Acton Weather

000
FXUS66 KLOX 250321
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
821 PM PDT Tue May 24 2022

.SYNOPSIS...24/521 PM.

High pressure will bring warmer weather to areas away from the
coast through Wednesday. Closer to the coast, a persistent marine
layer will continue to affect the coastal areas expanding into the
coastal valleys late in the week. A cooling trend is expected for
late week as onshore flow strengthens. Gusty onshore winds are
expected each afternoon and evening for the mountains and interior
valleys. A warming trend is possible early next week.

&&

.SHORT TERM (TUE-FRI)...24/741 PM.

***UPDATE***

Quiet conditions are underway for Southwest California tonight,
with light winds and clear skies away from the coast. The main
forecast challenge will be the amount of low cloud coverage
overnight into Wednesday morning. Low clouds will likely cover all
coastal areas, with some intrusion into the coastal valleys as
well. It is possible that a larger portion of the eastern Ventura
and San Fernando Valleys will see low clouds but for now will
retain mention of patchy coverage. A slightly warmer day is
likely for coastal areas thanks for somewhat earlier clearing
times compared to today.

***From Previous Discussion***

Onshore flow increases Wednesday, with the LAX-DAG onshore
gradient peaking around 6 to 7 mb in the afternoon hours. There
will also be a southerly component to winds, with the onshore LAX-
BFL gradient reaching 6 mb. Gusty west to southwest winds will
develop over the Antelope Valley in the afternoon, but should
remain below advisory levels. Still seeing hot temperatures in the
90s for the Antelope Valley and interior San Luis Obispo County,
but this additional onshore push should limit heating up north.

Thursday, onshore flow will peak with the LAX-DAG onshore gradient
peaking around 8 to 9 mb and the onshore LAX-BFL gradient peaking
at 7 mb. This will support potentially advisory level gusty winds
for the Antelope Valley and Santa Ynez Valley. Low clouds and fog
should push deeper into the valleys thanks to the increased
onshore flow.

.LONG TERM (SAT-TUE)...24/1130 AM.

Ensemble guidance shows good agreement from Friday through Monday
as upper level flow shifts to the west/northwest, and gradually
strengthens over the timeframe. Both the GFS and EC agree on a
trough passage by late Monday, but there is more uncertainty in
temperatures for the extended period. Currently going with a
middle of the road solution for now, with the potential for
warming early next week.

Friday, strong onshore flow continues, primarily from the west
with an LAX-DAG gradient around 7 to 8 mb. Heights trend lower,
which will support a deep morning marine layer to push far into
the valleys and the coastal slopes. Heights fall more
significantly on Saturday, so again expecting a very deep marine
layer that may try to spill over into the Antelope Valley. There
is the potential for gusty winds Friday and Saturday due to the
stronger onshore push. Onshore flow is forecast to weaken Monday,
and will gain more of a northerly component.

&&

.AVIATION...25/0016Z.

At 2255Z at KLAX, the marine layer was 1200 feet deep. The
inversion top as at 3300 feet and 26 degrees Celsius.

Overall moderate confidence in the 00Z TAFs, except low confidence
in the LA Valley sites. For the coastal sites, the onset of low
clouds and flight restrictions could differ by +/- 2 hours from
TAF times. For the Central Coast, IFR conditions are expected with
a chance of LIFR at KSMX. Further south, IFR to MVFR conditions
are expected, although the timing of flight category changes is
lower confidence. There is a 40 percent chance that KVNY and KBUR
will remain VFR through the period.

KLAX...Moderate confidence in the 00Z TAF. MVFR cigs expected to
arrive by 02Z, but the timing could differ by 1-2 hours. There is
a 30% chance of IFR cigs initially, then lifting to MVFR. High
confidence in and east winds staying under 8 knots.

KBUR...Low confidence in the 00Z TAF. There is a 40 percent
chance of VFR conditions through the period.

&&

.MARINE...24/753 PM.

Light and broad southerly flow will continue across much of the
coastal waters into the first half of Friday. By Friday night,
gusty northwest winds along with short period wind waves and rough
seas will make their return, especially in the outer waters.

Southerly winds will gradually expand through Thursday,
eventually pushing up to Monterey County and shove the seasonal
coastal jet well offshore. Local south to southeast winds of 10-15
knots are likely near all coasts in the morning hours, especially
Wednesday. More significantly, seas will fall to nearly lake-like
conditions by Thursday, with only 2-4 feet (locally 1 foot) total
waves everywhere including the Central Coast. The coastal jet
should reform quickly Thursday Night into Friday, with Gale Force
(focused outer waters to Central Coast) and widespread choppy seas
returning for the weekend.

&&

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

&&

$$

PUBLIC...Phillips/Smith
AVIATION...Smith
MARINE...Stewart/Sweet/Kittell
SYNOPSIS...Hall/Smith

weather.gov/losangeles

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