LA Area Forecast Discussion

FXUS66 KLOX 041249

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
449 AM PST Mon Dec 4 2023

.SYNOPSIS...04/1237 AM.

Breezy north to northeast winds will continue through Tuesday or
while afternoon high temperatures gradually warm under a ridge.
There is a slight chance of light rain Wednesday evening and
Thursday across the central coast. It will cool back to near
normal by Friday, before another round of Santa Ana winds arrive
next weekend.


.SHORT TERM (TDY-WED)...04/253 AM.

Ridging with hgts near 580 dam along with 3 to 5 mb of offshore
flow from both the north and east will bring two days of warming
and well above normal temperatures to the area today and Tuesday.
Today will start out partly to mostly cloudy as a weak upper level
disturbance passes overhead with plenty of mid and high level
clouds. These clouds will pass by early or mid afternoon leaving
skies mostly clear through Tuesday. Since there is no upper level
or thermal support for the offshore flow there will not be too
much in the way of canyon winds. Currently there is a wind
advisory in effect through noon for the Simi Valley Thousand Oaks
area but there is a fair chc the winds will not quite reach
advisory levels. Otherwise while there will be plenty of gusty
canyon winds this morning and Tuesday morning few if any of the
gusts will reach advisory levels. Max temps will be the most
talked about weather phenomena for the next two days. The higher
than normal hgts and offshore flow will combine to bring 4 to 8
degrees of warming today and 3 to 6 degrees on Tuesday. On Tuesday
most max temps across the csts/vlys will be in the mid 70s to
lower 80s or 10 to 15 degrees above norms.

The ridge flattens out on Wednesday and hgts drop to 578 dam. More
importantly the offshore flow weakens dramatically and even turns
onshore in the afternoon from the west. These two factors will
combine to knock about 10 degrees off the the coastal temps and 4
to 8 degrees from the vly max temps. The hgt falls will arrive too
late to affect the temps across the Antelope Vly and increase in
westerly onshore flow will likely warm that area 3 to 6 degrees.

More onshore flow, slight cyclonic turning aloft and most
importantly an eddy will likely bring low clouds to portions of
the LA coast and the Central Coast Wednesday night. A little bit
of energy from an approaching trof will bring a slight chc of
light rain to NW SLO county.

.LONG TERM (THU-SUN)...04/304 AM.

A weak trof ripples over the state on Thursday with almost all of
its energy staying up north. It will bring a slight chc of some
rain to SLO county but amounts will likely only amount to a trace
to 5 hundredths of an inch if anything. Skies will be partly to
mostly cloudy. There will be onshore flow and hgts will lower to
572 dam. All of these factors will combine to lower max temps 1
to 3 degrees at the cst (their big cool down came the previous
day), 4 to 8 degrees in the vlys and 10 to 15 degrees across the
interior. Despite this cooling most max temps south of Pt
Conception will be a few degrees warmer than normal.

The trof will push to the east overnight and fast moving NW flow
will set up over the state. There will likely be some gusty NW
winds in the mtns and across the SBA county south coast. Cooler
air filtering in behind the trof will knock a degree or two off of
temps making Friday the coolest of the next 7.

Ensemble based forecasts agree that a ridge will push into the
state from the SW and that moderate offshore flow will develop.
Low end wind advisories are possible. Max temps will bump up each
day and will be above normal both days.



Around 12Z at KLAX, the marine layer was around 600 feet deep
with an inversion top at 1100 feet with a temperature of 17 C.

High confidence in TAFs except moderate confidence in TAFs for
KLGB, KLAX and KPRB with a 20% chc of IFR conds through 17Z.

KLAX...Moderate confidence TAF through 17Z then high confidence.
There is a 25% chc of BKN007 conds through 17Z. There is a 20%
chance of a 6 kt east wind component through 16Z Mon, and again
09Z-17Z Tues.

KBUR...High confidence in TAF. There is a 30% chc of a north wind
after 00Z.


.MARINE...04/213 AM.

For the Outer Waters, moderate to high confidence in forecast.
Through tonight, there is a 60-80% chance of Small Craft Advisory
(SCA) level winds continuing across PZZ673/676, with a 50-60%
chance of SCA winds across portions of PZZ670. Seas at or above
SCA levels will likely continue into the weekend, with a slight
dip below advisory levels possible this afternoon and again
Tuesday afternoon. On Wednesday afternoon, there is a 40-50%
chance of SCA level winds returning to the waters south of Point
Conception. There is a 50-60% chance of winds expanding across
all the outer waters on Thursday and lasting through at least
Friday, with a 20% chance of increasing to Gale Force levels at

For the Inner Waters north of Point Sal, moderate confidence in
forecast. Seas are currently near 10 feet with SCA level winds
gusting across the southwest portion of the waters, with a 40-50%
chance of seas and winds continuing through the evening. For
Tuesday through Friday afternoon, there is a 30-50% chance of SCA
level seas, and a 30-40% chance of SCA level winds during the
afternoon/evening hours on Wednesday and Thursday.

For the Inner Waters south of Point Conception, moderate to high
confidence in forecast. There is a 20-30% chance of SCA level
northeast winds from Ventura south to Malibu this morning, and
again tonight into Tuesday morning. There is a 30-40% chance of
NW SCA level winds across the western portion of the Santa Barbara
Channel during the afternoon and evening hours on Wednesday and
Thursday. Elsewhere and otherwise, moderate to high confidence in
winds and seas remaining below advisory levels through Friday.


.BEACHES...04/209 AM.

A long period NW swell (17-19 seconds) will lead to high surf of
8-11 feet for the Central Coast beaches by this afternoon and into
Tuesday morning. A brief decrease in surf heights may occur
Tuesday afternoon and evening before another long period NW swell
(18-20 seconds) moves across the coastal waters Tuesday night
through Friday afternoon. Surf heights up to 10-14 feet across
Central Coast beaches may be possible Tuesday night into Friday,
with 6-8 feet possible across Ventura County beaches Wednesday
through Thursday night. Surf heights will be highest across west
and northwest- facing beaches.


CA...Wind Advisory in effect until noon PST today for zones
      88-374. (See LAXNPWLOX).
     High Surf Advisory in effect from 9 AM this morning to 9 AM
      PST Tuesday for zones 340-346. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PST Tuesday for
      zones 645-670-673-676. (See LAXMWWLOX).




Experimental Graphical Hazardous Weather Outlook at:

NWS LOX Office Area Forecast Discussion