107
FXUS66 KLOX 170343
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
843 PM PDT Thu May 16 2024

.SYNOPSIS...16/135 PM.

Strong onshore flow and a persistent marine layer will remain in
place at least through the weekend. Night through morning low
clouds and fog will be a staple of the forecast, clearing to the
beaches each afternoon. Breezy to gusty onshore winds will occur
each afternoon and evening across the interior valleys and
adjacent foothill areas. Some warming with earlier clearing is
possible next week.

&&

.SHORT TERM (THU-SUN)...16/841 PM.

***UPDATE***

Today was yet another May Gray day, with overnight/morning marine
layer clouds extending inland over the valleys to the lower
mountain slopes. A decrease in the onshore pressure gradients
resulted in better clearing today, thus high temperatures were
around 1 to 3 degrees warmer than yesterday everywhere.

Tomorrow onshore gradients for Ventura and Los Angeles Counties
will decrease further, giving coasts and valleys a better chance
of earlier sunshine. Highs for these areas are expected to be
around 2 to 4 degrees warmer than today. However, with a cooling
airmass aloft, the majority of other areas will see highs 2 to 5
degrees cooler than today. Wind tomorrow will continue to be
gusty out of the west across the Antelope Valley.

No major changes to the forecast with this update.

***From Previous Discussion***

Very seasonably typical deep marine layer pattern this week and
likely at least through the weekend as a weak troughing pattern
continues to promote strong onshore flow. Temperatures will
remain 3-6 degrees below normal across coast and valley into the
weekend with slow (if any) clearing. Most valley areas should see
at least some clearing in the afternoon but coastal areas will
struggle, especially south of Pt Conception. Some drizzle is
possible each morning, especially up against the coastal
foothills. Farther inland such as the Antelope Valley, mountains,
and interior SLO County skies will remains clear but breezy in the
afternoon (especially near the AV) with temperatures a few
degrees above normal.

.LONG TERM (MON-THU)...16/157 PM.

There is growing confidence that this persistent marine
layer/strong onshore flow pattern will at least temporarily take a
break early next week. The NAEFS ensemble gradients agree with
the deterministic model gradients in showing a much weaker onshore
flow by Tuesday following the passage of a trough through the
Great Basin. This would create a stronger northerly component to
the winds which will promote much earlier marine layer clearing
and a warming trend for coast and valleys. Current forecast for
next week still on the conservative side with very little change
in temperatures, but if the ensembles continues to trend this
direction the forecast should indicate a warming trend to at least
normal temperatures soon.

&&

.AVIATION...17/0029Z.

At 00Z at KLAX, the marine layer was 2600 ft deep. The top of the
inversion was 4600 feet with a temperature of 22 C.

Moderate confidence in coastal and valley TAFs, and high
confidence in desert TAFs. Expect similar conds tonight compared
to last night, with widespread cig restrictions for non-desert
sites. Timing of cig arrivals may be off by +/- 90 minutes from
the forecast time, and timing of clearing may be off by +/- 2
hours. There is a 20-30% chance of little-to-no significant
clearing tomorrow for coasts and valleys south of Point
Conception.

KLAX...Moderate confidence in TAF. OVC015-OVC25 cigs may return
tonight +/- 90 minutes from the forecasted time of 04Z, and there
is a 30% chance that the cigs will persist through the day
tomorrow. No significant easterly wind component is expected,
however there is a 30% chance of the south wind component reaching
6 kt from 10Z-17Z Fri.

KBUR...Moderate confidence in TAF. OVC015-OVC25 cigs may return
tonight +/- 90 minutes from the forecasted time of 05Z, and there
is a 20% chance that the cigs will persist through the day
tomorrow.

&&

.MARINE...16/812 PM.

Across the Outer Waters, moderate to high confidence in the
forecast. There is a 20-30% chance of Small Craft Advisory (SCA)
wind gusts this evening over the southern two zones (PZZ673/676,
but otherwise a diminishing trend in winds is expected for Friday
and Saturday. There is a 20-40% chance of SCA winds/seas over the
outer waters Sun night through Tuesday.

-- highest chances in the northern two zones (PZZ670/673).
Otherwise SCA conds are not expected.

For the Inner Waters N of Pt. Sal, high forecast confidence.
Winds and seas are expected to remain below SCA levels thru Tue.

Over the Inner Waters S of Pt. Conception, moderate to high
forecast confidence. There is a 20-30% chance of SCA level winds
in the western portion of the SBA Channel through late this
evening, and again during the afternoon to evening hours Mon and
Tue. Otherwise, SCA conds are not expected.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...MW/Schoenfeld/Smith
AVIATION...Schoenfeld
MARINE...Smith
SYNOPSIS...MW

weather.gov/losangeles

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