Sylmar, California Weather Forecast Discussion

421
FXUS66 KLOX 011125
AFDLOX
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
425 AM PDT Wed Oct 1 2025
.SYNOPSIS...01/215 AM.
A series of weak disturbances will keep a persistent night through
morning low clouds pattern going across most of the coasts and
some lower vlys through Friday. Weak offshore flow will bring
mostly sunny skies to the area for the weekend. Otherwise, skies
will be clear to partly cloudy. Afternoon high temperatures will
continue to run below normal through the period.
&&
.SHORT TERM (TDY-FRI)...01/245 AM.
Pretty benign weather for the short term save for some gusty
Sundowner winds.
Dry SW upper lever flow with 584 hgts will be over the area today.
There will be weak to mdt onshore flow at the sfc. There is 4000
to 5000 ft deep moist layer capped by an extremely weak inversion.
This has led to a rather haphazard low cloud pattern this morning.
Low clouds are mostly confined to the coasts. The SBA south coast
remains clear due to a weak Sundowner. The increased hgts will
bring 2 to 3 degrees of warming to almost all areas today. The
warming, however, will not be enough to bring max temps up to
normal levels and they will end up 3 to 6 degrees blo normal.
A little better marine layer cloud coverage tonight along the
coasts as the marine inversion reforms and the marine layer
shrinks. Onshore flow is on the weak side so the vlys (except the
Santa Ynez) will remain clear. The SBA south coast will also be
clear as another sub advisory level Sundowner will keep the clouds
away.
Not too much change Thursday. The SW flow tilts a little more as
an upper low off of Washington strengthens. Hgts and pressure
gradients do not change much and Thursday will be a very similar
day compared to today.
The upper level low moved into Nrn CA bring increasing cyclonic
flow to Srn CA. It will also bring increasing N flow to SW SBA
county and advisory level Sundowner Winds are likely through
through the predawn hours Friday.
Friday will be cooler and breezy in the wake of the dry trof. Look
for gusty wind in the mtns and Antelope Vly as well as increased
sea breezes at the csts. Hgts fall to 578 dam and this will cool
the cst/vlys (along with the increased sea breeze) by 2 to 4
degrees. Even more cool air advection across the interior will
lower max temps by 4 to 8 degrees. Max temps will end up 5 to 10
degrees blo normal.
Friday night looks like the windiest of the next three with gusty
advisory winds across the SBA south coast, the I-5 corridor and
western portions of the Antelope Vly.
.LONG TERM (SAT-TUE)...01/300 AM.
On Saturday the areas will be under the western portion of the
departing trof with strong NW flow aloft. At the sfc weak offshore
flow will develop from the east and mdt offshore flow will come
from the north. The offshore flow and mixing from the trof should
be enough to thwart the marine layer and skies will be mostly
clear. There will be some weak N to NE winds in the morning.
Rising hgts and the weak offshore flow will team up to bring 2 to
4 degrees of warming to most areas.
Medium range mdls are in good agreement for the Sunday forecast
calling for a long wave pos tilt trof to set up over CA and OR. At
the sfc onshore flow will return as will the coastal low clouds.
The switch to onshore flow will cool the csts/vlys by a few
degrees, while the interior continues to warm some.
On Monday the trof axis will move southward and directly over Srn
CA. Onshore flow will increase both to the N and E. Lower hgts and
the increased onshore flow will bring noticeable cooling of 3 to
6 degrees to the area. Max temps across the csts/vlys will only be
in the upper 60s and 70s or 6 to 12 degrees blo normal.
Some warming is forecast for Tuesday, but this seems questionable
as hgts and onshore flow are not forecast to change much. There is
certainly a decent chc of a day very similar to Monday.
&&
.AVIATION...01/1124Z.
At around 11Z at KLAX, there was a deep moist layer up to as
least 6000 feet.
High confidence in TAFs for desert airfields (KPMD and KWJF).
Moderate confidence in remaining TAFs. Timing of CIG/VSBY
restrictions may be off by +/- 3 hours & flight minimums may be
off by one category from current forecast. Cigs may bounce between
categories at times, especially at KSMX. There is a 20% chance of
VFR conditions through the period at KSMO, and a 10% chance of
IFR- MVFR cigs at KSBA, KVNY, and KBUR from 15Z-17Z Wed.
KLAX...Moderate confidence in TAF. Arrival and clearing times of
CIGs may be off by +/- 3 hours. BKN010 is expected to be the
lowest possible cig overnight, and no significant east wind
component is expected.
KBUR...Moderate confidence in TAF. Flight cat changes may be off
+/- 2 hours. There is a 10% chance for OVC010-018 cigs from
14Z-16Z Wed.
&&
.MARINE...01/257 AM.
There is a 40 percent chance of Small Craft Advisory (SCA) winds
and choppy seas across the Santa Barbara Channel late this
afternoon and evening, with sub advisory conditions elsewhere
through Thursday morning. High confidence in winds increasing to
SCA levels across the entire coastal waters Thursday afternoon
through the weekend, except for the inner waters adjacent to the
Los Angeles and Orange County coasts. The strongest winds are
likely Friday afternoon and evening, when there is a 30% chance
for Gale Force winds near Point Conception and into the western
half of the Santa Barbara Channel.
Tonight through Saturday northwest swell will build, with seas
peaking around 10 feet for the outer waters and nearshore waters
along the Central Coast. For the southern inner waters, seas will
peak around 4 to 7 feet, highest in the Santa Barbara Channel.
&&
.BEACHES...01/236 AM.
Southerly swell generated by Tropical Cyclone Narda may linger
through today, with a risk of elevated surf and rip currents
continuing for south-facing beaches (especially along the Malibu
Coast).
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect until 9 AM PDT this morning
      for zone 362. (See LAXCFWLOX).
PZ...NONE.
&&
$$
PUBLIC...Rorke
AVIATION...Schoenfeld
MARINE...Lewis/Schoenfeld
BEACHES...Schoenfeld
SYNOPSIS...Sirard
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox

NWS LOX Office Area Forecast Discussion