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221
FXUS66 KLOX 041648
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
948 AM PDT Sat May 4 2024

.SYNOPSIS...
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04/922 AM.

A cold storm system will move over the region through Sunday
bringing periods of light rain to the area this afternoon and
evening. Temperatures will be much cooler than normal through
Sunday and there will be gusty winds at times. Dry and warmer
weather is expected next week.
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&&

.SHORT TERM (TDY-MON)...
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04/947 AM.

***UPDATE***

A weak but unusually cold storm system will move through
California today into early Sunday. Really no changes in the
timing and amounts from earlier predictions. Light rain has made
it as far south as Monterey as of 9am and should be reaching the
SLO County line by early afternoon. While northwest SLO County
still stands to get around a quarter to half inch of rain with
this system, due to the storm moving inland over northern
California rain amounts drop off pretty fast to the south. The
exception being southeastern LA County and the north facing
mountain slopes where up to a third of an inch of rain is
expected. In the downsloping area between southern Santa Barbara
County and western LA County amounts drop off to a tenth of an
inch or less. In most areas the duration of rain will be short,
around 3-4 hours.

***From Previous Discussion***

Snowfall amounts will be light. While snow levels will lower down
to 4000 to 4500 feet late tonight or early Sunday morning, most
of the moisture will likely vacate the area by that time. At most,
a dusting to an inch of snow are likely with local amounts up to
two inches.

Gusty winds will start to develop across the San Gabriel
Mountains, and the Antelope Valley and the adjacent foothills
this afternoon and this evening as the surface pattern tightens
ahead of the cold front. A wind advisory remains in effect for
this afternoon and tonight for these areas. After the front
passes over the region, a tight surface pressure gradient will
remain into Sunday and Sunday night. There is a good chance
that the advisory for the San Gabriel Mountains, and the Antelope
Valley and the adjacent foothills may need to be extended into
Sunday and Sunday night. Wind advisories were added for the entire
coastal areas and into the Santa Ynez Valley for gusty west winds
on Sunday afternoon and evening, and for the Transverse Ranges and
into southern Santa Barbara County for gusty northwest winds
developing late tonight through early Monday morning.

A cold air mass will spread into the area today and Sunday. There
is a moderate chance that low maximum temperatures records could
fall on Sunday out in the desert as the air mass will be cold for
May, more inline with February or March. Temperatures in the 60s
will be common across most areas the next several days, coldest on
Sunday for areas south of Point Conception.

.LONG TERM (TUE-FRI)...04/529 AM.

The forecast ensemble members continue to suggest a warming and
drying trend developing through Wednesday as high pressure aloft
reestablishes over the eastern Pacific Ocean and a low pressure
system dives through the Great Basin. There is a chance that a
cool down could arrive for late week as onshore flow increases.
EPS ensembles continues to keep cloud cover means free of the
marine influence, but confidence remains moderate at best due to
the time of the year.
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&&

.AVIATION...04/1249Z.

At 12Z at KLAX, the marine layer was 3300 ft deep. The top of the
inversion was at 4200 ft with a temperature of 13C.

Deep marine layer with low clouds in all coastal/valley areas and
up to the coastal slopes. Conds were low MVFR in L.A. County.
except IFR-VLIFR in the foothills/mtns, and were mostly IFR-VLIFR
from VTU County northward. Skies will likely remain mostly cloudy
today, though cigs will gradually rise. Most areas should have MVFR
to possibly low VFR conds this afternoon, except IFR or worse in the
foothills/mtns. A frontal system will likely bring light rain to
SLO/SBA Counties this afternoon/evening, with a chance of showers
in L.A./VTU Counties this evening thru late tonight. Widespread MVFR
conds expected tonight with IFR-VLIFR cigs in the foothills/mtns.

KLAX...Moderate confidence in the 12Z TAF. There is a 30% chance
that MVFR conditions will linger thru the day, and not improve to
VFR from 20Z thru 04Z as predicted. There is also a chance that
MVFR conds tonight will linger thru 16Z Sun. No significant
easterly wind component is expected thru the pd.

KBUR...Moderate confidence in the 12Z TAF. There is a 30% chance
that MVFR conditions will linger thru the day, and not improve to
VFR from 20Z thru 03Z as predicted.

&&

.MARINE...
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04/710 AM.

In the Outer Waters, winds and seas may drop below Small Craft
Advisory (SCA) levels several hours late this morning/afternoon,
but are expected to increase again late today. Widespread SCA
level winds/seas are expected tonight thru Sunday afternoon,
except will likely drop below SCA levels in the northern zone
(PZZ670) late tonight. Winds will increase Sunday, with gales
possible late Sunday into Sunday night in the southern two zones
(PZZ673/676) and SCA conditions in the northern zone. SCA
conditions are expected Monday thru Wednesday, with a 40% chance
of gales Monday afternoon/eve.

In the Inner Waters North of Point. Sal, SCA level winds/seas
are likely in the afternoon/evening hours today thru Wednesday.
There is a chance that seas will remain at or above SCA levels
even when winds weaken, especially Sunday night/Monday night.

In the Inner Waters south of Point Conception, SCA level W-NW
winds are expected to spread from west to east across the waters
this evening and early tonight, then continue thru Sunday
afternoon. There is a 50% chance of gales Sunday afternoon into
late Sunday night, especially in western portions. SCA level seas
may persist into Monday. SCA winds are likely during the
afternoon/evening hours Monday thru Wednesday in the Santa Barbara
Channel, with a 30% chance of SCA conditions extending into the
southern inner waters from Anacapa Island to Malibu.
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&&

.LOX WATCHES/WARNINGS/ADVISORIES...
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CA...Wind Advisory in effect from 10 AM to 9 PM PDT Sunday for
      zones 87-340-341-346>348-354-355-362-366. (See LAXNPWLOX).
     Wind Advisory in effect from 11 PM this evening to 3 AM PDT
      Monday for zones 349>353-376>378. (See LAXNPWLOX).
     Wind Advisory remains in effect until 5 AM PDT Sunday for
      zones 379>383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Sunday for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 9 PM this evening to 3 PM
      PDT Sunday for zones 650-655. (See LAXMWWLOX).
     Gale Watch in effect from Sunday afternoon through late
      Sunday night for zones 650-655-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Sunday for zone
      670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT Sunday for
      zones 673-676. (See LAXMWWLOX).
-- End Changed Discussion --

&&

$$

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

weather.gov/losangeles

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