LA Area Forecast Discussion

FXUS66 KLOX 272051

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
151 PM PDT Tue Sep 27 2022

.SYNOPSIS...27/922 AM.

Persistent high pressure and the associated heat wave will peak
today and Wednesday before a weak low to the north brings cooler
conditions to the region Thursday. Cooler weather should last
through the weekend with increasing night to morning low clouds
and onshore winds.


.SHORT TERM (TDY-FRI)...27/128 PM.

Another hot day across the area, though not so bad near the coast
where temps have been mostly in the 70s and 80s despite the 2-4
degree rise today from yesterday`s highs. Light offshore gradient
trends are expected to continue into Wednesday with the only real
difference tomorrow being a stronger onshore push later in the
afternoon. That should help keep the coastal areas all below heat
advisory criteria but likely too late for the valleys and at least
the interior portion of the Santa Monicas where highs should top
out near or possibly just a degree or two lower than today. So
will end all coastal heat advisories today and continue the inland
warnings one more day.

After Wednesday high temps should begin a steady decline to normal
through the rest of the week as onshore flow returns and
heights/thicknesses drop. Expect we`ll see an eventual return of
the marine layer to areas south of Pt Conception but a persistent
northerly flow across western Santa Barbara County may limit that
to LA and possibly Ventura Counties until those lighten up
Thursday and Friday. Those winds could reach close to advisory
levels on the far western end between Refugio and Pt Conception the
next couple nights but will hold off on that for now.

.LONG TERM (SAT-TUE)...27/136 PM.

Ensembles showing high confidence in a continuing cooling trend
for coast and valleys through the weekend as weak troughing
develops. By Saturday most areas will be near to slightly below
normal. The far interior will be the only areas above normal. A
slow climb is expected to begin early next week as high pressure
redevelops. Overall, a very quiet pattern locally with no
temperature extremes and generally light winds.



At 1741Z, the marine layer depth was around 500 feet deep at
KLAX. The top of the marine inversion was near 1600 feet with a
temperature around 28 degrees Celsius. There was another inversion
up to around 3300 feet.

High confidence in the current forecast for valley and desert
terminals. Moderate confidence in the current forecast for coastal
terminals. There is a slight chance (20 percent) of LIFR to IFR
conditions after 09Z Wednesday south of Point Conception. The
highest chance (60 percent) of LIFR to IFR conditions will be for
coastal terminals north of Point Conception. Otherwise, VFR
conditions are expected through the period.

KLAX...There is a 20 percent chance of LIFR to IFR conditions
after 09Z Wednesday. Any easterly winds after 07Z Wednesday
should remain less than 7 knots.

KBUR...VFR conditions are expected through the period. There is a
20 percent of cross winds greater than 10 knots between 01Z and


.MARINE...27/151 PM.

No changes to the marine forecast in the afternoon issuance.

For the waters from southwest through northwest of the Channel
Islands and along the Central Coast, widespread SCA conditions
will develop through this afternoon and very likely persist
through at least Thursday night. Winds will likely be strongest
during the afternoon and evening hours and extend closer to the
shore in the nearshore waters. Winds and seas should drop below
SCA levels on Friday. In addition, a shallow marine layer depth
through Wednesday could produce dense fog, at times reducing
visibility to one nautical mile or less.

Inside the southern California bight, there is a moderate (30-50
percent) chance of SCA levels winds with choppy short period seas
across the western portion of the Santa Barbara Channel each
afternoon and evening through Thursday night, and a SCA has been
issued for this evening. Otherwise, winds and seas will likely
remain below SCA levels.


CA...Excessive Heat Warning in effect until 8 PM PDT Wednesday for
      zones 88-363-547-548. (See LAXNPWLOX).
     Heat Advisory in effect until 8 PM PDT Wednesday for zones
      356>359. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 8 PM PDT this evening
      for zone 365. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 670-673-676. (See LAXMWWLOX).




Experimental Graphical Hazardous Weather Outlook at:

NWS LOX Office Area Forecast Discussion