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000
FXUS66 KLOX 200616
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1116 PM PDT Fri Apr 19 2024

.SYNOPSIS...19/1118 PM.

Strong onshore flow in place will weaken on Saturday. Better
clearing is forecast for most of the area, except for the Ventura
County beaches. A warming trend will establish today through
Sunday as weak high pressure develops. Significant cooling along
with a deep marine layer are expected next week as low pressure
moves into the area. In addition, there is a slight chance of
showers or drizzle late next week.

&&

.SHORT TERM (TNT-MON)...19/943 PM.

***UPDATE***

Today saw persistent marine layer clouds for coasts and valleys,
lasting into the afternoon for LA County, and all-day for Ventura
County, eastern Santa Barbara County, and portions of the Central
Coast. These clouds dampened daytime heating, leading to highs
reminiscent of wintertime and 5 to 10 degrees cooler than
yesterday.

Winds will be calm tonight, except for the Santa Barbara SW
Coast, where NW gusts up to 35 mph are possible into early
tomorrow morning. Tomorrow afternoon and overnight, NW wind gusts
25-40 mph will develop for the mountains of SLO, SBA, and Ventura
Counties. The most impactful winds will be for the Santa Barbara
SW Coast and the I-5 Corridor, however gusts are currently
expected to remain below advisory level.

Tomorrow deep marine layer clouds will return, but will clear
earlier in the day. Temperatures are expected to be 2 to 6 degrees
warmer for most locations. However, there is the potential for
temperatures to be up to 5 degrees cooler than forecasted if
clouds persist into the afternoon, particularly for coasts and
adjacent valleys south of Point Conception.

Generally the forecast is on track, the most significant changes
for this update were slight dropping of coastal temperatures
south of Point Conception, in line with slow clearing marine
layer clouds.

***From Previous Discussion***

Models appear to be on track with the warming trend over the
weekend and decreasing stratus. Sunday is expected to be
significantly warmer at least for inland areas where highs in the
mid to upper 80s are expected. Most coastal areas will be warmer
too but still with the effects of the cool onshore breeze keeping
temps on the mild side, but with a degree or two of normal.

Monday will begin a long duration cooling trend that will last
through the following weekend as a series of low pressure systems
hit the West Coast. Still at or above normal in most areas Monday
but at least a few degrees cooler than Sunday.

.LONG TERM (TUE-FRI)...19/216 PM.

A series of troughs will move through the West Coast and
California next week keeping temperatures well below normal with
moderate to strong onshore flow each day, a solid marine layer
with slower than usual clearing, and breezy onshore winds in the
mountains and deserts. By Tuesday or Wednesday high temperatures
in all areas will in the mid to high 60s at most with chances for
morning drizzle each day through the week. The coolest days with
the highest chances for either drizzle or light rain will be
Thursday and Friday when the deepest trough arrives. Models have
bounced around with the trajectory, some showing a wetter and
farther west trajectory but more showing a less wet but cooler
inside track. 500mb heights drop into the high 550`s across the
area, and high temps may still be too high in the official
forecast as patterns like this often result in mostly low to mid
60s and little if any sunshine across coast/valleys. A lot will
depend on the ultimate track of the system and how deep the
moisture is.

Temps are expected to slowly rebound by next weekend but still
likely well below normal through the end of the month.

&&

.AVIATION...20/0616Z.

Around 0530Z, the marine layer depth was around 1000 feet deep at
KLAX. The top of the inversion was around 4000 feet with a
temperature near 15 degrees Celsius.

Moderate-to-high confidence in the current forecast. Higher
confidence in timing. Lower confidence in flight categories. IFR
to MVFR conditions are expected through at least 16Z at most
coastal and valley terminals. There is a moderate (30-40 percent)
chance that conditions could be one category lower than forecast
between 08Z and 14Z. Better clearing is expected on Saturday with
good confidence in the clearing times.

KLAX...MVFR conditions will spread into KlAX between 07Z and 09Z.
There is a 30 percent chance of IFR conditions between 10Z and
14Z. There is a 50 percent chance of VFR conditions developing
after 20Z.

KBUR...MVFR conditions will spread into KBUR between 08Z and 10Z.
There is a 30 percent chance of IFR conditions between 10Z and
14Z. VFR conditions should develop between 16Z and 18Z.

&&

.MARINE...19/1038 PM.

High confidence in winds staying below 20 knots through Saturday
morning, however may see local gusts around 20 knots tonight between
Point Conception and Santa Rosa Island. Seas will remain small as
well.

High confidence in Small Craft Advisory (SCA) winds and choppy
seas forming quickly Saturday afternoon for the Central Coast
offshore waters down to San Nicolas Island. These winds will
persist through the weekend. May need to expand the SCA for the
southern most outer waters. There is a 40 percent chance of SCA
winds for the nearshore Central Coast waters and a 10 percent
chance for the western half of the Santa Barbara Channel on
Saturday. Those chances increase by 20 percent on Sunday. All
areas will see building short period seas from these winds.

Winds will weaken Monday and Tuesday, but will stay near SCA south
of Point Conception with choppy seas over most areas continuing.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 2 PM Saturday to 6 AM PDT
      Monday for zones 670-673. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Schoenfeld/Phillips
AVIATION...Hall
MARINE...Phillips/RK
SYNOPSIS...MW/Hall

weather.gov/losangeles

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