809
FXUS66 KLOX 051513
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
813 AM PDT Wed Jun 5 2024

.SYNOPSIS...05/226 AM.

High pressure over the region will continue the warming trend
through today, most pronounced away from the coast. The marine
layer will continue to bring some night through morning low clouds
to the coastal and valley areas. well above normal temperatures
will continue across the interior valleys for much of this week.
Closer to the coast, high temperatures will be moderated by the
marine layer and moderate to strong onshore flow.

&&

.SHORT TERM (TDY-FRI)...05/812 AM.

***UPDATE***

Latest satellite and surface observations indicate low clouds/fog
across the coastal plain and into some the coastal valleys this
morning with clear skies elsewhere. Morning sounding data
indicates marine inversion ranging in depth from 500 feet north of
Point Conception to around 1500 south of Point Conception.

Forecast-wise for the immediate short term, main concern will be
interior heat, and to a lesser extent, the behavior of the marine
layer stratus. With regard to the heat, morning TEMP STUDY data
indicates 950/850 MB temperatures are up several degrees which
should result in some significant warming for interior sections.
Currently, EXCESSIVE HEAT WARNINGs for the Antelope Valley and
HEAT ADVISORIES for interior SLO/SBA counties and the Western San
Gabriel Mountains look on-track today with high temperatures
climbing into the upper 90s to 107. For areas closer to the coast,
the continuing marine influence will greatly limit the potential
warming. As for the low clouds/fog, will expect most areas to
clear by late morning, but some coastal areas could stay on the
cloudy side through the afternoon.

Overall, current forecast has good handle on the immediate short
term. So, no significant updates are expected. For the afternoon
forecast, attention will be focused on continued hot conditions
inland on Thursday and increasing marine influence this weekend.

***From Previous Discussion***

Today will be the warmest day of the next 7. Offshore trends will
lead to a weaker seabreeze, hgts will will approach 590 dam and
subsidence aloft will all combine to bring warmer conditions to
the area. Most areas will warm with the exception of the Central
Coast where an earlier sea breeze will knock off 2 or 3 degrees
from ydy`s readings. The marine layer will greatly temper the
coastal warming which will only be a degree or two. Further away
from the coast the vlys will warm 3 to 6 degrees where max temps
will end up in the 80s and lower 90s. The mtns and far interior
(which will be unaffected by the sea breeze) will see the
greatest warming of 5 to 10 degrees. This warming will bring max
temps up into the triple figures and will end up 15 to 20 degrees
above normal.

Dangerous heat will occur in the far interior both today and
Thursday. Heat Advisories continue for the I-14/Acton area of the
LA mountains, the Cuyama Valley, the interior San Luis Obispo
County including the Paso Robles area. An Excessive Heat Warning
also continues 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.

The ridge weakens a little on Thursday but not enough to cool the
interior where the heat advisories and warnings will continue. The
coasts and vlys will cool as a ~2mb onshore trend will bring a
stronger and earlier sea breeze. Just enough mid level moisture
will arrive from the south to warrant around a 15 percent chance
of showers or thunderstorms over the higher mountains in Los
Angeles, Ventura, and perhaps Santa Barbara County.

The ridge will weaken further on Friday and the onshore
gradients will continue to increase. In fact the onshore push to
the east may hit 10 mb. This will keep the morning low clouds
stuck to the west facing beaches. There may be advisory level wind
gusts across the western Antelope Vly foothills as well. Max
temps will cool 3 to 6 degrees across the board. This will cool
the interior to about 8 degrees above normal, while the coasts and
vlys will return to normal day time highs.

.LONG TERM (SAT-TUE)...05/315 AM.

The ensembles are all in decent agreement for the weekend forecast
and there is good confidence that a June Gloom pattern will occur.
A saggy baggy trof will be overhead and an east pac sfc high will
bring strong onshore flow to the area. Look for the night through
morning low cloud pattern to extend all the way to the coastal
slopes with slower than normal clear and no clearing at many west
facing beaches. There will be gusty winds each afternoon across
the interior and esp the western Antelope Vly. Temps will cool
some each day more so on Sunday when hgts fall some.

The ensembles diverge for Monday and Tuesday. The EC ensembles
favor a decent cut off low over or near to the state while most
GFS members favor a weaker and morn westward system. For now will
lean the forecast towards the GFS soln as it makes more
climatological sense. Look for a persistence night through morning
cloud pattern with slightly below normal coastal temps and
slightly above normal temps across the mtns and far interior.

&&

.AVIATION...05/1508Z.

At 15Z at KLAX, the marine layer was 1600 ft deep. The top of the
inversion was at 3600 ft with a temperature of 27 Celsius.

IFR/MVFR ceilings and visibility will be common today where/when
clouds exist. Moderate confidence in clearing being slower at
KSBA KOXR KCMA KSMO KLAX KLGB. There is a possibility in 2 hours
or less of clearing at KSBA (30%) KOXR (60%) KCMA (40%). High
confidence in all sites that saw ceilings again today will see
them again tonight into Thursday, with the possible addition of
KPRB (30%). Ceilings and visibility should be improved compared to
today, with 5-8SM and OVC008-015 most common.

KLAX...Ceilings likely to clear today, as early as 17Z and as
late as 20Z. Ceilings will return tonight as early as 02Z and as
late as 06Z. High confidence that any ceilings will be above
OVC010. High confidence in any east winds staying below 8 knots.

KBUR...Ceilings likely to clear today, as early as 16Z and as
late as 18Z. Ceilings will return tonight as early as 06Z and as
late as 10Z. Moderate confidence that ceilings OVC008-012 will be
common, but low confidence on timing of when it will be IFR or
MVFR.

&&

.MARINE...05/727 AM.

Moderate confidence that local Small Craft Advisory (SCA) winds
and seas will continue through this evening for the offshore
waters off the Central Coast. Otherwise, southeast to southwest
winds will be dominant through Thursday. Winds will peak around 15
knots in the afternoon and in the morning between the islands and
through any channels. There is a 30% chance of SCA level winds
late Sat thru Sun, especially off the Central Coast.

Reduced visibilities are expected each morning through at least
the weekend, possibly dense each morning and below one mile from
Santa Barbara to the Central Coast.

&&

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

&&

$$

PUBLIC...Rorke/Thompson
AVIATION...RK
MARINE...Kittell
SYNOPSIS...30

weather.gov/losangeles

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