207
FXUS66 KLOX 181134
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
434 AM PDT Wed Sep 18 2024

.SYNOPSIS...18/204 AM.

Much cooler than normal temperatures will continue through Friday
before warmer conditions return for the weekend. There is a
chance of showers and thunderstorms Wednesday night through Friday
(especially over the mountains) as a low pressure system moves
into the area.

&&

.SHORT TERM (TDY-FRI)...18/310 AM.

Not much to talk about today. A cool upper low will start its way
down the CA coast. Hgts will lower and the upper flow will become
more SW. There is not much of marine inversion south of Pt
Conception and low clouds there will be patchy at best. Better
onshore flow has brought plenty of low clouds to the Central
Coast these clouds will likely stay through the morning. The low`s
approach is now fcst to be a little slower and no rain is
forecast through the afternoon. Max temps will be similar to
Tuesday`s chilly readings with the csts and vlys only seeing temps
in the upper 60s and 70s. While the coasts will be 4 to 8 degrees
blo normal the rest of the area will be 8 to 16 degrees blo
norms.

The upper low will continue to march down the coast tonight and by
dawn it will be just to the north SLO county. A chance of rain
will develop over SLO and northern SBA counties overnight.
Rainfall amounts if any will be under .05 inches.

On Thursday and overnight into Friday the upper low will slowly
move from west to east over the area. There is little disagreement
among the mdls and ensembles about how far south the low will go
with the consensus being a more northerly track across the
northern half of SBA/VTA/LA counties. Most of the area will have a
chc of a rain shower anytime of the day with the least chc across
eastern LA County. The cold core (-21C at 500 mb which is some of
the coldest 500 mb temps ever recorded) of the low will move over
the area in the afternoon. The instability that will result from
this will increase the chc of showers to 70 percent and will also
bring a 20 percent chc of TSTMs to the interior of SLO county and
the northern mtns of SBA/VTA/LA counties. This system does not
have much moisture to work with and most areas away from the area
of maximum instability will likely see a trace to a tenth of an
inch. The area of maximum instability however could see a a
quarter to half inch of rain with a 10 percent possibilty of an
inch.

Look for a 3 to 6 degree drop in temps as hgts plummet and partly
to mostly cloudy skies restrict the sunshine. Max temps will be
January like with the csts and vlys peaking only in the 60s and
lower 70s (10 to 20 degrees blo normal.

With the low moving to the east the threat of showers will be
confined to LA county and there is a 20 percent chc they will
linger into Friday morning there. Otherwise skies will clear out
as the marine inversion will be obliterated. Friday morning`s
lows will be on the chilly side with many people waking up to
temps in the lower 50s or perhaps even the upper 40s.

Friday will turning into a sunny day everywhere by late morning and
with rising hgts max temps will rebound 6 to 12 degrees. Even with
this warming max temps will come in 5 to 10 degrees blo normal.

.LONG TERM (SAT-TUE)...18/317 AM.

Good confidence in a rapid reversal of temperatures for the
weekend. Hgts will quickly rise to 586-588 dam. There will only be
weak onshore flow and even some weak offshore flow in the morning.
Stratus will most likely be confined to the Central Coast.

Max temps will jump 5 to 10 on Saturday with an additional 3 or 6
degrees of warming on tap for Sunday. By Sunday temps will be 3
to 6 degrees above normal with 70s at beaches 80s a little
further inland and 90s in the vlys, lower elevation mtns and
inland areas.

Monday looks to be the warmest day of the next 7 with an
additional 1 to 2 degrees of warming likely.

Max temps will fall Tuesday as broad troffing affects the western
CONUS and onshore flow increases. The marine layer cloud pattern
may start to make a comeback as well.

&&

.AVIATION...18/1133Z.

At 1130Z at KLAX, There was a 5000 ft deep moist layer with no
inversion.

Good confidence in TAFs for KSBA, KPMD, and KWJF.

Fairly good confidence in TAFs for KOXR, KCMA, KBUR, and KVNY
with a 20 percent chc of MVFR cigs through 16Z Wed, and again
after 06Z Thu.

Moderate confidence in KPRB, KSBP, and KSMX TAFs through 03Z,
then low confidence. There is a 20 percent chc of high MVFR cigs
lifting to VFR with VCSH after 06Z.

Low confidence in the remainder of the TAFs with a 25 percent chc
of no low clouds. Cigs are very patchy in nature and could
dissipate and reform frequently until settling in by 14Z Wed.
There is a 30 percent chc of MVFR cigs after 08Z Thurs.

KLAX...Low confidence in TAF. There is a 25 percent chc of no low
clouds. If low clouds do form, they may scatter and reform
frequently. There is a 20 percent chc of BKN025 cigs 08Z-16Z
Thurs. No significant east wind component is expected.

KBUR...Moderate to high confidence in TAF. There is a 20% chance
of BKN020 conds through 16Z.

&&

.MARINE...18/313 AM.

For the Outer Waters, Small Craft Advisory (SCA) winds are
lingering across the waters north of Point Sal (Zone PZZ670) early
this morning, but expect winds to continue to weaken through the
morning so allowed the advisory to expire. SCA winds will
continue across the southern two zones south of Point Sal to San
Nicolas Island (PZZ673 and PZZ676) through late tonight and
accompanied by steep and choppy seas. For Thursday and Friday
through this weekend, SCA headlines will be unlikely, though a few
spots of marginal SCA winds cannot be ruled out (30% chance) from
areas around San Miguel and Santa Rosa Islands toward Pt.
Conception each afternoon and evening.

For the Inner Waters north of Pt. Sal, SCA conditions are not
expected through the period.

For the Inner Waters south of Pt. Conception, SCA winds are
expected across portions of the Santa Barbara Channel --
especially the western two-thirds -- this afternoon and evening,
accompanied by steep and choppy seas. For Thursday and Friday
through this weekend, SCA headlines will be unlikely, though a few
spots of marginal SCA winds cannot be ruled out (30% chance) over
the Los Angeles and Orange County waters within 20 NM from shore.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Thursday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Lund
MARINE...Cohen/Lund
SYNOPSIS...MW

weather.gov/losangeles

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