009
FXUS66 KLOX 012128
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
228 PM PDT Wed May 1 2024

.SYNOPSIS...01/207 PM.

Areas of night and morning low clouds and fog will be present
near the coast for the remainder of this week. Otherwise, dry
conditions and near-normal temperatures are expected through
Friday. This weekend, a storm system will pass by to the north of
the area. The main impacts from this system across southern
California will be areas of light precipitation late Saturday
into Sunday, along with cooler temperatures and gusty winds.
For next week, temperatures will warm back up to near-normal
readings, with dry conditions expected.

&&

.SHORT TERM (TDY-SAT)...01/207 PM.

Northwesterly midlevel flow will persist for the remainder of
this week between an upper trough being reinforced over the
western states, and a midlevel ridge well offshore over the
Pacific waters.

The enhanced flow aloft combined with nocturnal drainage flow will
support wind gusts of 45 mph and a Wind Advisory this evening into
tonight for the Interstate-5 Corridor and the western Antelope
Valley Foothills. Gusty northwest winds are expected across
portions of the Antelope and Santa Clarita Valleys to the southern
VTA County mountains and the SBA County interior mountains, and
there is a 40% chance that the Wind Advisory would need to be
expanded to include these areas. A similar pattern will support
gusty northwest winds over these areas Thursday night and Friday
morning, though the chance for a Wind Advisory becoming needed
over these areas is lower -- 30% chance.

Otherwise, in general, dry conditions and mostly clear skies are
expected across the region through the remainder of this week. An
exception will be over coastal areas and nearby valleys, where
neutral to slightly onshore pressure gradients will favor
night and morning low clouds and fog in the marine layer. There
will be a 30% chance for localized Dense Fog Advisories to become
necessary in conjunction with this activity.

Temperatures will be near-normal for the remainder of this week,
with high temperatures from the mid 70s to the lower 80s in most
areas.

Some change in these conditions is expected going into Saturday,
as temperatures cool by a few to several degrees as midlevel
heights fall in response to a deep upper cyclone moving southeast
along the Pacific Northwest coast. Gusty west-southwest to west-
northwest winds are expected area-wide on Saturday, as enhanced
tropospheric flow in the southern periphery of this cyclone
overspreads the area. While moisture will deepen over the area
well in advance of this system for Saturday and Saturday evening,
cooling aloft will tend to disrupt marine layer continuity and
related fog development. However, low clouds and drizzle could
occur within the deepening moist layer.

.LONG TERM (SUN-WED)...01/215 PM.

The aforementioned deep upper cyclone will track east-southeastward
across the Intermountain West on Sunday. A shortwave trough
pivoting around the southern semi-circle of the cyclone may bring
sufficient ascent and midlevel cooling to yield a few showers over
the area late Saturday afternoon through Sunday. Ample dry air
aloft should keep precipitation amounts below one-tenth inch, and
many locations may not experience precipitation. A light dusting
of snow could occur over the highest elevations of northern VTA
and LA Counties, though significant precipitation impacts with
this system appear to be unlikely. However, temperatures will be
noticeably cooler across the region on Sunday, with most locations
only experiencing high temperatures in the lower to middle 60s --
around 10-15 degrees below normal in many areas.

Looking further ahead, dry conditions are expected areawide for
next week, as midlevel heights rise behind the departing upper
cyclone and attendant shortwave trough. Local pressure gradients
for next week are expected to turn more neutral to offshore in
response to surface ridging north of the area -- beneath subsidence
in the wake of the departing upper cyclone. While this pressure
pattern will likely still facilitate diurnal wind fluctuations
and sea-breeze development, the development of a pronounced
marine layer fostering low-cloud and fog development appears
unlikely through at least the middle of next week. As a result,
clear skies and a warming trend are expected for early to middle
parts of next week, with high temperatures rebounding to the mid
and upper 70s in most areas Monday through Wednesday.

&&

.AVIATION...01/1800Z.

At 1746Z at KLAX, the marine layer was 3400 ft deep with an
inversion top at 4700 ft with a temperature of 15 C.

Low to moderate confidence in coastal TAF sites and KBUR and KVNY,
with high confidence elsewhere. Timing of flight cat changes
could be off by +/- 2 hours, and cigs may develop one category
lower than forecast in for coastal sites in Ventura and L.A.
counties. There is a 30% chance of no cigs developing for KSMX,
KSBA, KBUR, and KVNY.

KLAX...Low to moderate confidence in TAF. Timing of flight cat
changes could be off by +/- 2 hours, and cigs as low as BKN008 are
possible. High confidence in any east wind component remaining
less than 6 kt.

KBUR...Moderate confidence in TAF. Timing of flight cat changes
may be off by +/- 2 hours, with a 30% chance of no cigs
developing tonight, and a 30% chance of cigs as high as BKN015.

&&

.MARINE...01/157 PM.

For the outer waters, wind are currently below Gale Force at most
location. This lull is expected to be short lived, with a 70%
chance of gales redevelop this afternoon and tonight. Another
lull in wind is possible Thursday morning, followed by an 80%
chance of gales Thursday afternoon and night. At least SCA wind
are expected much of the time through Sunday, and Sunday
afternoon and night there is a 40% chance of gales returning. SCA
level seas are expected through Friday night followed by a 40-50%
chance of SCA seas on Sunday and Monday.

For the inner waters N of Pt. Sal, SCA level winds are likely to
continue through tonight, followed by a 80% chance of returning
during the afternoon/evening Thursday and Friday (25% chance of
brief gales during these times), and a 40% of SCA winds Saturday
afternoon/evening. SCA winds are then likely (70% chance) Sunday
and Monday. Current SCA level seas will subside Thursday night,
followed by a 20% chance of returning Sunday and Monday.

For the Santa Barbara Channel, SCA level winds will affect the
western portions of the the channel this afternoon and evening,
with a 20% chance of reaching the central/eastern portions.
Thursday onward, SCA level winds are generally expected to only
impact the extreme western portions of the channel, until
Saturday afternoon. Saturday afternoon through Sunday night there
is a 40-50% chance of widespread NW SCA winds for the entire
channel, with the potential (20% chance) for gales on Sunday.

For the southern inner waters, there is a 20% chance of SCA level
W to NW winds near Anacapa Island this evening. Otherwise
conditions are expected to remain below SCA levels until Saturday
afternoon. Saturday afternoon through Sunday there is a 40-50%
chance of widespread NW SCA winds for all the inner waters, with
the potential (20% chance) for gales on Sunday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 5 AM PDT Thursday for zones
      378-381. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Friday for zone
      645. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Friday for zones
      670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Cohen
AVIATION...Schoenfeld
MARINE...Schoenfeld/Lund
SYNOPSIS...Cohen

weather.gov/losangeles

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