some northerly
flow developing Friday into next weekend if the low moves inland
per the latest ensemble solutions.

&&

.AVIATION...
-- Changed Discussion --
08/0646Z.

At 0515Z at KLAX, the marine layer was 2100 ft deep. The top of
the inversion was at 5400 ft with a temperature of 23 degrees C.

High confidence in TAFs for KWJF and KPMD.

Moderate confidence in coastal and valley TAF sites. Timing of
flight category changes could be +/- 2 hours of current forecasts.
CIG fcsts may be off by +/-200ft. Brief VFR conditions after 22Z
are possible for coastal TAF sites from KSBA southward.

KLAX...Moderate confidence in TAF. Timing of flight category
changes could be +/- 2 hours of current forecasts. There is a 30
percent chc of SCT conds 23Z-02Z. No significant easterly wind
component is expected.

KBUR...Moderate confidence in 00Z TAF. There is a 30 percent chc
that cigs will not go below OVC006. There is a 20 percent chc of
VFR conds arriving at 18Z and a 30 percent chc at 19Z.
-- End Changed Discussion --

&&

.MARINE...07/1010 PM.

For the Outer Waters, moderate to high confidence in current
forecast. Tonight through Saturday morning, high confidence in
winds and seas remaining below Small Craft Advisory (SCA) levels.
From Saturday afternoon through Monday morning, there is a 50-70%
chance of SCA level winds. From Monday afternoon through
Wednesday, high confidence in winds and seas remaining below SCA
levels. SCA level winds may return by Friday.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Tonight through Saturday, high
confidence in winds and seas remaining below SCA levels. On
Sunday, there is a 40-50% chance of SCA level winds in the
afternoon and evening hours. For Monday through Wednesday, high
confidence in winds and seas remaining below SCA levels.

For the Inner Waters south of Point Conception, high confidence
in current forecast. Today through Wednesday, winds and seas are
expected to remain below SCA levels.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory remains in effect until 3 AM PDT Saturday for
      zone 381. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Hall/MW
AVIATION...Rorke
MARINE...Phillips
SYNOPSIS...Hall

weather.gov/losangeles

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