High Surf Advisory 28, NWS Los Angeles, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
344 AM PDT Wed Nov 2 2016

.SYNOPSIS...

A warming trend will develop through Thursday as an offshore flow
regime settles into the region. Breezy to gusty Santa Ana winds
will develop across the Los Angeles and Ventura Counties today,
possibly strengthening into Thursday. A cooling trend is expected
for the weekend as a weakening cold front brushes the region. High
pressure building in aloft should bring a slight warm-up for
early next week.

&&

.SHORT TERM...(TDY-FRI)

Upper-level high pressure centered near 32N and 123W, or about 300
miles west-southwest of Los Angeles is firmly in place this
morning. An upper-level trough of low pressure over the Lower
Colorado River Basin continues to move east of the area. At the
surface, high pressure is building into the Great Basin early
this morning and offshore flow is starting to develop. Surface
pressure gradients are turning offshore this morning and latest
model solutions suggest offshore flow continuing to strengthen
into Thursday. Santa Ana winds will develop today and likely be
strongest through the Los Angeles and Ventura County Mountains
where a marginal wind advisory has been added. Locally gusty
winds may also develop in the Ventura County Valleys, Santa
Monica Mountains, and the San Fernando and Santa Clarita Valleys
today. Daytime high temperatures looked agreeable for today, but a
few touches were made to warm temperatures slighly for the coastal
areas.

The wind advisory for the Los Angeles and Ventura County Mountains
will likely need to be extended and expanded for tonight through
Thursday morning. Winds will likely diminish below advisory
criteria during the afternoon and evening hours today, but winds
will likely strengthen tonight as better wind support and more
favorable offshore pressure gradients develop. Strengthening
offshore flow should lead to a warmer day on Thursday.
Temperatures were warmed subtantially along the coastal areas,
pushing high temperatures to around 90 for the coastal locales and
making Los Angeles and Ventura Coastal areas warmer than some of
the valley locations. Despite the warm-up forecast for Thursday,
forecast high temperatures will fall short of record levels. Most
records for Thursday are in the mid 90s to around 100.

With the drier air mass pushing into the region with the offshore
flow pattern, wind-sheltered areas will radiatively cool more
efficently tonight and again Thursday night. Locations in the
interior valleys such Ojai, Paso Robles, Cuyama, Palmdale and
Lancaster, and along the Central Coast such as Santa Maria and
Lompoc will see overnight low temperatures cool into the upper
30s to mid 40s tonight. Temperatures have been nudged cooler for
the period, but future shifts may need to tweak temperatures cooler
if more data arrives suggesting additional cooling.

Friday casts a bit of uncertainty for the forecast period. The
trough of low pressure will drift south into the Sonoran Desert
through tonight then start to lift back north into Arizona. Model
solutions kick out an easterly wave across the area on Friday,
possibly increasing clouds and maybe bringing an isolated shower
or two to the Southern California mountains and desert on Friday
afternoon and evening. Cloud cover has been increased for Friday
and Friday night and day/night temperature spreads have been
moderated some.

.LONG TERM...(SAT-TUE)

Broad troughing over the Eastern Pacific Ocean around the Aleutian
Low will continue to kick storms east towards the West Coast. A
disturbance near 45N and 173W early this morning will develop for
the latter half of the week and push a cold front into the West
Coast over the weekend. The frontal feature will fall apart as it
moves south down the state on Sunday, likely washing out just
north of the Bay Area. There is an outside chance that a few
showers could stray south into the area on Sunday, but the best
rain chances, if any, would be for extreme Northern San Luis
Obispo County. The main impact with this developing feature will
likely be gusty winds developing this weekend along with cooling
temperatures. Gusty northerly winds could impact Southern Santa
Barbara County and the Interstate 5 Corridor on Sunday night and
into Monday.

High pressure aloft should reestablish for early next week and
bring a warming trend into Monday. Model solutions suggest a
trough advancing toward the West Coast on Tuesday and Wednesday.
A majority of the GEFS solutions keep the area mainly dry into
midweek next week.

&&

.AVIATION...02/1100.

At 1030Z, there was no marine layer at KLAX.

VFR conditions are expected throughout the 24-hour period. There
is a 30%chance for LLWS at a few SFV taf sites after 10z to 20z
this afternoon.

KLAX...There is a 20 percent chance of MVFR conditions between
10Z and 17Z. Otherwise, VFR conditions are expected throughout the
period. Any east winds should remain less than 7 knots.

KBUR...VFR conditions are expected throughout the period. There is
a 30 percent chance of moderate wind shear and turbulence after
10Z.

&&

.MARINE...02/320 AM.

West to northwest winds have diminished to below SCA levels this
morning. Not anticipating SCA level wind gusts through at least
Friday.

Locally gusty northeast winds should stay below small craft
advisory levels this morning between Rincon Pt to Santa Monica.
There will be a high chance for stronger wind gusts in these same
areas Thursday morning for SCA gusts. Locally choppy seas may
also develop near shore. There will be local gusts e to ne winds
across the San Pedro Channel this morning and tomorrow morning as
well. Should remain below SCA levels.

A long period northwest swell will move into the coastal waters
Thursday night and Friday with hazardous seas in much of the
Outer Coastal Waters and near shore waters north of Point Sal.
Seas above advisory levels will likely occur between Thursday and
Thursday night and persist through at least Friday night. Travel
into and out of northwest facing harbors, such as Morro Bay could
be impacted by the long period northwest swells.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 2 PM PDT this afternoon For
      zones 53-54. (See LAXNPWLOX).
PZ...NONE.

&&

PUBLIC...Hall
AVIATION...CK
MARINE...CK
SYNOPSIS...Hall

weather.gov/losangeles