Acton Weather

000
FXUS66 KLOX 192114
AFDLOX

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

.SYNOPSIS...19/130 PM.

Strong onshore flow in place will continue the cooling trend into
today. Extensive low clouds and fog will struggle to clear as a
deep marine layer depth remains in place into tonight. A warming
trend is expected over the weekend 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 (TDY-MON)...19/202 PM.

A weak trough over California has induced a strong onshore flow
and deep marine layer that has kept skies cloudy across much of
the coast/valley areas through mid-afternoon and temperatures well
below normal. Skies have started clearing across LA County and
parts of the Central Coast but it remains socked in from Santa
Barbara to Thousand Oaks. Pressure gradients are starting to
trend weaker this afternoon and the trough that started all this
is shifting east so models appear to be on track with the warming
trend over the weekend and decreasing stratus. Saturday will be a
transition day, still with plenty of marine layer in the morning
through the coast and valleys, but likely earlier clearing and
warmer temps by afternoon. 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...19/1554Z.

At 15Z over LAX, the marine layer was 2500 feet deep with an
inversion top at 5200 feet and 15 degrees Celsius.

Moderate to high confidence in generally persistence forecast
(similar flight categories and timing for the next 24 hours as the
previous). While ceilings will be most common over the next 24
hours, low confidence on timing and coverage of any clearing.

KLAX...Moderate confidence in OVC015-025 being most common through
Saturday 18Z. Low confidence on when and if clearing will occur
today, but the window for that is 20-02Z. 30 percent chance of no
clearing in that window, 40 percent chance of 2-4 hours of
clearing, and 30 percent chance of 5+ hours of clearing. Southeast
winds of 4-6 knots is likely through 19Z today, and 10-18Z
Saturday, but the chance of exceeding 8 knots is less than 20
percent.

KBUR...Moderate confidence in OVC012-020 being most common
through Saturday 18Z. Moderate confidence on 3-6 hours of
clearing today in the 19-06Z window, with a 20 percent chance of
any clearing lasting less than 3 hours.

&&

.MARINE...19/1054 AM.

High confidence in winds staying below 20 knots through Saturday
morning, except for winds locally to around 20 knots this evening
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. 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
AVIATION...Kittell
MARINE...RK
SYNOPSIS...MW/Hall

weather.gov/losangeles

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