Sepulveda, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

477
FXUS66 KLOX 040525
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
925 PM PST Tue Dec 3 2024

.SYNOPSIS...03/144 PM.

Above normal temperatures are expected through the week, peaking
Friday and Saturday with highs in the 70s and 80s. Locally gusty
Santa Ana winds are possible Friday into early next week. Skies
will be partly cloudy at times with areas of morning fog. No rain
expected through the end of next week.

&&

.SHORT TERM (TDY-FRI)...03/921 PM.

***UPDATE***

A dense fog advisory has been issued for the coastal areas of SLO
and Santa Barbara Counties through Wednesday morning. Shallow
marine layer coupled with light flow regime will allow dense fog
to spread across the coastal areas. For now our confidence is very
low that dense fog will infiltrate Ventura and LA County coastal
areas, but may be needed later in the overnight period if the
dense fog develops further south. No other changes were needed to
the forecast this evening.


***From Previous Discussion***

Very low impact weather expected through the end of the week as
high pressure over the eastern Pacific deflects all incoming
systems well north and east of the area. As these systems pass us
by there will be periods of light to moderate offshore flow, the
next occurrence being this coming Friday when the NAM is
projecting a -4.5mb LAX-DAG gradient. Not a ton of upper support
with that but enough to likely generate wind gusts up to around 35
mph in the favored areas of LA/Ventura Counties and the Santa
Lucias in SLO County. Most areas will get a boost in temperatures
with that as well with coastal valley highs in the 80s and most
other areas in the 70s.

In the meantime, a little cooling today and Wednesday with a
return to light onshore flow before trending back up Thursday.
Some night and morning low clouds and locally dense fog expected
as well.

.LONG TERM (SAT-TUE)...03/142 PM.

Another warm early December day on Saturday as light offshore
continues. Then 4-8 degrees of cooling most areas Sunday as
gradients shift back onshore.

Sunday night into Monday an upper low will drop south out of
Canada and into the Great Basin. Models gradients have been
bouncing around quite a bit, at one point showing almost a -9mb
LAX-DAG gradient Monday morning. More recent deterministic runs
have settled in the -4 to -6 range (peaking Tuesday) with 850mb
winds between 35 and 45kt. The deterministic runs do show some
decent cold air advection with thicknesses ranging from 549dam at
the coast to 538 across the deserts. However, most of the EPS wind
forecasts are only in the 30-40 mph range, suggesting that the
deterministic models are on the higher end in terms of offshore
strength. So the most likely outcome at this point is a moderate
Santa Ana with peak gusts in the 35-45 mph range, but with maybe a
10-20 percent chance of a strong event with gusts up to 60 mph.
Given the cold air advection and moderate upper support Santa Ana
winds should have no trouble reaching the coast and well out
through the coastal waters.

High temperatures will drop at least 6-12 degrees starting
Monday, more so inland than at the coast and remain on the cooler
side. If the upper low makes a closer pass, temperatures may be
even cooler. Offshore flow expected to linger into mid week.

&&

.AVIATION...04/0034Z.

At 2357Z at KLAX, the marine layer was 700 feet deep, with an
inversion top at 2100 ft and a maximum temperature of 16 C.

High confidence in desert sites, moderate confidence in coasts
and valleys sites. Timing of cig development and flight category
chances may be off by +/- 3 hours tonight. Additionally during
cigs, period of dense fog with VSBY as low as 1/4SM, will be
possible for all coasts and valleys. The greatest chances for
dense fog are at KSBP and KSMX.

There is a 40% chance of no cigs developing at KBUR and KVNY
tonight.

KLAX...Moderate confidence in TAF. Timing of cig development and
flight category chances may be off by +/- 3 hours tonight. There
is a 20% chance of dense fog with VSBY as low as 1/4SM-1/2SM
during cigs. No significant easterly wind component is expected.

KBUR...Moderate confidence in TAF. There is a 40% chance of no
cigs developing through the period.

&&

.MARINE...03/756 PM.

For the Outer Waters, moderate to high confidence in current
forecast. Through Wednesday morning, high confidence in winds and
seas remaining below Small Craft Advisory (SCA) levels. From
Wednesday afternoon through Saturday evening, there is a 30-50%
chance of SCA level winds (with the best chances Thursday
afternoon and evening). For Sunday, there is a 20-30% chance of
SCA level winds, but a 50-70% chance of SCA level seas.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Through Wednesday night, high
confidence in winds and seas remaining below SCA level. For
Thursday, there is 30% chance of SCA level winds in the afternoon
and evening hours. For Friday through Sunday, high confidence in
winds remaining below SCA levels, but a 30-40% chance of SCA level
seas on Sunday.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. From Point Mugu to Santa Monica,
there is a 20% chance of SCA level northeast winds late Wednesday
night/Thursday morning then a 30-40% chance of SCA level northeast
winds late Thursday night/Friday morning. Otherwise for the rest
of the southern Inner Waters, high confidence in winds and seas
remaining below SCA levels through Sunday.

Patchy dense fog may affect the coastal waters tonight and
Wednesday morning with visibility of one nautical mile or less.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Dense Fog Advisory in effect until 9 AM PST Wednesday for
      zones 340-341-346>350. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...MW/JMB
AVIATION...Schoenfeld
MARINE...RAT/Schoenfeld
SYNOPSIS...MW

weather.gov/losangeles

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