Wind Advisory 14, NWS Los Angeles, CA

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
605 PM PST Tue Jan 30 2024

.SYNOPSIS...30/134 PM.

Cooler temperatures are expected through Wednesday as offshore
flow weakens. The first in a series of storms will bring rain and
mountain snow Wednesday night into Thursday. Dry weather is
expected most areas Friday and Saturday. A second and likely much
stronger storm will arrive Sunday with periods moderate to heavy
rain through Tuesday and likely beyond.

&&

.SHORT TERM (TUE-FRI)...30/231 PM.

Temperatures were much cooler today as offshore flow weakened and
the strong high pressure that had been in place shifted east.
These trends will continue into Tuesday with some coastal stratus
possible as well as some increasing high clouds.

The storm door open again later Wednesday with rain expected to
spread across the entire area by Thursday morning. This first
system is a fairly quick moving one but has a strong upslope
component that will enhance rain rates, especially in the
foothills and mountains. But models also indicate some instability
with this system so isolated thunderstorms are possible,
especially over and near the coastal waters. Hi res models
already showing pockets of half inch per hour rain rates with
isolated rates up to 0.75"/hour. So there will likely be typical
roadway (advisory level) flooding across the area but overall not
expecting any significant flooding problems.

Several inches of snow are likely across the higher mountain
elevations late Wednesday night into Thursday. Snow levels during
the main rain band are expected to be 7000 feet or higher, then
drop off Thursday afternoon and evening to around 6000 feet. Gusty
south to southeast winds expected in the mountains as well up to
50 mph.

Drier west to northwest flow will follow this first system with
rain tapering off from west to east through the day Thursday. For
areas west of Ventura County a large portion of the storm will be
through before sunrise Thursday, then moving out of LA County by
Thursday afternoon and evening. Still some scattered showers into
Friday but mostly Central Coast areas and the mountains. Snow
levels overnight into Friday morning could fall to around 4000
feet, but with very low chances (under 20%) of any snow
accumulations over Interstate 5 on the Grapevine.

.LONG TERM (SAT-TUE)...30/230 PM.

Fairly moist northwest flow continues into Saturday morning with
some lingering showers possible mainly northern areas, otherwise
one last dry day before a lengthy storm cycle begins Sunday and
lasts well into next week. While there is still some uncertainty
with the timing and amounts, ensembles continue to trend quite
wet, especially Sunday through Tuesday with greater emphasis south
of Pt Conception where widespread rain amounts of 2-4 inches are
common in the ensemble solutions for lower elevations with likely
twice those amounts in the south facing mountains. Significant
hydrologic issues are a strong possibility next week, including
rock and mud slides in the mountains and flooding of small streams
and rivers. And based on the latest ensembles some chances for
flooding of the larger rivers and streams.

Snow levels are lower as well, especially getting into Tuesday.
Higher mountain elevations above 6000 feet, are likely to receive
significant amounts of snow with this event, possibly 2-4 feet by
the middle of next week. Lower elevation snow down to around 4000
feet is possible by later Tuesday into Wednesday.

&&

.AVIATION...31/0203Z.

At 0024Z, there was a surface-based inversion with a top at 1400
feet at 20 degrees Celsius.

Moderate confidence in ceilings forming at all coastal airports
and KPRB tonight into Wednesday. Lower confidence in ceiling
heights however, with a range of outcomes between LIFR-IFR
OVC002-010. There chance for dense fog VLIFR is generally 20-30%,
except 60% at KPRB. A storm system will impact the area Wednesday
night through Thursday with periods of heavy rain, gusty southeast
winds, and a 10-20% chance of thunderstorms.

KLAX...Moderate confidence in VFR conditions through at least
04Z. Ceilings likely starting 06-12Z, and there is a wide range
of outcomes between VLIFR (20%), LIFR (30%) and IFR (50%). There
will likely be a prolonged period of east winds sometime between
01/01Z and 01/20Z.

KBUR...High confidence in VFR conditions through at least 06Z.
There is a 20 percent chance of LIFR conditions 10-16Z.

&&

.MARINE...30/327 PM.

High confidence in generally calm conditions through most of
tonight, except for random patches of dense fog that could form
anywhere including nearshore. Expect very low visibilities with
this fog.

High confidence in a storm system impacting the area Wednesday
afternoon into Thursday morning. This storm will bring periods of
heavy rain with low visibility and widespread south to southeast
wind gusts of 30 to 40 knots with large steep seas. The worst
conditions will be along the Central Coast, including Port San
Luis, where gusts near 40 knots and south wind swell near 10 feet
are expected. Avalon Harbor will also see southeast to east winds
near 20 knots Thursday morning, creating wind waves for the
unprotected harbor areas. There is also a 10 to 20 percent chance
of thunderstorms Thursday morning through the evening hours.
Mariners should stay in safe harbor Wednesday Night through
Thursday.

Post-frontal west to northwest winds will quickly form during the
day on Thursday and peak Thursday Night through Friday. Moderate
confidence in widespread gusts of 20 to 30 knots, with a small
chance of Gale Force winds, focused over waters south of Point
Conception including nearshore. A large west swell will also fill
in, which will create nearshore hazards including a high risk for
breaking waves over the Morro Bay and Ventura Harbor entrances.

Moderate confidence in improving conditions on Saturday. Another
potentially strong multiple day storm will impact the area as
early as Sunday lasting as late as Tuesday.

&&

.BEACHES...30/340 PM.

An extended period of high surf will impact the beaches. Surf will
build first over the Central Coast tonight (a possibly the Ventura
County Coast), then for all beaches Wednesday Night, and persist
through Sunday or Monday. The largest waves are expected Thursday
and Friday. At this time, confidence is high for all west facing
beaches to see surf over 8 feet, with the Ventura Coast peaking at
12 feet, and the Central Coast at 18 feet. This puts most coasts
into High Surf criteria, with hazardous surf for most people and
dangerous waves on rocks and jetties. There is a 30 percent chance
that waves will reach warning levels Thursday afternoon and
evening over the Central Coast (20+ feet) and the Ventura Coast
(15+ feet). If waves reach these levels, there is a risk for pier
damage as well as significant beach erosion and inundation of
sandy beach areas despite high tides not being very high (4.5 to
5.0 feet). Further complicating the situation, during the peak of
our next storms Wednesday Night and possibly Sunday, a large wind
swell will create breaking waves and a possible push of water
into unprotected south facing areas like Port San Luis and Santa
Barbara Harbor.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect from 2 AM Thursday to 6 AM PST
      Saturday for zones 87-349-350-354-362-366. (See LAXCFWLOX).
     High Surf Advisory in effect until 5 PM PST Saturday for
      zones 340-346. (See LAXCFWLOX).
     Winter Storm Watch in effect from late Wednesday night
      through Thursday afternoon for zones 376-377. (See LAXWSWLOX).
     Winter Storm Watch in effect from late Wednesday night
      through Thursday evening for zones 378>380. (See LAXWSWLOX).
PZ...Small Craft Advisory in effect from 9 AM to 3 PM PST
      Wednesday for zones 645-673. (See LAXMWWLOX).
     Gale Warning in effect from 3 PM Wednesday to 6 AM PST
      Thursday for zones 645-670-673. (See LAXMWWLOX).
     Gale Watch in effect from Wednesday evening through Thursday
      morning for zones 650-676. (See LAXMWWLOX).
     Gale Watch in effect from late Wednesday night through
      Thursday afternoon for zone 655. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 AM to 3 PM PST
      Wednesday for zone 670. (See LAXMWWLOX).

&&

PUBLIC...MW
AVIATION...Phillips/Kittell
MARINE...Kittell
BEACHES...RK
SYNOPSIS...MW

weather.gov/losangeles

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