National Weather Service Raw Text Product

100 
FXUS66 KLOX 230520
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA 
1020 PM PDT Mon Apr 22 2024

.SYNOPSIS...22/217 PM.

Strengthening onshore flow and a deepening marine layer will 
bring low clouds, fog, and drizzle to the coast and coastal 
valleys throughout this week. Cool conditions will continue, with
high temperatures several degrees below normal each day this week.
A couple of weather disturbances will track across the area later
in the week, bringing a small chance for light rain showers for 
mid to late week.

&&

.SHORT TERM (MON-THU)...22/222 PM.

Strong onshore pressure gradients will persist through much of
this week. These onshore gradients will further strengthen through
mid-week in response to midlevel ridging focusing the strongest 
surface heating over the central Great Basin. Diurnally enhanced 
onshore gradients for LAX-DAG are forecast to reach 8-9 mb each 
day through Thursday. In addition, for Wednesday night into 
Thursday, a midlevel low will progress eastward over the East 
Pacific and across southern California. This will further 
reinforce and deepen the marine layer over coastal areas and 
coastal valleys later this week.

Widespread low clouds and fog are expected to accompany the 
deepening marine layer, which will also cool temperatures across 
the region. High temperatures are expected to be in the 60s in 
most areas each day, except rising into the 70s over the Antelope
Valley away from the marine layer. In addition, the marine layer 
will significantly deepen to depths over 2500-3000 feet tonight 
into Tuesday and then depths over 4000 feet for Thursday. This 
will support drizzle over many areas -- especially during the 
evening, overnight, and morning hours. Dry conditions in the mid 
and upper troposphere will limit the potential for measurable 
rainfall, though a few light showers could accompany the passage 
of the midlevel low late Wednesday night and Thursday morning.

.LONG TERM (FRI-MON)...22/227 PM.

Following the passage of the aforementioned midlevel low, 
temperatures aloft will cool and onshore pressure gradients will 
weaken. These factors will allow the marine layer to lose depth 
and weaken to some extent by the end of this week, with the extent
of fog and drizzle correspondingly lessening. Thereafter, further
cooling aloft, decreasing onshore flow, and weakening of the 
marine layer will occur with the glancing influence of a deep 
midlevel trough amplifying over the Great Basin late Friday into 
the upcoming weekend. However, despite the weakening marine layer,
cooling aloft will maintain high temperatures in the 60s in most 
areas through Friday. Thereafter, temperatures are expected to 
warm a few degrees by Sunday as midlevel heights rise behind the 
deeper trough. Regarding precipitation, there will be a slight 
chance for light showers Friday into Friday night in conjunction 
with the second disturbance glancing the area, which will be 
followed by dry conditions.

&&

.AVIATION...23/0137Z.

Moderate/Low confidence in coastal and valley TAFs and high 
confidence in desert TAFs. Lower confidence for coastal/valley 
sites due to uncertainties in timing of flight category changes. 
For tonight, drizzle is likely for much of the coast as the marine
layer grows, likely bringing MVFR to IFR CIGs. Low confidence in
timing of lowest cigs and drizzle. 

KLAX...Moderate to low confidence in 00Z TAF. Timing of flight 
category changes between IFR and MVFR conditions could be +/- 3 
hours of current forecasts. No significant easterly wind component
is expected.

KBUR...Moderate to low confidence in 00Z TAF. Lower confidence in
timing of IFR conditions and drizzle.

&&

.MARINE...22/1019 PM.

For the Outer Waters, moderate to high confidence in current
forecast. Today through Wednesday, high confidence in winds and
seas remaining below Small Craft Advisory (SCA) levels. Wednesday
night, there is a 40-50% chance for winds near SCA levels south 
of Point Conception. High confidence in winds increasing to SCA 
levels, with a 30% chance of Gale force winds across PZZ673 and 
PZZ676 Thursday. Winds continue to increase into Friday night, and
there is a 60% chance for gales Friday night into Saturday. Seas
increase Thursday, peaking near 10 feet Friday night into the
weekend. 

For the Inner Waters north of Point Sal, high confidence in
current forecast. Today through Wednesday, winds and seas will
remain below SCA levels. For Thursday there is a 40% chance of 
winds increasing to SCA levels mainly in the afternoon and 
evening hours. Friday evening SCA winds appear likely with a 30%
chance for gales. 

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. Today through Wednesday morning, 
high confidence in winds and seas remaining below SCA levels.
There is a 30-40% chance for SCA level winds through the Santa
Barbara Channel Wednesday evening. There will likely be a break in
the winds in the overnight to morning hours, and SCA winds appear
likely again Thursday. Friday into Saturday morning SCA winds 
also look likely, with a 20% chance for brief gale force winds 
Friday evening.

&&

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

&&

$$

PUBLIC...Cohen
AVIATION...Phillips
MARINE...Phillips
SYNOPSIS...Cohen

weather.gov/losangeles

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