Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 260709
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1209 AM PDT Fri May 26 2017

.SYNOPSIS...
The low will push the marine layer...possible precipitation and
below normal temperatures farther inland into Saturday. A high will
build in over the weekend to push the marine layer back to the coast
with above normal temperatures for early next week. Another low may
approach near midweek for increasing clouds and cooling trend.

&&

.SHORT TERM...(TDY-SUN)

A weak upper-level trough of low pressure currently centered over
the Southern California Bight will move east into the Los Angeles
County later tonight and into the Lower Colorado River Basin by
Friday morning. A strong onshore flow and deep marine layer in
place will continue a cool and cloudy weather pattern into Friday.
The deep marine layer could interact with the upper-level dynamics
to squeeze out drizzle or light showers through Friday morning. A
weak warm air advective pattern does develop later tonight in the
lower levels, possibly producing light rain or rain showers
across the Southland. PoPs have been nudged higher for tonight and
Friday morning and mentions of isolated showers have been
expanded across the South Coast Basin.

A wind advisory for the San Luis Obispo County Valleys was allowed
to expire at 9 pm this evening, but extended for the Antelope
Valley through 9 am Friday. There is a decent chance that this
advisory could be extended for the Antelope Valley through Friday
evening as strong southwest winds could linger.

The marine layer depth currently near 3700 feet deep could deepen
slightly overnight and push stratus clouds into the Antelope
Valley around daybreak Friday. Some clouds have been introduced
into the Antelope Valley for Friday morning, but there is a chance
that the cloudiness mentioned could be well underdone.

*** FROM PREVIOUS DISCUSSION ***

With the inversion continuing to weaken tomorrow there`s a chance
that we could see a reverse clearing pattern Friday where it
stays cloudy inland but clears better towards the coast.

Warming aloft will begin Saturday behind the trough passage but
the marine lyr should still be at least 3000` deep. Better
clearing expected Saturday as the ridge builds aloft and onshore
gradients weaken. Temps will warm around 5 degrees most areas.

The warming trend will continue Sunday as the ridge continues to
build over the west coast. Inland highs expected to climb around
10 degrees from Saturday`s levels and coastal areas warming 2-5
degrees.

.LONG TERM...(MON-THU)

Warming trend to continue at least into Monday before the ridge
starts to shift east ahead of an advancing trough over the eastern
Pacific. Both the GFS and ECMWF split off some energy from the
trough and develop a closed low circulation over nrn Baja late
Tuesday into Wednesday. So probably one more day of either similar
or slightly warmer temps Tuesday and then cooling by Wednesday
with the upper low. Again there is no moisture with this low but
it will deepen the marine lyr and cool things off slightly for the
latter half of the week. Nothing like what we`re seeing now but at
least back to near normal temps.

&&

.AVIATION...25/0700Z.

At 06Z, the marine inversion at KLAX was 4500 feet deep. The top
of the inversion was 5700 feet with a temperature of 14 degrees
Celsius.

Moderate confidence in respect to VFR cigs with deep moist layer
across forecast areas W of the deserts. Lower confidence in some
MVFR cigs possible, especially across the CentralCoast and near
the foothills. Also, it`s hard to maintain a deep marine layer for
a period of time. There will be a 30% chance that the moist layer
could dissolve sometime this morning. Also figuring low clouds
will scour out quicker at the coast and probably linger across
valleys and adjacent foothills today. Typical for this kind of
regime. Also known as reverse clearing. Lower confidence for
timing if low clouds redevelop tonight into Sat. Low clouds should
redevelop before 06z in most coast and valley locations.
KLAX AND KBUR...Ceilings at or below 5000 feet are expected to
persist through today. Confidence is moderate for VFR or high
MVFR cigs to fill in again after 02Z to 06Z.

&&

.MARINE...25/900 PM.

High confidence sub-Small Craft Advisory conditions through
Friday. Gusty northwest winds should reform over the
weekend...with Small Craft Advisory level winds developing from
the Central Coast to San Nicolas Island and short period seas
likely for the Santa Barbara Channel and Santa Monica Basin. There
is a 30 percent chance for Small Craft Advisory conditions over
the western half of the Santa Barbara Channel on Saturday
afternoon and evening, increasing to 60 percent on Sunday
afternoon and evening.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 9 AM PDT this morning for zone
      59. (See LAXNPWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK...(SUN-THU)
No significant hazards expected.

&&

$$

PUBLIC...Hall/MW
AVIATION...Kaplan
MARINE...Hall
SYNOPSIS...STu

weather.gov/losangeles


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