950
FXUS66 KLOX 270457
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
957 PM PDT Wed Jun 26 2024

.SYNOPSIS...26/806 PM.

Cooling temperatures are expected through Friday as high pressure
weakens over the area and onshore flow strengthens. Night through
morning low clouds and fog will become more widespread through
the end of the week. Warmer weather is expected over the weekend
and into early next week as high pressure returns.

&&

.SHORT TERM (WED-SAT)...26/957 PM.

***UPDATE***

The strong upper level ridge that has been centered over New
Mexico will finally start eroding away as low pressure pushes
towards southern California from the north. This will deepen the
marine layer, and southwest flow will shift to the northwest/west,
ushering in drier air to the area. Temperatures trend cooler
Thursday and Friday under falling heights and increased onshore
flow with highs near normal Thursday, and about 5 degrees below
normal in many areas Friday.

Gusty north to northwest winds of 20 to 35 mph with gusts to 45
mph have developed over western portions of the Santa Barbara
south coast. Wind advisories have been issued for both the western
Santa Ynez Range and the western portions of the Santa Barbara
south coast. The other area to watch for gusty winds tonight is
from the I-5 Corridor to the western Antelope Valley Foothills.
Currently holding off on wind advisories in this area. The marine
layer is about 800 feet under a strong inversion tonight, and clouds
and patchy fog have redeveloped over the coastal waters. They are
expected to push into coastal areas by Thursday morning supported
by eddies in the Santa Barbara Channel and southeast of the
Channel Islands. Expecting advisory level Sundowner winds to
reoccur Thursday night, and possibly Friday night.

***From Previous Discussion***

Synoptically, the area is under the western portion of a 595 dam
high centered over New Mexico and a 558 dam low is dropping down
the west coast. By Thursday the high moves to the south and the
low begins its trek 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. By Tuesday the eastPac high
begins to move eastward and higher heights look to remain over
most of California through the extended.

Skies cleared by mid morning except for portions of the central
coast. Temperatures are down 3-5 (or more) degrees in most places
as the high pressure overhead decreased a bit and onshore
winds were slightly stronger this afternoon. N-S gradients will
increase across SBA County and thru the I-5 Corridor later today
and tonight, so expect some gusty NW to N winds across the western
portions of the south coast of SBA County, the western Santa Ynez
mtns and thru the I-5 Corridor. Winds are expected to remain
below advisory levels in most areas. Expect the marine layer to
deepen a bit tonight as the upper low in the Pacific will move
into the Pac NW late tonight/Thu, with a trough extending
southward into the forecast area. Clouds should be widespread in
coastal areas, with the possible exception of the south coast of
SBA County due to the northerly flow.

Expect somewhat slower clearing of the low clouds on Thursday,
with a better chance that clouds will linger at some beaches. With
lowering heights and cooling at 850 mb and 950 mb, expect a few
degrees of cooling just about everywhere Thu. The exception may be
on the south coast of SBA County, where temps may even edge
slightly upward due to downslope northerly flow. N-S
gradients will peak across SBA County and in the VTU/northwestern
L.A. County mtns Thu evening, and winds could reach advisory
levels in some areas.

A broad trough will linger across the region Friday. Expect
little change from Thursday, except that low clouds may be a bit
more widespread in the valleys. Additional slight cooling at 850
mb/950 mb may allow for a bit more cooling in most areas Fri.

Heights will rise across the region over the weekend as a large
upper high in the south central U.S. begins to expand westward.
Expect the marine layer to become increasingly shallow, with less
in the way of inland and valley low clouds each night. In fact,
low clouds may be squeezed out of most valley areas by Sat
night/Sun morning. Rising heights/thicknesses, weakening onshore
flow, and less low cloud coverage should lead to a few degrees of
warming Saturday.

.LONG TERM (SUN-WED)...26/222 PM.

The peak of the heat will likely be Sunday and Monday. Max temps
will probably exceed 100 degrees in the Antelope Valley and the
interior valleys of SLO County, with highs near 100 degrees in
some of the warmer locations in the valleys of VTU and L.A.
Counties. N-S gradients will increase both Sun night and Mon
night, which could bring some gusty winds to southern SBA County
and the I-5 Corridor, along with a reduction in coastal stratus in
southern SBA County.

Heights will remain quite high across the region Tue and Wed,
although they will lower a bit as the upper high weakens and
shifts eastward. Onshore flow will increase each day. The extended
pattern into next weekend looks like it will be a hot one.

&&

.AVIATION...27/0339Z.

At 0013Z over LAX, the marine layer was 800 feet deep. The top of
the inversion was 4400 feet and 25 degrees Celsius.

High confidence in VFR conditions through Thursday at KPRB KWJF
KPMD, moderate confidence at KBUR KVNY. All other sites have a
chance ceilings tonight into Thursday, with moderate to low
confidence in timing of cigs and vis. Expecting some breezy
conditions at KSMX, KSBP, KWJF and KPMD.

KLAX...Moderate confidence in VFR conditions through at least 05Z.
Low confidence on ceilings tonight. Cigs are possible as early as
07Z, but higher confidence in cigs after 11Z. Southeast winds
will likely form after 09Z, but high confidence that they will
stay under 8 knots.

KBUR...There is a 10% chance of IFR ceilings Thursday 10-15Z,
otherwise high confidence VFR conditions through at least
Thursday. High confidence in seasonal winds.

&&

.MARINE...26/821 PM.

There is a moderate threat for dense fog to form again later
tonight into Thursday for the waters off the Central Coast.
High confidence in at least Small Craft Advisory (SCA) winds and
seas through Friday Night for the Outer Waters (offshore waters
of the Central Coast to San Nicolas Island). There is a 50-60
percent chance of reaching Gales tonight, especially the northern
most areas. For Thursday, the chance for Gales increases to 90
percent for that area. High confidence in Gales ending by Friday
morning. Moderate confidence in much less wind on Saturday, but
winds will pick up again on Sunday.

Elsewhere there the SCA level northwest winds will push into the
Santa Barbara Channel but high confidence that they will stay
confined to the western half. There is a chance that enough of the
channel will be covered with these winds to warrant an SCA: 20
percent chance tonight and 40 percent chance on Thursday Night.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 3 AM PDT Thursday for zones
      349-351. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Phillips/jld
AVIATION...Phillips
MARINE...RK/Smith
SYNOPSIS...jld/Smith

weather.gov/losangeles

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