423
FXUS66 KLOX 140445
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
945 PM PDT Mon May 13 2024

.SYNOPSIS...13/903 PM.

Quiet weather will continue the next several days with near
to slightly below normal temperatures. Widespread night and
morning low clouds are expected across coast and valleys as
onshore flow increases. Temperatures will cool slightly through
Wednesday, then warm slightly the end of the week. Gusty winds are
likely across the mountains and Antelope Valley each afternoon.

&&

.SHORT TERM (MON-THU)...13/915 PM.

***UPDATE***

Another night of quick arriving stratus, though for many areas
near the coast the stratus never left. A weak upper low is
approaching which will bring some cooling and additional
instability the next couple days. Tuesday will be another slow
clearing day and temperatures 2-4 degrees below normal for coast
and valleys but 2-4 degrees above normal for the interior. May
also have some morning drizzle under the stratus layer.

***From Previous Discussion***

Overall, 12Z models in good synoptic agreement through the period.
At upper levels, weak low will slowly move southeast across the
bight and into northern Mexico today through Wednesday with ridge
building in from the west on Thursday. Near the surface, moderate
to strong onshore flow will continue.

Forecast-wise for the short term, a "May Gray" pattern will be the
main story. With the weak upper low being the main player, the
marine inversion will remain deep tonight through Wednesday with
low clouds likely pushing into the the Santa Clarita Valley each
night. Also with the strong onshore gradients, stratus dissipation
will likely be slower than usual with some coastal spots remaining
cloudy through the afternoon hours. For Wednesday night/Thursday,
H5 heights increase which should result a bit less inland
penetration of stratus and a better/quicker dissipation.

Other than the stratus issues, there is enough mid-level moisture
and instability to generate some afternoon cumulus buildups over
the mountains today through Wednesday. However, both parameters
are rather limited, so do anticipate much more than a 5-10% chance
of mountain thunderstorms each afternoon.

With respect to winds and temperatures, do not anticipate any
significant issues through Thursday. Afternoon temperatures will
exhibit minor day-to-day changes, but generally will remain at or
a couple degrees below seasonal normals. As for winds, the strong
onshore gradients will generate gusty southwesterly winds across
interior sections, including the Antelope Valley. However, outside
of the local wind tunnels like Lake Palmdale, do not expect any
widespread advisory-level gusts for the area.

.LONG TERM (FRI-MON)...13/153 PM.

For the extended forecast, no significant issues are anticipated.
The upper level ridge will peak in strength on Friday. This should
result in some slightly warmer temperatures and less extensive
marine layer clouds and fog.

For Saturday through Monday, an upper level low will move in from
the west. This will bring cooler temperatures and more extensive
marine layer stratus. Also, could be enough lift to generate some
drizzle Saturday night and Sunday morning. Main issue for the
weekend will be the onshore winds. Latest ensemble forecasts
indicate an increase in the potential for advisory-level southwest
winds across interior sections, especially the Antelope Valley and
the adjacent foothills. At this time, there looks to be about a
30-40% chance of advisory-level southwesterly winds and this
potential will need to be watched.

&&

.AVIATION...14/0221Z.

At 0021Z at KLAX, the marine layer was 2000 feet deep. The top of
the inversion was around 3400 feet with a max temp of 18 C.

High confidence in desert TAFs.

Moderate confidence in all other TAFs. Arrival time of cigs may be
off by 1-2 hrs. Cig hgt could be off by +/- 200 ft.

KLAX...Moderate confidence in TAF. There is a 30% chance cigs will
clear briefly around 21-22Z. Good confidence that any east wind
component will be under 5kt.

KBUR...Moderate confidence in TAF. Cig arrival and clearing
time may be off +/- 1 hour.

&&

.MARINE...13/944 PM.

Moderate to high confidence in the current forecast.

For southern outer waters, there is good chance 40-60% of local
gusts to Small Craft Advisory (SCA) levels developing during the
afternoons/evenings through Thursday. Winds will be the strongest
around Point Conception and the Channel Islands.

For the inner waters south of Point Conception, there is a 30%
chance of SCA conditions for the western third of the Santa
Barbara Channel and near the Channel Islands during the
afternoon/evening hours through Thursday evening.

Patches of dense fog and drizzle are possible overnight and in
the mornings through Sunday, with the best chance for drizzle
Saturday night into Sunday morning.

&&

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

&&

$$

PUBLIC...MW/Thompson
AVIATION...Phillips
MARINE...Phillips/Schoenfeld
SYNOPSIS...MW

weather.gov/losangeles

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