000
FXUS66 KLOX 171033
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
333 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...17/1026Z.

At 11Z, the marine layer at KLAX was about 400 ft deep. The top
of the inversion was at 1800 ft with a temp of 20 deg C.

Some low clouds/fog, locally dense, have pushed into southern
portions of the Central Coast and Santa Ynez Valley, with LIFR to
VLIFR conds. Those clouds should clear by mid to late morning.
Otherwise, skies were mostly clear, but some stratus was forming
off the coast of L.A. County and there may be a few hours of IFR
to LIFR conds at KLAX and KLGB from 13Z-17Z.

VFR conds are expected in all areas from late morning thru this
evening, with just some high clouds. Widespread low clouds are
expected in all coastal areas tonight, with IFR to LIFR conds, and
local VLIFR conds on the Central Coast. There is a 20% chance that
LIFR conds will spread into the valleys late tonight.

KLAX...Moderate confidence in the 12Z TAF. There is a 30% chance
of IFR to low MVFR cigs from 12Z-17Z today. There is a 20% chance
that cigs tonight will be in the MVFR category and a 20% chance
that cigs will not arrive until as late as 12Z. Any east wind
component should remain less than 6 knots.

KBUR...High confidence in the 12Z TAF with VFR conds thru the pd.
There is a 20% chance of LIFR cigs after 11Z Thu.

&&

.MARINE...17/305 AM.

Generally high confidence in the current forecast.

In the outer waters, there is a 20-30% chance of Small Craft
Advisory (SCA) level wind gusts thru this evening, but for the
most part, winds and seas are expected to remain below SCA levels
thru Fri afternoon. SCA level winds are likely Fri night thru Sun.

In the inner waters N of Pt. Sal, SCA conds are not expected thru
Sat a.m., then are likely during the afternoon/eve hours Sat/Sun.

In inner Waters S of Pt. Conception, there is a 30% chance of SCA
level winds during the late afternoon thru evening hours Fri thru
Sun. Otherwise, SCA conds are not expected.thru Sun.

&&

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

&&

$$

PUBLIC...Rorke
AVIATION...DB
MARINE...DB
SYNOPSIS...Sirard

weather.gov/losangeles

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