406
FXUS66 KLOX 010238
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
738 PM PDT Sat Oct 31 2026

.SYNOPSIS...31/737 PM.

Numerous showers will prevail tonight into Sunday morning. Some
showers may be heavy at times. Warmer and drier conditions can be
expected next week.

&&

.SHORT TERM (SAT-TUE)...31/733 PM.

***UPDATE***

Forecast continues on track this evening as an upper level trof
over the E Pac is forecast to move into the CA coast overnight,
bringing numerous showers to SW CA. The area will be under the
favored right rear quadrant of a strong 160 kt jet this evening
which, combined with some divergence aloft, will enhance dynamic
lift and help to produce convective showers with locally heavy
rain. These convective showers have already developed early this
evening along portions of the SLO/SBA Counties as well as the VTU
County coast. The HRRR was forecasting enhanced convective showers
for various parts of the region closer to the coast overnight as
well. Altho this model may be over-forecasting the intensity of
these showers, it may have the right idea about the prevalence of
heavier showers given the current activity and the favored upper
level dynamics. At any rate, numerous showers with locally heavy
rain continues to be in the offing with this weather system
tonight, with lingering showers expected into Sun morning. Current
forecast is in good shape and no updates are expected this
evening.

***From Previous Discussion***

Overall, latest models remain in decent synoptic agreement through
the short term period. At upper levels, a low will impact the area
through Sunday (bringing widespread shower activity) then a ridge
will build over the area on Monday before getting "flattened" on
Tuesday. At the surface, weak onshore flow will prevail through
Sunday with weak offshore flow developing on Monday and Tuesday.

Forecast-wise for the short term, main issue remains rain chances
for the area. Based on latest guidance, no major changes to
previous forecast thinking. Scattered showers will continue
through this afternoon, before more substantial rain moves into
the area tonight/Sunday morning. As has been the case over the
last several days, models indicate heaviest rainfall will remain
south of the LA county. So, for our area, most locales can expect
between 0.25 and 0.75 inch rain totals through Sunday afternoon.
However, based on high resolution models (HRRR, RRFS, etc.), there
may be some locally moderate to heavy showers through Sunday
morning. Local totals between 1 and 2 inches will be possible with
any heavy shower activity. As for any thunderstorm threat, the
chances look to be in the 5-10% range for our area. So, that
potential will need to be monitored through tonight. As for
rainfall rates, hourly rates of 0.10 to 0.33 will be common, but
isolated rates of 0.50+ inches/hour will be possible with any
heavier showers.

After the system moves east and shower activity ends Sunday
evening, the upper level ridge and weak offshore flow will bring
dry and warmer conditions to the area on Monday. At this time,
upper level support looks minimal, so any offshore winds on Monday
are expected to remain below advisory levels. On Tuesday, the
ridge will flatten, but weak offshore flow will still prevail. So,
there may be a degree or two of warming on Tuesday.

.LONG TERM (WED-SAT)...31/1250 PM.

For the extended period, models continue to exhibit broad synoptic
agreement through the period. Cyclonic flow aloft will prevail
over the area Wednesday/Thursday then an upper level ridge builds
in from the west on Friday/Saturday. At the surface, weak diurnal
flow will likely prevail although the ECMWF indicates a bit of
weak offshore flow in the Thursday-Saturday time frame.

Overall, the above synoptic pattern will result in benign weather
for Southwestern California. Dry conditions will prevail through
the period. High temperatures will remain relatively persistent on
Wednesday/Thursday with some warming expected on Friday and
Saturday. There may be some gusty offshore winds through the
period, but nothing that looks to be near advisory levels.

&&

.AVIATION...31/2337Z.

At 23Z at KLAX, there was no inversion or marine layer.

Overall, moderate confidence in 00Z TAF Package. -RA with
MVFR-VR ceilings and visibility expected. Isolated and brief
IFR conditions possible tonight, especially from KSBA through
KLGB. Improvement likely 12-18Z. Wind gusts of 20-30 knots likely
at most coastal sites starting around 21Z.

KLAX...Moderate confidence in TAF. -RA with MVFR ceilings will
likely become more common by 06Z, with possible brief IFR RA under
any heavier cells. Improvement likely by 01/15-18Z. 30% chance of
east wind component developing and reaching 8 kts from 01/10-16Z.
West winds 20-30 knots likely starting around 21Z Sunday.

KBUR...Moderate confidence in TAF. -RA with MVFR ceilings will
likely become more common by 06Z, with occasional IFR RA under any
heavier cells. Improvement likely by 15-18Z.

&&

.MARINE...31/707 PM.

Moderate confidence in winds and seas staying well below Small
Craft Advisory (SCA) through this evening, except for a low chance
of brief gusty downdraft winds with any heavier showers. There is
a very low chance of a waterspout forming in a stronger cell.

High confidence in post-frontal SCA-level W-NW winds and choppy
seas forming later tonight from the Central Coast to San Nicolas
Island, then spreading to most coastal waters on Sunday, including
the entire Santa Barbara Channel and the Santa Monica Bay. The
winds turn to the NE on Monday and will likely stay below SCA-
levels. There is a chance for another round of post-frontal
winds on Tuesday and Wednesday, but likely a step below in
strength compared to Sunday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 11 AM to 9 PM PDT Sunday
      for zones 645-650-655-670. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 AM Sunday to 3 AM PDT
      Monday for zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Thompson/Sirard
AVIATION...Black
MARINE...RK/Ciliberti
SYNOPSIS...Sirard

weather.gov/losangeles

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