Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 150423

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
923 PM PDT Fri Aug 14 2020

.SYNOPSIS...14/757 PM.

Very hot conditions will continue into the middle of next week,
especially for valley and interior areas. There is a slight
chance of isolated afternoon and evening thunderstorms through


.SHORT TERM (FRI-MON)...14/921 PM.

Hot weather materialized as expected today with some locations
tying or setting new records. The hot air mass will remain in
place through the weekend as an upper-level ridge of high pressure
over southern Arizona will strengthen and build into southwest
Utah through Sunday. Minimal, if any, stratus coverage will exist
Low clouds and fog will be patchy at best as onshore flow is
fairly weak. Excessive heat warnings remain in place across much
of southern California, except for the South Coast portion where
enough marine influence exists.

A tricky forecast is in play tonight and into Saturday as model
solutions are suggesting instability and moisture moving north
late tonight or early Saturday morning across the area. PoPs have
been nudged a little higher through Saturday and Saturday evening.
Increasing the chances for showers and thunderstorms over the
mountains and desert. A little less clear are the areas west of
the mountains. Some model solutions do indicate convection
spilling over west of the mountains between Saturday morning and
Saturday night. PoPs have been nudged higher, but it is not clear
cut.The next shift will be briefed accordingly.

***From Previous Discussion***

High-resolution models show an eddy circulation spinning up Sat
night/Sun morning, with some night thru morning low clouds getting
pushed into coastal sections of L.A. and VTU Counties. Otherwise,
expect mostly clear to partly cloudy skies. The clouds could
bring some cooling on Sunday in the LA basin. For the rest of the
area, GEFS pulls monsoonal moisture in from the southeast making
conditions hot and humid with chances of afternoon thunderstorms.

The upper pattern will change little Monday, with the strong
upper high centered in southern Nevada peaking in strength at
around 600 dm. Chances of afternoon thunderstorms persist.

.LONG TERM (TUE-FRI)...14/156 PM.

There will be very little change in the pattern on Tuesday, with
the high continuing at nearly 600dm. Tuesday is the last day of
the monsoonal flow and afternoon thunderstorm chances. The high
remains in place but slowly weakens Wednesday though Friday when
it has dropped nearly 10 dm in strength.



At 23Z, the marine layer depth was around 500 feet deep at KLAX.
The top of the inversion was around 2600 feet with a temperature
near 32 degrees Celsius.

Moderate confidence in the current forecast for coastal terminals.
High confidence in the current forecast for valley terminals.
There is a slight chance to chance of LIFR conditions at coastal
terminals, highest from KSBA north. There is a chance of MVFR
conditions in smoke for desert terminals between 10Z and 16Z.
Otherwise, VFR conditions are expected through the period.

KLAX...There is a 10 percent chance of LIFR conditions between 11Z
and 15Z. No wind impacts are expected at this time.

KBUR...VFR conditions are expected through the period. No wind
impacts are expected at this time.


.MARINE...14/905 PM.

Across the outer waters, winds will continue near Small Craft
Advsory levels through at least early next week across much of the
outer waters. Otherwise and elsewhere, conditions will remain
below SCA level.

Across the nearshore waters of the Central Coast, winds will
likely increase to SCA level in the afternoon and evening hours of
Monday through Wednesday. Otherwise, conditions will remain below
SCA level through the forecast period.

Across the inner waters south of Point Conception, there is a
chance of SCA level winds for the western portion of the Santa
Barbara Channel Saturday evening. Otherwise, conditions will
remain below SCA level throughout the forecast period.


CA...Excessive Heat Warning in effect until 9 PM PDT Saturday for
      zone 36. (See LAXNPWLOX).
     Heat Advisory in effect from 9 PM Saturday to 9 PM PDT Sunday
      for zone 36. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 9 PM PDT Wednesday for
      zones 37-38-44>46-51>54-88-547. (See LAXNPWLOX).
     Heat Advisory in effect until 9 PM PDT Sunday for zone 41. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 9 PM PDT Thursday for
      zone 59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 3 PM Saturday to 3 AM PDT
      Tuesday for zones 670-673-676. (See LAXMWWLOX).



Triple digit high temperatures and very warm nights will bring
the potential for excessive heat over many areas into Tuesday or
longer. There is a slight chance of afternoon thunderstorms through



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