844
FXUS66 KLOX 242059
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
159 PM PDT Tue Sep 24 2024

.SYNOPSIS...24/131 PM.

Low clouds and fog will continue across coastal areas through the
week with some afternoon clearing and below normal temperatures.
Valley temperatures will begin a cool down today and be at or
below normal the rest of the week. Far interior areas will remain
above normal. Otherwise, a quiet weather pattern will continue.

&&

.SHORT TERM (TDY-FRI)...24/147 PM.

Big cool down today across the valleys, several degrees more than
expected, as a big increase in the onshore flow to the north
(LAX-BFL) brought a solid cloud layer farther inland and it was
slow to clear. The result was a 6-12 degree drop in high temps
there. In an odd twist areas that were within 5 degrees of the
coast were slightly warmer than yesterday. As was the Antelope
Valley and interior SLO County.

Looks like a very similar pattern tomorrow with a decent onshore
flow to the north and east so likely a degree or two of additional
cooling for the valleys and little change elsewhere.

The deterministic models indicate weakening onshore flow Thu/Fri
but ensemble based guidance shows little change in temperatures
the rest of the week, meaning onshore flow will likely change
little through the period. Overall a quiet period of weather this
week that will likely carry into the weekend and possibly into
early next week.

.LONG TERM (SAT-TUE)...24/158 PM.

Longer range ensembles continue to show a weak upper low lingering
just off the coast through the weekend and into early next week
but with some height rises as high pressure tries to build in from
the southeast. However, given the rather large spread in the
ensemble solutions confidence is lower than usual with the
specifics during this period. Probably no significant warming
trends coming, but a few degrees of warming is possible, mainly
away from the coast as onshore flow is expected to be fairly
strong later in the period.

&&

.AVIATION...24/1717Z.

At 1609Z at KLAX, the marine layer was 1500 ft deep. The top of
the inversion was near 4100 ft with a temperature of 26 deg C.

High confidence in TAFs for KPRB, KPMD, and KVNY. There is a 10%
chance for LIFR-IFR cigs at KPRB between 08Z and 15Z.

Low confidence in LA County coastal and valley TAFs. There is a
30% chance KLAX/KSMO briefly become VFR between 19Z and 00Z.
There is a 10% chance for VLIFR cigs/vsbys between 02Z and 15Z.
There is also a 20% chance that conds remain IFR or higher thru
the period. There is a 20% chance KBUR and KVNY remain VFR thru
the period, there is also a 30% chance KBUR and/or KVNY become
LIFR due to cigs and/or vsbys between 04Z and 15Z.

Low confidence in remaining TAFS. There is a chance KSMX (40%)
and KSBP (20%) become VLIFR between 02Z and 15Z. KSBA, KOXR, and
KCMA all have a 10% chance for VLIFR conds during the same
period.

At all sites with cigs, minimum flight cat may frequently bounce
around tonight and the arrival time of cigs may be off by +/- 3
hours.

KLAX...Low confidence in TAF. There is a 30% chance for brief VFR
conditions between 19Z and 00Z. There is a 10% chance for
VV001-VV002 cigs and/or vsbys 1/2SM or lower between 02Z and 15Z.
However, there is also a 20% chance for cigs to remain OVC005 or
higher thru the period. High confidence in no significant east
wind component.

KBUR...Low confidence in TAF. There is 20% chance for VFR conds
thru the entire period, there is also a 30% chance for cigs
OVC002-005 and/or vsbys 1SM or lower between 04Z and 15Z if cigs
arrive.

&&

.MARINE...24/146 PM.

For the Outer Waters (Central Coast south to San Nicolas Island),
moderate to high confidence in the forceast. High confidence in
the northern zone (10 to 60 NM off the Central Coast) remaining
below Small Craft Advisory (SCA) level thru Thursday, then there
is a 40-60% chance of SCA winds Thurs afternoon thru evening. In
the two Southern Zones (Pt Sal to San Nicolas Islands), moderate
confidence in conditions remaining sub advisory thru tomorrow
afternoon. Then there is a 30-50% chance of SCA level winds form
Pt Conception to San Nicolas Island in the afternoon thru evening
tomorrow and Thurs. Then, moderate confidence in the Outer Waters
remaining sub advisory Friday thru late Saturday, then increasing
to SCA level thru late Sunday.

For the Inner Waters along the Central Coast, moderate to high
confidence in conditions remaining sub advisory thru the period,
with highest chances (20-40%) of SCA conditions Thurs afternoon
thru evening and late Sat thru late Sun.

For the Inner Waters south of Pt Conception, moderate confidence
in winds and seas remaining below SCA level thru tomorrow morning.
Local gusts to 25 kt are possible (20-30%) this afternoon thru
evening in the Santa Barbara Channel and from Anacapa Island to Pt
Dume. Higher confidence (50-70% chance) in more widespread SCA
level winds in this area and the San Pedro Channel tomorrow
afternoon thru evening. Then, moderate confidence in winds
remaining sub advisory thru Sunday, and increasing Sunday
afternoon thru evening in the Western Portion of the Santa Barbara
Channel.

A shallow marine layer will bring at least patchy dense fog thru
tomorrow, especially in the afternoon thru evening hours. Please
refer to our marine weather statement for more information.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...MW
AVIATION...Lewis
MARINE...Lewis
SYNOPSIS...MW

weather.gov/losangeles

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