808
FXUS66 KLOX 042020
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1220 PM PST Wed Mar 4 2026

.SYNOPSIS...04/840 AM.

Near to slightly above normal are temperatures expected through
Friday, except significant cooling in the mountains and interior
areas Thursday and Friday. Temperatures will increase region wide
Saturday and Sunday. Strong and gusty northerly winds expected
across much of the area Wednesday night into Thursday morning.
Moderate to strong Santa Ana winds likely over the weekend.

&&

.SHORT TERM (TDY-FRI)...04/906 AM.

***UPDATE***

The forecast through Friday remains largely unchanged. The first
of two upper level lows will move through tonight into Thursday
morning bringing significant northerly winds to many areas, but
especially the mountains. Temperatures at higher elevations and
far interior areas will drop several degrees Thursday but closer
to the coast not much change expected as downslope warming will
compensate for most of the cold air advection.

Some light showers are still possible near the north facing
mountain slopes later tonight into Thursday morning with the snow
level lowering rapidly overnight to possibly around 4000 feet,
meaning some very light snow is possible near the summit on I5,
but only a 5% chance or less of any accumulations at that level.

There are some potential changes to the forecast for the second
trough over the weekend as models are indicating a minor
adjustment to the low`s path. This is resulting in the upper
jet sliding a little farther south again as well as having a
little more northerly component than yesterday`s models. The
latter meaning some areas (such as the eastern San Fernando Valley
and even parts of the San Gabriel valley) that typically don`t
get much wind in a Santa Ana may get some strong winds by
Saturday. These path fluctuations are not uncommon and things can
still change over the next day or two so much uncertainty still
remains. But chances remain that many areas will get strong winds
over the weekend with warming temperatures.

***From Previous Discussion***

The trough that we have been writing about for days will swing
through Northern California today, diving to the southeast and
working its way into the Great Basin by Thursday. The passage of
this trough will help drive a moderate to strong northerly wind
event Wednesday afternoon through Thursday. Winds will peak
tonight into Thursday morning with speeds of 35-50 mph with
isolated higher elevation gusts of 55-65 mph. Winds will diminish
some Thursday morning, but still remain fairly breezy through the
day, potentially even pulsing up slightly in the evening. All High
Wind Watches have been upgraded to High Wind Warnings, and
widespread Wind Advisories are issued for much of Santa Barbara,
Ventura, and Los Angeles counties. As mentioned previously, winds
will diminish some on Thursday, but Wind Advisories may be needed
on the heels of the High Wind Warnings, as well as extensions of
current Advisories.

By Friday morning, winds will turn to the northeast into a
traditional Santa Ana Wind event, and this event will continue
into Sunday. The cutoff low will begin to form as it detaches from
the jet stream, moving across Southern California Friday night
into Saturday. Saturday will be the windiest day of the weekend as
the upper level support lines up almost perfectly. At 500 mb, a
near 100 mph northeasterly jet will move over SoCal around late
morning on Saturday. The most likely wind speeds for this event
will be 20-30 mph with gusts of 40-50 mph. However, damaging gusts
of 55-70 mph are still possible, with a 40% chance in the
mountains and a 20% across coasts and valleys. Widespread Wind
Advisories are again likely all weekend, but High Wind Warnings
will be needed in the case of the stronger scenario coming to
fruition.

IMPACTS: The event beginning this afternoon and continuing
through Thursday night will bring north winds down to fairly
atypical areas. Notably, the northerly winds will squeeze through
canyons and passes of the Santa Monicas, which will funnel winds
into the western part of Los Angeles County, mostly remaining west
of the 1-110. These winds will create hazardous travel conditions
across major freeways such as the I-5, the I-405, and even travel
delays due to crosswinds at LAX. For Friday-Sundays Santa Ana
event, there is again a risk for downed trees and power lines (and
power outages), as well as hazardous travel conditions across the
typical Santa Ana wind corridor. Blowing debris may also create
further hazards on the roads from this afternoon through the
weekend.

High temperatures today will generally be in the upper 60s to
upper 70s, but western San Fernando cities may touch the low 80s.
Thursday will cool across most areas as north winds diminish some
and 500 mb heights rapidly plummet. However, coastal areas from
Santa Barbara south will warm up at least a few degrees due to the
influence of the north winds. Then the Santa Ana Wind influence
will rapidly warm and dry the region Friday through Sunday. Temps
will peak Sunday with widespread 70s to mid 80s. Patchy marine
layer clouds may develop again tonight, but that will be the last
we see of the marine layer through the weekend.

.LONG TERM (SAT-TUE)...04/252 AM.

After the cutoff low spins in place off the coast of Baja
California on Sunday, it will eject to the east on Monday. Fairly
weak ridging will move in and a dramatic swing to onshore flow
will usher in cooler air from natures air conditioner (Pacific
Ocean). The marine layer will likely return after a few day
hiatus, with better chances late Monday into Tuesday. The chances
for any very light precipitation from wrap-around moisture has
decreased and dry conditions are expected for at least the next
couple of weeks.

&&

.AVIATION...04/2019Z.

Around 1915Z, the marine layer was around 2200 ft deep at KLAX.
The top of the inversion was around 3300 feet with a temperature
near 17 degrees Celsius.

Moderate to high confidence exists in the current forecast. High
confidence exists in the forecast in desert terminals. Lower
confidence exists in the forecast for all remaining terminals,
lowest for Los Angeles County coastal terminals. Timing of winds
and flight category changes could be off by up to two hours
earlier or later. Periods of moderate to strong wind shear and
turbulence will be possible after 20Z. There is chance that MVFR
conditions may linger through the day at Ventura and Los Angeles
County coastal terminals.

KLAX...MVFR conditions could clear as soon as 21Z but more likely
around 22Z. There is a 30 percent chance of clearing at all with
MVFR conditions remaining in at KLAX through at least 08Z
Thursday. North winds greater than 10 knots are likely after 07Z
Thursday. There is a 20 percent chance that wind gusts to 25 knots
may not occur after 10Z. There is a 10 percent chance of
sustained northerly cross winds greater than 20 knots between 10Z
and 16Z. Periods of moderate to strong low-level wind shear and
turbulence are likely between 10Z and 16Z.

KBUR...VFR conditions are expected through the period, but there
is a low chance of MVFR visibilities developing overnight for up
to two hours. North winds greater than 10 knots are likely after
04Z Thursday. There is a 10 percent chance that wind gusts to 25
knots may not occur after 10Z. There is a 20 percent chance of
sustained northerly winds greater than 20 knots between 08Z and
16Z. Periods of moderate to strong low-level wind shear and
turbulence are likely between 08Z and 16Z.

&&

.MARINE...04/1219 PM.

Moderate to high confidence in the current forecast. Higher
confidence exists in the forecast for winds. Less confidence in
the forecast for seas. Seas could be up to 1-3 feet higher than
forecast, especially today through Saturday.

Marine weather conditions will deteriorate through tonight with
widespread strong Small Craft Advisory (SCA) and GALE conditions
expected through at least Thursday night. GALE WARNINGS remain in
effect through Friday morning for some waters.

Another period of strong winds will develop across the region as
an offshore flow pattern will set up Friday through Sunday. There
is a high to likely (40 to 60 percent) chance of SCA level winds
between Friday night and Sunday. There is a moderate (30-40
percent) chance of GALE FORCE wind gusts inside the southern
California bight, and high (40-50 percent) chance of SCA level
winds along the nearshore waters of the Central Coast.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory remains in effect from midnight tonight to 9 AM
      PST Thursday for zones 87-366-367. (See LAXNPWLOX).
     Wind Advisory remains in effect from 6 PM this evening to 9
      AM PST Thursday for zones 88-371>375. (See LAXNPWLOX).
     Wind Advisory remains in effect until 2 AM PST Thursday for
      zones 346-347. (See LAXNPWLOX).
     Wind Advisory remains in effect from 4 PM this afternoon to 9
      AM PST Thursday for zones 349>352-356-357-381>383. (See LAXNPWLOX).
     High Wind Warning remains in effect from 4 PM this afternoon
      to 7 AM PST Thursday for zones 353-376>378. (See LAXNPWLOX).
     High Wind Warning remains in effect from 2 AM to 9 AM PST
      Thursday for zones 362-369-370. (See LAXNPWLOX).
     High Wind Warning remains in effect from 9 PM this evening to
      9 AM PST Thursday for zones 379-380. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PST this afternoon
      for zones 645-650. (See LAXMWWLOX).
     Gale Warning in effect until 9 AM PST Thursday for zones
      645-650. (See LAXMWWLOX).
     Gale Warning in effect from 10 PM this evening to 10 AM PST
      Thursday for zone 655. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PST Friday for zones
      670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/BL
AVIATION...Hall
MARINE...Hall
SYNOPSIS...BL

weather.gov/losangeles

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

NWS Los Angeles (LOX) Office