Gale Warning 19, NWS Los Angeles, CA

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
238 PM PDT Mon May 20 2019

.SYNOPSIS...20/237 PM.

Partly to mostly cloudy conditions are expected this week with
chances of showers mainly over the mountains and interior valleys.
Periods of widespread gusty winds are also expected through
Wednesday. High temperatures will remain well below normal
through the period.

&&

.SHORT TERM (TDY-THU)...20/235 PM.

A very challenging seven day forecast. An unseasonable (but not
unprecedented) cool and moist pattern will persist into next
week, with a series of upper level lows that drop through the
southern half of California.

The first upper level low will drop through northern California on
Tuesday, then swing through southern California by Wednesday
afternoon. There isn't a lot of moisture or lift with this one,
and the flow stays northwesterly. As a result, there is a decent
chance for showers over the mountains and areas north of Santa
Barbara sometime on Tuesday or Wednesday. Ventura and most of Los
Angeles Counties should be spared because of the shadowing
northwest flow, but feel a little uneasy about that because the
low itself will move over the area on Wednesday. Any
precipitation that does fall will be light (under 0.25 inches),
except for local amounts up to 0.50 inches on the northern slopes.
Thunderstorms are not in the forecast at this point, but there is
a little bit of instability Tuesday night and Wednesday, and a
stray thunderstorm or two is possible. Probably the most
noteworthy part of this storm will be the winds. Gusty west to
northwest winds will increase tonight and peak on Tuesday. The
winds should be very similar to what occurred last Friday, with
low-end Wind Advisory gusts likely over the most coastal areas, as
well as the mountains and Antelope Valley. This includes the
Sundowner territory of SBA County, especially Tuesday night. The
winds will continue through Wednesday, but be a touch lighter than
Tuesday.

For Wednesday night and Thursday, a piece of energy will rotate
around the Tuesday/Wednesday low and push through California. This
feature has better southerly flow compared the previous day, and
most of the ensemble members spit out some rain. Upped the PoPs
over the area, especially south and east of Santa Barbara as a
result, but still under what the ensembles suggest.

Temperatures will remain cooler than normal through Thursday, but
the northerly flow and near neutral onshore pressure gradients on
Wednesday may result in temperatures closer to normal nearer to
the coast.

.LONG TERM (FRI-MON)...20/233 PM.

Better chance than not that Friday and Saturday will be dry,
except for an outside chance of a light shower over the interior
areas. Temperatures will increase a little but remain below
normal with generally clearer skiers. Although very different in
the path of it, most computer projections continue to show yet
another upper level low pressure system moving through California
on Sunday, resulting in additional chances of rain. The difference
in the expected paths is leading to a large difference in
potential rain outcomes, so will have to wait a little longer
before trying to be too detailed on this one.

&&

.AVIATION...20/1805Z.

At 1730Z at KLAX, there was no marine layer nor an inversion, but
there was a moist layer up to 6000 feet or so.

Scattered to broken VFR clouds mainly across the mountains and
central coast terminals this morning and into the afternoon.
Gusty northwest winds expected for most areas through the early
evening hours. Expect patchy MVFR cigs across the LA coastal areas
after 09Z and areas of MVFR/IFR cigs and fog with vsbys 3 miles
at times north of Pt Conception until 17Z Tuesday.

Gusty west to northwest winds will affect the mountains and
Antelope Valley through Tuesday. Gusty west to northwest winds
will affect coastal areas this afternoon and evening. There will
be some gusty northwest to north winds through and below passes
and canyons of the Santa Ynez Range tonight. Some LLWS is expected
across the region through tonight.

KLAX....Moderate confidence in the 18Z TAF. There is a 30% chance
of MVFR cigs developing 10-17Z, otherwise VFR conditions
expected.

KBUR...High confidence in the 18Z TAF. There is a 20% chance of
MVFR cigs developing 11-16Z, otherwise VFR conditions expected.

&&

.MARINE...20/150 PM.

For the Outer Waters, seas will near or above Small Craft
Advisory (SCA) levels through Wed night, and winds will remain
gusty at 25-30 kts at times during the period. There is a 30%
chance of gale force winds Tuesday in zones PZZ673-676. In
addition, large hazardous seas are expected through Wednesday due
to a combination of the moderate period W-NW swell and steep wind
waves.

For the Inner Waters north of Point Conception, seas will likely
be at or above Small Craft Advisory (SCA) levels through Wed
night. Winds will likely reach SCA levels during the afternoon and
evening hours through Wed.

For the Inner Waters south of Point Conception...SCA level
conditions due to either winds or seas, or a combination of both
are likely to continue through Wed night. There is a 20% chance
of gale force winds Tuesday, mainly across western portions.

&&

.BEACHES...20/148 PM.

Large NW to W swell will generate periods of high surf along west
and northwest facing shores into Tuesday morning.

The largest surf will affect the Central Coast where a High Surf
Advisory is in effect through at least early Tuesday. The surf
will subside some on Tuesday but will remain close to advisory
level, then increase again by Wednesday. A High Surf Advisory is
also in effect for through early Tuesday for the Ventura County
beaches, where surf of 5 to 7 feet is expected on west facing
beaches.

A Beach Hazard Statement is in effect through Tuesday morning for
the Los Angeles County beaches for surf generally 3 to 6 feet.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 3 AM PDT Tuesday for zones
      34-35. (See LAXCFWLOX).
     Wind Advisory in effect until 6 AM PDT Wednesday for zone 39. (See LAXNPWLOX).
     High Surf Advisory in effect until 9 AM PDT Tuesday for zone
      40. (See LAXCFWLOX).
     Wind Advisory in effect from noon to 11 PM PDT Tuesday for
      zones 40-41-59. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Tuesday morning for
      zone 41. (See LAXCFWLOX).
     Wind Advisory in effect from noon Tuesday to 6 AM PDT
      Wednesday for zones 52>54. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 645-650-655-670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (THU-MON).

High surf should affect the beaches early Thursday.

&&

PUBLIC...Kittell
AVIATION...EB
MARINE...EB
BEACHES...EB
SYNOPSIS...Phillips

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