Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 230244
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
744 PM PDT Fri Mar 22 2024

.SYNOPSIS...22/133 PM.

A storm will move into the area Saturday with rain and mountain
snow that will taper off by Saturday afternoon. Scattered showers
with isolated thunderstorms are possible Saturday night into
Sunday with snow levels lowering to as low as 4000 feet. Gusty
west to northwest winds are expected as well. Dry and warner
weather is expected Monday through at least Wednesday. More
storms are possible Friday into next weekend.

&&

.SHORT TERM (FRI-MON)...22/742 PM.

***UPDATE***

The current forecast is on track for tonight. Partly to mostly
cloudy skies covered the forecast area early this evening as
mainly mid and hi level clouds moved into the area in response to
an approaching E Pac upper level trof and surface cold front.
Clouds will continue to increase overnight as the cold front
pushes E. The front is forecast to move into SLO/SBA Counties with
rain becoming likely by late tonight. There will also be an
increasing chance of rain for VTU County by daybreak Sat. Decent
onshore gradients will help to bring gusty mainly sub-Advisory
winds to the interior mtns and vlys overnight, including the
Antelope Vly.

***From Previous Discussion***

The next storm is on our doorstep and is expected to move into the
area later tonight into Saturday morning. Most of the forecast
models their ensembles showed a slight uptick in intensities as
the first part of the system is taking a more over-water
trajectory which also is forcing the winds to back more to the
south. This latter development creates a more favorable pattern
for rain locally as this generates a little more upslope flow due
to the presence of the coastal mountains. While this will still
be a very modest system at best with regard to rainfall amounts,
the rain forecast has been nudged upwards in most areas to reflect
the latest model developments. The forecast is now calling for a
quarter to half inch of rain south of Pt Conception for the
weekend and a half to one inch north. The Saturday rain will be
fairly quick in duration, lasting only a few hours in any one
location, starting overnight along the Central Coast, around
sunrise in Ventura, and an hour or two later in LA County. Snow
levels with this part of the system will be around 6000 feet so no
snow impacts Saturday for most of the major mountain roads,
including the Grapevine. Following the rain, gusty west winds will
kick up across coastal areas and the Antelope Valley, though
likely below advisory levels.

For some areas, especially from southern Santa Barbara County to
southern Ventura County, that may be the end of it for this
weekend. Rapidly increasing northwest to north flow aloft will
provide a significant downsloping and drying effect in those areas
that will not be favorable for additional precip as the main
upper low moves in Sunday into Sunday evening. Central Coast and
LA County will be less impacted by that effect so chances for
additional showers are definitely higher in those areas. However,
since the upper low will be ushering in much colder air aloft,
around -29c at 500mb, showers and even an isolated thunderstorm
can`t be ruled out even in those less favorable areas. Not
everywhere will see additional rain Sunday but certainly the
Central Coast and the northern mountains will be the most likely
to get more showers. Snow levels will be dropping rapidly with the
colder air moving in with light snow accumulations possible as
low as 4000 feet Sunday morning. Even stronger west to northwest
winds expected to kick up Sunday afternoon with some wind
advisories possible, especially near the coast.

Precip chances drop off quickly Sunday night but can`t completely
rule out some upslope showers through Sunday night on the north
facing slopes. In fact, the 18z NAM is showing a little increase
in moisture and lift across interior SLO County Monday afternoon
and the adjacent mountains so some light precip is possible there.
Dry elsewhere but cool and breezy.

.LONG TERM (TUE-FRI)...22/226 PM.

Dry and warmer weather expected Tue/Wed as a weak and transient
upper ridge moves through the area. Some breezy northerly winds
are possible at times, mainly in the mountains.

Latest ensembles continue to show a likely return to wet weather
later next week into Easter weekend. A quick moving trough could
bring some light rain mainly north of Pt Conception Wednesday
night and/or early Thursday. Then most of the ensembles are
showing a very cold upper low dropping out of the Gulf of Alaska
next Friday into Saturday. 60-70% of the grand ensemble members
show at least some rain returning to the entire forecast area as a
very cold upper low moves into California.

&&

.AVIATION...23/0243Z.

At 00Z over KLAX, the marine layer was 1100 feet deep, with an
inversion top at 2000 feet and 15 Celsius.

Light -RA likely everywhere tonight into Saturday. Moderate
confidence in timing (+/- 3 hours) and categories (+/- 1
category). Brief IFR conditions possible with any randomly placed
heavier cell. Gusty winds Saturday afternoon will also bring low-
end LLWS.

KLAX...See above on confidence and details. East winds are
likely, as early as 12Z lasting as late as 22Z, with 16-20Z the
period of most concern. 50% chance of exceeding 8 knots.

KBUR...See above on confidence and details.

&&

.MARINE...22/545 PM.

Overall, moderate confidence in current forecast. Through
tonight, high confidence that winds and seas will remain below
Small Craft Advisory (SCA) levels across all coastal waters.

On Saturday, high confidence in development of SCA level winds
and seas across all the coastal waters with the SCA conditions
continuing through Saturday night. For Sunday and Sunday night,
winds are expected to increase to GALE FORCE (60-80% chance) with
large and steep SCA level seas. On Monday and Tuesday, the winds
will gradually subside, but remain around SCA levels for many
areas. As for seas, expect seas to drop to below SCA levels by
Tuesday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect from Sunday morning through
      Monday morning for zones 87-362-366. (See LAXCFWLOX).
     High Surf Advisory in effect from 3 AM Sunday to 9 AM PDT
      Monday for zones 340-346-354. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect from 3 PM Saturday to 3 AM PDT
      Sunday for zones 645-670. (See LAXMWWLOX).
     Gale Watch in effect from late Saturday night through late
      Sunday night for zones 645-650-655-670-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect from 9 AM Saturday to 3 AM PDT
      Sunday for zones 650-655-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Sirard
AVIATION...Kittell
MARINE...RAT/Schoenfeld
SYNOPSIS...MW

weather.gov/losangeles

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


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