Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 250342
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
842 PM PDT Sun Mar 24 2024

.SYNOPSIS...24/842 PM.

A cold convective system will continue to bring isolated showers
tonight, mainly north slopes. Dry and breezy conditions will
prevail through Thursday. A significant late season storm is
possible next weekend.

&&

.SHORT TERM (SUN-WED)...24/840 PM.

Scattered showers and thunderstorms developed this afternoon
across the region, most numerous across LA county. Several
special weather statements were issued across LA county earlier
this afternoon to highlight strong thunderstorms, along with two
severe thunderstorm warnings for the San Gabriel Valley due to
larger hail threat. There were numerous hail reports across the
region with the convective activity, some of which produced
significant accumulations. After sundown, the convective activity
has diminished considerably, with just isolated showers across
interior San Luis Obispo and Santa Barbara counties. The very cold
air aloft today (-29 degrees Celsius at 500 mb) helped fuel the
instability associated with the thunderstorms activity. While most
of the shower activity will continue to diminish tonight, there
will continue to be the threat of upslope showers across north
facing slopes, especially near the Kern County line. The snow
level has lowered to around 4000 feet tonight, so there is the
potential for a dusting to 1 inch accumulations across I-5 near
the Grapevine. A winter weather advisory remains in effect for the
interior mountains of Santa Barbara and Ventura counties as well
as the I5 corridor.

Gusty west to northwest winds this afternoon, with widespread
advisory level This evening into tonight winds turn more
northerly with a 20-40 percent chance of warning level gusts
across prone interior mountains of Ventura County, far northwest
LA county mountains and possibly extending into the eastern Santa
Ynez Range of Santa Barbara County. Current Wind Advisory looks
well placed for tonight, but extended a wind advisory for Catalina
Island and the San Fernando Valley through 3 am tonight.

*** From previous discussion ***

Broad northwest flow will continue across the area through
Tuesday, although gradually weakening. The coverage of advisory
level winds will drop through the period with only most prone
mountains and coasts remaining at advisory level at best by
Tuesday. The cold airmass will shift east of the area through this
time frame allowing temperatures to rebound to closer to seasonal
values. However, Monday and Tuesday mornings may see frost/freeze
conditions to some interior areas and other sheltered valleys.

An eddy may spring the marine layer back to life under weak
ridging by Wednesday with low clouds possibly pushing well into
the valleys if not the foothills. This should put an end to the
warming trend for areas west of the mountains. A rapidly weakening
cold front will bring a slight chance of rain as early as
Wednesday evening mainly for San Luis Obispo County.

.LONG TERM (THU-SUN)...24/311 PM.

Any lingering rain should be over by midday Thursday.

The main concern is the potential for a significant late season
storm sometime in the Friday through Sunday time frame. We have
low confidence in the details as the strength and location of the
storm remains uncertain, but we have moderate confidence that most
of the area will see at least some rain and mountain snow. There
is a 5-10 percent chance of thunderstorms with the storm and this
estimate will likely increase should the storm track dial in on
our area. Our early estimate is for 1-3 inches of rain for much of
the area with locally higher amounts possible for south facing
slopes. Snow levels will be closely tied to the eventual storm
track and may be as high as 6-7K feet or as low as 4-5K feet for
much of the storm. The storm has the potential for at least
moderate impacts (i.e. minor flooding and mountain winter driving
conditions) in this time frame.

&&

.AVIATION...24/2347Z.

At 23Z at KLAX, there was no marine layer nor inversion.

Moderate confidence in the 00Z TAFs due to strong gusty winds,
scattered/isolated showers and thunderstorms through 02Z.
Generally VFR conditions are expected except MVFR to locally IFR
near convective showers thru early evening, ending sooner N of
Point Conception. After 02Z this evening, VFR conds are expected
at all the airfields and will continue thru Mon.

KLAX...Moderate confidence in the 00Z TAF. VFR conds are expected
to prevail except 20% chance of BKN025 to brief BKN015 conds in
showers/thunderstorms to early this evening. Lower confidence for
the end times of stronger gusty winds. There is a 20% chance of
an east wind component of 06 kt or more with any thunderstorm that
may form near the airfield. VFR conds are expected at 01Z thru the
end of the fcst period. Gusty W winds are expected Mon afternoon.

KBUR...Moderate confidence in the 00Z TAF. VFR conds are expected
for most of the fcst period. However, best chances for
showers/thunderstorms and possible brief MVFR cigs will be from
00Z-02Z.

&&

.MARINE...24/125 PM.

Dangerous large seas and strong winds will continue through at
least Monday night for much of the coastal waters. Seas are
expected to peak near 12 to 15 feet over the outer waters, and 9
to 13 feet over the inner waters tonight then slowly subside into
mid week. Gale force winds are expected for much of the coastal
waters at times thru Monday night, and for much of the outer
waters west and south of point Sal Tuesday and Tuesday night.
Small Craft Advisory winds are expected for much of the outer
waters Wednesday morning, and for much of the coastal waters
Thursday. Conds should then be below SCA levels Friday.

In addition to the winds, there is a 10 to 20 percent chance of
thunderstorms into early this evening especially for the waters W
and S of Point Conception. There will be the potential for brief
heavy rainfall and/or hail, and dangerous cloud to surface
lightning. The combination of strong winds, high, choppy seas, and
potential for thunderstorms create dangerous conditions for
vessels. Boaters, especially small vessels should postpone
traveling the coastal waters at least until conditions improve
around Tuesday/Wednesday.

&&

.BEACHES...24/126 PM.

Large swells moving into the coastal waters will generate high
surf along all west and northwest facing beaches into Monday
afternoon. For the Central Coast, surf of 7 to 12 feet with max
sets to 13 feet can be expected. For west-facing beaches south of
Point Conception, surf of 4 to 8 feet with max sets to 9 feet is
expected. The high surf will also generate dangerous rip
currents.

With the high surf, there is an increased risk for ocean
drowning. Rip currents can pull swimmers and surfers out to sea.
Large breaking waves can cause injury, wash people off beaches and
rocks, and capsize small boats near shore.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 6 PM PDT Monday for zones
      87-340-346-354-362-366. (See LAXCFWLOX).
     Wind Advisory in effect until 3 AM PDT Monday for zones
      88-349>352-356-379. (See LAXNPWLOX).
     Winter Weather Advisory in effect until 6 AM PDT Monday for
      zones 353-376>378. (See LAXWSWLOX).
PZ...Gale Warning in effect until 3 AM PDT Monday for zones
      645-650-655-670. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Tuesday for zones
      673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Gomberg/Munroe
AVIATION...Sirard
MARINE...Sirard
BEACHES...Sirard
SYNOPSIS...Gomberg

weather.gov/losangeles

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


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