Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 220655

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1155 PM PDT Sat May 21 2022

.SYNOPSIS...21/1258 PM.

Warmer temperatures and less marine layer are expected through the
middle of next week as high pressure develops. Night and morning
low clouds are still expected along the coast with some clouds
lingering into the afternoon, especially after Monday. A cooling
trend is expected to begin Thursday with a deepening marine layer.


.SHORT TERM (SAT-TUE)...21/808 PM.


Overall, a very quiet evening across the forecast district. Latest
satellite and surface observations indicate some low clouds/fog
across the coastal waters as well as the LAX county coast. Current
AMDAR sounding data indicates marine inversion around 4000 feet
deep south of Point Conception with the inversion likely much
shallower north of Point Conception. As for winds, just the
typical onshore winds lingering with gusts 20-35 MPH in the

Forecast-wise for the immediate short term, main issue will be the
extent of the marine layer stratus and fog. With inversion in
place and onshore gradients overnight, stratus should develop and
push well into the coastal valleys south of Point Conception
overnight. North of Point Conception, stratus will mainly be
confined to the coastal plain, but will sneak into the Santa Ynez
Valley. Given the more shallow inversion, there could be some
patchy dense fog overnight north of Point Conception. Other than
any stratus/fog, skies should remain clear overnight. As for
winds, expect the current gusty onshore winds to diminish later
this evening.

Overall, current forecast has good handle on the immediate short
term. Did make some minor tweaks to the sky cover grids, but no
significant updates are anticipated.

***From Previous Discussion***

Deep marine layer still in place south of Pt Conception but skies
are slowly clearing. With much weaker onshore flow today and the
added sunshine in many areas temps are running warmer by 3-6
degrees on average but as much as 10 degrees in some of the
valleys. The eddy has collapsed but low clouds are expected to
return to many of the same areas as last night as well as the
Central Coast.

With a weak upper ridge moving into the state Sunday through
Tuesday and slowly increasing north to northwest flow aloft the
marine layer should clear earlier with warmer temps, especially
inland. Low clouds will become confined to just the coastal zones
by Monday or Tuesday as the marine layer depth lowers to under
1500`. Locally breezy north to northwest winds likely in the far
western part of Santa Barbara County and the I5 corridor but
likely below advisory levels. Then some breezy northeast winds by
Tuesday, mainly in the LA mountains.

.LONG TERM (WED-SAT)...21/106 PM.

The warming trend is expected to peak Wednesday, though there
remains some differences in the models on how strong the upper
ridge will get. Most of the ensembles seem to support the warmer
EC solution but even that solution is fairly moderate in terms of
heat with highs in the mid to high 90s in the Antelope Valley and
near 90 in the coastal valleys, basically about 10 degrees above
normal. Troughing will develop along the west coast Thu/Fri for a
cooling trend with a deepening marine layer and increasing
southerly flow. The GFS continues to advertise an 8-9mb gradient
to BFL late in the week which if true would likely keep low
clouds pretty well socked in along the coast through the
afternoon, especially from Malibu north.



At 2310Z at KLAX, the marine layer was 3100 feet deep. A weak
inversion extended up to 6400 feet with a temperature of 12 deg C.

Good confidence in TAFs for KPRB, KPMD and KWJF.

Above normal confidence in return to MVFR or lower cigs to
coast/valley TAFs, but below normal confidence in timing (could be
off by 2 hours) and flight category. Near normal confidence in
return to VFR today with return to VFR expected to be within 2
hours of forecast for most terminals. Low confidence on return of
low cigs/vsbys after 00Z, with a 20 percent chance of return by
04Z at any coastal terminal.

KLAX...Moderate confidence in the 06z TAF. There is a 30 percent
chance of ceilings returning plus or minus two hours from the
forecasted time. There is a 10 percent chance that the east wind
component could reach 8 kts after 05Z. Low confidence on return
timing of low cigs/vsbys tonight with a 20 percent chance of
arrival by 04Z.

KBUR...Moderate confidence in the 06z TAF. There is a 30 percent
chance of ceilings returning plus or minus two hours from the
forecasted time.


.MARINE...21/807 PM.

The Marine Weather Statement (MWS) for patchy dense fog across
the Outer Waters and Inner Waters north of Point Sal looks good to
continue through tonight.

Marginal Small Craft Advisory (SCA) was allowed to continue for
the Outer Waters north of Point Sal. North to northwest winds are
still expected to increase through Monday. There is a 50 percent
chance of Gales developing across the Outer Waters, especially
north of Point Conception as early as Sunday night and again
Monday. The GALE WATCH remains in place and may be upgraded to
WARNING overnight tonight if model trends continue to support
GALE force wind gusts. SCA conditions are likely (50-70 percent
chance) for the Inner Waters north of Point Sal and western
portions of the Santa Barbara Channel Sunday and Monday
evenings/nights. There is a 20-30 percent chance of at least brief
Gales developing during this time frame.

The strong northerly winds will likely spin up an eddy by Monday
morning, strongest late night to morning with south to southeast
winds possibly peaking between 15 to 20 kts for portions of the
southern Inner Waters, mainly south of Point Mugu.


PZ...Small Craft Advisory in effect until 3 AM PDT Sunday for zone
      670. (See LAXMWWLOX).
     Gale Watch in effect from Sunday afternoon through Monday
      evening for zones 670-673. (See LAXMWWLOX).




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