Castaic, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

158
FXUS66 KLOX 161005
AFDLOX

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

.SYNOPSIS...16/207 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)...16/247 AM.

A 3000+ foot marine layer capped by a weak inversion is in place
over Srn CA. Weak lift from an upper low spinning to the west of
Pt Conception has slowly produced a layer of stratus that covers
most of the coasts and vlys and may produce some drizzle closer to
the foothills and vlys. The marine layer is so deep that reverse
clearing seems likely this afternoon so look for cloudier skies
over the vlys and sunnier ones over the csts. Aside from the low
clouds, mid and high level clouds will drift overhead as the spin
around the upper low. Better clearing will bring 1 to 3 degrees of
warming to the csts/vlys but cool air advection will knock 4 to 8
degrees off of the interior temps. There is just enough moisture
and instability to allow for a slight chc of a TSTM to form over
the higher peaks of the VTA mtns near the Kern County line.

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...16/0541Z.

At 0418Z at KLAX, the marine layer was around 2400 ft deep, with
an inversion top at 5700 ft and a maximum temperature of 13 C.

High confidence in TAFs for KPMD and KWJF.

Moderate confidence in remaining TAFs. There is up to a 40% chance
for coastal and valley sites to remain VFR through the period with
a deepening marine layer. Highest chances exist north of Point
Conception. Otherwise, high confidence in MVFR conds being lowest
flight cat, and timing of flight cat changes may be off +/- 4
hours. A reverse clearing pattern is expected Wednesday, therefore
confidence in clearing times for KVNY and KBUR is low.

KLAX...Moderate confidence in TAF. High confidence in MVFR conds
(BKN015-030 cigs) being the minimum flight cat, but there is a
20% chance VFR conds prevail through the period. Timing of flight
cat changes may be off +/- 3 hours. No significant east wind
component is expected.

KBUR...Moderate confidence in TAF. Low confidence in clearing time
of cigs due to reverse clearing pattern forecast. There is a 20%
chance for VFR conds to prevail, otherwise, timing of flight cat
changes may be off +/- 4 hours.

&&

.MARINE...16/156 AM.

High confidence in current forecast. Conditions are expected to
remain below Small Craft Advisory (SCA) levels through Saturday
night, then moderate confidence in winds increasing to SCA levels
(21+ kts) across the Outer Waters Sunday afternoon into early
next week.

&&

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

&&

$$

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

weather.gov/losangeles

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