Duarte Weather

819
FXUS66 KLOX 190118
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
518 PM PST Tue Dec 18 2018

...Aviation discussion updated...

.SYNOPSIS...18/1210 PM.

High pressure aloft will build in over the region the next
several days. A warming and drying trend with gusty northerly
winds will develop through Thursday with temperatures warming to
above seasonal levels from Wednesday to Friday. A cool down is
likely Friday, becoming more pronounced over the weekend into next
week.

&&

.SHORT TERM (TUE-FRI)...18/216 PM.

Upper ridge building in over California and the west coast
beginning a period of a few days with above normal temps.
Northerly flow is increasing today and will shift to northeast
Wed/Thu and provide an additional warming influence at lower
elevations due to the downsloping winds, especially south of Pt
Conception. Tonight`s northerly winds should be at least
marginally advisory criteria in the hills and below passes and
canyons of the Santa Ynez Range in srn SB County. SBA-SMX and
SBA-BFL gradients are decent but the 18z NAM backed off somewhat
on the winds aloft from what the 12z run showed so it may not be
quite as strong as expected earlier nor last as long into
Wednesday. Will go with a 3am expiration for now and if winds
develop and are still going that can be extended.

Otherwise forecast more or less on track. The Santa Ana winds do
not appear to be advisory level strength Wed/Thu but will be
enough to warm up temps with highs near 80 possible Thu.

Cooling expected for coast/valleys Fri as gradients trend onshore
due to an approaching trough that will will move through Friday
afternoon but generate nothing more than some clouds.

.LONG TERM (SAT-TUE)...18/208 PM.

The Friday trough will be the first in a line of impulses moving
through a broad west to northwest flow aloft across the eastern
Pacific into next week. Through Monday none of these systems are
expected to drop far enough south to bring rain south of Monterey
County. However, there will be periods of extensive mid and high
clouds, especially over the weekend. Temps on Sunday are expected
to warm up slightly as gradients briefly turn weakly offshore.
Then turn cooler Mon/Tue as another possibly stronger system moves
into the area. Models differ quite a bit on this with the GFS
taking it more north and east (ie. drier inside slider path) while
the ECMWF is much colder and farther west (though still more
inland than over water). Definitely not a sure bet for rain and
ensemble members favor the drier inside path that the operational
GFS shows. But the pattern definitely is changing next week and
precip looks to be a good bet at some point with below normal
temps and potentially low snow levels.

&&

.AVIATION...19/0116Z.

At 23z at KLAX... there was an inversion near 2250 feet. The top
of the inversion was near 5000 feet with a temperature of about 14
degrees Celsius.

Overall... Moderate to high confidence in the TAFs. KPRB will have
VLIFR/LIFR conditions 10z-21z. There is a less than ten percent
chance of patchy low clouds and fog along the coast south of Point
Conception 10z-18z. Otherwise and elsewhere VFR conditions will
prevail.

KLAX... Moderate to high confidence in the TAF. There is a less
than ten percent chance of patchy low clouds and fog 10z-18z.
Otherwise VFR conditions will prevail throughout the forecast
period. No east winds greater than eight knots will occur during
the forecast period.

KBUR... High confidence in the TAF. VFR conditions will prevail
throughout the forecast period.

&&

.MARINE...18/955 AM.

Moderate to high confidence in the current forecast. A very large
WNW swell will continue to move through the coastal waters
through today. This swell will affect west to northwest facing
harbors, including Morro Bay, where dangerous breaking waves will
be possible in the harbor entrance. In addition, breaking waves
will be possible in shallower water areas outside the typical surf
zone. Moderate-to-high seas will then persist Wednesday through
Thursday.

Small Craft Advisory (SCA) winds will affect the southern outer
waters zones (PZZ673 and PZZ676) through tonight or Wednesday.
Another round of SCA winds will be possible for the entire outer
waters Friday and Saturday, with a 50%-60% chance of this
occurring.

For the inner waters, winds are expected to remain below SCA
levels through Saturday.

&&

.BEACHES...18/959 AM.

Surf heights will slowly subside the rest of today through mid
week before another large west northwest swell moves into the area
for later in the week. High Surf Advisories are likely to be
needed for several days.

The Coastal Flood Advisory has expired. Water could locally spill
into normally dry beaches, beach parking lots and harbor
walkways. There is a risk of large breaking waves across the
Morro Bay Harbor entrance, which could capsize small boats.

Some of this large swell energy has affected areas south of Point
Conception, impacting west-facing beaches of LA, Ventura, and
southern SBA Counties. High Surf Advisories remain in effect for
this area through 10 PM PST this evening, where west-facing
beaches will generally see 6 to 10 foot breakers, with the
highest surf for the Ventura County Coast. Local sets to 12 feet
will likely continue across Ventura Harbor as well. Surf of 5 to 8
feet is expected for the Santa Barbara South Coast, highest on
beaches that have some west exposure, such as Rincon Point.

High surf could continue at least through Wednesday morning for
all areas.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 4 PM PST Thursday for
      zones 34-35-40. (See LAXCFWLOX).
     High Surf Advisory in effect until 10 PM PST this evening for
      zones 39-41-87. (See LAXCFWLOX).
     Wind Advisory in effect until 3 AM PST Wednesday for zones
      39-52. (See LAXNPWLOX).
PZ...Small Craft Advisory for hazardous seas in effect until 2 AM
      PST Thursday for zones 645-670. (See LAXMWWLOX).
     Small Craft Advisory for hazardous seas in effect until 3 AM
      PST Wednesday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PST Wednesday for
      zone 673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PST Wednesday for
      zone 676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (FRI-TUE).

No significant hazards expected.

&&
$$

PUBLIC...MW
AVIATION...Kj
MARINE...Sweet
BEACHES...Sweet
SYNOPSIS...Hall/Stewart/RK

weather.gov/losangeles

NWS LOX Office Area Forecast Discussion