102 
FXUS66 KLOX 041501
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA 
801 AM PDT Sun Apr 4 2021

.SYNOPSIS...04/351 AM.

Dry weather with varying amounts of night through morning coastal
low clouds and fog can be expected through the week. After a bit 
of a cooling trend through Monday, there will be mostly minor day 
to day fluctuations in high temperatures. There will be areas of 
gusty winds at times, especially across southern Santa Barbara
County.

&&

.SHORT TERM (TDY-TUE)...04/801 AM.

***UPDATE***

Latest satellite and surface observations indicate mostly clear
skies across the area except for some patchy stratus across
interior SLO/SBA counties and the immediate LA coast. Current
sounding data indicates marine inversion is very shallow, ranging
around 500 feet. As for winds, some gusty northerly winds continue
across southern SBA county (gusts around 50 MPH at Gaviota). 

Forecast-wise, the immediate short term looks rather unremarkable.
Any current stratus/fog should dissipate by late morning with 
mostly sunny skies for all areas this afternoon. In general, 
onshore gradients will strengthen today, bringing a little bit of 
cooling for most areas. The only exceptions may be the Antelope 
Valley as well as southern SBA county (due to the northerly 
winds). For later this afternoon/evening, the models indicate a 
bump up in the northerly gradients. So, north winds will continue 
across southern SBA county and increase in speed this evening.

Overall, current forecast looks good for the immediate short term.
With strengthening northerly gradients, advisory-level north winds
will continue across southern SBA county through tonight. So,
current WIND ADVISORY for this area look good. Otherwise, main
focus with the afternoon forecast will continue to be the
potential for northerly winds.  

***From Previous Discussion***

Patchy low clouds and fog were confined to portions of the Central
Coast, interior SLO County, and immediate coastal sections of L.A.
County. Clouds may become a bit more widespread and develop
elsewhere by daybreak, but do not expect any widespread clouds, 
except for possibly on the Central Coast. Any low clouds should 
clear by mid or late morning, although strengthening onshore 
gradients would be concerning if there were a solid deck of low 
clouds near the coast.

Strengthening N-S gradients across SBA County were producing
advisory level winds in western portions of the Santa Ynez Range
and across the south coast of SBA County from Refugio westward. 
While winds will likely drop off by mid morning, expect them to
increase again this afternoon and evening, to even stronger
levels, with gusts over to 50 likely in some of the windier
locations. Therefore, have issued a Wind Advisory through late
tonight, keeping in mind that there will be somewhat of a lull in
the wind later this morning through mid afternoon. 

Max temps should be down a couple of degrees in most areas today,
except possibly up a couple of degrees in the Antelope Valley, 
and across the south coast of SBA County. 

An upper low will drop through the Pac NW tonight and into
northern Nevada by late Monday afternoon. Models show more in the
way of low clouds tonight and Mon morning in coastal areas and 
the San Gabriel, Salinas and Santa Ynez Valleys. However, with the
NW to N winds across SBA County, expect skies to remain clear
there, and the same may be true for the Ventura County coast as
well. Falling heights and thicknesses and increasing W-E 
gradients between KLAX and KDAG should lead to a few more degrees 
of cooling in all areas on Mon, with the exception of the south 
coast of SBA County, where little change in expected. 

The upper low will move across northern Utah and into Colorado 
Monday night and Tue. N-S gradients will increase a bit more and
there will be some subsidence across SBA County as well. Expect
another round of even stronger winds across southern SBA County
late Mon afternoon through late Mon night, with isolated
gusts to 60 mph a possibility. Expect low clouds in coastal areas,
with the exception of the SBA County south coast and the Ventura
County coast. Clouds will likely push into the Santa Ynez and San
Gabriel Valleys. With decreasing onshore gradients on Tue, and
rising heights due to weak ridging building into the area, expect
a few degrees of warming in most areas.

.LONG TERM (WED-SAT)...04/432 AM.

An upper level ridge across the region Wed will flatten on Thu, 
with zonal or broad WNWLY flow pattern aloft across the region 
through Sat. Expect areas of night through morning low clouds and 
fog in many coastal and some lower valley areas through the 
period. However, N-S gradients across SBA County will remain 
strong all week, so expect gusty and likely advisory level winds 
each night across southern SBA County. The winds should keep any 
stratus out of southern SBA County and possibly Ventura County. 

Temps Wed thru Sat are expected to be several degrees above normal 
away from the coast, while they will be near normal close to the
coast due to rather below normal water temperatures.

&&

.AVIATION...04/1226Z.

At 0520Z, the marine inversion at KLAX was based at 800 feet. The
top of the inversion was 2000 feet with as temperature of 20 
degrees Celsius. (No updated soundings as of 12z)

S of Point Conception...High confidence for Desert and Valley TAFs
through the period. Moderate confidence with coastal TAF sites.
There is a 30% chance that LIFR/IFR CIGS and VSBYS could develop
through 16z. Only moderate confidence with timing of IFR/MVFR CIGs
late this evening or after midnight.

N of Point Conception...Low confidence with Coastal TAF sites
through 17z. There is a 40% chance that LIFR/IFR CIGs could
develop. Better confidence with more widespread LIFR/IFR CIGs this
evening into Monday morning. Moderate confidence with KPRB TAF
with see VLIFR/LIFR CIGs between 13-17z this morning.

KLAX...Moderate confidence in 12Z TAF. 30% chance for LIFR/IFR
CIGs and VSBYS between 13z-17z. There is a 20% that an easterly
component wind will exceed 8 knots between 10z-14z Monday. 

KBUR...High confidence in 12Z TAF. Except 30% chance for IFR CIGs
between 08z-12z Monday.

&&

.MARINE...04/744 AM.

There will be patchy dense fog with visibility of one nautical mile 
or less over the waters during the overnight and morning hours 
through at least Thursday.

For the Outer Waters... Northwest winds will continue at Small 
Craft Advisory (SCA) levels or higher through at least Thursday, 
strongest during the afternoon and evening hours. There is a 
thirty percent chance of Gale force winds across zones 673/676 
late Sunday afternoon and evening and a forty percent chance 
across all of the Outer Waters Monday afternoon and evening. There
will be SCA level seas across the outer waters Monday afternoon 
and evening.

For the Inner Waters north of Point Sal... SCA level winds will 
develop this afternoon and likely continue through Thursday,
primarily during the afternoon and evening hours.

For the Inner Waters south of Point Conception... SCA level winds
will develop this afternoon and evening through the Santa Barbara
Channel. SCA level winds will develop across all of the inner
waters Monday afternoon and will likely continue through 
Thursday, primarily during the afternoon and evening hours.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 3 AM PDT Monday for zones
      39-52. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Tuesday for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Monday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT Monday for
      zones 670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from Monday afternoon through late
      Monday night for zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (TUE-SAT).

No significant hazards expected.

&&

$$

PUBLIC...DB
AVIATION...Kaplan
MARINE...Kj
SYNOPSIS...DB

weather.gov/losangeles