Castaic, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

249
FXUS66 KLOX 142157
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
257 PM PDT Mon Apr 14 2025

.SYNOPSIS...14/455 AM.

A deep marine layer depth with strong onshore flow will continue
a cooling trend through the work week. Night through morning low
clouds and fog can be expected with drizzle possible each night
and morning. A cold upper level low pressure system is forecast
to bring showers to the area between Thursday night and Friday
night. A thunderstorm cannot be ruled out especially in the
mountains and deserts on Friday. Dry and milder conditions with a
warming trend can then be expected for next weekend.

&&

.SHORT TERM (TDY-THU)...14/245 PM.

A slow moving closed low pressure system will remain offshore
through roughly Wednesday, before likely pushing ashore while
merging into a much deeper trough into Thursday. This is a low
predictability weather pattern, although the resultant weather
probably will not change much even if the weather pattern evolves
differently than anticipated.

High confidence in continued marine layer pattern with increased
inland penetration each day through at least Wednesday. Night to
morning drizzle is possible at times within the expanding marine
layer cloud deck. There is a 5 percent chance of an elevated
thunderstorm focused across the interior through tonight and again
Tuesday afternoon and evening. Dry lightning or gusty winds would
likely be the main threat should a thunderstorm develop. Slow to
no clearing is likely each day, especially for south facing coasts
and foothills. A cooling trend will continue through at least
Thursday with widespread highs only in the 60s by Wednesday. Local
advisory level winds will be possible for interior areas
especially into Wednesday afternoon and evening for the Antelope
Valley foothills thanks to the deep marine layer and strong
onshore gradients.

Theres a 20 percent chance that the trough will deepen fast
enough to bring increased shower and isolated thunderstorm
activity as early as Thursday, especially in the evening.

.LONG TERM (FRI-MON)...14/245 PM.

Below normal confidence in the extended forecast period,
especially Friday as there is a 50-60 percent chance of deep
trough across the region supporting convective showers and
thunderstorms focused across the interior, but a few may enter
coastal areas, especially the coastal valleys of Los Angeles and
Ventura County thanks to northwesterly steering flow aloft.
Rainfall amounts in this scenario would mostly be under a quarter
of an inch with the greatest rainfall chances in the mountains to
interior valleys, although isolated amounts above a half of an
inch would be possible with any thunderstorms or training showers.
Gusty northwest to onshore winds would likely reach advisory
levels, especially across the high terrain into the interior
deserts. Snow levels initially above 8000 feet may dip to 6000 to
7000 feet and locally lower in heavier showers or in the overnight
period Thursday into Friday or Friday into Saturday with light
accumulations generally above 6000 or 7000 feet. Colder interior
valleys may see frosty morning lows Friday or Saturday morning
with lows potentially down into the mid to upper 30s with 40s
potentially becoming common in most areas away from the coast.
Quite chilly for late April!

High pressure building in behind the departing storm may support
advisory level northwest to onshore winds for prone areas this
weekend with rebounding temperatures. Marine layer clouds may be
slow to reform, possibly taking hold across many coastal areas by
Sunday.

&&

.AVIATION...14/1644Z.

At 1600Z at KLAX, the marine inversion was based 2500 feet.
The top of the inversion was 5500 feet with a temperature of
15 degrees Celsius.

Overall, moderate to high confidence in 18Z TAF package. High
confidence in desert TAFs. Moderate confidence in coastal and
valley sites due to uncertainties in the marine layer behavior.
High confidence in return of CIG/VSBY restrictions to coastal and
valley sites, but only moderate confidence in flight categories
and timing of category changes.

KLAX...Moderate confidence in 18Z TAF. There is a 30% chance of
MVFR CIGs 19Z-02Z. Moderate confidence in timing of flight
category changes. No significant easterly wind component is
expected.

KBUR...Moderate confidence in 18Z TAF. Timing of return of
CIG/VSBY restrictions tonight could be +/- 3 hours of current 06Z
forecast.

&&

.MARINE...14/1215 PM.

Overall, high confidence in current forecast. Tonight through
Saturday, winds and seas are expected to remain below Small Craft
Advisory (SCA) for all the coastal waters.

&&

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

&&

$$

PUBLIC...Munroe
AVIATION...RAT
MARINE...RAT
SYNOPSIS...Hall

weather.gov/losangeles

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