Area Forecast Discussion
Issued by NWS Los Angeles, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS66 KLOX 210320

820 PM PDT Sun Aug 20 2017

Possible afternoon and evening showers and thunderstorms into
Monday for the mountains of Ventura and Santa Barbara. A low will
bring local drizzle into Monday morning, with overnight low clouds
and fog into next week. The temperatures will be near normal into
Thursday, then a warmup on Friday and the weekend as a high moves



Weak upper level low pressure system centered off the coast of
Point Conception will move very little through Wednesday,
though it will weaken and fill slightly Tue into Wed. There were
some afternoon cumulus buildups over the mountains of Santa
Barbara and Ventura counties that produced a couple of showers,
but no thunderstorms this afternoon. Otherwise satellite imagery
showing a solid bank of low clouds for the Central Coast this
evening, with some low clouds beginning to fill in across coastal
areas south of Point Conception. With the upper level low pressure
system off the coast and fairly strong onshore flow in place,
looking for marine layer clouds to fill in across most coastal
and valley areas tonight into Monday morning, with possibly
some patchy drizzle in the foothill areas. By 10 am tomorrow
for the eclipse, low clouds are expected to have burned off
across interior sections, but some coastal areas will likely
have lingering cloud coverage.

The upper level low pressure system is expected to bring some
drier air aloft from the east into our forecast area on Monday,
with precipitable water values continuing to trend downward,
especially Los Angeles and Ventura counties. However, still some
residual moisture and instability to warrant a slight chance of
tstms for the SBA County mountains and adjacent Cuyama Valley on
Monday afternoon. But mostly just expecting some afternoon cumulus
buildups across the local mountains.

*** From previous discussion ***

With the upper low weakening Tue and Wed expect temps to start
climbing, especially inland, with less overnight marine lyr
coverage and earlier clearing times.


Inland warming trend expected to continue into next weekend as
high pressure returns and onshore gradients weaken. Could see
warmer valley highs reaching triple digits by the weekend,
especially Sunday with weak offshore flow possible in the morning.
Coastal areas also expected to see some warm up by Sunday. Today`s
model runs didn`t suggest any return of monsoon moisture through
early next week, though this could change as the door is open for
some should a source develop.



At 0930Z at KLAX, the marine layer depth was near 2400 feet. The
top of the inversion was 3100 feet with a temperature of 19
degrees Celsius.

Low clouds lingering this afternoon across much of the Central
Coast and will advance inland quickly this evening, reaching KPRB
overnight. South of Point Conception, low clouds have generally
cleared well off the coast, except a few patches across LA/Ventura
coastal areas. Less confidence in arrival of low clouds tonight
for TAF locations south of Point Conception, but have trended
back arrival times based on latest satellite and model trends.

KLAX...Have delayed onset of MVFR cigs at KLAX in latest TAF
based on latest satellite/model trends. However, there is fairly
low confidence in arrival time, and could see +/- 3 hours from
07z indicated in TAF.

KBUR...Have delayed onset of MVFR cigs at KBUR in latest TAF
based on latest satellite/model trends. However, there is fairly
low confidence in arrival time, and could see +/- 2 hours from
12z indicated in TAF. Thee is a 20 percent chance that cigs could
lower to IFR category.


.MARINE...20/800 PM

Outer Waters...high confidence in forecast. Winds and seas will
remain below Small Craft Advisory (SCA) levels through Tuesday. On
Wednesday through Friday, SCA level winds are likely. Gale force
gusts will be possible over the northern portion Thursday
afternoon and evening.

Inner Waters...high confidence in forecast. For the waters north
of Point Sal, winds and seas will remain below SCA levels through
Tuesday. On Wednesday and Thursday, SCA level winds are likely
each afternoon and evening. For the waters south of Point
Conception, winds and seas are expected to remain below SCA levels
through Thursday.


CA...Beach Hazards Statement in effect until midnight PDT tonight
      for zones 40-41. (See LAXCFWLOX).


No significant hazards expected.



SYNOPSIS...STu is the U.S. government's official web portal to all federal, state and local government web resources and services.