Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 170533

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1033 PM PDT Wed Jun 16 2021

.SYNOPSIS...16/914 PM.

A very warm to hot air mass will remain in place through the end
of the week as high pressure continues to dominate over the Desert
Southwest. A cooling trend is expected over the weekend and into
early next week with an increase in coastal low clouds and fog.


.SHORT TERM (WED-SAT)...16/952 PM.

High pressure remains anchored over the Four Corners region this
evening. A very warm to hot air mass will continue across the area
through the end of the week, except for the coastal sections where
onshore flow will likely keep the air mass moderated and bring a
slight cooling trend. As a bit more onshore flow brought cooler
temperatures for the Los Angeles County, onshore flow is likely
to continue the cooling along the beaches. The latest satellite
imagery is currently showing low clouds and fog starting to fill
in across the coastal waters as an eddy circulation gains
strength. Low clouds and fog are already pushing north from
between Pacific Palisades west to Point Mugu and into the Oxnard
Plain. The marine layer deck is acting very aggressively and it
is looking like it will make a good push along the coastal waters
tonight and push into most beaches by Thursday morning. As a
result, temperatures were tweaked down slightly for Thursday along
the beaches. With the tight marine inversion in place, clouds
could struggle to clear from the beaches on Thursday afternoon.

Outside of the marine layer, temperatures will remain very warm
and downright hot away from the coast. High temperatures are
forecast to hit record levels again across the interior at sites
such as Paso Robles, Sandberg, Palmdale, and Lancaster. Excessive
heat warnings remain in effect through Saturday evening across
the interior, while heat advisories remains in effect for the
coastal valleys through Thursday evening.

***From Previous Discussion***

.LONG TERM (SUN-WED)...16/209 PM.

The ridge remains in place through early next week though it
weakens as a trough approached northern California. Sunday is a
marginal heat risk day for the interior but ensembles suggest
highs across the Antelope Valley to drop under 105 which would
take it out of the heat warning category. Elsewhere, the cooling
trend that had begun earlier will continue as onshore flow
increases into next week. Temps will remain above normal most
areas until Monday or Tuesday, then hover within a few degrees of
normal through the remainder of the week. Expect marine layer
stratus to deepen enough to reach the coastal valleys by Tuesday
if not sooner. Otherwise, a pretty quiet week with more seasonable



At 0453Z, the marine inversion at KLAX was based at 1400 feet.
The top of the inversion was 4800 feet with a temperature of 32
degrees Celsius.

Overall, moderate to high confidence in 06Z TAFs. High confidence
in VFR conditions for the desert sites. Moderate confidence in
return of CIG/VSBY restrictions to KSMX, KSBA, KCMA, KSMO, and

KLAX...Overall, moderate confidence in 06Z TAF. For tonight,
moderate confidence in return of CIG/VSBY restrictions, but low
confidence in timing and flight category. Easterly wind component
should remain below 7 kt, with the best chance now until 07Z

KBUR...High to moderate confidence in 06Z TAF, with a 20% chance
of cigs after 09Z.


.MARINE...16/911 PM.

For the Outer Waters, moderate to high confidence in current
forecast. High confidence in Small Craft Advisory (SCA) level
winds through tonight/Thursday morning. For Thursday afternoon
and Friday, high confidence in winds and seas remaining below
SCA levels. For Saturday through Monday, there is a 50% chance
of SCA level winds.

For the Inner Waters north of Point Sal, high confidence in
current forecast. SCA level winds will develop this afternoon
and evening. For Thursday through Monday, winds and seas will
remain below SCA levels.

For the Inner Waters south of Point Conception, moderate to high
confidence in forecast. Today through Saturday, high confidence in
winds and seas remaining below SCA levels. For Sunday and Monday,
there is a 50% chance of SCA level winds across the western half
of the Santa Barbara Channel while winds and seas are expected to
remain below SCA levels elsewhere.

Patchy dense fog will impact the southern coastal waters tonight
and Thursday.


CA...Heat Advisory in effect until 9 PM PDT Thursday for zones
      36-44>46-547. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 9 PM PDT Saturday for
      zones 37-38-51>54-59. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 9 PM PDT Thursday for
      zone 88. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 645-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Thursday for
      zone 670. (See LAXMWWLOX).



Very hot temperatures are expected across the mountains and
Antelope Valley Saturday, with heat-related illness concerns.



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