754
FXUS66 KLOX 021307
AFDLOX
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
607 AM PDT Thu May 2 2024
.SYNOPSIS...02/455 AM.
A dry weather pattern will continue through Saturday as the region
remains between high pressure aloft to the west and an exiting
trough to the east. Warming will continue to take shape across the
northern and interior portions of the area today, while a
persistent marine layer will moderate the warming across the South
Coast of California. An unseasonably cold storm system will brush
the area to the north this weekend and bring cooler temperatures,
gusty winds, and a chance for light precipitation Saturday into
Sunday. A warming and drying trend will develop for the work week
next week.
&&
.SHORT TERM (TDY-SAT)...02/455 AM.
Zonal flow remains aloft over the region early this morning as the
area sits between a broad upper-level trough to the east and an
upper-level ridge over the eastern Pacific Ocean. A fairly complex
surface pattern exists across the area as ridging to the west has
created a weak offshore flow pattern across the area. Offshore
flow is present across the Central Coast of California this
morning, but a persistent eddy circulation remains intact across
the southern California bight. With the offshore flow pattern
being too weak, it is unlikely for the eddy to get dislodged from
the bight. As a result, a persistent marine intrusion will remain
wedged in place for today across the South Coast of California.
Low clouds and fog have spread into the the Los Angeles County
coastal plain and into the San Gabriel Valley. Clouds are starting
to push north along the Ventura County coast and the south coast
of Santa Barbara County. Clouds are expected to push into most
coastal and valley areas south of Point Conception this morning,
but there is a moderate chance that the eddy circulation could
pull too far offshore and result into some clearing skies to start
the day.
A warming trend should develop today as offshore flow should
assert some influence with the compressional heating, but the
warming trend could be more muted or even closer to persistence
along the South Coast of California due to the low cloud field
already present across the area. The forecast preserves a warming
trend continuing into today while moderating the warming along
the Los Angeles, Ventura, and southern Santa Barbara Counties.
There is a moderate chance that clouds could hug the beaches and
struggle to clear off the southern coastal areas this afternoon,
but more confidence exists in the offshore push being able to
clear off the clouds just off the coast.
A wind advisory was cancelled early this morning as northerly
winds weakened with the northerly surface gradient relaxing some,
but there is another chance of gusty northerly winds through the
Interstate 5 Corridor tonight as the surface pressure gradient
tightens again. There is a moderate chance that a wind advisory
could be issued for the same areas tonight and into Friday
morning as NAM-WRF boundary layer winds increase to 25 knots.
With the ridge aloft and offshore flow weakening later today, the
marine layer cloud field should become a bit more entrenched
tonight and into Friday morning. Ridging aloft should tighten the
marine inversion some and possibly inhibit clearing on Friday at
the beaches. A return of low clouds and fog should occur along the
Central Coast, but there is a moderate chance that the low cloud
forecast could be a little too expansive along the Central Coast
for late tonight and into Friday morning.
By Friday night, cyclonic flow will start to develop and a
deepening marine layer should be expected as onshore flow
strengthens. Marine layer induced low clouds and fog should be
fairly aggressive on Friday night and Saturday as low clouds and
fog will likely push into the coastal slopes of the mountains.
Much cooler temperatures will start to spread into areas north of
Point Conception on Saturday as an unseasonably cold upper-level
trough digs into northern California. A cold frontal boundary will
drop south into the region late Saturday and bring an increase in
chances for precipitation on Saturday night.
.LONG TERM (SUN-WED)...02/455 AM.
The frontal boundary will continue to move south and east over
the area into Sunday while weakening some. The highest chance for
precipitation will be for areas north of Point Conception, along
the northern slopes of the mountains, and into the San Gabriel
Valley between Saturday night and Sunday. EPS, GEFS, and CMC
ensemble members buy into this idea emphasizing these areas being
wetter. Southern Santa Barbara County, Ventura County, and western
Los Angeles County could end up being in a rain shadow effect as
downsloping occurs from the Transverse Ranges. PoPs break away
from NBM values between Saturday night and into Sunday, and go
higher than the previous forecast for the wetter areas. Likely
PoPs may be needed by future shifts if the pattern continues for
areas north of Point Conception, along the northern slopes of the
mountains, and into the San Gabriel Valley. Almost all solutions
of the EPS suggest rain for terminals north of Point Conception,
KSDB, KEMT, and KPOC.
Temperatures will be quite cool for Sunday across the area. Record
cold high temperatures could be tied in some areas as a cold
pattern for May sets up. Temperatures go colder than NBM values
for Sunday.
Gusty winds could end being the main story with this system. EPS
members produce a broad period of gusty winds between Sunday and
Monday morning. Gusty west to northwest will likely develop on
Sunday across most areas, and a wide swath of wind advisories
might be needed for Sunday afternoon and evening. Gusty northwest
to north are likely to linger through the Interstate 5 Corridor
and into southern Santa Barbara County for Sunday night and into
Monday morning.
A warming and drying trend should develop for the work week next
week as forecast ensemble advertised a consistent warming trend in
the temperature means.
&&
.AVIATION...02/1306Z.
At 12Z at KLAX, the marine layer was 1900 ft deep with an
inversion top at 4100 ft and a temperature of 17 C.
Skies were clear north of Pt Conception, and with the exception of
some MVFR vsbys through 16Z, conds will be VFR there thru this
evening. Some low clouds will likely affect portions of the
Central Coast late tonight, with IFR to LIFR conds expected.
S of Pt. Conception, good eddy circulation was in progress. Low
clouds were widespread in all coastal areas except for SW SBA
County, and the valleys of L.A./VTU Counties except for the Santa
Clarita Valley and the most interior valleys of VTU County. Conds
were mostly low MVFR to high IFR, except LIFR to VLIFR in the
higher valleys, foothills and the Santa Monicas. Skies should
clear by mid morning in the valleys and by noon on the coastal
plain, but may linger all day at some beaches. Expect similar
conditions tonight, with widespread low clouds in coastal and most
valley areas, and low MVFR to high IFR conds, except LIFR to
VLIFR conds in the foothills and Santa Monicas.
KLAX...Low to moderate confidence in the 12Z TAF. There is a 30%
chance that cigs will linger until at least 20Z-21Z. There is a
30% chance that cigs will arrive as early as 05Z. There is a 20%
chance of an E wind component of 7-8 kt thru 17Z and 09Z-15Z Fri.
KBUR...Low to moderate confidence in the 12Z TAF. There is a 30%
chance of IFR conds lingering until 18Z. There is a 30% chance of
cigs will arrive as early as 07Z tonight.
&&
.MARINE...02/538 AM.
In the outer waters, Small Craft Advisory (SCA) level winds are
expected to increase to Gales (70-80% chance) this afternoon, then
continue thru late tonight. Winds will likely drop to SCA levels
late tonight thru Fri afternoon, then Gales are likely (60-70%
chance) late Fri afternoon thru late Fri night. Winds will drop
Sat morning, possibly even below SCA levels, but seas will remain
at SCA levels. SCA level winds are expected Sat afternoon thru
Mon, with a 40% chance of Gales Sun afternoon/evening.
In the inner waters N of Pt. Sal, SCA level winds and seas will
develop this morning, then continue thru late tonight. SCA level
winds are likely during the afternoon/eve hours Fri, Sun and Mon
(60-70% chance), with a 40-50% chance Sat afternoon/eve.
In the SBA Channel, SCA level winds are likely in western portions
of the channel during the late afternoon thru late night hours
today and Fri (60% chance), and in most of the SBA Channel during
the late afternoon thru late night hours Sat thru Mon. There is a
20% chance of gales Sun afternoon/eve.
In the southern inner waters, there is a 20% chance of SCA level
winds in NW portions (from Anacapa Island to Malibu) during the
late afternoon/eve hours today and Fri. SCA level winds are likely
during the late afternoon thru late evening hours Sat thru Sun,
especially in western portions, then there is a 40% chance Mon.
There is a 20% chance of gales Sun afternoon/evening.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Friday for zone
645. (See LAXMWWLOX).
Small Craft Advisory in effect from 3 PM this afternoon to 3
AM PDT Friday for zone 650. (See LAXMWWLOX).
Gale Warning in effect until 3 AM PDT Friday for zones
670-673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...Hall
AVIATION...DB
MARINE...DB
SYNOPSIS...Hall
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox
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