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000
FXUS66 KLOX 171007
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
307 AM PDT Wed Apr 17 2024

.SYNOPSIS...16/952 PM.

Dry and warmer conditions will prevail across the region this
week and through the weekend. Night through morning low clouds
and fog will affect portions of the coast and valleys through the
period.

&&

.SHORT TERM (TDY-FRI)...17/240 AM.

Clouds and temperatures are the only forecast concerns for the
next three day short term fcst.

Srn CA will be under the top end of ridge poking up from the SW
hgts will be near 582 dam. While there is still offshore flow form
the north it is about 2 mb weaker than this time ydy and will turn
onshore in the afternoon. The onshore push to the east is about 2
mb stronger than it was ydy and should be nearly 6 mb onshore by
mid afternoon. There is not much in the way of low clouds at the
moment just some patchy clouds across western SBA county. Hi rez
ensemble guidance continues to bring low clouds to the LGB-LAX
area around dawn and will continue with that fcst. A mass of high
clouds to the west of the area will move overhead this afternoon
and skies will turn partly cloudy. The onshore this afternoon will
allow for an earlier seabreeze which will bring 2 to 4 degrees of
cooling to the csts/vlys. Then interior, however will warm 3 to 6
degrees under the strengthening April sunshine.

The ridge will flatten tonight and hgts will fall. Falling hgts
combined with increased onshore flow should bring a return of
marine layer clouds to most of the coasts and vlys by dawn. A grip
of mid and high clouds advecting in on westerly flow aloft will
make the day a mostly cloudy one regardless of the low clouds.
That said an increase in the west to east onshore flow to over 7mb
will likely prevent the low clouds from clearing at more than a
few west facing beaches. This onshore push will also bring
stronger than normal westerly winds to the Antelope Vly. The
clouds and lower hgts will combine to bring 4 to 8 degrees of
cooling across the board - this will bring the csts and vlys max
temps down below normals. The mtns and the far interior, however,
will remain likely above normal. Max temps across the csts and
vlys will end up in the mid 60s to the mid 70s.

A weak trof will slide over the area on Friday and hgts will dip
to 574 dam. Onshore flow will be 2 to 3 mb onshore from both the W
and S. This will bring another round of slowly developing low
clouds across the coasts and most of the vlys. Ensemble gradient
fcsts now show even stronger afternoon onshore flow than on
Friday. This runs contradictory to the hi rez ensemble cloud
forecast which shows good clearing by afternoon. Will keep the
afternoon fcst sunny, but there is now a higher chc of some low
clouds lingering at the beaches in the afternoon. The other change
for the Friday forecast is with the max temps which have switched
from little change to a solid 3 to 6 degrees of cooling mostly due
to the lower hgts and increased onshore flow. Max temps across the
csts and vlys will in the mid 60s to mid 70s or 3 to 6 degrees blo
normal. Despite the cooling the mtns and far inland areas will
end up about 6 degrees above normal.

.LONG TERM (SAT-TUE)...17/300 AM.

Model solutions both deterministic and ensemble based are in good
agreement in the long term.

Over the weekend a ridge will slowly build over the state and
hgts will reach 580 dam on Sunday. At the same time the onshore
flow will weaken. The marine layer cloud coverage will diminish on
Saturday and will likely be confined to the Long Beach area on
Sunday. Look for 3 to 6 degree of warming each day except that the
Central Coast will not see much change on Sunday. Sunday`s max
temps will end up 2 to 4 degrees above normal across the cst/vlys
while the mtns and far interior will be 5 to 10 degree warmer than
normal. Almost all of the vlys will see temps in the 80s.

A trof moves in on Monday and this along with a substantial
increase in onshore flow will bring a return of the low level
clouds in the morning. Max temps will fall 3 to 6 degrees.

The mdls begin to diverge on Tuesday but the most likely outcome
will be a deeper trof, more marine layer clouds and cooler temps.

Beyond Tuesday there is some signal that an upper low will move
close enough to bring light rain to the area (best chc SLO county)
but the ensembles are all over the place with the exact timing and
details.

&&

.AVIATION...17/0153Z.

At 00Z, there was a weak marine inversion at KLAX at about 800 ft.
The top of the inversion was at 1700 ft with a temp of 21 deg C.

High confidence in the 00Z TAFs for deserts and valleys. Moderate
confidence in coastal TAFs as cigs are possible in the early
morning hours. The timing of any low clouds may be off +/- an
hour or so.

KLAX...Moderate confidence in the 00Z TAF. There is a 40%-50%
chance of MVFR cigs about 11Z-16Z Wed. Otherwise VFR conds will
prevail. Any east wind component should remain less than 6 knots.

KBUR...High confidence in the 00Z TAF with VFR conds thru the pd.

&&

.MARINE...16/752 PM.

Generally high confidence in the current forecast.

In the outer waters, Small Craft Advisory (SCA) level winds and
steep seas will continue thru late tonight, then SCA conds are not
expected through Friday. There is then a 40%-50% chance of SCA
conds Friday night through Sunday.

In the inner Waters N of Pt. Sal, SCA conds are not expected
through Sunday, except there is a 20%-30% chance of SCA wind gusts
at times especially during the evening hours Friday through
Sunday.

In the Inner Waters S of Pt. Conception, SCA conds are not
expected through Sunday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT early this
      morning for zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Phillips
MARINE...Sirard/Smith
SYNOPSIS...Sirard

weather.gov/losangeles

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