523
FXUS66 KLOX 261124
AFDLOX

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

.SYNOPSIS...25/727 PM.

A gradual cooling trend will continue through midweek as high
pressure weakens over the area and onshore flow strengthens. Night
through morning low clouds and fog will slowly return to the
coastal areas. Temperatures will likely rebound late this coming weekend
into early next week as high pressure rebuilds over the region.

&&

.SHORT TERM (TDY-FRI)...26/423 AM.

Low clouds have become widespread in coastal areas N of Pt.
Conception, and were beginning to push into the Santa Ynez Valley.
S of Pt. Conception, the stratus field was less organized, but
some clouds have pushed into coastal areas from southeastern SBA
County to western L.A. County. Clouds should become more
widespread in these coastal areas by daybreak, and could even
push into the lower valleys of VTU County and the San Gabriel
Valley for a few hours. Pressure gradients between KLAX and KDAG
were moderately onshore, slightly more so that at this time
yesterday morning. Expect skies to clear by mid morning in the
valleys and late morning across most of the coastal plain. Clouds
could linger at some beaches into the afternoon hours, but even
there, skies should eventually become mostly sunny today.

The forecast area was sandwiched between the western periphery of
a large and strong upper high over New Mexico, and an upper low
well of the coast of the Pacific Northwest, with a broad west
southwesterly flow pattern aloft overhead. Heights today will
change little from those on Tue, but onshore gradients between
KLAX and KDAG will be slightly stronger this afternoon. In
addition, temps at 950 mb will drop a degree or two. With the
addition of some extra marine influence to start the day, expect a
couple of degrees of cooling in most areas west of the mtns
today, with the best cooling across the coastal plain. Max temps
should change little in the mtns and the Antelope Valley. 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.

The upper low in the Pacific will move into the Pac NW late
tonight/Thu, with a trough extending southward into the forecast
area. Expect the marine layer to deepen a bit tonight, and clouds
should be widespread in coastal areas (with the possible exception
of the south coast of SBA County due to the northerly flow.
Clouds will have a better chance at pushing more forcefully into
the valleys tonight. There could even be some local drizzle,
mainly south of Pt Conception. Expect somewhat slower clearing of
the low clouds Thu, 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 edge upward due to downslope northerly flow.

A broad trough will linger across the region Thu night and Fri.
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. Elsewhere, expect little
change from tonight/Thu morning, except that low clouds may be a
bit more widespread in the valleys. Once again, due to northerly
flow, clouds may be limited across southern SBA County or arrive
very late Thu night. Expect the clearing pattern Fri to be
similar to that on Thu. Additional slight height falls and
slightly cooling at 850 mb/950 mb may allow for a bit more
cooling in most areas Fri.

.LONG TERM (SAT-TUE)...25/117 PM.

We have moderate confidence in the extended period with a warm up
as early as the weekend but more likely (70-80 percent chance)
into early next week due to a building ridge. Low to moderate
heat impacts may return by Sunday with a 30-40 percent chance of
moderate to high heat impacts and the need associated heat
products for at least interior areas by Tuesday of next week. The
ridge may squash the marine layer and associated low clouds back
to the coast with an uptick of northerly flow Sunday potentially
clearing at least south facing coasts. Southwest Santa Barbara
County and the mountains near the I-5 corridor may reach advisory
level northwest winds around the Sunday/Monday time frame, which
could locally enhance warming trends such as for the Santa
Barbara County South Coast including Santa Barbara City.

&&

.AVIATION...26/1102Z.

Around 0730Z, the marine layer was around 900 feet deep at KLAX.
The top of the marine inversion was around 3000 feet with a
temperature near 23 degrees Celsius. There was another inversion
above up to around 4500 feet.

Moderate confidence in the current forecast for coastal terminals
south of Point Conception, otherwise high confidence in the
current forecast. LIFR to IFR conditions will be prevalent at
coastal terminals, higher south of KSBA.

KLAX...IFR conditions will continue through at least 17Z. There
is a 30 percent chance of IFR to MVFR conditions lingering past
17Z until as late as 22Z. An early return of IFR conditions should
be expected as early as 02Z Thursday, or as late as 06Z Thursday.
No wind impacts are expected at this time.

KBUR...VFR conditions are expected through the period. No wind
impacts are expected at this time.

&&

.MARINE...26/352 AM.

Moderate to high confidence in the current forecast. Higher
confidence in seas relative to winds.

Northwest winds will increase through Thursday. There is a 80 to
100 percent chance of Small Craft Advisory (SCA) level winds by
this afternoon for the waters southwest through northwest of the
Channel Islands and the nearshore waters along the Central Coast
and lasting into late Thursday night. There is a 50-60 percent
chance of the northwest Gales west through northwest beyond 10 NM
from the Central Coast shoreline this evening through Thursday
night, extending farther to the south on Thursday afternoon and
evening.

Inside the southern California bight, there is a moderate-to-high
(30-50 percent) chance of SCA levels winds for the western Santa
Barbara Channel, dropping off a nil-to-low chance (0-20 percent)
chance to the east and southeast. Chances will increase by about
10 percent on Thursday and Thursday evening.

Areas of dense fog will affect most of the coastal waters this
morning with the highest likelihood to the southwest through
northwest of the Channel Islands and the nearshore waters along
the Central Coast this morning. There is a low-to-moderate chance
of similar dense fog tonight and into Thursday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 1 PM this afternoon to 3
      AM PDT Friday for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 5 PM PDT this afternoon
      for zone 670. (See LAXMWWLOX).
     Gale Warning in effect from 5 PM this afternoon to 8 AM PDT
      Thursday for zone 670. (See LAXMWWLOX).
     Gale Watch in effect from Thursday morning through late
      Thursday night for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT Thursday for
      zone 673. (See LAXMWWLOX).
     Gale Watch in effect from Thursday afternoon through late
      Thursday night for zone 673. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 PM this afternoon to 3
      AM PDT Friday for zone 676. (See LAXMWWLOX).

&&

$$

PUBLIC...DB/Munroe
AVIATION...Hall
MARINE...Hall
SYNOPSIS...Smith

weather.gov/losangeles

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