873
FXUS66 KLOX 161621
AFDLOX

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

Updated Aviation Discussion

.SYNOPSIS...16/852 AM.

Strong onshore flow and a persistent marine layer will remain in
place through the middle of next week. 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.

&&

.SHORT TERM (TDY-SAT)...16/911 AM.

***UPDATE***

May Gray conditions remain firmly in place across southwest
California with strong onshore flow and a marine layer depth
around 3500 feet across the LA Basin, sloping to around 2000 feet
along the Central Coast. Clearing is expected across the coastal
valleys by afternoon but clearing chances decrease closer to the
coast. Not expecting any significant changes to this for the next
several days. Highs today and for the next week or so are expected
to be 4-8 degrees below normal across coast and coastal valleys.
For interior areas highs will be 3-6 degrees above normal through
this weekend, then turn below normal next week.

***From Previous Discussion***

Away from the coast into the interior portions of the area, breezy
to gusty onshore winds will create elevated fire weather
conditions during the afternoon and evening hours when warmer
daytime temperatures and drier humidities combine with breezy to
gusty winds. Over the next several days, winds will be marginal
for advisory levels, but as the upper-level trough of low pressure
draws closer to the area over the weekend, winds could approach
advisory levels. EPS solutions suggest wind gusts approaching
advisory levels on Saturday afternoon and evening, and again on
Sunday afternoon and evening at KPMD and KWJF.

Lingering instability from the trough could bring a few isolated
showers to the mountains, but it will likely just be some clouds
over the mountains this afternoon and evening. Moisture parameters
are down much from yesterday, but PoPs are non-zero over the
mountains this afternoon and evening. As the trough offshore move
closer to the region, a slight chance of showers and thunderstorms
over the Ventura and Santa Barbara County mountains could reenter
the forecast over the weekend during the afternoon and evening
hours. Stay tuned to the latest as this could be a wrinkle that
changes the forecast.

.LONG TERM (SUN-WED)...16/349 AM.

A deep marine layer depth and strong onshore flow is likely to
continue into early half of next week, keeping the forecast near
persistence into at least Tuesday. The forecast changes little as
a deep marine layer and expansive low clouds field could bring the
threat of night through morning drizzle along the South Coast of
California.

The forecast ensemble members are highlighting the potential for a
weak trough of low pressure dropping south down the coast between
Wednesday and Thursday. Gusty northerly winds appear in a majority
of the EPS ensemble members at KSDB and KSBA, but there is some
spread in the ensemble members into late next week. Pattern
recognition in the deterministic solutions would confirm the
possibility of a tightening northerly gradient for late next week.

&&

.AVIATION...16/1620Z.

At 16Z at KLAX, the marine layer was 3000 ft deep. The top of the
inversion was 5000 feet with a temperature of 20 C.

Moderate confidence in coastal, valley, and mtn-slope TAFs, and
high confidence in desert TAFs. Persistent low stratus will bring
cig restrictions from the coast to mtn slope areas through much
of the forecast period. Expect only slow clearing today, with
skies clearing by early this afternoon in the valleys and later
in the afternoon across interior sections of the coastal plain. It
will likely remain cloudy near the coast, but cigs may rise into
the VFR category. Expect similar conds tonight compared to last
night, with widespread cig restrictions for all coast, valley and
mtn slope areas. Timing of cig restrictions could vary +/- 3 hours
of current forecasts. VFR conditions are expected for desert
sites.

KLAX...Moderate confidence in TAF. There is a 20-30% chance that
cigs will scatter out between 21Z and 02Z. No significant
easterly wind component is expected.

KBUR...Moderate confidence in TAF. There is a 20-30% chance that
cig restrictions will persist thru the day.

&&

.MARINE...16/914 AM.

In the Outer Waters, moderate to high confidence in the forecast.
There is a 20-30% chance that winds reach Small Craft Advisory
(SCA) levels this afternoon and evening -- highest chances in the
southern two zones (PZZ673/676). There is a 30% chance of SCA
level winds/seas over the entire outer waters Sun night thru Tue.
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.

In 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 this afternoon/evening and
again during the afternoons of Mon and Tue. Otherwise, SCA conds
are not expected.

&&

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

&&

$$

PUBLIC...MW/Hall
AVIATION...DB/Cohen
MARINE...DB/Cohen
SYNOPSIS...Hall

weather.gov/losangeles

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