503
FXUS66 KLOX 161023
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
323 AM PDT Mon Sep 16 2024

.SYNOPSIS...16/240 AM.

Much cooler than normal temperatures will continue through the
next several days, before warmer conditions return for next
weekend. It will be windy at times today and tonight. There is a
small chance of rain or drizzle today and a better chance on
Wednesday. Areas of low clouds will be common over the coast and
coastal valleys, with areas of clearing each afternoon.

&&

.SHORT TERM (TDY-WED)...16/313 AM.

Today`s forecast is shaping up to be drier than previously
thought. A 556 dam upper low over Sacramento will bring cool
cyclonic flow to the area through the day. The marine layer has
responded to the lift associated with the flow by rising to 4000
or 4500 ft. Clouds almost too high to call stratus cover much of
the area including much of the lower elevation mtns. Due to the
depth of marine layer and the weak capping inversion expect to see
reverse clearing this afternoon with the coasts mostly clear but
the vlys covered with a BKN strata cu deck. It looks like the
layer of maximum humidity is thinner than fcst and also the
satellite shows the band of best PVA to already be east of the
area. These two things will really make it difficult to produce
rain or drizzle. The geography of the San Gabriel mtns and vly
will interact with the WSW flow and form one favorable area for
rain. Rain in this area is still likely, but have scaled back the
rain chances in other areas. Rainfall amounts could still reach a
quarter inch across the San Gabriel foothills but most other areas
that see rain will only see a trace or a couple hundredths.

The strong upper level WSW flow will interact with the moderate W
to E sfc flow to bring a 9 to 12 hour period of strong winds. The
winds will be strongest along the beaches, mtns and the Antelope
Vly Where wind advisories are in effect or will go into effect
later this morning. Look for 35 mph to 45 mph westerly gusts.

The real talking point for today`s weather will be the
temperatures as hgts fall to 569 dam. These low hgts will combine
with the strong afternoon onshore flow to lower max temps 2 to 4
degrees across the coasts, 3 to 6 degrees across the vlys, 5 to 10
degrees across the mtns and 10 to 15 degrees over the far
interior. Max temps today will almost all be in the mid 60s to
lower 70s or 10 to 20 degrees below normal.

NW flow will develop between today`s departing low and Wednesday
stronger low. Hgts will rise to 578 dam. There will only be
minimal low clouds in the morning as the marine inversion
struggles to reform. Max temps will rebound 3 to 6 degrees but
will still end up many degrees blo normal.

A second stronger upper low will move down into Srn CA on
Wednesday. Although this system does not carry that much more
moisture with it than today`s system, it is colder and more
unstable. By Wednesday afternoon the low will be over the Bay Area
with a 563 dam central hgt. Overnight it will move into SLO
county. A chance of rain will develop over SLO county Wed morning
and spread through SBA county in the afternoon. The chance of rain
will overspread the entire 4 county region Wednesday evening and
overnight. Its likely that most areas will see a period of rain or
two during this period but rainfall amounts will likely not exceed
a tenth of an inch and will probably register less than 5
 of an inch. Max temps will fall a few degrees (fortunately the
coldest portion of the storm will pass during the overnight hours)
and will remain 8 to 16 degrees blo normal.

.LONG TERM (THU-SUN)...16/323 AM.

The low will push to the east on Thursday morning. A chance of
rain will continue through the morning over VTA and esp LA
counties. Rainfall amounts if any will be light. There will be
clearing in the wake of the low and the afternoon should be sunny.
The winds behind he system do not look as strong and while the
afternoon winds will be stronger than normal they will likely not
reach advisory levels. Max temps will change little from
Wednesday`s cool readings.

Upper level ridging will build in Friday and persist through the
weekend. Hgts will rebound to 590 dam. The onshore flow will
weaken and may even turn slightly offshore in the early morning.
Skies will be mostly clear and any marine layer clouds will likely
be confined to western SBA county. Max temps will rise 4 to 8
degrees on Friday, 5 to 10 degrees on Sat and 1 or 2 additional
degrees on Sunday. Max temps will reach or slightly exceed normals
on Saturday and will mostly be 3 to 6 degrees over normal on
Sunday. For Sat and Sun look for 70s and lower 80s for the coastal
sections and 90s in the vlys.

&&

.AVIATION...16/0630Z.

At 0415Z at KLAX, there was a weak marine layer around 4000 feet
deep. The top of the marine inversion was near 5000 feet with a
temperature around 16 C.

Low confidence TAFs except for KPMD and KWJF. Cigs will likely
vary between 010 and 040 through mid morning. There is 40 percent
chc of no drizzle at any site. Better confidence in TAFs aft 18Z.

There is a 25 percent chance of MVFR cigs between 10Z-17Z for
KPMD with otherwise high confidence for the desert TAFs.

KLAX...Low confidence in TAF. Cigs will likely vary between
BKN010 and BKN040 through 17Z. There is a 40 percent chc of no
drizzle. No significant east wind component expected.

KBUR...Low confidence in 00Z TAF. Cigs will likely vary between
BKN010 and BKN040 through 17Z with a 20 percent chc of bkn008
conds 11Z-16Z. There is a 30 percent chc of 2SM -DZ BR if drizzle
develops but there is a 30 percent chc of no drizzle.

&&

.MARINE...15/858 PM.

For the Outer Waters (Central Coast to San Nicolas Island),
moderate to high confidence in the forecast. For the northern zone
(Pt Piedras Blancas to Pt Sal), winds should remain near or above
Small Craft Advisory (SCA) level until late tonight. Then, winds
are likely to remain below SCA level until Tues afternoon, where
there is a 50-60% chance of SCA level winds thru early Wed
morning. From Wed afternoon thru late Sat, moderate confidence in
winds remaining below SCA level, with the highest chances in the
afternoon thru evening hours Fri and Sat. For the southern zones
(Pt Sal to San Nicolas Island) moderate to high confidence in
winds persisting thru late Tues or early Wed. Moderate to high
confidence in winds then picking back up to SCA level Wed
afternoon thru late, especially from Pt Conception to San Nicolas
Island. From Thurs thru Sat, moderate confidence in winds
remaining under SCA thresholds, with a 20-30% chance of SCA winds
Sat afternoon.

For the Inner Waters off the Central Coast. Moderate confidence
in SCA level winds lasting thru late tonight with a 30% chance
that SCA conds remain isolated. High confidence winds will remain
sub advisory level thru Tues midday, then there is a 30-50%
chance in SCA winds in the afternoon thru evening hours Tues thru
Wed, with best chances Tues. Moderate to high confidence in winds
being sub advisory Thurs thru Sat.

For the Santa Barbara Channel, high confidence in winds reaching
SCA level, but moderate confidence in timing. Winds may increase
as early as this evening, but higher confidence in or early
Monday. High confidence in GALES across the channel, specifically
from Santa Cruz Island east to the coast beginning Mon mid day
and lasting thru at least late Tues. An upper level trough passing
overhead will lead to an abrupt enhancement of the surface level
winds, leading to very choppy seas and strong rip currents. Winds
will decrease into the early morning hours Tues, with moderate
confidence in them remaining above SCA level thru late Wed,
especially in the afternoon and evening. Then, there is a 20-40%
chance of SCA level winds Thurs thru Sat, with best chances Fri
and Sat.

For the nearshore waters off the Los Angeles and Orange County
coasts, SCA level winds will develop in the morning throughout
much of the zone. In the northwest portion of the zone from
Malibu west to the Channel Islands, and as far south as Santa
Barbara Island, winds will likely (70-80% chance) rapidly
increase to GALE FORCE by midday. Seas will be choppy in this
area, and exposed beaches may see strong rip currents. Winds will
drop off to SCA level late Mon/early Tues. Moderate to high
confidence in winds remaining below SCA level Tues afternoon thru
Sat.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from noon today to midnight PDT
      tonight for zones 354>357. (See LAXNPWLOX).
     Beach Hazards Statement in effect from this afternoon through
      this evening for zones 354-362-366. (See LAXCFWLOX).
     Wind Advisory in effect until midnight PDT tonight for zones
      379-380-382. (See LAXNPWLOX).
     Wind Advisory remains in effect until 9 PM PDT this evening
      for zones 381-383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until noon PDT today for zone
      650. (See LAXMWWLOX).
     Gale Warning in effect from noon today to 3 AM PDT Tuesday
      for zones 650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect from 9 AM this morning to noon
      PDT today for zone 655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Tuesday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Rorke
MARINE...Munroe/Lewis
SYNOPSIS...JB

weather.gov/losangeles

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