593
FXUS66 KLOX 171147
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
447 AM PDT Sat May 17 2025

.SYNOPSIS...17/447 AM.

A cool weather pattern will continue through the weekend as a
deep and persistent marine intrusion and a strong onshore flow
will remain in place with an upper-level trough. Night through
morning drizzle or light rain is possible today and tonight. Gusty
onshore to west to northwest winds are expected across portions
of the coast and the interior. High pressure aloft building into
the region will bring a warming trend through much of next week.
Temperatures more typical of the summer season are likely away
from the coast for the latter half of next week.

&&

.SHORT TERM (TDY-MON)...17/445 AM.

A deep marine layer depth is well-entrenched across the region
this morning with clouds extending into the Cuyama Valley and the
coastal slopes of the mountains. The latest AMDAR soundings from
KLAX around 10Z indicate the marine layer depth to be around 2600
feet deep, but it is likely slightly deeper than that based upon
the areal extent through the Soledad Canyon and Highway 14
Corridor. If NAM BUFR time height sections play out as
advertised, the marine layer depth should deepen to near 4000
feet deep later this morning.

Strong onshore flow, driving the marine layer depth, remains
across the area ahead of an upper-level trough moving over far
northern California. KLAX-KDAG pressure gradients peaked at 7.2
mb a few hours ago, while KSMX-KBFL surface pressure gradients
peaking near 7.1 mb last evening. These values will likely
strengthen a bit more this afternoon or evening.

While the trough is strengthening the onshore push, the dynamics
with the trough scraping the area today and tonight could bring
either night through morning drizzle or light showers to the
region. As the marine layer deepens, it could interact with the
upper-level dynamics to lift the marine layer cloud deck and
squeeze out some drizzle or light rain. The latest high-resolution
multi-model ensemble members lean wetter. As a result, PoPs in
the forecast PoPs were trended slightly higher for today and
tonight. Slight chance to chance PoPs are being mentioned for now.
Precipitation could fall as a heavy drizzle or light showers, but
amounts will be on the order a few hundredths or less.

With the deep marine layer depth and strong onshore flow in
place, a cooler weather pattern will remain in place through the
weekend. Today will very likely be the coolest day of the period
with temperatures ranging 8 to 15 degrees below normal for this
time of year. Temperatures in the 60s to lower 70s will be common
across most of coastal and valley areas. Some warming will take
place on Sunday as onshore flow starts to weaken, but strong
onshore flow will still keep most areas 5 to 10 degrees below
normal.

Gusty onshore to west to northwest winds will develop over the
next couple of days. Strong onshore pressure gradients will bring
advisory level winds to the Antelope Valley and adjacent foothills
this afternoon and evening, but the pressure gradient will get
some thermal support this afternoon as a weakening and dying
frontal boundary slides down the coast. The dying boundary
combined with some wind support aloft will give a extra kick to
the winds. Wind advisories were added for the Central Coast and
the Santa Ynez Valley, the southern Salinas Valley, and across
southern Santa Barbara County as enough support will be in place
to bring advisory level winds. As we get into this evening, colder
thermal support and developing northerly gradient will add into
the mix to support gusty winds through the Interstate 5 Corridor
and across broader portions of southern Santa Barbara County.
While advisories were drawn for the highest confidence areas,
there is a chance that a wind advisory could also be needed for
the Ventura County beaches and across the Carrizo Plain this
afternoon and evening. Much will depend how much thermal and wind
support makes it far enough south with the boundary that is
falling apart.

A tight northerly pressure gradient will remain in place into
Sunday and Monday keeping wind advisories in effect across
Southern Santa Barbara County, through the Interstate 5 Corridor,
and down into the Antelope Valley. There is a small chance that
a high wind watch could be needed for Sunday night and into Monday
for eastern Santa Ynez Range at 850 mb winds are marginally
strong enough.

The flow pattern will turn northeasterly between Monday and
Tuesday and an atypical but not unusual weak offshore flow
pattern for May could develop for Monday. Winds look to wanes and
only breezy to locally windy conditions look on tap. The forecast
has warming temperatures, breaking away from NBM values for the
period. No adjustments were made temperatures for Monday as the
warming looked agreeable.

.LONG TERM (TUE-FRI)...17/439 AM.

A warming trend will continue through at least Wednesday, and
possibly into Thursday as high pressure aloft build over the
region and weak flow settles into region. EPS ensemble members
advertise a warming trend in place through Thursday across most
locations, but there is a bit more uncertainty for Thursday.
Cluster analysis of the ensembles would agree that the air mass
should warm into Thursday as a majority of the clusters lean
toward the ridge axis being overhead on Thursday. The forecast
breaks away from NBM values and maintains a warmer stance, but
the wrinkle will likely need to be addressed for Thursday as it
could end up being the warmest day of the stretch. Summer-like
temperatures should be expected, especially away from the coast,
for Tuesday through Friday. Heat advisory headlines may be needed
for the stretch of hot temperatures, especially Wednesday and
Thursday.

&&

.AVIATION...17/1050Z.

At 1000Z at KLAX, the marine inversion was based around 2800 feet.
The top of the inversion was 6000 feet with a temperature of
12 degrees Celsius.

Overall, moderate confidence in 12Z TAF package. Timing of flight
category changes could be +/- 2 hours of current forecasts. There
is a chance of drizzle or very light showers 12Z-18Z.

KLAX...Moderate confidence in 12Z TAF. Timing of flight category
changes could be +/- 2 hours of current forecasts. There is a 30%
chance that conditions will remain VFR this evening and overnight.
Southeasterly wind component around 6 knots will continue through
18Z. For 12Z-16Z, there is a 30% chance of easterly winds around 7
knots.

KBUR...Moderate confidence in 12Z TAF. Timing of flight category
changes could be +/- 2 hours of current forecasts. There is a 20%
chance that VFR conditions will prevail this evening and
overnight.

&&

.MARINE...17/350 AM.

For the Outer Waters, high confidence in current forecast. Small
Craft Advisory (SCA) level winds this morning will increase to
Gale force this afternoon. The GALE FORCE winds will continue
through Sunday night although there may be a bit of a lull Sunday
morning. Along with the GALE FORCE winds, seas will hover around
10 feet through Sunday night. For Monday through Wednesday, winds
will diminish to SCA levels while seas drop below 10 feet.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. For today, high confidence in SCA
winds developing this morning then increasing to GALE FORCE this
afternoon through tonight. For Sunday and Sunday night, high
confidence in SCA level winds with a 30-40% chance of GALE FORCE
winds developing. Through Sunday night, seas will hover near 10
feet. For Monday through Wednesday, there will be a 30-40% chance
of SCA level winds in the afternoon and evening hours each day.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. Today through tonight, high
confidence in the development of SCA level winds with a 60-70%
chance of GALE FORCE winds across the western half of the Santa
Barbara Channel. For Sunday and Sunday night, there is a 60-80%
chance of SCA level winds across the western half of the Santa
Barbara Channel and a 20-30% chance of SCA level winds elsewhere
south of Point Conception. For Monday through Wednesday, high
confidence in winds and seas remaining below SCA levels.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from 10 AM this morning to 9 PM PDT
      this evening for zones 340-341-343-346>348. (See LAXNPWLOX).
     Wind Advisory in effect from noon today to 3 AM PDT Sunday
      for zones 349>352. (See LAXNPWLOX).
     Wind Advisory in effect from 10 PM this evening to 10 AM PDT
      Monday for zone 378. (See LAXNPWLOX).
     Wind Advisory now in effect from 10 AM this morning to 3 AM
      PDT Monday for zones 381-383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PDT this afternoon
      for zones 645-670-673-676. (See LAXMWWLOX).
     Gale Warning in effect from 3 PM this afternoon to 3 AM PDT
      Sunday for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from noon today to 6 PM PDT
      this evening for zone 650. (See LAXMWWLOX).
     Gale Warning in effect from 6 PM this evening to 3 AM PDT
      Sunday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect from 6 PM this evening to 3 AM
      PDT Sunday for zone 655. (See LAXMWWLOX).
     Gale Warning in effect from 3 PM this afternoon to 3 AM PDT
      Monday for zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall
AVIATION...RAT
MARINE...RAT
SYNOPSIS...Hall

weather.gov/losangeles

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