NWS Forecast Area Discussion - Los Angeles Area
905
FXUS66 KLOX 221737
AFDLOX
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
937 AM PST Sun Dec 22 2024
.SYNOPSIS...22/859 AM.
A significant high surf event with coastal flooding is expected
through the week, with the most dangerous conditions expected
Monday and Tuesday. Patchy fog near the coast will create low
visibilities at times through Monday. Aside from a small chance
for light rain near San Luis Obispo County coast this morning, it
will be dry through Monday. A stronger weather system will bring
light rainfall to more areas Tuesday and Tuesday night.
Temperatures will range from near normal near the coast, to well
above normal for interior areas.
&&
.SHORT TERM (TDY-TUE)...22/906 AM.
***UPDATE***
***Significant high-surf event with coastal flooding expected
this week, with the most dangerous conditions Monday into
Tuesday***
A rapidly weakening storm system is arriving along the Central
Coast this morning with some light rain mainly from San Luis
Obispo north. Amounts expected to be under a tenth of an inch.
Elsewhere just a lot of high clouds and cool temperatures. Skies
expected to clear out later this afternoon and evening with
plenty of sunshine expected Monday.
***From Previous Discussion***
Pretty benign weather on track for Monday. The aforementioned
higher clouds will thin out overnight tonight, and given the time
of year and weak gradients, patchy dense fog and low clouds have a
higher chance of making a return tonight, possibly even pushing
into the valleys. Temperatures will have the chance to warm up
Monday with the lack of high level clouds, bringing highs at the
coasts into the low to mid 60s, while valleys will be in the 70s,
and the warmest valleys in the mid to high 70s.
Tuesday will be the most interesting day weather-wise in the
short term forecast. A trough extending from a low pressure system
over the Pacific NW will cross the region, bringing rain chances
further south and into L.A. County. Rain amounts are expected to
be a half to one inch across coastal SLO county, then dropping
off quickly to around a quarter inch or less in Santa Barbara
County, Eastern Ventura, and across the eastern San Gabriel
Mountains. Elsewhere, around a tenth of an inch or less is likely.
The slight southerly component of this system will cause the
south facing mountains south of Pt. Conception to have slightly
higher rain totals. The system will cause high temps to crash
around 5 to 10 degrees compared to Monday, resulting in temps in
the 60s range, to 50s across the higher elevations and at the
immediate coasts.
Please reference the High Surf Warning and High Surf Advisory, as
well as the Coastal Flood Advisory, regarding the significant
high-surf event.
.LONG TERM (WED-SAT)...22/508 AM.
Following the system, winds will start to pick up in the evening
on Tuesday with moderate to locally strong northerly flow settling
across the area. Winds will pick up that evening with the
strongest winds in the mountains/canyons, including the Santa Ynez
Range, where some Wind Advisories may be needed into
Wednesday/Christmas morning. Christmas day will be sunny but
remain on the cooler side. The GFS/ECMWF deterministic models show
a ridge gradually building over the area through the week after
the trough passes through Tuesday. Periods of gusty winds will
continue all week with a slow warming trend going into next
weekend. Longer range ensembles show very little in terms of
precipitation chances through the first week in 2025. Possibly a
couple very weak systems for the Central Coast Thursday night,
next weekend, and early the following week but these show little
hope of bringing any meaningful rain.
&&
.AVIATION...22/1737Z.
At 1631Z at KLAX, there was no marine layer. The top of the
inversion was at 3500 ft with a temperature of 16 C.
High confidence in TAFs for KBUR, KVNY, KPMD, and KWJF. Max wind
gusts at KPMD and KWJF may be 5 kts higher. There is a 20% chance
for LIFR to IFR conds at KBUR and KVNY between 10Z and 17Z.
Low to moderate confidence for remaining TAFs. Moderate confidence
through this afternoon, then low confidence for the remainder of
the period. Very low confidence in minimum flight cats beyond 00Z
and through 18Z Monday. There is a 20-40% chance for VLIFR conds
due to the formation of ground fog, with highest chances at KSBP,
KSMX, KSBA, KLAX, KSMO, and KLGB. Flight cat changes may also be
off +/- 4 hours. High and mid level clouds may hinder the ability
for low clouds to form, similar to this morning.
KLAX...Moderate to low confidence in 18Z TAF. Moderate confidence
through 00Z, then low confidence thereafter. There is a 40% chance
for vsbys of 1/2SM or less and cigs VV002 or less from 06Z through
16Z. Low clouds may also struggle to form due to the presence of
high and mid level clouds in the region. Otherwise, lowest flight
cat may be off by at least 1 cat and arrival/dissipation of cigs
may be off by +/- 3 hours. No significant east wind component
expected.
KBUR...High confidence in 18Z TAF. There is a 20% chance of LIFR
to IFR cigs between 10Z and 16Z.
&&
.MARINE...22/749 AM.
Large, long period west to northwest swell will affect the waters
most of this week. Seas will peak at 15-22 ft in the Outer
Waters. For the inner waters, seas will peak at 13-18 ft north of
Pt. Sal, 9-12 ft in the Santa Barbara Channel, and 7-10 ft in the
southern inner waters. These conditions pose a risk for
damaging breaking waves at times at Morro Bay and Ventura Harbor
entrances.
Small Craft Advisory (SCA) seas will likely (80% chance) affect
outer and northern inner waters much of this week. SCA level seas
will affect the Santa Barbara Channel thru Tue night, with seas
possibly dipping below advisory levels tonight for a short period.
In the southern inner waters, there is a 40% chance of SCA level
seas later today into tonight, and a 50-60% chance of SCA level
seas Mon night thru Tue night.
Along with the high seas, there is a 70% chance of SCA level winds
for the waters around the Channel Islands this afternoon thru
late tonight, and again Mon afternoon thru late Mon night.
In the outer waters, SCA level winds are expected to be widespread
Tue afternoon thru at least Thu (80-90% chance). In the inner
waters north of Pt. Sal and the Santa Barbara Channel, SCA level
winds are likely (70% chance) during the afternoon/eve hours Tue
and Wed, with a 40% chance of SCA conds Thu afternoon/eve. In the
southern inner waters, brief local gusts to 25 kt may occur
tonight in the far western portion of the zone and again tomorrow
evening. SCA conds are then likely (60% chance) Tue
afternoon/eve, with a 20-30% chance Wed afternoon/eve. There is a
20% chance of GALE force gusts from around Pt Conception south to
San Nicolas Island Wed morning into Thu.
&&
.BEACHES...22/751 AM.
A large and long period west to northwest swell will bring
dangerously high surf, especially to west and northwest facing
beaches at times through the week. Surf will peak at 18 to 25
feet on the Central Coast, 12 to 18 feet on the Ventura County
Coast and 8 to 12 feet of the west facing beaches of L.A. County.
Even on west-facing beaches on the south coast of SBA County,
surf will peak at 6 to 10 feet. The peak of the surf is expected
Monday afternoon into early Tuesday.
For the rest of the week, advisory level surf is expected at times.
Minor to moderate coastal flooding is possible near the times of
high tides through at least Tuesday morning on the Central Coast
and the Ventura County Coast, with nuisance to minor coastal
flooding elsewhere. Please reference our SRF and CFW products for
more details.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 4 AM PST Wednesday for
zones 87-349-350-362-366. (See LAXCFWLOX).
High Surf Warning in effect until noon PST Tuesday for zones
340-346-354. (See LAXCFWLOX).
Coastal Flood Advisory in effect until 9 AM PST Tuesday for
zones 340-346-354. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 2 AM PST Thursday for
zones 645-670-673-676. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PST Wednesday for
zone 650. (See LAXMWWLOX).
&&
$$
PUBLIC...MW/Lund
AVIATION...Lewis
MARINE...DB/Lewis
BEACHES...DB/Lewis
SYNOPSIS...Phillips/KL
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox
NWS LOX Office Area Forecast Discussion
