093
FXUS66 KLOX 070313
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
813 PM PDT Thu Jun 6 2024

.SYNOPSIS...06/227 PM.

Fairly widespread low clouds and nighttime fog will affect areas
near the coast each day into next week, with areas of partial
clearing during the afternoon. While temperatures will be a few to
several degrees below normal close to the coast with onshore
flow, temperatures will be considerably warmer over interior
sections. Precipitation is not expected over the region through at
least the middle of next week.

&&

.SHORT TERM (THU-SUN)...06/227 PM.

A strong ridge of high pressure aloft extends west of a
593-decameter 500-mb anticyclone centered over AZ and NM. This is
supporting mid-afternoon temperatures of 100-105 degrees across
ongoing Excessive Heat Warnings and Heat Advisories across
portions of the interior valleys and nearby foothills. The strong
heating over the Intermountain West beneath the midlevel ridge is
maintaining strong onshore pressure gradients, along with the
marine layer firmly entrenched near the coast -- where
temperatures are holding in the upper 50s to the middle 60s. Only
partial clearing has occurred amid marine stratus, and the marine
stratus is expected to fill back in and extend inland across the
coastal valleys tonight, with some fog mixing in.

Little change in this overall pattern is expected for the
remainder of this week and this weekend. One exception will be the
anticipated modest cooling trend, from day-to-day, over interior
sections in response to the eastward-translation of the
aforementioned midlevel ridge. Correspondingly lowering heights
aloft will be the result of generally weak midlevel waves
suppressing the ridge over the region, with a more prominent
midlevel trough setting up along the California coast this
weekend. However, dry profiles aloft are expected to prevent
precipitation development through the weekend. Before daily high
temperatures settle to values within a few degrees above normal
this weekend across interior sections, very warm conditions are
once again expected on Friday across the Antelope Valley and
nearby foothills.

Also of note, the strong onshore pressure gradient is expected to
drive daytime enhancements in southwest winds across the Antelope
Valley and nearby foothills, where local wind gusts to 40-45 mph
will be possible each day. However, without stronger upper
support, Wind Advisories appear generally unlikely but cannot be
ruled out (10-30 percent chance of issuance).

.LONG TERM (MON-THU)...06/228 PM.

Only gradual change is expected in the overall weather pattern going
from the weekend into next week. Within the base of the previously
mentioned prominent upper trough, an upper low is expected to
gradually close off and drift southward near or just off the coast
of Southern California through early next week. Thereafter, it
may slowly advance eastward or northeastward later in the week.
This will occur within a semi-blocking pattern over the southwest
states, responsible for the limited overall change in weather
conditions.

Midlevel ridging extending northwest from the southern Rockies to
the central Great Basin will correspond to strong heating over
interior sections and a strong onshore pressure gradient. This
will cause the marine layer to be entrenched over coastal areas
and nearby valleys, with widespread nighttime stratus and patchy
fog partially clearing each afternoon. Temperatures each day will
range from the 60s near the coast, to the 70s over coastal
valleys, to the 80s and 90s over interior sections -- warmest over
the Antelope Valley.

If the upper low were to track directly over the area, there is
some potential for cooling aloft to disrupt the strength of the
thermal inversion surmounting the marine layer. If this were to
occur, a deepening moist layer could cause overnight and morning
drizzle near the coast -- especially early next week. Diurnal
cumulus development may also occur over the mountains, if the
upper low were to track directly over the area. And then with the
departure of the upper low by the middle of next week, temperatures
could increase by a couple degrees, though uncertainty regarding
the track of the upper low extends to the strength of the marine
layer and temperatures. Regardless, measurable precipitation is
not expected without greater midlevel moisture content. Also,
diurnally-enhanced southwest wind gusts are expected over
interior areas each afternoon -- especially for the Antelope
Valley.

&&

.AVIATION...07/0306Z.

At 0008Z at KLAX, the marine layer was 1100 ft deep. The top of
the inversion was at 4300 ft with a temperature of 25 degrees
Celsius.

Overall for the 00Z TAF package, high confidence in KWJF and
KPMD...and moderate confidence for all other coastal and valley
TAF sites. There is a 20% chance for brief cigs at KPRB around
12Z. Lower confidence for coastal and valley sites is due to
uncertainties in the marine layer. Timing of flight category
changes through the TAF period could be +/- 2 hours of current
forecasts.

KLAX...Moderate confidence in 00Z TAF. For tonight, high
confidence in return of cigs, but lower confidence in flight
categories. No significant easterly wind component is expected.

KBUR...Moderate confidence in 00Z TAF. Timing of return of
IFR/MVFR conditions could be +/- 2 hours of current 06Z forecast.
There is a 20-30% chance for LIFR conditions.

&&

.MARINE...06/137 PM.

For the Outer Waters, moderate to high confidence in current
forecast. Today through Saturday, high confidence in winds and
seas remaining below Small Craft Advisory (SCA) levels. From
Saturday night through Sunday night, there is a 50-60% chance of
SCA level winds. For Monday and Tuesday, high confidence in winds
and seas remaining below SCA levels.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Today through Saturday, high
confidence in winds and seas remaining below SCA levels. For
Sunday, there is a 30-40% chance of SCA level winds in the
afternoon and evening hours. On Monday and Tuesday, high
confidence in winds and seas remaining below SCA levels.

For the Inner Waters south of Point Conception, high confidence
in current forecast. Today through Tuesday, winds and seas are
expected to remain below SCA levels.

Through the weekend, dense fog, with visibility of one mile or
less, will continue to impact the coastal waters north of Point
Conception during the night and morning hours.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory remains in effect until 8 PM PDT Friday for
      zones 382-383. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Cohen
AVIATION...Phillips
MARINE...RAT
SYNOPSIS...Cohen

weather.gov/losangeles

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