583
FXUS66 KLOX 130117
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
617 PM PDT Sun Oct 12 2025

.SYNOPSIS...12/606 PM.

An early season storm system will move across the area late
Monday through Tuesday, with most of the rainfall likely Monday
night through Tuesday. Expect widespread light to moderate rain
with potential for locally heavy showers and thunderstorms, and
gusty southerly winds.

&&

.SHORT TERM (TDY-WED)...12/200 PM.

Overall, 12Z models in good synoptic agreement through the short
term period. Upper low develops off the Northern California coast
on Monday, drops south/east into Central California on Tuesday,
then into the Great Basin on Wednesday. With this pattern, a
rather dynamic weather pattern is still on track for the area
Monday night through Tuesday night, with things quieting down on
Wednesday.

Wind...

Northeasterly winds, gusting 20-35 MPH, continue this afternoon,
but will continue to diminish into the evening as offshore
pressure gradients continue to decrease. So, no issues are
expected.

However, for Monday and Tuesday, expect a dramatic increase in
south to southwest winds as the upper low impacts the area. Winds
will first increase across the deserts and interior sections on
Monday then increase west of the mountains Monday night and
Tuesday. At this time, advisory-level winds are likely across the
deserts and interior sections (with a chance of warning level
winds across the LA Mountains and Antelope Valley foothills). For
coastal and valley areas, there is a 30-50% chance of widespread
advisory level winds Monday night and Tuesday.

Precipitation...

All systems are still a big "GO" for the storm Monday night
through Tuesday night. Based on latest guidance, expected rainfall
totals have adjusted from previous thinking. Right now, coastal
and valley areas can expect 0.75-1.50 inches of rainfall with 1.50
to 3.50 inches across the mountains/foothills. Of course, given
the southerly flow, some favored upslope areas could receive even
higher amounts.

As for rainfall rates, generally will be expecting hourly rates
of 0.25-0.50 inches. However, high resolution models are still
indicating the potential for a QLCS-type feature on Tuesday which
would generate higher rates of 0.50-1.00 inches per hour or even
higher. Additionally, sub-hourly rates could be quite intense. So,
given the potential for rain rates to meet/exceed USGS thresholds
for the burn scars, a FLOOD WATCH will be in effect for the burn
areas (see LAXFFALOX for details). There will be the potential for
significant mud/debris flow issues.

As for thunderstorms, the risk still remains for the area. Looking
at the model solutions, the setup is looking more conducive for
widespread thunderstorm potential for all areas Monday night and
Tuesday. Although CAPE values are not impressive, the potential
diffluent flow aloft, strong jet dynamics and low level wind
shear will bring the possibility of strong thunderstorms (gusty
winds, hail and heavy rain) along with waterspouts/weak tornadoes.
For reference, the setup is looking similar to conditions
indicated by the Hales study for Southwestern California severe
weather.

Finally, there still looks to be the potential for some snowfall
accumulations at the higher elevations. Based on thickness and
Wet Bulb Zero forecasts, snow levels look to drop into the
5500-7000 foot range on Tuesday (but locally lower with any
significant convection). So, several inches of snowfall
accumulation will be likely above 6000 feet. Given the strong
southerly winds anticipated, Winter Storm criteria conditions
could develop. Will let the next couple of shifts look at the next
suite of model runs to make the final determination for any
winter products.

.LONG TERM (THU-SUN)...12/200 PM.

For the extended, 12Z models continue to exhibit good synoptic
agreement. At upper levels, ridge gradually builds over the
Eastern Pacific Thursday through Saturday, before weakening on
Sunday as a trough moves across Northern California/Pacific
Northwest. Near the surface, weak diurnal gradients will prevail.

Forecast-wise, no significant issues are expected. For Thursday
through Saturday, dry conditions are expected along with a warming
trend. At times, there could be some offshore winds across the
area, but any winds look to be weak (if they do develop). On
Sunday, as the trough rolls across the West Coast, cooler
conditions are anticipated along with the possibility of some
additional rainfall (but confidence in that potential remains very
low).

&&

.AVIATION...13/0053Z.

At 0007Z at KLAX, the marine layer was 700 ft deep. The top of
the inversion was near 1800 ft with a temperature of 19 C.

Low confidence in the 00Z TAFs for the coastal and valleys sites
and high confidence in the desert sites.

Generally expecting VFR conditions through the period, but there
is a 30% chance of stratus affecting portions of the coast and
valleys, with generally IFR to LIFR possible north of Point
Conception and IFR to MVFR further south.

Moderate confidence in wind forecasts.

KLAX...Low to moderate confidence in the 00Z TAF. MVFR CIGs
forecast to arrive by 09Z but the timing could differ by +/1 2
hours, with a 20-30% chance that no low CIGs occur. There is a
60-70% chance of an east wind component reaching 7-8 knots from
08Z Mon thru 18Z Mon.

KBUR...High confidence in the 00Z TAF. VFR conditions expected
thru forecast period, but with a 10-20% chance of MVFR CIGs during
the overnight period, most likely between 10Z-16Z.

&&

.MARINE...12/207 PM.

For the outer waters southwest through northwest of the Channel
Islands, including the nearshore waters along the Central Coast,
Small Craft Advisory (SCA) level winds and seas continue across
the waters north of Point Sal (PZZ670/645). Winds will remain
strong from Point Conception south to San Nicolas Island, thus
GALE Warning remains in effect across this area through late
tonight (PZZ673/676). SCA conditions are likely to linger in some
fashion through Monday morning.

For the inner waters south of Point Conception, winds are expected
to increase to SCA levels this afternoon across western & southern
portions of the Santa Barbara Channel. Likely reaching the Anacapa
Passage by early evening. Good confidence that winds calm to below
SCA levels by early Monday morning.

Monday afternoon into Tuesday afternoon, a storm system and
associated cold front will move across the region. This will bring
a 20-40% chance of thunderstorms across all the coastal waters
during that timeframe.

Any thunderstorm that forms may be capable of frequent cloud to
surface lightning, gusty and erratic winds, small hail, and even a
waterspout. Additionally, widespread SCA level SW winds and seas,
with a moderate chance of GALES between Monday night and Tuesday
night due to the aforementioned storm.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Flood Watch in effect from Monday evening through Tuesday
      afternoon for zones
      38-88-342-344-345-348-353-355-358-362-368>375-377>380-548. (See LAXFFALOX).
PZ...Small Craft Advisory in effect until 9 AM PDT Monday for
      zones 645-670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Monday for zone
      650. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Monday for zones
      673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Thompson
AVIATION...Ciliberti
MARINE...Black/Lund
SYNOPSIS...Schoenfeld/Ciliberti

weather.gov/losangeles

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