Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 200435
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
935 PM PDT Tue Jun 19 2018

.SYNOPSIS...19/934 PM.

High pressure in place over the region will bring above normal
temperatures with fair skies through the week, except for near
persistent conditions near the coast with night through morning
low clouds and fog. A cooling trend is expected over the weekend
into early next week as the high weakens.

&&

.SHORT TERM (TUE-FRI)...19/933 PM.

A high pressure system remains over the area this evening as the
ridge center aloft nudges closer to the Baja California coast.
Subsiding air with the high pressure system is pressing down on
top of the marine layer. Onshore flow will continue to weaken into
Wednesday as the ridge axis moves across the area. A warming
trend will continue along with a stretch of several very warm
days across the region. Marginal criteria could be met for an
Excessive Heat Advisory or Excessive Heat Warning over the next
several days. The next shift will be briefed about heat criteria
as it is borderline.

A shallow marine layer in place will hug the coast the next
several days, possibly creating June Gloom type conditions across
portions of the coastal sections. The beaches north of Point Mugu
could struggle to clear the next several days as the subsidence
inversion combines with the marine inversion and limits mixing
into the boundary layer. Near persistence seems to be the best
forecast at the beaches the next several days.

A Wind Advisory was added for the Santa Barbara South Coast and
Mountains through 4 am PDT as KSBA-KSMX surface pressure
gradients have tightened to -3.7 mb. Wind gusts between 45 and 50
mph have developed in the foothills this evening and should spread
down into the South Coast portion late this evening.

An update will be issued shortly.

*** FROM PREVIOUS DISCUSSION ***

The ridge does weaken slightly Thursday as a trough pushes
onshore across the Pac NW and this probably will lead to a degree
or two of cooling but may not even be noticeable to most. With the
marine layer shrinking to 1000` or less there will likely be some
patchy dense fog, especially north of Pt Conception.

.LONG TERM (SAT-TUE)...19/152 PM.

The ridge gets knocked down a little Saturday as a trough drops
into the Great Basin. Onshore flow will be increasing as well both
west/east and south/north so a stronger and earlier sea breeze
will definitely be cutting into the temperatures over the weekend
despite heights staying at or above 590dm. Temperatures will more
or less level off Sunday/Monday at near to slightly above seasonal
norms as the sea breeze can only cool temps so much with the air
mass aloft still being very warm. Marine layer will push a little
further inland but the subsidence and warm air aloft will keep
clouds mostly confined to coastal areas. Overall a very quiet
pattern. Only concern might be with the increasing onshore flow
and still warm and dry conditions inland leading to an enhanced
fire risk.

&&

.AVIATION...20/0010Z.

At 23Z, the marine layer depth was around 1400 feet deep at KLAX.
The top of the inversion was near 3500 feet with a temperature
around 23 degrees Celsius.

Moderate confidence in the current forecast. LIFR to IFR
conditions will likely develop at most coastal terminals through
12Z. There is a chance of LIFR conditions at valley terminals
between 10Z and 16Z. Conditions should improve one category
between 15Z and 16Z. There is a chance of IFR to MVFR conditions
lingering into Wednesday afternoon, highest at Ventura County
coastal terminals.

KLAX...There is a 80 percent chance of IFR to MVFR conditions
developing as soon as 02Z or as late as 08Z. There is a 30
percent chance of IFR to MVFR conditions lingering until as late
as 19Z, but more likely between 16Z and 18Z.

KBUR...There is a 30 percent chance of LIFR conditions between
10Z and 16Z.

&&

.MARINE...19/748 PM.

For the Outer Waters, high confidence in current forecast. There
is an 80% chance of Small Craft Advisory (SCA) level northwest
winds tonight through Saturday with the strongest winds during
the afternoon and evening hours.

For the Inner Waters, high confidence in current forecast. For the
waters north of Point Sal, there is a 60%-70% chance of SCA level
northwest winds each afternoon/evening Thursday through Friday.
For the waters south of Point Conception, winds and seas are
expected to remain below SCA levels through Saturday although
there is a 30% chance of SCA level winds each afternoon/evening
across the western half of the Santa Barbara Channel.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 4 AM PDT Wednesday for zones
      39-52. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (FRI-TUE).

No significant hazards expected.

&&

$$

PUBLIC...Hall/MW
AVIATION...Hall
MARINE...Sweet/Sirard
SYNOPSIS...STu/Hall

weather.gov/losangeles


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