Monterey Park, California Weather Forecast Discussion

133
FXUS66 KLOX 191955
AFDLOX
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1255 PM PDT Fri Sep 19 2025
.SYNOPSIS...19/1231 PM.
A moist air mass remains in place over the region today but
convective storms will become primarily confined to the mountains
and desert. Expect some drying on Saturday, but monsoonal
moisture will begin to move north again on Sunday and a return of
convective storms is possible for the coastal and valley areas
early next week.
&&
.SHORT TERM (TDY-MON)...19/1236 PM.
Synoptically, the area is under an upper-level trough that
extends the length of California. Since yesterday, a closed 577
dam Low has formed within the trough and this feature will drive
our weather early next week. A ridge will begin to push in from
the southeast later today and through the weekend, moving the
closed Low further off the coast. By Monday afternoon, the Low
will be in a position to our southwest that will be favorable for
transporting more moisture back into the area and fueling another
round of rain and thunderstorms. Model solutions differ on the
speed with which this Low feature will move through the area to
our northeast so ensemble solutions are fairly widely spread on
details for Monday through Wednesday, but rain chances should
start Monday, peak on Tuesday, and decrease on Wednesday.
Mostly cloudy skies prevail over the area due to the moist
air mass remaining in place over the region. Morning showers in
Santa Barbara and San Luis Obispo Counties have stopped, and so
far the cumulus clouds over the mountains don`t seem to be
producing any rain. Models continue to indicate showers and
isolated thunderstorms favored over the mountains this afternoon
and early evening. The main area of concern for today appears to
be the Ventura County mountains. People planning to travel
mountain roads and/or participate in outdoor activities today
should be prepared for brief heavy downpours, gusty and erratic
winds, and dangerous lightning. Humid conditions with warmer
temperatures will make for more muggy and uncomfortable
conditions.
Some semblance of a low cloud field should return to the coastal
areas tonight and into Saturday morning. Low clouds are most
favored along the Central Coast, but moderate confidence that low
clouds and fog could make a return into the Los Angeles and
Ventura County coastal plains.
Areas under the marine layer should be a bit cooler on Saturday
than today, but outside of the marine layer, a slight warming
trend will begin.
A small amount of ensembles bring more tropical moisture into the
region as soon as Sunday so likely more cloudy than Saturday but
it looks like rain will wait until Monday.
Another surge of tropical moisture will most likely push into the
region Monday as the closed Low to our southwest transports the
moisture from what could be a developing tropical system.
Precipitable water value at KLAX climb back over an inch in all
of the forecast ensembles, potentially approaching or exceeding
1.50 inches. Increasing cloudiness with all the moisture in the
forecast.
.LONG TERM (TUE-FRI)...19/1255 PM.
Tuesday look to be the most active day to see showers and
thunderstorms. Rain totals for Tuesday are currently on the low
end, but any area under a strong shower could have much more rain.
Wednesday looks less likely, but rain cannot yet be ruled out.
Cloud cover is likely to increase across the region for early
portion of next week and could keep the temperatures on the cool
side of normal to near normal.
Thursday and Friday will bring gradual clearing and warming, with
downtown LA getting into the mid 80s. No impactful weather
expected those days.
&&
.AVIATION...19/1633Z.
At 1615Z at KLAX, the marine layer was around 1500 feet deep.
The top of the inversion was 2600 feet with a temperature of
18 degrees Celsius.
For 18Z TAF package, moderate to high confidence in desert and
valley sites, but low to moderate confidence in coastal sites.
For coastal sites, timing of flight category changes could be
+/- 4 hours of current forecasts.
KLAX...Overall, moderate confidence in 18Z TAF. There is a 20-30%
chance of MVFR CIGs 18Z-04Z. For tonight and Saturday morning,
timing of flight category changes could be +/- 3 hours of current
forecasts. No significant easterly wind component is expected.
KBUR...Overall, moderate confidence in 18Z TAF. There is a 15-20%
chance of MVFR CIGs 18Z-03Z. For tonight, there is a 20% chance of
a return of IFR/LIFR conditions 08Z-16Z.
&&
.MARINE...19/1238 PM.
For the Outer Waters, moderate to high confidence in current
forecast. Today through Saturday morning, high confidence in winds
and seas remaining below Small Craft Advisory (SCA) levels. For
Saturday afternoon and evening, there is a 60% chance of SCA
level winds across PZZ673/676 and a 30% chance across PZZ670.
For Sunday through Tuesday, there is a 60-80% chance of SCA level
winds across all of the Outer Waters. On Wednesday, high
confidence in winds and seas dropping below SCA levels.
For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Today through Saturday, high
confidence in winds and seas remaining below SCA levels. For
Sunday through Tuesday, there is a 30-40% chance of SCA level
winds in the afternoon and evening hours. On Wednesday, high
confidence in winds and seas remaining below SCA levels.
For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western half of the Santa
Barbara Channel, there is a 50-70% chance of SCA level winds in
the late afternoon and evening hours Saturday through Tuesday.
Otherwise across the southern Inner Waters, high confidence in
winds and seas generally remaining below SCA levels through
Wednesday.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...Hall/jld
AVIATION...RAT
MARINE...RAT
SYNOPSIS...jld
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox

NWS LOX Office Area Forecast Discussion