754
FXUS66 KLOX 261846
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1146 AM PDT Fri Apr 26 2024

.SYNOPSIS...26/1145 AM.

An upper-level trough of low pressure will continue to move over
the region through tonight. Any shower activity will likely be
across the northern portion of the area and along the northern
slopes of the mountains and into the San Gabriel Mountains and the
San Gabriel Valley. A tightening pressure difference across the
region will bring gusty and potentially damaging winds to the
region through tonight. Otherwise, dry weather can be expected
along with gradually warmer temperatures this weekend into the
middle of next week.

&&

.SHORT TERM (TDY-SUN)...26/1141 AM.

An inside slider type trough of low pressure continues to push
south into the region this morning. This trough of low pressure,
originating from the Gulf of Alaska will usher in a cooler air
mass today. Limited moisture with system and the trough`s position
will likely inhibit some of the shower activity, especially
across southern Santa Barbara and Ventura Counties today, and some
what into western Los Angeles County. The latest satellite shows
clear skies across much of the southern California bight this
morning. Clouds are banking across the northern interior portions
of the area and along the northern slopes of the mountains, and as
the downsloping effect recede from the Transverse Range, clouds
start to pickup again across eastern Los Angeles County and into
the counties south and east. PoPs have been nudged higher inline
with EPS ensemble members and high-resolution multi-model ensemble
solutions indicating a bit higher chance for the northern areas,
into eastern San Gabriel, and across the San Gabriel Valley. There
is a non-zero chance of thunderstorms for this afternoon and
evening, but the best chance of thunderstorms will be to the east
of the area where the steepest lapse rates exists.

The main story will likely be the strong winds expected to
develop today in the wake of a dying cold frontal boundary and
tightening northerly pressure gradients. A broad swath of wind
headlines have been issued across the region. The strongest winds
are expected through the Interstate 5 Corridor and across the
Channel Islands offshore. Strong pressure gradients will tighten
through the day today with gusty west to northwest winds
developing through this afternoon and evening, then shifting to
northerly overnight tonight. In the latest update, a High Wind
Warning was added for the Channel Islands for this afternoon and
tonight, while wind advisories were expanded across much of
Ventura County and into western Los Angeles County for this
afternoon and this evening. A wind advisory was also added for
the Cuyama Valley. There is a good chance that some advisories
will need to extended for the northerly winds tonight through
Saturday morning.

***From Previous Discussion***

The strongest winds will occur this evening over the mtns as the
inside slider moves into AZ and the best upper level support
develops. The strong winds will prevent any coastal clouds. The
north winds will continue to bring plenty of upslope clouds to the
north slopes as well as a chc of showers. An inch or 2 of snow is
possible over 6000 ft. Gradients and upper level support will
slowly fade starting late in the evening and winds will diminish
after midnight.

Saturday will be a nice if somewhat breezy day. A ridge will move
into the state and hgts will rise to about 572 dam. These hgt
rises along with continued offshore flow form the north and cloud
free skies will result in 3 to 6 degrees of warming across the
area.

Weak ridging and 574 dam hgts will make for a very pleasant
weather day on Sunday. The winds will be greatly diminished and
most areas will see 1 to 3 degrees of warming. Most cst/vly max
temps will end up in the mid 60s to mid 70s.

.LONG TERM (MON-THU)...26/347 AM.

The EC and GFS deterministic and mean ensembles are in generally
good agreement during the extended period. Weak cyclonic flow will
be over the state on Mon and Tue there will be an increase in
cyclonic flow on Wed and Thu.

Onshore flow will slowly increase through the period and will end
up being fairly strong towards the end of next week. There may be
a slight return of low clouds Mon and Tue but more extensive low
clouds are likely in the latter half of next week.

Despite the cyclonic flow hgts are fcst to rise Monday and Tue
and this should allow for two more day of warming. Tuesday should
be the warmest day of the next 7 with most max temps 2 to 4
degrees above normal (the beaches might be below normal). The
increased onshore flow slightly lower hgts and increased marine
layer will bring a cooling trend for Wed and Thu.

&&

.AVIATION...26/1840Z.

At 1802Z at KLAX, there was a deep moist layer to around 6500 ft,
but there was no real marine inversion.

Expect much less in the way of clouds tonight, with most areas
remaining VFR. The exception may be on north facing slopes and in
interior SLO/SBA Counties, where IFR to VLIFR conds are possible.
Widespread gusty NW winds will affect the mtns and much of SLO/SBA
Counties, with gusty W-NW winds in coastal and some valley
sections of L.A./VTU Counties and the Antelope Valley. Speeds may
be of by 5 kts during peak winds.

There is the potential for LLWS and turbulence, with mdt UDDF, until
15Z Sat.

KLAX...Moderate to high confidence in TAF until 09Z Sat, followed
by lower confidence due to uncertainty in wind direction. Strong
and gusty west winds are expected 20Z Fri - 09Z Sat, and there is
the potential for LLWS and turbulence, with mdt UDDF, until 15Z
Sat. Gusts could reach up to 40 kt (20% chance) from 22Z-03Z.
There is a 30% chance of northerly cross winds of 15 kt from
09Z-14Z Sat, followed by a 20% chance of the east wind component
reaching 6 kts from 14Z-18Z Sat.

KBUR...Moderate to high confidence in TAF for cigs and vis, but
low confidence in winds. Speeds and direction will be highly
variable until 09Z Sat. There is a 20-30% chance of SW wind
direction (220 to 250) at 12-15 kt with gusts to 20 kt, until 01Z
Fri.

&&

.MARINE...26/905 AM.

In the Outer Waters, gale force NW winds are expected to become
widespread this morning, then continue thru late Sat night.
However, winds will likely decrease to Small Craft Advisory (SCA)
levels late tonight in the northern zone (PZZ670). There is a
40-50% chance of gales in the northern zone (PZZ670) again Sat
afternoon into Sat night. SCA level winds and seas are expected
Sun thru Tue. There is a 30-40% chance of gale force winds Sun
afternoon/eve, and a 20-30% chance of gale force winds Mon
afternoon/eve, with the lowest threat in the northern zone.

In the Inner Waters N of Pt. Sal, winds will increase to SCA levels
this morning, then to gale force this afternoon. Winds will drop
to SCA levels late tonight. SCA level winds/seas are expected Sun
thru Mon night, with a 40% chance Tue. There is a 25% chance of
gales during the afternoon/eve Sun and Mon.

In the Inner Waters S Pt Conception, winds will increase to SCA
levels rapidly this morning. Winds will increase to gales across
the SBA channel late this morning, and gales will overspread the
channel and the southern inner waters this afternoon. Gales will
likely continue thru late tonight, then decrease to SCA conds.
SCA level wind and seas are likely to continue through late Sun
night, (or Mon night in the western SBA Channel), with the
strongest winds during the late afternoon thru late evening hours.
There is a 50% chance of gales across the western portions of the
SBA Channel late Sat afternoon into late Sat night, with a 30%
chance elsewhere during that time.

Widespread strong to gale force winds will create dangerous sea
conditions across the coastal waters thru the weekend, with
short-period, steep, and choppy waves. There may be dangerous
breaking waves near west-facing harbors. Mariners should remain in
safe harbor until conditions improve.

&&

.BEACHES...26/617 AM.

Moderate W swell and large wind waves are expected to produce low
end High Surf Advisories on west-facing beaches of L.A//VTU Counties
and Catalina Island, and on W and NW facing beaches on the Central
Coast from early this afternoon thru Sat morning. Surf is expected
to reach 4-7 ft with local sets to 8 ft in L.A./VTU Counties, and
7-10 ft with local sets to 12 ft on the Central Coast. Confidence
in high surf is moderate at best. Surf will be choppy and rough.
There is a high risk of rip currents on all beaches thru Sun.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 9 PM PDT this evening for zones
      38-358-369-371-372-374. (See LAXNPWLOX).
     Wind Advisory in effect until 3 AM PDT Saturday for zone 87. (See LAXNPWLOX).
     High Surf Advisory in effect until 10 AM PDT Saturday for
      zones 87-340-346-354-362-366. (See LAXCFWLOX).
     Wind Advisory remains in effect until 3 AM PDT Saturday for
      zones 88-352-353-375>377-379-380. (See LAXNPWLOX).
     Wind Advisory remains in effect until 9 PM PDT this evening
      for zones 340>342-346>348-350-354-355-362-366>368. (See LAXNPWLOX).
     Wind Advisory remains in effect until 3 AM PDT Sunday for
      zones 349-351. (See LAXNPWLOX).
     Wind Advisory in effect from 3 PM this afternoon to 3 AM PDT
      Saturday for zone 356. (See LAXNPWLOX).
     High Wind Warning remains in effect until 3 AM PDT Saturday
      for zones 378-381-383. (See LAXNPWLOX).
     Wind Advisory remains in effect until noon PDT today for zone
      383. (See LAXNPWLOX).
     High Wind Warning in effect from 3 PM this afternoon to 3 AM
      PDT Saturday for zones 549-550. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PDT this afternoon
      for zones 645-655-670. (See LAXMWWLOX).
     Gale Warning in effect from 3 PM this afternoon to 3 AM PDT
      Saturday for zones 645-655-670. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Saturday for zone 650. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Sunday for zones
      673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall/Rorke
AVIATION...DB/Schoenfeld
MARINE...DB/Schoenfeld
BEACHES...DB
SYNOPSIS...Hall

weather.gov/losangeles

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