138
FXUS66 KLOX 201007
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
307 AM PDT Sun Apr 20 2025

.SYNOPSIS...20/154 AM.

Mostly clear skies and a warming trend will occur today and
Monday. A slow cooling trend will develop Tuesday and continue
through the remainder of next week with increasing night and
morning low clouds and fog.

&&

.SHORT TERM (TDY-TUE)...20/249 AM.

Benign weather will prevail through the short term (Tuesday).

Synoptically...dry NW flow aloft will transition to broad pos
tilt troffing. 576 dam hgts today will fall to 572 dam during the
period. Onshore flow will increase each day and will reach
moderate levels Tuesday afternoon.

Hard to ask for better weather this Sunday. Areas of morning low
clouds will affect the csts/vlys of SLO/SBA counties, while only
patchy low clouds will occur south of Pt Conception. By late
morning all areas will be sunny. Most areas will warm 2 to 4
degree. Coastal max temps will be in the mid 60s to lower 70s
while the vlys will reach the mid 70s to lower 80s. These max
temps are within a few degrees of normal.

Stronger onshore flow and a little better marine inversion will
lead to more low clouds Monday morning. Still, by late morning all
skies will be sunny. The inland areas will warm some making it the
warmest day of the next 7 there. The csts, however, will cool some
as the stronger onshore flow will bring an earlier seabreeze.

Not much change on Tuesday. The stronger onshore grads will bring
more extensive low clouds esp to the Central Coast and the LA
coast and lower vlys. Max temps will fall a few degrees as hgts
fall and the onshore push increases. The moderate onshore flow in
the afternoon will bring an increase in northwest winds to the
nearshore are and interior, despite the increase the gusts will
very likely remain safely below advisory levels.

.LONG TERM (WED-SAT)...20/307 AM.

A series of trof will move through the PACNW during the long term
Wed thru Sat period. Deterministic and ensemble based mdls are in
good agreement through Thursday but then diverge Friday and esp
Saturday.

The increased troffing along with increased onshore flow on both
Wed and Thu will bring increased marine layer coverage. Low clouds
will likely xtnd deep into the vlys. Moderate to strong onshore
flow in the afternoon will slow clearing at the coasts and some
beaches may stay cloudy all day. Gusty westerly winds will occur
in the Antelope Vly and its western foothills each afternoon and
may approach advisory levels. Max temps will cool 1 to 3 degrees
each day with most areas 4 to 8 degrees under normal by Thursday.

Deeper troffing is a certainty for Fri and Sat. The real question
is, however, how much and how strong the troffing will be. The EC
and most of its ensembles are stronger and colder bringing 566
hgts to the area. The GFS is weaker and further north with hgts
near 576 dam. The current forecast takes a middle of the road
approach but if the EC is more correct max temps will end up much
cooler than currently fcst. Given that there is increased cyclonic
turning aloft along with the onshore flow there deep marine layer
pattern will likely continue and there may be enough lift to bring
drizzle to the are in the mornings.

&&

.AVIATION...20/0940Z.

At 0930Z at KLAX, the marine inversion was 500 feet deep. The
top of the inversion was 1500 feet with a temperatures of
17 degrees Celsius.

For 12Z TAF package, high confidence in KBUR...KVNY...KWJF and
KPMD. For all other sites, moderate confidence due to
uncertainties in behavior of marine layer stratus. North of Point
Conception, timing of flight category changes could be +/- 2 hours
of current forecasts. For coastal sites south of Point Conception,
there is a 20-30% chance of IFR/LIFR CIGs and VSBYs 12Z-17Z.

KLAX...Overall, moderate confidence in 12Z TAF. There is a 20%
chance of IFR/LIFR CIGs and VSBYs 12Z-17Z. For tonight, moderate
confidence in return of CIG/VSBY restrictions with timing of
return +/- 3 hours of current 08Z forecast. No significant
easterly wind component is expected.

KBUR...High confidence in 12Z TAF.

&&

.MARINE...20/240 AM.

For the Outer Waters, moderate to high confidence in current
forecast. Today through Monday, there is a 20-30% chance of Small
Craft Advisory (SCA) level winds around Point Conception. For
Tuesday through Thursday, there is a 60-80% chance of SCA level
winds across all the Outer Waters.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Today through Tuesday, high
confidence in winds and seas remaining below SCA levels. For
Wednesday through Thursday, there is a 40-50% chance of SCA level
winds in the afternoon and evening hours.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. Today through Thursday, high
confidence in winds and seas remaining below SCA levels across
most areas. The only exception will be the western half of the
Santa Barbara Channel where there is a 20-30% chance of SCA level
winds Tuesday through Thursday, mainly during the late afternoon
through evening hours.

&&

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

&&

$$

PUBLIC...Rorke
AVIATION...RAT
MARINE...RAT
SYNOPSIS...30

weather.gov/losangeles

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