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903
FXUS66 KLOX 190317
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
817 PM PDT Tue Jun 18 2024

.SYNOPSIS...
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18/435 PM.

Onshore flow will maintain near-normal temperatures across the
region through Thursday. Night through morning low clouds and fog
will continue along the coastal and valley areas. A warming trend
will establish on Friday with above normal temperatures
developing across the valleys, mountains, and desert through the
weekend, and likely into early next week. Dangerously hot weather
is possible across the interior on Saturday and Sunday.
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&&

.SHORT TERM (TUE-FRI)...
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18/801 PM.

***UPDATE***

Relatively quiet weather this evening with a broad trough taking
hold over the region. Wind gusts of 30-50 mph were noted across
southwest Santa Barbara County where a Wind Advisory is in effect
through 3 am. Breezy (but sub-advisory) and dry conditions will
likely bring elevated fire weather conditions well into the
evening for the I-5 corridor in the mountains and vicinity. A
weaker eddy tonight may be a bit slower in pushing clouds into the
LA County valleys along with western Ventura and Southern Santa
Barbara County. The latter areas mentioned have a 20-30 percent of
remaining mostly clear overnight as the marine layer has shrunk
to around 1500 feet deep. An increase in cyclonic flow aloft and
repositioning of the trough axis just to our west Wednesday may
wedge low clouds against the coast across at least a portion of
the area between Santa Barbara City and Palos Verdes for most of
if not all day, potentially leading to little to no clearing along
some immediate coastal areas. Where this occurs daytime highs
Wednesday may only reach the low 60s. The Central Coast is also
expecting a decent cool down into Wednesday with most other areas
likely experiencing similar temperatures to today (widespread 80s
to near 90 away from the coast).

***From Previous Discussion***

A broad upper-level trough of low pressure over the western States
will keep an onshore flow pattern in place, likely strengthening
into Wednesday as offshore push weakens. This will bring some
cooling to the region and take most areas back down to near normal
for this time of year. A return of coastal stratus is expected
tonight through Wednesday for most areas south of Point
Conception. The marine layer depth will thin some into Wednesday
and Thursday as 500 mb heights climb slightly, but in general, an
onshore flow pattern should keep low clouds and fog a staple of
the weather for the coastal and valley areas through Thursday.

A northerly surface pressure gradient across the region the last
several days will continue to wane. A wind advisory was allowed to
expire through the Interstate 5 Corridor earlier, but gusty
Sundowner winds will continue over the coming afternoons and
evening. A wind advisory remains in effect from this afternoon
through 3 am PDT tonight for the Southwestern Coast of Santa
Barbara County and the Santa Ynez mountains, but there is a
moderate-to-high chance that advisory level winds may develop
again on Wednesday afternoon and evening across the same areas.
Winds should weaken gradually each afternoon and evening as the
northerly gradient fades.

Onshore flow will weaken for late week as high pressure aloft over
the Eastern Seaboard today starts to slide closer to the region on
Friday. 500 mb heights will start to climb as upper-level
troughing vacates the region. A warming trend will take shape on
Friday and likely turn more significant over the weekend.

.LONG TERM (SAT-TUE)...18/231 PM.

High pressure aloft will continue to slide west through Sunday,
settling into the Desert Southwest while building to near 595
decameters on Monday. The latest forecast continue to break away
from NBM values to advertise hot conditions developing across the
region for the weekend. Dangerously hot conditions, if they were
to develop, would likely descend upon the Antelope Valley over the
weekend. Low confidence should be exercised in the low cloud
forecast as the coverage could be vastly overdone. Low clouds
could be confined to the coast over the weekend, which would warm
temperatures by a couple of degrees across the valley areas. Above
normal temperatures are likely to continue into early next week.
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&&

.AVIATION...
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19/0029Z.

At 00Z at KLAX, the marine layer was 1400 feet deep. The top of
the inversion was at 2100 ft with a temperature of 19 deg C.

Good confidence in TAFs for KPRB, KSBP, KSMX, KPMD and KWJF.

Moderate confidence in TAFs for KSBA, KOXR, KCMA, KSMO, KLAX,
KLGB, KBUR, KVNY. There is a 20-30 percent chance that the flight
category associated with cigs is one lower than forecast. Flight
category changes may be off by 2 hours with a 10-20 percent
chance of limited to no clearing for KLAX, KSMO, KSBA.

There is a 20-30 percent chance that VFR conds prevail for KBUR,
KVNY, KCMA, and KSBA.

KLAX...Moderate confidence in TAF. There is a 20 percent chance of
at least brief IFR cigs/vsbys 04-14Z. Any east wind component
should be less than 6 knots.

KBUR...Moderate confidence in TAF. There is a 20-30 percent
chance that VFR conditions prevail. There is a 20 percent chance of
at least brief LIFR cigs/vsbys 08-14Z.
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&&

.MARINE...
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18/754 PM.

For the Outer Waters, high confidence in current forecast. Small
Craft Advisory (SCA) Winds are expected through Thursday night
and perhaps as late as Friday night. Conditions are then expected
to be below SCA levels Saturday through Sunday night.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. SCA level winds will persist
through Thursday night, likely strongest during the afternoons and
evenings. For Friday through Sunday night, winds and seas should
remain below SCA levels.

For the inner waters south of Point Conception, moderate to high
confidence in current forecast. For the western Santa Barbara
Channel, winds gusts will be at SCA levels each afternoon and
evening through Thursday. Elsewhere and otherwise over the
southern inner waters, winds and seas should remain below SCA
levels through Sunday night.
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&&

.LOX WATCHES/WARNINGS/ADVISORIES...
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CA...Wind Advisory remains in effect until 3 AM PDT Wednesday for
      zones 349-351-352. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 645-650-670-673-676. (See LAXMWWLOX).
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&&

$$

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

weather.gov/losangeles

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