Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 140553
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
953 PM PST Thu Dec 13 2018

.SYNOPSIS...13/314 PM.

Temperatures will cool on Friday and there is a slight chance of
showers north of Point Conception. Saturday and most of Sunday will
be dry and a bit warmer then a chance of rain develops across the
region by Sunday night and continues into Monday. Dry and warmer
conditions return on Tuesday.

&&

.SHORT TERM (THU-SUN)...13/913 PM.

The latest satellite imagery indicates a ridge of high pressure
starting to break down and move east. A trough of low pressure
near 37N and 135W, or about 900 miles west-northwest of Point
Conception will dig into northern California through Friday
afternoon. A frontal boundary can be seen stretching from 500
miles of the Oregon Coast out to 32N and 142W. A lot of middle and
high level moisture moving in with the trough will stream over the
area through Friday and bring mostly cloudy skies to the region.
The frontal boundary looks to stall out near the Bay Area, but
enough of the trough`s influence could push into northern San
Luis Obispo County. PoPs have been nudged a tad higher for the
foothills of northwestern San Luis Obispo County for Friday.
Rainfall if any will depend where the frontal boundary stalls
out. Any amounts will be light, with a few hundredths at most. A
few minor tweaks were made to temperatures to cool them for Friday
and increase dewpoints and humidity across the Central Coast and
San Luis Obispo County.

*** From Previous Discussion ***

Skies will clear out Saturday with seasonal weather through the
weekend. We will start to see some increasing clouds from the
northwest Sunday ahead of the next system which could bring some
light precip to areas north of Pt Conception late Sunday night.

.LONG TERM (MON-THU)...13/220 PM.

The Monday system looks pretty similar as it has the last few days
with the bulk of the moisture and energy passing through northern
California. Still looks like a high chance of rain north of Pt
Conception and down to about SBA but chances fade to the east as
there`s very little southerly flow with the cold front and the
front will weaken as it moves across the area. Could see up to
around a half inch of rain across SLO County, but then tapering
down to a tenth or less in the south.

Skies and precip will clear out from the northwest starting
Monday afternoon with sunny/clear skies the rest of the week as
strong high pressure aloft builds over the area and gradients turn
offshore again. Gradients peak on Wednesday with enough upper
support to probably generate some advisory level Santa Anas across
LA/Ventura Counties. Temps will be warming up quite a bit, likely
mid to high 70s by Wed and Thu and possibly some lower 80s in the
warmest areas.

Although the ridge will flatten out somewhat later in the week
overall high pressure will dominate into next weekend with dry
weather and well above normal temps into early the following week
at least.

&&

.AVIATION...14/0551Z.

At 0510Z at KLAX, there was no marine layer. There was a surface
inversion up to around 1000 feet with a temperature near 22
degrees Celsius.

Very good confidence in TAFs. There is a 20 percent chc of a
shower at KSMX, KSBP and KPRB aft 21Z.

KLAX...Very good confidence in TAF. Any east winds are expected
to be less than 7 knots.

KBUR...Very good confidence in TAF.

&&

.MARINE...13/854 PM.

Moderate-to-high confidence in the current forecast. A moderately
large northwest swell across the coastal waters will persist
through Saturday night. This swell will diminish some Sunday.
Hazardous seas will likely persist for periods of time across
outer and northern coastal waters through Saturday night. Between
Sunday night and Tuesday, a very large swell is expected to build
into the coastal waters and affect west to northwest facing
harbors, including Morro Bay. Ventura Harbor could also be
affected on Monday through at least Tuesday as some of the energy
from the swell filters into the Southern California Bight.

&&

.BEACHES...13/841 PM.

An extended period of high surf continues to be likely at Central
Coast beaches through the early half next week. There is a 60
percent chance of very large and potentially damaging surf
developing between Sunday night and Monday. The latest swell
models build a west-northwest swell to between 18-22 feet off the
central California coast with periods between 19 and 20 seconds.
Swell energy could possibly push into Southern California Bight
between Sunday and Monday.

If swells develop inline with model guidance, surf of 15-20 feet
with sets up to 25 feet will be possible at west and northwest
facing beaches along the Central Coast between Sunday night and
Tuesday. South of Point Conception, west facing shores could
potentially see surf between 8-12 feet.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 8 PM PST Saturday for
      zones 34-35. (See LAXCFWLOX).
PZ...Small Craft Advisory for hazardous seas in effect until 9 AM
      PST Friday for zones 645-670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SUN-THU).

Very high surf and dangerous rip currents are expected Monday and
Tuesday.

&&

$$

PUBLIC...Hall/MW
AVIATION...Rorke
MARINE...Hall
BEACHES...Hall
SYNOPSIS...Kj

weather.gov/losangeles


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