Acton Weather

000
FXUS66 KLOX 211157
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
457 AM PDT Fri Sep 21 2018

.SYNOPSIS...20/741 PM.

Above normal temperatures will continue through this weekend, and
are likely through much of next week. Fair skies are expected,
except for overnight to morning low clouds and fog for the coast,
and some coastal valleys. An upper low crossing Central California
will cool temperatures some Sunday and Monday, followed by high
pressure and gradual warming starting Tuesday.

Smith

&&

.SHORT TERM (TDY-SUN)...21/255 AM.

The marine layer stratus came back with vengeance last night as
an eddy spun up and drove the marine layer up to 1600 ft. A
southerly surge set up soon after and pushed low clouds around Pt
Conception and into the Central Coast. Gradients are onshore and
trending more onshore. The inversion is not that strong and
ordinarily would allow for total clearing but suspect that more
than a few beaches will stay cloudy today esp the SBA south coast.
Max temps on a roller coaster up nicely ydy and plummeting down
today. (esp across the Central Coast where there will be 8 to 12
degrees of cooling.)

Gradients reverse Saturday as high pressure builds across the
Sacramento Vly and NV. Right now it looks like the grads will end
up near neutral not offshore. Not enough really push the low
clouds. The coasts will remain covered but there will be a
noticeable reduction (but not elimination) of low clouds in the
vlys. Max temps will warm some esp in the vlys but not as much as
ydy.

On Sunday a trof will slowly push into the state from the north.
Hgts will slowly fall. At the sfc there will be a slight
increasing in the onshore flow. Low clouds will cover the coasts
and some of the vlys. The slightly lower hgts and slightly
stronger onshore flow will bring a degree or two of cooling. Max
temps will end up very close to normal.

&&

Rorke

.LONG TERM (MON-THU)...21/307 AM.

EC and GFS are now pretty much on the same page and it is pretty
certain that the benign weather will persist through the end of
the month.

On Monday a trof moving through NV brushes the state. On Tuesday
and Wednesday there is very weak flow over the state as the Jet is
well to the NE and all of the features in the east pac are too far
to the west to influence the west coast weather. On Thursday weak
ridge pops up ahead of an upper low that is approaching the
northern half of the state. Hgts will fall on Monday and then rise
steadily through Wednesday before falling again on Thu. The GFS
has H5 hgts about 3 DM higher than the EC.

At the sfc the grads change little from day to day and the night
through morning cloud pattern will continue across coasts. Current
forecast keep the vlys mostly clear and this might be a touch
optimistic.

Wednesday will be the warmest day esp if the GFS is correct but
aside from a noticeable warm up Tuesday there will not be much
day to day change in max temps. Max temps from Tuesday on will be
a couple degrees above normal.

&&

.AVIATION...21/1148Z.

At 1123Z at KLAX, the marine was 1500 feet deep. Likely deeper
across inland areas. The top of the inversion was 3800 feet with
a temperature of 23 degrees Celsius.

N of Point Conception...Moderate confidence with VLIFR to IFR
conds through 18z this morning. Southern surge of stratus could
keep low clouds lingering near the coast into this afternoon. 50%
chance for cigs to linger after 18z for coastal tafs. High
confidence with KPRB TAF. Lower confidence with timing of return
of stratus tonight. There is a chance that stratus will be more
patchy in nature but continue to be LIFR/IFR with earlier scour
out times Saturday morning.

S of Point Conception...Higher confidence with MVFR cigs for
coastal TAFS. the SE flow was beginning to pull low clouds away
from valley TAF sites. Lower confidence with MVFR cigs and scour
out times for Valley TAF sites. Moderate confidence for similar
return of low clouds with MVFR and 30% chance for IFR cigs early
this evening before going up a category. Scour out times should be
an hour earlier with higher confidence.

KLAX...Moderate confidence in 12z TAF. There is a 30% chance that
MVFR cigs will linger a few hours past 18z this afternoon. There
is a 30 percent chc of an east wind component of 8 kt through 16z.

KBUR...Low confidence in 12z TAF due to stratus pulling out from
east to west across valleys this morning. MVFR cigs should scour
out before 16z. 50% chance that cigs could become VFR by 14z. Low
confidence if IFR/MVFR cigs will return after 10z Sat morning.

&&

.MARINE...21/233 AM.

For the Outer Waters, high confidence in current forecast. There
is a 60% chance of Small Craft Advisory (SCA) level winds Sunday
across the two northern zones PZZ670-673 then expanding into the
NW portion of PZ676 for Monday.

For the Inner Waters north of Point Sal, high confidence in
current forecast as conditions are expected to remain below SCA
levels through Tuesday.

For the Inner Waters south of Point Conception, high confidence in
current forecast as conditions are expected to remain below SCA
levels through Tuesday. For this morning, southeast winds 5-15 kt
are expected to surge north of Pt. Conception. These types of
stratus patterns can keep low clouds lingering along the coast
into the afternoon hours with some patchy fog N of Point
Conception.

&&

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

&&

.HAZARD POTENTIAL OUTLOOK (SUN-THU).

No significant hazards expected.

&&

$$

PUBLIC.../Rorke
AVIATION...Kaplan
MARINE...Kaplan
SYNOPSIS...Smith

weather.gov/losangeles