092
FXUS66 KLOX 140433
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
933 PM PDT Thu Jun 13 2024

.SYNOPSIS...13/909 PM.

Low clouds and fog will continue across coast and valleys through
Friday morning. High pressure developing aloft along with
increasing northerly flow will decrease marine layer coverage and
bring warmer temperatures and areas of very gusty winds Friday
through the weekend. Strongest winds will be in southern Santa
Barbara County and the mountains.

&&

.SHORT TERM (THU-SUN)...13/932 PM.

***UPDATE***

Marine layer stratus is slowly filling in across the coast this
evening but later than previous nights. The upper low has moved
east of the area with rising heights and thicknesses behind it as
well as weakening onshore flow, especially to the north. The LAX-
SFO gradient is almost 4mb weaker than it was 24 hours ago and
northwest winds are picking up across the coastal waters west and
north of Pt Conception. All these were well predicted in the
models over the last several days so confidence is high that we
are moving into a warmer pattern with gusty northerly winds in the
usual favored areas. The focus of these winds will be across and
below the Santa Ynez Range and where strong sundowners are
expected beginning Friday night and continuing through at least
early next week. And on Friday night (and to a lesser extent
Saturday night) the winds will be accompanied by very warm
temperatures and some parts of southern Santa Barbara County will
stay well into the 80s all night long. Will likely need wind heat
advisories.

Marine layer status will decrease substantially later Friday into
Saturday, with low clouds only across coastal LA and possibly
Ventura County. Temperatures Saturday will warm several degrees in
most areas, making Saturday the warmest day for many areas in
quite some time, with the exception of southern Santa Barbara
County, not quite warm enough for heat advisories.

***From Previous Discussion***

The upper low will continue to move eastward tonight and Fri, and
a weak broad upper ridge will build into the region. The marine
layer will likely begin to shrink in depth due to height rises, so
expect less inland penetration of the low clouds tonight/Fri
morning, with clouds likely below the coastal slopes, and possibly
not even pushing into the Santa Clarita Valley. With weakening
onshore flow, expect faster clearing in most areas Fri, with the
sun probably making an appearance at most beach locations. Rising
heights, weakening onshore gradients, and decent warming at 850
and 950 mb should lead to significant warming on Fri across
interior areas. Max temps in most valley, mtn and desert locations
will be 5 to 10 degrees warmer on Fri than they are today, and
some locations, such as in the Salinas Valley, max temps may be 20
degrees or more higher than those today.

N-S gradients will increase sharply late Fri into Fri night, and
gusty NW to N winds will reach Wind Advisory levels across the
southwestern SBA County coast, the western Santa Ynez Mountains,
and thru the I-5 Corridor. Low clouds should be less widespread,
especially in the valleys and across SLO/SBA Counties Fri
night/Sat morning, and in fact, may be confined to southern and
eastern L.A. County. Gusty N winds will keep temps elevated Fri
night in the mtns/foothills, especially in SBA County.

N-S gradients will continue to increase across the region Sat.
Expect any low clouds to clear fairly quickly Sat. Falling heights
may bring a bit of cooling to interior areas Sat, but strong N-S
gradients will likely bring some additional warming to coastal
and valley areas. This will be especially true for the south coast
of SBA County. Winds will remain gusty from the NW-N across
southwestern SBA County and the I-5 Corridor, and will likely
increase and become more widespread Sat afternoon, affecting the
Central Coast, the interior mtns of SBA County and northern
Ventura County, the Antelope Valley and foothills, and some L.A.
County valley locations.

N-S gradients will peak across the region Sat night, with models
showing an offshore gradient of over 5 mb between KSBA and KSMX,
and increasing offshore gradients between KSBA/KBFL and KLAX/KBFL.
There will also be increasing W-NW flow at 500 mb, strengthening
NW winds at 700 mb and N winds at 850 mb. At the same time, cold
air advection will spread into the region late Sat, and subsidence
will increase. This will bring the potential for NW-N winds to
increase to damaging levels across much of southern SBA County
including the foothills near the cities of Santa Barbara and
Montecito, the northern mtns of VTU County, the I-5 Corridor, and
the western Antelope Valley foothills. There is a High Wind Watch
from Sat evening thru Sun morning for the potential for wind
gusts of 60-70 mph in the more wind prone locations in these
areas.

The powerful NW winds across SLO/SBA Counties and the coastal
waters will gin up a good eddy circulation across the inner waters
late Sat night/Sun. This will set up the age-old battle between
the NW flow and the eddy, making for a difficult cloud forecast
for Sat night/Sun morning. If the northerly flow wins out, some
gusty winds will affect the L.A. County valleys, and clouds will
be confined to southern L.A. County. There may also be clouds
across southern portions of the Central Coast due to northerly
upslope flow against the northern slopes of the Santa Ynez Range.
If the eddy wins, low clouds will push farther north and west,
possibly into the valleys of L.A./VTU Counties. Not only will
cloud cover be dependent on the outcome of the eddy/NW flow
battle, but so will max temps Sun. In general, expect a few
degrees of cooling Sun as heights fall, but cooling will be more
significant and widespread in areas south of Pt Conception if the
eddy becomes the dominant player.

N-S gradients will remain steep across SLO/SBA Counties Sun into
Mon morning, so advisory level NW winds are likely in southern SBA
County again late Sun afternoon into Sun night.

.LONG TERM (MON-THU)...13/125 PM.

Low clouds should become more widespread south of Pt Conception
late Sun night/Mon morning. There should several degrees of
cooling in most areas Mon as heights continue to fall.

An upper low will move thru the Pac NW Mon and into the northern
Rocky Mountains Tue, with a sharpening trough across CA. The
trough axis will be located right across the region Tue, then it
will move to the east Wed. N-S gradients will remain offshore
across SLO/SBA Counties Mon night, then actually increase Tue
night. This should keep gusty N winds late each afternoon/evening
across southern SBA County Mon thru Wed.

Expect night thru morning low clouds to remain fairly minimal
across SLO and SBA Counties, with clouds in most coastal and
valley areas of L.A./VTU Counties. Expect minor changes in max
temps Tue with some warming possible Wed and Thu as heights begin
to rise.

&&

.AVIATION...13/2022Z.

At 2000Z at KLAX, the marine layer was 2000 ft deep. The top of
the inversion was at 4000 ft with a temperature of 19 C.

High confidence in deserts TAFs, but low to moderate confidence
in coastal/valley TAFs. For tonight, high confidence in return of
CIG/VSBY restrictions to coastal/valley sites, but only moderate
confidence in timing and flight category.

KLAX...Moderate confidence in TAF. For tonight, timing of return
of CIG/VSBY restrictions could be +/- 2 hours of current forecast
with a 40% chance conditions could drop to LIFR levels. No
significant easterly wind component is expected.

KBUR...Moderate confidence in TAF. Timing of return of LIFR
conditions could be +/- 2 hours of current 08Z forecast.

&&

.MARINE...13/733 PM.

For the Outer Waters, moderate to high confidence in current
forecast. Small Craft Advisory (SCA) level winds will develop late
tonight and Friday morning, then will increase to Gale Force
levels from Friday afternoon through Monday. Seas will peak in the
12 to 15 foot range this weekend. GALE WARNINGS are in effect
from Friday afternoon through Monday, and high-end Gale Force
Winds around 45 kt are expected. Additionally, there is a 30%
percent chance of Storm Force gusts (48 knots or greater) Friday
night through Sunday night.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Through much of Friday morning,
winds and seas will remain below SCA levels. SCA-level winds will
develop late Friday morning, and then increase to potentially Gale
Force Winds (60-80% chance) Saturday morning through the
remainder of the weekend. A GALE WATCH is in effect for Saturday
afternoon through Sunday night.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western Santa Barbara
Channel, SCA-level winds will develop late Friday morning and then
increase to potentially Gale Force Winds (60-80% chance) Saturday
morning through the remainder of the weekend. A GALE WATCH is in
effect for Saturday afternoon through Sunday night. The strongest
winds, including high-end Gale Force Winds around 45 kt, are
expected in the far western Santa Barbara Channel south of
Gaviota. For the rest of the southern Inner Waters, winds will be
notably weaker, though there is a 30-40% chance of SCA level winds
Saturday and Sunday.

Across all the coastal waters, steep and dangerous seas can be
expected this weekend.

&&

.BEACHES...13/738 PM.

There is increasing concern for hazardous beach conditions from
Friday afternoon through this weekend and into early next week.
Wind-wave energy from relatively short-period swell, around
10-second wave periods and generated by strong winds over the
nearby coastal waters, will impact the beaches starting late
Friday. This will bring elevated surf conditions this weekend
into early next week.

There is a 30% chance for High Surf conditions for west-facing
beaches along the Central Coast, and Ventura and Los Angeles
Counties through the weekend, and a 40%-60% chance of High Surf
conditions early next week. Locally elevated surf is expected for
the Santa Barbara County South Coast beaches as well. Dangerous
rip currents will be of concern for all beaches Friday through at
least early next week.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect from Friday afternoon
      through Sunday evening for zones 87-340-346-354-362-366. (See LAXCFWLOX).
     Wind Advisory in effect from 3 PM Friday to 6 PM PDT Saturday
      for zones 349>353-377-378-381. (See LAXNPWLOX).
     High Wind Watch remains in effect from Saturday evening
      through Sunday morning for zones 349>353-377-378-381. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 11 AM Friday to 11 AM PDT
      Saturday for zones 645-650. (See LAXMWWLOX).
     Gale Watch in effect from Saturday morning through late
      Sunday night for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 AM to 5 PM PDT Friday
      for zones 670-673-676. (See LAXMWWLOX).
     Gale Warning in effect from 5 PM Friday to 2 PM PDT Monday
      for zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/DB
AVIATION...Cohen/RAT
MARINE...Cohen/Sirard
BEACHES...Cohen/Sirard
SYNOPSIS...MW

weather.gov/losangeles

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