Pico Heights, California Weather Forecast Discussion

874
FXUS66 KLOX 230455
AFDLOX
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
955 PM PDT Mon Sep 22 2025
.SYNOPSIS...22/912 AM.
Dry conditions with warmer temperatures are expected today.
Monsoon moisture will be increasing tonight into Tuesday
resulting increasing shower and thunderstorm chances that will
continue into at least Wednesday. Cooler temperatures are expected
through the weekend as well.
&&
.SHORT TERM (MON-THU)...22/830 PM.
***UPDATE***
The core of the low pressure system that will be driving our
weather for the next 48 hours is currently 400 miles southwest of
Los Angeles. The latest projections continue to favor the most
westward track of the system as it moves to the north, which means
the bulk of the rain will be over the ocean off the Central Coast,
and to a lesser degree over San Luis Obispo and Santa Barbara
Counties where the impact risk is the highest.
Made a few updates to the forecast that covers the next 24 hours.
Sped up the advancement of mid-to-high level clouds, as the clouds
on satellite are already knocking on the door and most of the
models (except the NBM oddly enough) have the clouds spreading
over the entire region by Tuesday morning. Also seeing some
isolated showers from the Channel Islands southward which none of
the models see, so added some mention of those into Tuesday
morning. Otherwise, the chances for rain (PoPs) all look good,
with the highest PoPs over San Luis Obispo and Santa Barbara
Counties. There is a very real possibility that Los Angeles County
gets nothing. Tuesday afternoon through early Wednesday still
looks quite convective, with K-Indicies of 36-40, strong vorticity
advection, and healthy difluent flow aloft. Again, the focus is
over the ocean off the Central Coast and to a lesser degree, San
Luis Obispo and Santa Barbara Counties. The previous numbers on
rainfall totals, rates, and potential impacts all look on track.
Most of the area should see only minor impacts, but a few isolated
locations could see more significant impacts in terms of frequent
lightning, strong winds, and heavy rain.
***From Previous Discussion***
Quiet weather day today with a shallow marine layer creating
patches of dense fog near the coast and temperatures a little
warmer than yesterday, especially inland.
The weather pattern becomes much more complex Tuesday and
Wednesday as the next surge of monsoon moisture arrives. The main
complication is the wandering upper low which with each run
results in a slightly different outcome, mostly in terms of the
location of the expected activities. Models have been consistent
showing the next moisture surge coming up Tuesday, but really
peaking Tuesday night into Wednesday. This coincides with
increasing instability as the upper low wobbles towards the
northeast, settling just off the Central Coast. Forecast soundings
show some strong signals for heavy lightning activity along and
off the Central Coast, including the western portion of southern
Santa Barbara County and possibly including the outer channel
islands. Will probably see lightning picking up from the south
well offshore in the afternoon, but then peaking Tuesday night
into Wednesday morning along the Central Coast. In addition,
there will be periods of heavy showers in these areas,
particularly where there is training of storms, but also some
areas where thunderstorms may not receive significant rain
creating localized dry lightning strikes. The high potential for
strong updrafts means there will also be hail and gusty winds at
times.
Again the location of all this is largely based on the model
forecast of the upper low, which could swing as much as 100 miles
in any direction. So while confidence in the resulting weather
conditions is at least moderate to high, confidence in the
location of those conditions is still on the lower side. As an
example of this, the last couple model runs have shifted the low a
little more to the west and if this continues a lot the severe
weather could remain over the coastal waters.
With the low expected to start drifting slowly towards the east
on Wednesday, areas to the east, including Ventura and LA
Counties, will have increasing chances of showers but thunderstorm
chances will be decreasing and sounding profiles become less
favorable for convection. Not a zero chance but definitely lower
than areas to the west.
The forecast for Thursday is dry for now, but the upper low is
still expected to be in the area so as it gets closer would not be
surprised if some shower/storm chances are added, especially in
the mountains. Otherwise, temperatures will continue a slow
cooling trend.
.LONG TERM (FRI-MON)...22/239 PM.
Forecast is rain free through the weekend but the same upper low
remains in the vicinity into early next week so can`t totally
rule out a shower or thunderstorm, especially in the mountains.
PW`s remain well above normal so the muggy conditions will
continue, though temperatures are expected to cool to near normal
levels. Also, there are a couple tropical systems off Mexico that
could introduce additional moisture and instability depending on
how the upper level pattern evolves.
&&
.AVIATION...23/0243Z.
Around 2044Z, the marine layer depth was around 300 feet deep at
KLAX. The top of the marine inversion was near 2000 feet with a
temperature near 21 degrees Celsius.
High confidence in TAFs for KPRB, KBUR, KVNY, KPMD, and KWJF.
Moderate confidence in coastal TAFs. Arrival times may be off +/-
2 hours for KSMX and KSBP, and +/- 3 hours for remaining TAFs.
There is a 20% chance for vsbys 1/2SM to 1SM for most coastal
sites.
KLAX...Moderate confidence in TAF. Arrival may be off +/- 3 hours.
15% chance for vsbys 1/2SM to 1SM between 08Z and 15Z. Any east
wind component should remain less than 6 knots.
KBUR...High confidence in TAF with VFR conditions expected.
&&
.MARINE...22/953 PM.
Moderate confidence in the current forecast.
For the outer waters and the nearshore waters along the Central
Coast, some localized Small Craft Advisory (SCA) level conditions
may linger early tonight, highest across the northern outer
waters. Winds and seas will fall below SCA levels between late
tonight and Tuesday morning. Local NW gusts of 20-25 knots are
possible Tuesday afternoon and evening. There is a 30-50 percent
chance of SCA level winds on Wednesday afternoon and evening,
increasing to 50-70 percent on Thursday and Friday afternoon and
evening. The highest chances will be for the waters beyond 30 NM
offshore.
Inside the southern California bight, winds and seas will likely
remain below SCA levels through Tuesday morning. Lower confidence,
but some gusty, mainly sub-advisory level winds are possible
Tuesday afternoon into Tuesday night. There is a 30-50 percent
chance of SCA levels winds Wednesday and Thursday afternoons and
evenings. The highest chances will be for the western Santa
Barbara Channel.
Moisture with a tropical disturbance to the south will bring a
chance of showers and thunderstorms to the coastal waters from
Tuesday into at least Wednesday night. Low confidence exists in
the exact timing and location of showers and thunderstorms.
However, current guidance suggests more widespread thunderstorm
activity will be for the waters north and west of San Miguel
Island Tuesday night. Any thunderstorm that forms will be capable
of producing locally gale force winds and rough seas, dangerous
lightning, heavy rainfall with reduced visibility, small hail, and
waterspouts.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...MW/RK
AVIATION...Phillips/Lewis
MARINE...Phillips/Lewis
SYNOPSIS...MW
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox

NWS LOX Office Area Forecast Discussion