196
FXUS66 KLOX 281759
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
959 AM PST Fri Feb 28 2025

.SYNOPSIS...28/906 AM.

A cooling trend will develop through Saturday as the first of a
series of cold storm systems move over the region. A cool and
unsettled weather pattern is likely to develop for much of next
week with chance of light rain Sunday and possibly a stronger
storm next Wednesday and Thursday.

&&

.SHORT TERM (TDY-SUN)...28/926 AM.

***UPDATE***

An compact upper low is about 200 miles southwest of Pt Conception
as of 9am. It`s trajectory has shifted more to the east, though
there is still a southerly component to it and will likely steer
it too far south to have any impact to north of Orange County. So
rain chances for tonight and Saturday have been removed, which
goes along well the 12z HREF. Will likely see some increasing high
clouds this afternoon into Saturday with much cooler temperatures.

The next system for Sunday still looks on track. This one is not
completely cut off from the westerlies and models have been pretty
consistent with its expected path and timing so confidence is
higher that most areas will see at least some light rain Sunday
into Sunday night, mostly under a quarter inch. It`s quite cold
aloft with 500mb temps near -30c and models do show some
instability as it comes through. May have to eventually consider
adding some thunderstorm chances with brief periods of heavy
showers, at least for SLO County. Also, snow levels lower rapidly
and there is a chance of light accumulating snow Sunday night over
the Grapevine.

***From Previous Discussion***

Brief shortwave ridging aloft will develop on Saturday, then the
next system will dig into the region between Saturday night and
Sunday morning. The trough, a broader double-barreled feature will
sag south into the region through the remainder of the weekend. A
leading frontal boundary could bring a few hours of light rain to
the region between Saturday night and Sunday, then a cold and
unstable air mass should spread over the area into Sunday and
Monday. The trough again will be moisture-starved, but a very cold
air mass aloft could produce an environment for isolated showers
and thunderstorms on Sunday and Monday. EPS precipitable water
mean values increase to 0.6-0.7 inch, which is more than ample
moisture to support shower activity. EPS 850 mb temperature means
drop to near -1 degree Celsius, which would produce a threat of
snow through the Interstate 5 Corridor. 700 mb temperatures in the
deterministic solutions of the GFS suggest snow levels dropping
locally down to 3000 feet.

With the colder air mass spreading into the region on Sunday,
there is a growing chance for gusty west to northwest winds
developing. EPS members have highlighted KOXR and KSBA for the
past several days, while deterministic solutions suggest a tight
surface pressure pattern developing on Sunday.

.LONG TERM (MON-THU)...28/443 AM.

A break in the pattern will occur on Monday and Tuesday, but a
cool air mass will remain in place. A northerly wind event is
shaping up for Monday night as EPS ensemble members leans towards
wind through the Interstate 5 Corridor and across southern Santa
Barbara County.

The next storm system will spread into the region between Tuesday
night and Wednesday as the last system of the three moves into the
region. This system could the most significant of the three
systems in terms of precipitation as there are better moisture
components and a better shot of southwesterly flow out ahead of
the storm system. Precipitable water value means climb to about
0.70 inch again, there are several solution leaning more strongly
on the higher end in the latest EPS solutions. While a vast
majority of the forecast ensemble members have precipitation, the
exact timing and amounts are still in question. Confidence remain
high in rain and mountain snow developing sometime between Tuesday
night and Thursday.

&&

.AVIATION...28/1758Z.

At 1654Z at KLAX, the marine layer was about 300 ft deep. The top
of the inversion was around 1000 ft with a temperature of 20 C.

Overall, moderate confidence in 18Z TAF Package. Timing of
cig/vsby restriction may be off +/- 2 hours. Flight cats could be
off one or two, especially for SLO/SBA county airfields. There is
a 30-40% chance for LIFR conds at KSBP and KSMX from 06Z-16Z Sat.

There could be a few showers this evening into the overnight
hours for SLO/SBA Counties, and after midnight into the morning
hours for VTU/L.A. Counties.

KLAX...Moderate to high confidence in 18Z TAF. There is a 20%
chance east wind component lingers until 20Z Fri. VFR conds with
BKN100-150 expected until around 03Z Sat. MVFR cigs 020-030 likely
thereafter, with PROB30 -SHRA from 12Z to 15Z Sat (+/- 2 hours).

KBUR...High confidence in 18Z TAF. There is a 20-30% chance of
MVFR conds after 06Z Sat.

&&

.MARINE...28/808 AM.

In the outer waters, seas have increased to Small Craft Advisory
(SCA) levels, and will likely remain at those levels thru late
tonight. NW winds will mostly be below SCA levels, but there
could be local SCA level gusts this afternoon/eve. Seas will
likely build to SCA levels (70% chance) Sat afternoon and remain
at or above SCA levels thru Tue. SCA level NW winds are likely
Sat afternoon thru Tue morning, except then may not reach SCA
levels until Sun afternoon in the northern zone (PZZ670). There
is a 40% chance of gale force winds Sun afternoon thru Mon eve.

In the inner waters N of Pt. Sal, there is a 40% chance of SCA
level seas this afternoon into tonight. Seas will likely reach SCA
levels Sat afternoon and continue at those levels until at least
late Mon night. There is a 40-50% chance of SCA level winds
during the afternoon/eve hours Sat, then SCA level winds are
likely (70% chance) in the afternoon/eve hours Sun thru Mon. There
is a 30% chance of gale force winds Mon afternoon/eve.

In the inner water S of Pt. Conception, there is a 70% chance of
SCA level W winds in the Santa Barbara Channel Sat afternoon/eve.
Likely chance for widespread SCA level winds during the afternoon
thru late night hours Sun thru Mon night. There is a 30% chance
of Gale force winds Mon afternoon/eve.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect until 9 PM PST this evening
      for zones 87-349-350-362-366. (See LAXCFWLOX).
     High Surf Advisory in effect until 9 AM PST Saturday for
      zones 340-346-354. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PST Saturday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Hall
AVIATION...Black
MARINE...DB/Black
SYNOPSIS...MW/Hall

weather.gov/losangeles

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