San Marino, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

985
FXUS66 KLOX 161604
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
904 AM PDT Wed Apr 16 2025

.SYNOPSIS...16/851 AM.

Today through Friday will feature partly to mostly cloudy skies
and much cooler than normal temperatures. A chance of showers
and a slight chance of a thunderstorm will develop Thursday and
Friday with the best chance over the mountains and far interior.
Dry and warmer conditions are expected for the weekend into early
next week.

&&

.SHORT TERM (TDY-FRI)...16/904 AM.

***UPDATE***

The marine layer has blasted up to 5500 feet based on the latest
pilot reports out of KLAX. Satellite imagery shows a very distinct
back edge of the stratus rapidly approaching the coastline and
this may indeed be a classic reverse clearing day with clearing
near the coast but remaining cloudy inland well into the afternoon
at least. In any case temperatures will be at least 4-8 degrees
below normal today and as much as 15 degrees below normal across
the valleys.

Models are still showing a small area of enhanced instability
across the northern Ventura County mountains today as the upper
low gets closer and temperatures aloft cool. So there is a slight
chance of showers and possibly even an isolated thunderstorm in
that area, which could also include northeastern Santa Barbara
County mountains as well.

***From Previous Discussion***

The upper low will move eastward overnight into Thursday. It will
open up and then be subsumed into a colder stronger upper low
centered over SW Idaho. The lift and instability assoc with the
upper low will interact with the deep marine layer and bring
clouds and a 20 to 30 percent chc of light rain. Skies will be a
pretty chaotic mix mid of low and mid level clouds. Rainfall
amounts will not exceed a couple tenths of an inch. The cool upper
low passing overhead will bring even colder max temps with most
highs across the csts/vlys only in the lower to mid 60s which
would be below normal even in January.

The slow moving low (now trof) will linger Thursday night and
will bring a partly to mostly cloudy skies and slight chc of light
showers to areas south of Pt Conception.

Mdls continue to show the Idaho upper low moving into SE NV on
Friday. It will bring another round of lift and instability. A chc
of showers and a slight chc of TSTMs will develop over the
interior. The north flow from the upper low could push any
shower/TSTM out of the mtns and into the vlys or even csts. That
said the latest ensembles show an eastward trend in the location
of the upper and if this continues the chc of showers will
diminish. Most areas will warm a few degrees as there will be a
little more sunshine and the upper low will not be overhead. Max
temps, however will remain 6 to 12 degrees blo normal.

.LONG TERM (SAT-TUE)...16/305 AM.

Good agreement with the deterministic and ensemble mdls for the
extended fcst. All signs point to at least 4 days of benign
weather. The upper low will push to the east on Saturday and weak
ridging and/or dry NW flow will set up over the state. Moderate to
strong onshore flow will occur all 4 days. The marine layer
stratus pattern will slowly redevelop as well. Max temps will warm
each day Sat through Mon. The biggest jump in temps will occur
Saturday. By Monday max temps will be 2 to 4 degrees blo normal
across the csts/vlys but will have risen to 3 to 6 degrees above
normal across the interior. Max temps will cool Tuesday as hgts
fall ahead of a trof. The moderate onshore push to the east will
bring gusty afternoon winds to the Antelope Vly and foothills.

&&

.AVIATION...16/1112Z.

At 0736Z at KLAX, the marine layer was around 4100 ft deep, with
an inversion top at 6100 ft and a maximum temperature of 10 C.

High confidence in TAFs. VFR cigs are expected to dominate the
period, but brief MVFR cigs may occur through 18Z, especially at
Ventura and Los Angeles County sites.

KLAX...High confidence in TAF. There is a 30% chance for brief
MVFR cigs through 18Z. No significant east wind component is
expected.

KBUR...High confidence in TAF. Cigs may bounce between MVFR and
VFR through 18Z..

&&

.MARINE...16/852 AM.

High confidence in the current forecast through early Friday, then
moderate confidence thereafter. Wind and seas conditions are
expected to remain below Small Craft Advisory (SCA) levels through
at least Friday, then there is a moderate-to-high chance of SCA
level winds developing each afternoon and evening over the
weekend.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...MW/Rorke
AVIATION...Lewis
MARINE...Hall
SYNOPSIS...LP/MW

weather.gov/losangeles

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