-- Discussion containing changed information from previous version are highlighted. --
000
FXUS66 KLOX 280639
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1139 PM PDT Thu Jun 27 2024

.SYNOPSIS...27/828 PM.

Slight cooling is expected into Friday as high pressure aloft
weakens. Gusty northwest winds will affect southwestern Santa
Barbara County and the Interstate 5 Corridor tonight. Warmer
weather is expected over the weekend as high pressure returns, and
above normal temperatures will continue through next week.

&&

.SHORT TERM (THU-SUN)...27/949 PM.

***UPDATE***

Southern California remains between high pressure centered over
Texas, and low pressure over the northern Pacific Ocean. Heights
are expected to fall 1-2 dam overnight as the low sinks closer
and with increasing northwest flow, interior temperatures north
of Point Conception look about 5 degrees cooler than today.
Otherwise, temperatures will be very similar to today`s highs
with upper 90s in the Antelope Valley, 80s for the valleys, 70s to
80s for the mountains, and low 70s to upper 60s for the coastal
areas. By Saturday, high pressure starts building in, allowing
warming through the weekend. Highs start pushing into the triple
digits over the interior Sunday.

Marine layer clouds and patchy fog are starting to fill into
coastal areas just north of Point Conception tonight. Clouds and
fog are expected to eventually push into many immediate coast
areas north of Point Concpetion and for the LA County Coast as
eddy circulations begin to spin up. Clouds should clear out
during the day Friday. With falling heights, the marine layer
should deepen Friday night supporting clouds pushing deeper into
the coasts north of Point Conception.

Sundowner winds of 20-30 mph with gusts to 45 mph have developed
over western portions of the Santa Ynez Range to the southern
coast. Gusts could reach as high as 50 mph. Winds will decrease
to below advisory levels before sunrise Friday. Aside from some
gusty afternoon winds in the Antelope Valley, winds will remain
rather light over the region through Saturday. There is also
potential for gusty winds along the Central Coast Sunday
afternoon. The current forecast looks on track, with just minor
changes made to the cloud/fog forecast tonight/Friday morning.

***From Previous Discussion***

Synoptically, the area is still under the western portion of a
593 dam high centered over southern New Mexico. To our north, a
559 dam low is trekking roughly along the US/Can border. By
Saturday the low will make it to the Great Lakes region and the
high begins to build back in over northern Texas. While this high
pushes in from the east, by Tuesday the eastPac 597 dam high
begins to approach us from the west. Higher heights look to
remain over most of California through the extended in what may be
a prolonged heat event.

N-S gradients are forecast to increase very slightly across SBA
County tonight, so expect another round of low-end wind advisory
level NW winds across the western portions of the south coast of
SBA County and the western Santa Ynez Range. Have issued wind
advisories there for late this afternoon thru late tonight. Gusty
winds thru the I-5 Corridor will also return tonight but should
stay below advisory levels. Expecting more widespread low
clouds tonight, affecting most coastal areas (with the exception
of the S coast of SBA County due to the N flow).

on Friday a weak short wave trough will approach the West Coast.
Heights will actually fall a bit, as will temps at 850/950 mb.
Should stratus become widespread Fri morning, clouds may linger
into the afternoon, especially near the coast. Max temps may be
down a couple of degrees in most areas on Fri.

Heights will begin to rise across the region on Saturday as a
large upper high over the southeastern U.S. gradually expands
westward. There should be areas of low clouds and fog in coastal
and some lower valley areas Sat morning, but clearing should be
rather quick. Height rises and warming at 950 mb should bring
several degrees of warming in most areas Sat, especially away from
the coast. The best warming will likely be in the valleys as the
marine inversion lowers, decreasing the marine influence there.
High temps may rise well into the 90s in the warmest locations in
the valleys of L.A. County on Sat. Gradients should be steep
enough for some gusty winds in southwestern SBA County and thru
the I-5 Corridor Sat night, possibly to advisory levels.

The upper high will continue to expand westward on Sunday causing
heights to rise. Onshore flow will weaken, and the marine layer
will become increasingly shallow. Low clouds Sunday morning
should be confined to locations within a few miles of the coast.
Max temps will likely exceed 100 degrees in the Antelope Valley,
Paso Robles and the interior valleys of SLO County, with highs
near 100 degrees in some of the warmer locations in the valleys of
VTU/L.A. Counties. Gradients could again drive near advisory
strength gusty wind in southwestern SBA County and thru the I-5
Corridor.

.LONG TERM (MON-THU)...27/114 PM.

Heights will change little from Sunday into Monday so expect only
minor changes in night/morning low cloud coverage and temperatures.

There is still uncertainty in the forecast, but ensembles include
the possibilty of developing the upper high in the eastern
Pacific on Tuesday through at least Thursday, with high heights
across the region, and continued hot, to very hot, weather -
especially across the interior where temperatures could exceed
100-105 degrees. There is growing concern that this could become a
potentially hazardous heatwave with impacts around the 4th of
July.

&&

.AVIATION...
-- Changed Discussion --
28/0638Z.

At 06Z over LAX, the marine layer was 900 feet deep. The top of
the inversion was near 5000 feet with a temperature of 23 degrees
Celsius.

High confidence in VFR conditions through Friday at all sites away
from the coast, and for KSBA. Low to moderate confidence in the
coastal sites due to uncertainty in how widespread marine layer
clouds will be for the overnight period, the timing and flight
category. In general, LIFR conditions are expected for the Central
Coast sites, with MVFR conditions for the Ventura and LA Coastal
sites. The timing of low CIGs arrival could differ by up to 2
hours from TAF times.

KLAX...Moderate confidence in the 06Z TAF. Cigs may arrive as
early as 08Z, and become more likely after 10Z. There is
potential for an east wind component up to 6 kt from 10Z-15Z,
with high confidence it will remain under 8 kt. There is a 20-30
percent chance that the site will remain VFR overnight, or that
CIGs will be periodic and/or short-lived.

KBUR...Moderate to high confidence in the 06Z TAF. VFR conditions
are expected through the period, with just a 10-20 percent chance
of MVFR CIGs between 12Z-15Z.
-- End Changed Discussion --

&&

.MARINE...27/833 PM.

There is a moderate threat of dense fog late tonight into Friday
for the waters along the Central Coast.

Moderate confidence in low-end Gale conditions for the outer waters
from the Central Coast to San Miguel Island through late tonight.
There is a 20 percent chance of these Gales extending south to
San Nicolas Island, otherwise high confidence in Small Craft
Advisory (SCA) winds. SCA level west to northwest winds will push
into the Santa Barbara Channel as well but high confidence that
they will stay confined to the western half.

High confidence that winds will decrease each day Friday through
Saturday morning, but increase again Saturday afternoon into Monday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory remains in effect until 3 AM PDT Friday for
      zones 349-351. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Friday for zone
      645. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Friday for zones
      670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Saturday for
      zone 676. (See LAXMWWLOX).

&&

$$

PUBLIC...DB/jld
AVIATION...Smith
MARINE...Kittell
SYNOPSIS...jld/Smith

weather.gov/losangeles

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