392
FXUS66 KLOX 131746
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1046 AM PDT Tue Aug 13 2024

.SYNOPSIS...13/1226 AM.

Temperatures will remain near normal this weekend with little
day-to-day changes. Night- to- morning low clouds and fog will
push into coastal areas at times.

&&

.SHORT TERM (TDY-THU)...13/947 AM.

***UPDATE***

Dense fog that occurred this morning along the Central Coast and
Santa Ynez Valley is retreating as the morning sunshine
intensifies. Low clouds and fog are currently only present at the
Central Coast and Ventura County beaches, and is expected to clear
by around noon today.

The temperature forecast for today has been adjusted upwards
slightly for some locations, including San Luis Obispo and Santa
Barbara, to align with 24-hr temperature trends. However
temperatures are generally still expected to be a couple degrees
cooler than yesterday as a result of a decrease in 500 mb heights
and decreasing onshore flow.

Sundowner winds are likely to be advisory level across the Santa
Barbara Southwest Coast tomorrow night and again Thursday night.
Gusts are expected to be 30 to 45 mph, and temperatures across
the whole Santa Barbara South Coast (including Santa Barbara
City) will be several degrees warmer than normal.


***From Previous Discussion***

Low clouds were widespread on the Central Coast and in the Santa
Ynez Valley this morning, as they have been during the past few
mornings. The difference was S of Pt. Conception, where there was
a more expansive area of low clouds off the coast, some of which
had already surged into southern L.A. County.

W-E pressure gradients were about the same as they were on Mon
morning. N-S offshore gradients have increased slightly across
SBA County, and have gone from onshore to neutral across L.A.
County. However, there were no wind issues early this morning.
This afternoon, there will be some gusty winds in the Antelope
Valley and thru the Highway 14 Corridor, but winds should remain
below advisory levels. N-S gradients will increase across SBA
County later today and tonight, with gusty winds likely across the
southwest coast of SBA County and the Western Santa Ynez Range.
Even there, winds should stay just below advisory levels. Slight
height falls with a weak trough pushing in the West Coast and
some cooling at 950 mb should lead to a couple of degrees of
cooling in most areas today. The exception may be across southern
SBA County foothills, where north winds may bring some warming if
they surface by evening.

The weak upper trough will move east of the region later today and
tonight, and an upper level high will begin to build into the
forecast area from the southwest. Moderate onshore pressure
gradients from W to E will keep gusty winds Wed afternoon and
evening across the Antelope Valley and the Highway 14 Corridor
Wed, but again, likely below advisory levels. N-S gradients across
SBA County will increase, likely enough for some wind advisory
level winds across the southwestern coast and the western Santa
Ynez Range late Wed afternoon into Wed night. Gusty winds are also
likely in the I-5 Corridor Wed night. Expect the low cloud
pattern tonight/Wed morning to be similar to that of this morning,
confined to the coastal plain, except it should remain clear
across the south coast of SBA County. Height rises and some
warming at 950 mb should lead to some warming in most areas Wed,
but do not expect max temps to be much (if at all) above normal
in most areas.

The upper high will strengthen a bit Thu, and heights will rise
slightly. There may be some reduction in low cloud coverage Wed
night/Thu morning as the marine layer thins. Expect another round
of gusty W winds in the Antelope Valley and Highway 14 Corridor
Thu afternoon and evening, with advisory level NW to N winds
possible across southern SBA County late Thu/Thu night. Max temps
should be up slightly on Thu, with highs peaking near 100 degrees
in the Antelope Valley and the hottest valley locations west of
the mountains.

.LONG TERM (FRI-MON)...13/500 AM.

The upper high will shift just to the east of the forecast area
Fri as a broad trough moves into the eastern Pacific. The upper
high will strengthen and move to a location just to the southeast
of the Four Corners area Sat, then it will move little thru Mon.
Meanwhile, a trough will linger just to the west of CA Sat thru
Mon. The position of the forecast area between these two upper
features will make for a rather uneventful weather pattern Fri
thru Mon. Southwesterly flow aloft is expect most of this period,
which should keep any monsoonal moisture and any chance of
showers/tstorms to the east of the region. Heights will fluctuate
slightly thru the period. In a very general sense, based on heights
and pressure gradients, expect some cooling Fri and Sat, with small
warming Sun and Mon. Night/morning low clouds and fog will be
confined to the coastal plain and possibly the lower valleys. Do
not expect wind issued Fri and Sat, except for some gusty
afternoon/eve winds in the Antelope Valley. N-S gradients will
become increasingly offshore across SBA County Sun and Mon, so
expect some gusty NW winds across southwestern SBA County during
the late afternoon thru evening hours on those days.

&&

.AVIATION...13/1746Z.

At 1702Z at KLAX, the marine layer was 1300 ft deep. The top of
the inversion was at about 4800 ft with a temperature of 23 C.

High confidence in CAVU TAFs for KPRB, KBUR, KVNY, KPMD, and
KWJF.

Moderate confidence in LA coastal TAFs. Timing of cat changes may
be off by +/- 2 hours from current fcst. There is a 20-30% chance
of IFR conditions after cigs arrive. VFR conditions expected at
these sites by 17Z.

Low to moderate confidence in remaining coastal TAFs. Timing of
cat changes may be off by +/- 4 hours. Minimum flight cats may be
off by one cat at any point after cigs arrive. There is a chance
that KSBA (30%), KOXR (20%), and KCMA (40%) site will remain VFR
through the period.

KLAX...Moderate confidence in TAF. Timing of cat changes may be
off by +/- 2 hours from current fcst. There is a 30% chance of
cigs lower than 005 at any point between 08Z and 13Z. 20% chance
of VFR conditions before 17Z. No significant east wind component
expected.

KBUR...High confidence in CAVU TAF.

&&

.MARINE...13/908 AM.

For the outer waters, moderate to high confidence in current
forecast. Small Craft Advisory (SCA) level winds and seas expected
through at least Sunday night. There is a 20-30% chance of low
end gale force wind gusts in the afternoon thru late night hours
Wednesday thru Friday, and a 10% chance Saturday and Sunday.

For the inner waters north of Point Sal, moderate confidence in
current forecast. SCA level winds and seas are likely (60-70%
chance) in the afternoon through evening hours through tomorrow
night. There is a 50-60% chance of SCA level winds and seas in
the afternoon thru evening hours Thursday and Friday, and a 30-40%
chance Saturday and Sunday Sunday.

For the inner waters south of Point Conception, moderate
confidence in current forecast. There is a 30-50% chance of SCA
level wind gusts for the western Santa Barbara Channel during the
afternoon into late evening hours through Thursday, and a 20-30%
chance of SCA level winds Saturday and Sunday in the afternoon to
evening hours. Otherwise, conds will remain below SCA levels over
the southern inner waters through Sunday night.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 645-670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...DB/Schoenfeld
AVIATION...Lewis
MARINE...Lewis/Lund
SYNOPSIS...Munroe/KL

weather.gov/losangeles

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