Gale Warning 38, NWS Los Angeles, CA

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
936 PM PDT Wed Sep 23 2020

.SYNOPSIS...23/838 PM.

A minor cooling trend will develop Thursday and Friday as a weak
low moves over the area. Low clouds and dense fog are likely near
the coast from Santa Barbara south tonight into early Thursday.
A stronger ridge aloft will rebuild over the weekend, with high
temperatures slightly above normal by Sunday. More significant
warming is expected Monday through Wednesday with valley highs in
the triple digits and coastal areas in the 80s.

&&

.SHORT TERM (WED-SAT)...23/934 PM.

The latest satellite imagery shows ridging aloft over the
Southwest. Ridging aloft will attempt to cling to the area over
the next several days as an upper-level trough of low pressure
advances toward the Pacific Northwest. A small piece of the
trough will clip the area Thursday and should bring slight cooling
to the area.

Stratus coverage is minimal at this time. The latest fog product
imagery shows stratus very disorganized south of Point Conception
but becoming more organized along the Central Coast of California.
A shallow marine layer should remain in place tonight and any
stratus forming over the coastal areas should become dense fog.

An update will issued for the stratus coverage for tonight through
Thursday morning.

***From Previous Discussion***

The ridge will weaken through Fri as a trough passes north of the
area, cooling temps a few degrees. Then high pressure will start
to rebuild Saturday beginning a warming trend that will continue
into next week. A shallow marine layer will maintain areas of low
clouds and dense fog near the coast. Though increasing northerly
flow Thu/Fri will likely push that even farther south over the
weekend. Northerly winds not expected to reach advisory levels but
could get some gusts close to 35 mph in the usual favored srn SB
County areas such as the Gaviota/Refugio areas.

.LONG TERM (SUN-WED)...23/157 PM.

The warming trend will continue Sunday and really kick into gear
Monday and Tuesday as a strong ridge encompasses most of the
western third of the US. Still not seeing much in terms of
offshore flow so while temps will be well above normal at the
coast the inland areas will be feeling it the most with widespread
temps in the triple digits each day, and the warmest day either
being Tuesday or Wednesday. Records are quite high during this
period (including the all time Downtown LA high of 113 on Sunday)
so it will be a stretch to break them, though if it happens
Tuesday is likely the best chance as records aren't quite as high
that day. Current forecast temps place many inland areas into heat
advisory criteria Monday and even more so Tuesday/Wednesday and
including some coastal zones. Strong consideration will need to be
given for an Excessive Heat Watch next week and people planning
outdoor activities should be aware of the heat risks next week and
plan accordingly. The high pressure ridge is expected to remain in
place most of next week so while temps are expected to cool a few
degrees after Wednesday it will still be 5-10 degrees above normal
in many areas.

&&

.AVIATION...24/0032Z.

At 23Z, the marine layer depth was around 700 ft deep at KLAX.
The top of the marine inversion was near 1600 ft with a
temperature near 26 degrees Celsius. There was another inversion
above to around 2200 feet.

Low to moderate confidence in the current forecast for coastal
terminals. High confidence in the current forecast for valley
terminals. There is a chance of LIFR to IFR conditions for coastal
terminals between 08Z and 17Z. There best chance of LIFR
conditions will be for terminals from KLAX north.

KLAX...There is a 50 percent chance of LIFR to IFR conditions for
coastal terminals between 08Z and 17Z. The onset of LIFR to IFR
conditions could delay up to 4 hours later than forecast. VFR
conditions should develop between 16Z and 18Z. 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...23/917 PM.

Across the outer waters, Small Craft Advisory (SCA) level NW
winds will continue through Sat, except possibly only through Fri
night in the southern zone. There is a 60% chance of Gale Force
winds late Thursday afternoon through Thursday night, and a Gale
Watch has been issued for that time period. Large seas will
affect the outer waters Thu night through Friday night into early
Saturday.

Across the inner waters north of Point Sal, SCA level winds are
likely during the afternoon and evening hours Thursday, and again
on Friday. Seas will likely rise to near or above 10 feet Thursday
night and remain above that level through Friday.

Across the inner waters south of Pt Conception, there is a 40%
chance of SCA level winds across the western Santa Barbara Channel
late Thurday afternoon and evening. Otherwise, SCA conds are not
expected through Sunday.

Patchy dense fog will affect the coastal waters tonight through
Thursday morning.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 PM PDT Thursday for
      zones 670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from Thursday afternoon through late
      Thursday night for zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SAT-WED).

Strong high pressure is expected to build over the West Coast
next week. Heat stress and elevated fire weather conditions will
be possible, especially Monday through Wednesday.

&&

PUBLIC...Hall/MW
AVIATION...Hall
MARINE...Smith
SYNOPSIS...MW/Smith

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