Pasadena, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

424
FXUS66 KLOX 240513
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1013 PM PDT Wed Apr 23 2025

.SYNOPSIS...23/926 AM.

A persistent marine layer with stronger onshore flow will keep a
cooler weather pattern in place through Saturday. Night through
morning low clouds and fog with drizzle will be a staple of the
forecast with clouds struggling to clear from beaches each day.
Gusty onshore winds are possible across the interior portions of
the area through the end of the week. A warming trend is expected
for next week.

&&

.SHORT TERM (WED-SAT)...23/843 PM.

***UPDATE***

The marine layer is now 3800 ft the onshore push is an impressive
7.5 mb onshore to the east (down from a very impressive 9.5 mb).
Marine layer stratus covers all of the csts/vlys and coastal
slopes of VTA/LA counties. Low clouds are filling back in over the
Central Coast. The SBA south coast is cloud free and will remain
that way for a while. Low clouds will again spread across all but
the farthest inland areas and highest peaks again. Drizzle is
likely again in the morning esp near the foothills.

Max temps today would have been considered cool for January with
cst/vly highs in the upper 50s and lower 60s. There may be some
warming tomorrow but max temps will remain many degrees blo
normal. The clouds showed some signs of disruption this afternoon
and there may be slightly better clearing tomorrow afternoon.

Latest NAM continues to show a well defined cold front moving
into the area Saturday morning.

Forecast was updated for the short term clouds.

***From Previous Discussion***

No real change in the forecast through the week as a trough of low
pressure maintains cool conditions along with lots of marine layer
stratus. The marine layer depth rose to 4000 feet this morning
across the LA Basin and only slightly lower along the Central
Coast. In theory tomorrow will be almost a carbon copy of today as
forecast soundings indicate little change in the marine layer
depth and onshore gradients. Temperatures again mostly in the
lower 60s for coast/valleys and low to mid 70s in the deserts,
which is 5-10 degrees cooler than normal. And some areas of
drizzle or light rain, especially near the foothills south of Pt
Conception.

On Friday a slightly deeper upper low will approach the Bay Area
with even colder air aloft that will push the marine layer up to
at least 5000 feet and possibly as high as 7000 feet. The
additional rising motion created by the colder air aloft should
theoretically generate more widespread drizzle or light rain but
at the very least it will maintain a cool and cloudy pattern with
minimal chances of sunshine for coast/valleys. The one exception
could be the immediate coastal areas if a reverse clearing
scenario develops.

As that upper low moves onshore near the Monterey/SLO County
border Saturday morning, chances for light rain will increase
area-wide. Official NBM Pops are still on the lower side and
probably not representative of the actual chances for rain due to
how light it will be. Virtually all the EPS and now also the GEFS
ensembles are showing at least some light measurable rain across
the Central Coast Saturday morning. This percentage drops to
around 75% across Ventura County and around 40% for southern LA
County and 10-15% across the Antelope Valley. Some areas,
especially eastern Ventura and LA Counties may not actually
receive measurable rain Saturday but that doesn`t mean it won`t be
damp from drizzle.

In addition, with the close proximity of the upper low, can`t rule
out an isolated thunderstorm across SLO County, particularly the
interior which could see some sunshine and surface heating in
addition to the instability aloft. There are still a handful of
EPS solutions indicating around a half inch of rain and this could
be in part from convective cells with heavier rain rates.

.LONG TERM (SUN-WED)...23/218 PM.

The upper low is expected to be moving into NV Sunday morning but
temperatures will still be 5-10 degrees below normal. Skies may
still be cloudy in some areas Sunday morning but rapidly rising
heights and increasing subsidence should clear most areas out by
afternoon if not sooner.

High pressure will continue to build over the region into early
next week bringing high temperatures to 3-6 degrees above normal
in most areas. The one exception may be the immediate coast where
persistent onshore flow and cool ocean temps will keep
temperatures closer to normal or even slightly below.

&&

.AVIATION...24/0016Z.

At 2346Z at KLAX, the marine layer was 2700 feet deep. The top of
the inversion was around 4800 feet with a temperature of 13 C.

High confidence in TAFs for KPMD AND KWJF.

Moderate confidence in remaining TAFs. Flight Cat changes may be
off by +/- 2 hours. There is a 25% chance for IFR cigs at KPRB,
KSBP, KSMX. Better confidence in clearing fcst for sites Thursday
afternoon.

KLAX...Moderate confidence in TAF. Low clouds may reform as early
as 05Z or as late as 09Z. There is a 30% chance of cigs remaining
AOA 022. There is a 15% chance of an east wind component reaching
8 kt from 11Z-17Z.

KBUR...Moderate confidence in TAF. There is a 30% chance of no
clearing. There is a 30% chance of cigs remaining AOA 022.

&&

.MARINE...23/1012 PM.

In the Outer Waters, good confidence in the forecast. Winds will
be close to low-end Small Craft Advisory (SCA) levels at times
thru Fri night. SCA level wind gusts are likely (50-60% chance)
across much of the Outer Waters this afternoon through late
tonight. There is a 20-40% chance of low-end SCA level winds
anywhere across the outer waters Thu afternoon thru Thurday night.
However, best chances for SCA winds will be south of Point
Conception Thursday. SCA level conds are likely (70% chance) Sat
afternoon thru Mon night.

For the Inner Waters north of Pt. Sal, moderate to high
confidence in the forecast. There is a 30% chance of SCA level
winds tonight and Friday afternoon/evening. SCA conds are likely
(60% chance) during the afternoon/eve hours Sat thru Mon.

For the Inner Waters south of Pt. Conception, moderate confidence
in the forecast. SCA level winds are expected over western and
southern portions of the Santa Barbara Channel Thursday
afternoon/evening, but most likely will not affect the Santa
Barbara Harbor. Gusty winds look more widespread throughout the
Santa Barbara Channel Friday, but may not be strong enough to
reach SCA levels. Then SCA conds are likely (60% chance) during
the afternoon/eve hours Sun thru Mon. There is a 40% chance for
SCA level winds to enter the western portion of the southern Inner
Waters Sun afternoon/eve. Otherwise, SCA conds are not expected
thru Mon night.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 650-670-673-676. (See LAXMWWLOX).

&&

$$

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

weather.gov/losangeles

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