642
FXUS66 KLOX 230542
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
942 PM PST Sat Feb 22 2025

.SYNOPSIS...22/807 PM.

High pressure aloft will keep a warmer than normal weather
pattern in the forecast through Monday, then a significant
widespread warming trend is likely Tuesday through Thursday.
Periods of dense fog will continue at the coast through Monday.
Much cooler conditions are expected to follow into next weekend
with chances of rain.

&&

.SHORT TERM (SAT-TUE)...22/941 PM.

The water vapor imagery indicates a blocking upper-level ridge of
high pressure over the region this evening. Some high clouds are
streaming over the region as a storm system moves over the top of
the ridge. Temperatures today were warmer than normal for this
time of year with 70s and lower 80s being common across the
coastal and valley areas. Another series of warm days are shaping
up over the next several days.

The latest ensemble members indicate 500 mb heights climbing and
850 mb temperatures warming into midday Sunday. NAM-WRF solutions
suggest surface pressure gradients turning onshore on Sunday
afternoon, but the model suggested weak onshore flow developing
today, and it never materialized. Higher confidence exists in
onshore flow returning weakly by Sunday afternoon, but with
gradient remaining offshore, climatological wind processes should
keep the offshore gradients in place at this time. The forecast
takes a slightly warmer stance on Sunday with temperatures warming
by about 2 to 4 degrees across the region versus today`s values.
The exception could be the beaches, which could be closer to
persistence as some low clouds and dense fog could form with a
shallow marine layer depth in place. The latest KLAX AMDAR
soundings indicate the marine layer depth to be around 100 feet
deep at this time. With value that shallow and an eddy circulation
progged to develop later tonight and early Sunday morning, any
low clouds and fog that form will likely be in the form of dense
fog. Dense fog advisory may be needed once confidence is high
enough in the coverage of the low cloud pattern.

An update was issued to the forecast to warm temperature and add a
little more low cloud coverage into the Ventura County coast and
southeastern Santa Barbara County.

***From Previous Discussion***

Overall, 12Z models in good synoptic agreement through the short
term period. At upper levels, ridge will peak in strength on
Sunday then will be flattened Monday/Tuesday as zonal flow
develops. Near the surface, weak diurnal flow will persist with a
slight strengthening of the afternoon onshore gradients each day.

Forecast-wise, no significant issues are expected in the short
term as there should be three nice "Chamber of Commerce" days for
Southwestern California. Through Monday morning, expect skies to
remain mostly clear except for some night/morning stratus and
dense fog across the immediate coast of Ventura/LA counties. For
Monday night and Tuesday, mostly clear skies will prevail as no
stratus/fog is expected. As for temperatures, will expect all
areas to warm up a couple of degrees with ridge peaking in
strength. After some slight cooling on Monday (with uptick in
onshore gradients), some slight warming is expected on Tuesday. As
for winds, do not anticipated any significant issues.

.LONG TERM (WED-SAT)...22/142 PM.

For the extended, 12Z models remain on the same synoptic page. At
upper levels, ridge will strengthen over the area on Wednesday
then a cutoff low develops west of Point Conception on Thursday
then meanders southeast to northern Baja California by Friday
night and Saturday. Near the surface, weak to moderate offshore
flow is expected on Wednesday/Thursday then onshore flow returns
Friday/Saturday.

Forecast-wise, Wednesday looks to be a spectacular day as the
combination of the upper level ridge and offshore surface
gradients allow temperatures to warm noticeably with most of the
area in the 80s to lower 90s. Based on some ensemble solutions,
the temperatures could be even be higher. So, the possibility of
record or near-record temperatures for some areas will need to be
watch closely.

For Thursday through Saturday, as the cutoff low begins to meander
southeast, there will be some slight cooling on Thursday then much
more pronounced cooling on Friday/Saturday with temperatures
dropping into the mid 60s to mid 70s. As for precipitation
chances, the deterministic runs of both the GFS and ECMWF indicate
very little QPF. However, their respective ensembles do have some
members indicating some showers which matches up well with the NBM
numbers. So, there will be some slight chances of light showers in
the forecast for Thursday through Saturday. Rainfall amounts, if
any, will be quite light and should not have much impact upon the
area.

&&

.AVIATION...23/0223Z.

At 2219Z at KLAX, there was no marine layer or inversion.

Overall, moderate to high confidence in 00Z TAF Package. Good
confidence in VFR conditions for SLO/SBA county airfields. Could
see periods of low cigs as early as 03Z for KOXR, with a better
chance for more continuous cigs after 11Z. Higher confidence in
VFR conds prevailing at KCMA with a 20% chance of cigs. Moderate
confidence in timing of cigs at KSMO, KLAX, and KLGB.

KLAX...Moderate to low (timing) confidence in 00Z TAF. Low
clouds/fog could arrive as early as 04Z and depart as late as 18Z.
There is a 30-40% chance of VLIFR conds (<1/2SM, <0VC002) from 12Z
to 15Z. No significant east wind component expected thru the fcst
pd.
KBUR...High confidence in 00Z TAF.

&&

.MARINE...22/1123 AM.

For all the Outer Waters and the nearshore waters along the
Central Coast, there is a 20-30% chance of Small Craft Advisory
(SCA) conditions this afternoon and evening. Best chances for
PZZ670 and northwestern portions of PZZ673. There is a 50-60%
chance of SCA level NW-N winds for PZZ673 and the waters around
Port San Luis (PZZ645) Sunday afternoon/eve.

High chances for SCA conditions Monday into Tuesday. The areas
favored will be the waters around Point Conception, Northern
Channel Islands, and down to San Nicolas Island - with a 20-30%
chance for GALE force winds. Seas are expected to be at SCA
levels on Tuesday.

For the inner waters south of Point Conception, wind and seas are
likely to remain below SCA levels through Sunday. Followed by a
30-50% chance of SCA level winds on Monday and Tuesday. The
highest chance will be across the western portion of the Santa
Barbara Channel.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 2 PM Sunday to 1 AM PST
      Monday for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 PM Sunday to 8 AM PST
      Monday for zones 670-673. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall/Thompson
AVIATION...Phillips
MARINE...Black
SYNOPSIS...Hall

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox