181
FXUS66 KLOX 042141
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
241 PM PDT Tue Jun 4 2024

.SYNOPSIS...04/240 PM.

High pressure aloft over the region will continue a warming trend
through Wednesday, most pronounced away from the coast. Weakening
onshore flow will thin the marine layer depth some and keep clouds
confined to coastal and valley areas. A hot air mass will remain
in place across the interior valleys for much of this week, with
temperatures well above normal for this time of year. Closer to
the coast, the warming trend will be moderated due to persistent
night through morning low clouds and fog and a moderate to strong
onshore flow.

&&

.SHORT TERM (TDY-FRI)...04/240 PM.

No significant changes to the forecast. Heat Advisories were
added for the I-14/Acton area of the LA mountains and Cuyama
Valley Wednesday and Thursday, complementing the already issued
Heat Advisory for interior San Luis Obispo County including the
Paso Robles area and the Excessive Heat Warning for the Antelope
Valley. The heat can have significant impacts on anyone, but
sensitive groups like the very young or old and those with
prolonged exposure outside are particularly vulnerable to heat
impacts. If possible, take steps to limit exposure from the heat
by taking breaks inside with air conditioning or by finding shade
and also drinking plenty of water.

High confidence in a warming trend focused across Coastal Valleys
to interior through Wednesday as a strong (for early in the
season) ridge of high pressure builds into the region. The marine
layer will continue to shelter coastal areas from much of the
warming compared to interior areas. It will also continue to
provide night to morning low clouds with dense fog becoming more
Low confidence in the extent of the marine layer especially into
Tuesday due to competing forces between the building ridge
pressing down on the marine layer and the potential for a Catalina
Eddy acting to prop it up. This leaves us with only moderate
confidence in daytime highs across coastal valleys in particular.
If marine influence is less than anticipated, Heat Advisories may
need to be expanded to a few inland coastal valleys. We continue
to advertise daytime highs of 98-108 for interior areas, 85-95
coastal valleys, and 70-85 coastal areas.

Guidance has slowed with the breakdown and eastward progression
of the ridge, so the cool down may be slow enough to maintain heat
impacts through Friday with some potential for some of the heat
products to be extended through then.

There is just enough mid level moisture arriving from the south to
warrant around a 10 percent chance of showers or thunderstorms
focused across the higher mountains in Los Angeles, Ventura, and
perhaps Santa Barbara County as early as Thursday.

.LONG TERM (SAT-TUE)...04/240 PM.

Lower confidence in the forecast next weekend the details related
to the ridge breaking down remains elusive. There is a 10 percent
chance (leaving a 90 percent chance that unremarkable early June
weather continues) a baggy trough setting up will be favorable for
showers or thunderstorms for interior areas and drizzle or light
showers for closer to the coast. Either way temperatures should
cool at least somewhat, possibly significantly for interior areas
should the more active weather scenario play out.

&&

.AVIATION...04/1637Z.

At 16Z at KLAX, the marine layer was 1900 ft deep. The top of the
inversion was at 5200 feet with a temperature of 20 Celsius.

Moderate confidence on better clearing today compared to
yesterday. High confidence in all valley airports becoming VFR by
19Z. Moderate confidence in VFR at all coastal sites by 19-22Z.
Chances of VFR today at KSBA (50%) at KOXR (50%) KCMA (70%) KSMO
(80%) KLAX (80%) KLGB (80%). Timing of cloud arrival and coverage
of low clouds tonight expected to be later and less than
yesterday. Ceilings likely to be lower as well.

KLAX...80% chance of ceiling clearing. 19Z is the most likely
time, but could be as early as 18Z or as late as 21Z. Clouds will
return as early as as 02Z and as late as 06Z. Ceilings should be
OVC008-012. High confidence in any east winds staying well below
08 knots.

KBUR...High confidence in VFR conditions today by 17-18Z. There is
a 50% chance of ceilings forming again tonight, as early as 09Z
and as late as 12Z. If ceilings form, expect 1-3SM BKN005-008.

&&

.MARINE...04/937 AM.

Gusty northwest winds will remain over the offshore waters off the
Central Coast, but will be less expansive. There is a 70 percent
chance of Gale Force winds this afternoon and evening beyond 30
miles from the coast. Otherwise, Small Craft Advisory (SCA) winds
and/or seas will impacts the offshore waters down to San Nicolas
Island and the nearshore Central Coast Waters. These winds will
generate choppy seas over most of the coastal waters.

SCA winds are likely through Thursday through the offshore waters
off the Central Coast. Otherwise, high confidence winds will stay
under SCA, although seas near 10 feet are possible offshore.
Southeast winds will be prevalent each morning south of Point
Conception, which locally could exceed 15 knots near islands and
Channels.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory remains in effect from 10 AM Wednesday to 8 PM
      PDT Thursday for zones 38-343-344-379. (See LAXNPWLOX).
     Excessive Heat Warning remains in effect from 10 AM Wednesday
      to 8 PM PDT Thursday for zones 381>383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zones 645-676. (See LAXMWWLOX).
     Gale Warning in effect until 11 PM PDT this evening for zones
      670-673. (See LAXMWWLOX).

&&

$$

PUBLIC...Munroe
AVIATION...RK
MARINE...Kittell
SYNOPSIS...Hall/RM

weather.gov/losangeles

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