NWS Forecast Area Discussion - Los Angeles Area
004
FXUS66 KLOX 191018
AFDLOX
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
318 AM PDT Mon May 19 2025
.SYNOPSIS...19/201 AM.
A ridge of high pressure will result in an extended period of very
hot weather this week, peaking on Wednesday and Thursday. High
temperatures will be well above normal. Gusty winds are expected
across southern Santa Barbara County and in the Los Angeles County
Mountains near the Grapevine.
&&
.SHORT TERM (TDY-WED)...19/315 AM.
A ridge is beginning to move into the state and hgts will rise to
582 dam by the afternoon. Currently there is weak onshore flow to
the east and weak offshore flow from the north. There are no
marine layer clouds although some clouds may form near Long Beach
around sunrise. The afternoon pressure gradients will remain
slightly onshore to the east and slightly offshore from the
north. Rising hgts and the weak pressure grads will team up with
the totally sunny skies to bring 3 to 6 degrees of warming to the
coasts and 6 to 12 locally 15 degrees over the rest of the area.
Most max temps will end up 4 to 8 degrees above normal. There will
be another round of Sundowner winds across the SBA south coast
tonight.
The ridge flattens out on Tuesday but hgts remain at 582 dam.
There should be offshore flow from both the north and the east in
the morning although the E/W gradient will turn onshore in the
afternoon. The airmass will continue to warm under cloud free
skies. Most of SLO and SBA counties will only warm 1 or 2
degrees. VTA and LA counties, however, will see another 4 to 8
degrees of warming as the offshore flow will have the greatest
affect in this location. Max temps across the csts will be in the
70s except the interior portions of the LA/VTA csts where lower
to mid 80s will be common. The vlys will see max temps in the
90s. These temps will be close to advisory criteria but just
under. Still, people working or playing outside in the vlys
should be aware of heat dangers.
.THE HOTTEST DAYS (WED-THU)
Another little ridge moves into the state on Wednesday and hgts
will peak at 595 dam. There will not be much change with the
gradients which will be weak. Wednesday will be the hottest day.
The vlys will see max temps from 95 to 103 degrees (15 to 20
degrees above normal). In addition there will be a very strong
inversion around 1000 ft (right at many vly elevations) and this
will keep many overnight lows well above normal. Warmer than
normal highs and lows will combine to bring moderately dangerous
heat conditions to the vlys and lower mtn elevations.
Thursday will be a little cooler as slightly lower hgts and
slightly stronger onshore flow arrives, but it will not be enough
to reduce the heat danger. There may even be some shallow marine
layer clouds at the beaches with dense fog in the morning. There
will be stronger onshore flow to the east and this will make the
beach temperature forecast tricky as there could be a huge temp
gradient between the beaches and the inland areas.
People planning outdoor activities for this two day period should
take precautions to avoid heat related dangers.
.LONG TERM (FRI-SUN)...19/1204 AM.
Good mdl agreement that a trof will ripple through the state on
Friday. Hgts will not fall too much only about 2 dam. More
importantly there will be strong onshore trends leading to mdt to
stg onshore flow both to the north and east in the afternoon. The
increased onshore flow and cyclonic turning aloft will produce an
abundance of morning low clouds that will cover most of the csts
and some of the lower vlys. Almost all areas will see 3 to 6
degrees of cooling. Still with cstl highs mostly in the mid 70s to
lower 80s and the vlys coming in the upper 80s to lower 90s, max
temps will remain well above normal.
The real cooling will hit Saturday as hgts fall and onshore flow
remains strong. Coastal low clouds are likely although many
ensembles show slightly less coverage than on Friday. The big news
will be the temps: look for 5 to 10 locally 12 degrees across the
area. The biggest cooling will occur in the LA/VTA vlys. Max temps
will drop to a few degrees either side of normal.
Slightly higher hgts and slightly less onshore flow will bring a
few degrees of warming to the area on Sunday.
&&
.AVIATION...19/0958Z.
Around 0930Z, the marine layer depth was around 1000 feet deep at
KLAX. The top of the weak inversion was 3000 feet with a
temperature near 16 degrees Celsius.
Moderate confidence in the current forecast for Los Angeles County
coastal terminals, otherwise high confidence exists. There is a
low-to-moderate chance of IFR to MVFR conditions between 13Z and
16Z. Otherwise, VFR conditions are expected through the period.
KLAX...There is a 30 percent chance of IFR to MVFR conditions
between 13Z and 16Z. Otherwise, VFR conditions are expected
through the period. No significant east wind component is expected
at this time.
KBUR...VFR conditions are expected through the period. No wind
impacts are expected at this time.
&&
.MARINE...19/311 AM.
Moderate to high confidence in the current forecast. Higher
confidence exists in the forecast for seas relative to the
forecast for winds.
For the Outer Waters and the nearshore waters along the Central
Coast, there is a 80-100 percent of Small Craft Advisory (SCA)
conditions through Tuesday night, except for lulls nearshore along
the Central Coast during late night and early morning hours.
There is a 60-90 percent chance for GALE Force winds this
afternoon through this evening, decreasing to a 50-80 percent
chance from early Tuesday through Tuesday night. There could be a
brief decrease to SCA levels in the central and southern zone
possible Monday morning. The highest chances will be for the
majority of the Outer Waters, while the lowest chances will be for
the nearshore waters along the Central Coast and the for southern
Outer Waters. There remains a moderate to high chance for GALE
Force winds through the work week, but low confidence in timing
and max wind speeds exists beyond Tuesday.
In the Santa Barbara Channel, there is a 50-70 percent chance of
SCA level winds through this afternoon and tonight, followed by a
40-60 percent chance on Tuesday afternoon and night. The highest
chances are for the western portion of the Santa Barbara Channel,
while the lowest is for the eastern portion of the Santa Barbara
Channel. There are lesser chances for Wednesday and Thursday
afternoons and evenings.
South of Point Mugu, into the Santa Monica Bay and the San Pedro
Channel. Winds and seas are expected to remain below SCA levels
in the southern Inner Waters, but there is a moderate chance of
SCA level winds gusts briefly from Point Dume to Pacific Palisades
this afternoon and evening.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory remains in effect until 6 AM PDT early this
morning for zones 349-351. (See LAXNPWLOX).
Wind Advisory remains in effect until 10 AM PDT this morning
for zones 352-353-376>378. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PDT this afternoon
for zone 645. (See LAXMWWLOX).
Gale Warning in effect from 3 PM this afternoon to 9 PM PDT
this evening for zone 645. (See LAXMWWLOX).
Gale Watch in effect from Tuesday afternoon through Tuesday
evening for zone 645. (See LAXMWWLOX).
Small Craft Advisory in effect from 3 PM this afternoon to 3
AM PDT Tuesday for zone 650. (See LAXMWWLOX).
Gale Warning in effect until 3 AM PDT Wednesday for zones
670-673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...Rorke
AVIATION...Hall
MARINE...Hall
SYNOPSIS...KL/Ciliberti
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox
NWS LOX Office Area Forecast Discussion
