409
FXUS66 KLOX 131509
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
809 AM PDT Mon May 13 2024

.SYNOPSIS...12/837 PM.

Quiet weather will continue the next several days with near
to slightly below normal temperatures. Widespread night and
morning low clouds are expected across coast and valleys as
onshore flow increases. Temperatures will cool slightly through
Wednesday, then warm slightly the end of the week. Gusty winds are
likely across the mountains and Antelope Valley each afternoon.

&&

.SHORT TERM (TDY-WED)...13/808 AM.

***UPDATE***

Latest satellite and surface observations indicate widespread
stratus west of the mountains (and the Salinas River Valley) and
clear skies elsewhere. Morning sounding data indicates marine
inversion ranging in depth from 1400 feet north of Point
Conception to around 2400 feet south of Point Conception.

Forecast-wise for the immediate short term, classic "May Gray"
will be the story. With moderate onshore gradients forecast
through the day, stratus will gradually clear to the immediate
coastal plain this afternoon with a quick return this evening.
Otherwise, skies should be mostly sunny with just some scattered
high clouds. The onshore gradients will produce some gusty winds
this afternoon across interior sections, including the Antelope
Valley, but speeds will remain below advisory levels. As for
temperatures, morning TEMP STUDY data indicates today should be
a few degrees cooler all areas with cooler boundary layer and
greater marine influence.

Current forecast has good handle on the immediate short term. So,
no significant updates are anticipated. For the afternoon forecast
suite, focus will be on a continuation of the "May Gray" theme for
the area.

***From Previous Discussion***

A high hgt (574 dam) upper low will slowly transit over the area
from the NW to SW over the next three days. There will be strong
onshore flow from the west and moderate onshore flow from the
south. The spectral mdls (GFS and EC) show an increasing trend in
the onshore push to the east but now the NAM show little day to
day change.

So the May Grey will continue through the short term (sneak peak -
through the long term too) Look for early to arrive and late to
leave low clouds every day. Just like the last few days some
coastal areas will see no clearing at all (esp from Malibu and
points north)

Max temps will not change much from day to day. Look for mid 60s
to lower 70s across the coasts and 70s through the vly. The inland
areas will be much warmer with max temps in the 80s. (A switch to
SE flow will make Paso Robles the temp outlier with a 10 degree
drop likely today). As it has been for the last few day the
csts/vly will be 3 to 6 degrees blo normal and the inland areas
will wind up 3 to 6 degrees above normals.

Like ydy there will be some mtn cloud build ups in the afternoon
but only a 5 to 10 percent chc of an TSTM developing as the upper
low nears the area.

There 8 mb onshore push in the afternoon will bring stronger than
normal seabreezes and gusty winds (30 to 40 mph gusts) across the
interior, especially the Antelope Valley. If the 10 mb onshore
push advertised by the GFS pans out there will be advisory level
(45 mph) gusts across the western Antelope vly and foothills
Wednesday afternoon.

.LONG TERM (THU-SUN)...13/308 AM.

Deterministic mdls are in good agreement with the ensemble means
and have good confidence in the xtnd forecast. Look for a week
ridge to move in on Thu and Fri. The ridge will push to the east
Saturday and an upper low will encroach on the area. Mdl
agreement falls off on Sunday but there will likely be some sort
of low pressure near the area.

The night through morning low cloud pattern will continue unabated
through the period. There maybe slightly better clearing on Thu
and Fri and then slower to no clearing on Saturday. The troffing
on Sunday may provide enough lift for some drizzle in the morning.

Higher pressure and better clearing on Thu/Fri may lead to a few
degrees of warming while the weekend will likely end up a few
degrees cooler.

&&

.AVIATION...13/1146Z.

At 0905Z at KLAX, the marine layer was 2000 feet deep. The top of
the inversion was around 3100 feet with a max temp of 19 C.

High confidence in desert TAFs.

Moderate confidence in the remainder of the TAFs. Flight cat
change timing could be off by +/- 90 minutes and cig hgt could be
off by +/- 200 ft.

KLAX...Moderate confidence in TAF. There is a 30 percent chc of
BKN004 conds thru 15Z. There is a 25 percent chc of BKN012 conds
20Z-01Z. Good confidence that any east wind component will be
under 5kt.

KBUR...Moderate confidence in TAF. There is a 30 percent chc of
BKN004 conds thru 15Z. There is a 25 percent chc of a 17Z VFR
transition and a 30 percent chc of a delay until 19Z. Cigs will
very likely return between 04Z and 06Z this evening.

&&

.MARINE...13/744 AM.

Moderate to high confidence in the current forecast.

For southern outer waters, there is a 50% chance of Small Craft
Advisory (SCA) winds developing this afternoon or evening and
lasting into tonight, and a 30-50% chance of returning again late
Tuesday and Wednesday. There is a 10-20 percent chance of SCA
conditions for the western third of the Santa Barbara Channel
during this time.

There is a 10-20 percent chance of SCA conditions across the
southern inner waters including nearshore LA and Ventura County
Wednesday afternoon and evening.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Tuesday for zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Rorke
MARINE...Munroe/Schoenfeld
SYNOPSIS...MW

weather.gov/losangeles

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