100
FXUS66 KLOX 131129
AFDLOX

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

.SYNOPSIS...12/725 PM.

Low clouds and fog are expected through at least Friday morning
across the coast and coastal valleys, with temperatures 3-6
degrees below normal. Gusty north winds are expected Friday into
the weekend, mainly in the mountains and southern Santa Barbara
County and adjacent coastal waters. Warming temperatures are
expected Friday through weekend, with faster clearing of low
clouds.

&&

.SHORT TERM (TDY-SAT)...13/429 AM.

A deep marine layer continued across the forecast area this
morning, and was running around 2500 feet deep or so. Low clouds
and fog were widespread in all coastal and valley areas with the
exception of the far interior valleys of SLO County and the Cuyama
Valley. Even in the far interior valleys of SLO County, there
will likely be some low cloud infiltration this morning, and
clouds will push into the lower coastal slopes from SLO County
thru L.A. County. There will likely be some local drizzle as
well, as model cross sections show some lift within the deep moist
layer.

An upper low centered about 200 NM SSW of KLAX early this morning
will move eastward to near San Diego this afternoon. Strong
onshore gradients will continue across the region. Clearing will
be fairly slow today, with skies becoming mostly sunny by late
morning in the valleys, but not until the afternoon across much of
the coastal plain. In some immediate beach locations, skies will
probably remain cloudy for much of the day once again. Max temps
should be within a couple of degrees of those observed on Wed in
most areas, except there will likely be cooling across far
interior sections of SLO and SBA Counties. There will be some
gusty west winds in the mtns and the Antelope Valley this
afternoon and evening but they should remain below advisory
levels.

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 reached today.

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

A trough will move into the Pac NW Fri night and Sat, with a broad
trough sagging southward down the West Coast. 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 warming to coastal and valley areas. 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 to 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 as well. This will bring the
potential for NW to N winds to increase to damaging levels across
much of southern SBA County including the foothills near the city
of Santa Barbara and Montecito, the northern mtns of Ventura
County, the I-5 Corridor, and the western Antelope Valley
foothills. Have issued a High Wind Watch from Sat evening thru
Sun morning, for the potential for wind gusts of 60 to 70 mph in
some of the wind prone locations in these areas.

.LONG TERM (SUN-WED)...12/230 PM.

Sunday will be an interesting day as there will still be strong
northerly winds continuing across the western counties, adjacent
coastal waters, and the northern mountains. However, models have
been consistent showing the development of a coastal eddy
circulation developing off the coast of LA and Orange Counties and
significant cooling at least for LA/Ventura County coast and
valley areas. And most of the models are even showing several
degrees of cooling across inland areas of LA/Ventura Counties as
well. Will likely still see advisory level Sundowner winds again
Sunday into Monday for the Santa Barbara area but probably not
quite as warm as the previous couple days. With the eddy
developing later in the weekend will likely see marine layer
stratus moving up from the south and into coastal LA/Ventura
Counties.

Northerly flow expected to remain quite strong across the offshore
coastal waters through the middle of next week, which will keep at
least a threat of Sundowner winds going for southern Santa Barbara
Counties going into next week as well. For this reason, stratus
coverage should be confined to just LA/Ventura Counties at least
for the first half of the week. Temperatures in these areas will
drop back to normal or slightly below normal levels.

For SLO and northern Santa Barbara Counties, gusty northwest winds
will continue, especially near the coast, but little or no marine
layer stratus is expected. Temperatures will generally be within a
few degrees of normal.

&&

.AVIATION...13/1123Z.

At 0930Z at KLAX, the marine layer was 1600 ft deep. The top of
the inversion was at 2900 ft with a temperature of 22 C.

For 12Z TAF package, high confidence in deserts TAFs, but low to
moderate confidence in coastal/valley TAFs. Timing of dissipation
of CIG/VSBY restrictions could be +/- 2 hours of current
forecasts...with a 30-40% chance that coastal sites south of Point
Conception may not clear this afternoon. 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 12Z TAF. Timing of dissipation of
CIG/VSBY restrictions today could be +/- 2 hours of current 20Z
forecast (with a 30% chance that CIG/VSBY restrictions will not
dissipate). 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 12Z TAF. Timing of dissipation of
CIG/VSBY restrictions today could be +/- 2 hours of current 18Z
forecast. Timing of return of LIFR conditions could be +/- 2 hours
of current 08Z forecast.

&&

.MARINE...13/411 AM.

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 WATCHES are currently in effect
from Friday afternoon through Monday, but these will likely
upgraded to warnings this afternoon or tonight. Additionally,
there is a 20% 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. Today through Friday morning,
winds and seas will remain below SCA levels. From Friday afternoon
through Monday, a combinations of SCA level winds and seas can be
expected. Additionally, there is a 30-40% chance of Gale force
winds Saturday night through Sunday night.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the Santa Barbara Channel,
high confidence in SCA level winds developing Friday afternoon and
continuing through Monday with a 40% chance of Gale force winds
across the western half of the Santa Barbara Channel Saturday
through Sunday. For the rest of the southern Inner Waters, 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.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Watch in effect from Saturday evening through
      Sunday morning for zones 349>353-377-378-381. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 2 AM to 2 PM PDT Friday
      for zones 670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from Friday afternoon through Monday
      afternoon for zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...DB/MW
AVIATION...RAT
MARINE...RAT
SYNOPSIS...MW/Smith

weather.gov/losangeles

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