Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 311839
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1139 AM PDT Sun May 31 2020

.SYNOPSIS...31/903 AM.

Partly to mostly cloud skies will prevail over the region today.
Varying amounts of night and morning low clouds should affect
mainly the coast tonight into the middle of the week. Otherwise
partly to mostly cloudy skies will prevail through the period.
Temperatures will turn warmer to near normal today and to several
degrees above normal Monday into mid week.

&&

.SHORT TERM (TDY-TUE)...31/856 AM.

The marine inversion was well-defined and near 2400 ft deep at VBG
early this morning. However, at LAX there was a very weak inversion
if you can call it that somewhere around 2500-3000 ft deep. Low
clouds were much more organized N of Point Conception this morning
and covered much of the Central coast, Santa Ynez Vly and into the
northern SLO County interior vlys. S of Point Conception, low clouds
were primarily over the eastern SBA County S coast into the VTU
County coast and some vlys, as well over Santa Catalina Island.
Patchy low clouds were noted in the San Gabriel Vly as well.
Otherwise, sunny to partly cloudy skies were noted across the
region. The low clouds are forecast to clear back to or off the
coast by late this morning. However, plenty of mid and hi level
clouds to the W and SW of the forecast area this morning will move
into the region thru this afternoon to leave mostly cloudy skies
overall.

There will be decent onshore gradients this afternoon (e.g. NAM
fcst LAX-DAG +7.9 mb at 00Z) to help bring breezy to gusty NW to
SW winds to many areas. Despite the cloud cover, temps are still
forecast to turn warmer today back to near normal for the most
part. Highs in the warmest vlys and lower mtns should reach the
upper 70s to lower 80s.

A broad upper level trof will develop over the E Pac just off of the
CA coast through tonight, with S to SW flow aloft over the forecast
area. On Mon, a 572 dm H5 low will develop at the base of the upper
trof about 300 NM SW of Point Conception. The upper level low should
then remain nearly stationary Mon night thru Tue. This will allow H5
heights to increase over swrn CA from about 577-580 dm Mon afternoon
to around 581-584 dm Tue afternoon.

An inversion around 1000 ft deep will develop tonight into Mon
morning, and a weak eddy is forecast over the SoCal Bight. It looks
like more low clouds will develop along the coast and perhaps into
some adjacent vlys altho there should be northerly canyon winds
along the SBA County S coast which should keep low clouds away from
there. It looks like the marine inversion will lower to near
surface-based S of Point Conception Mon night into Tue morning,
while remains about 1000 ft deep along the Central Coast. Marine
layer clouds should affect the immediate Central Coast Mon night
into Tue morning, but should be patchy at best S of Point
Conception. If any low clouds sneak into the L.A. County coast Tue
morning they could be accompanied with some dense fog. Otherwise,
there will be plenty of mid and hi level clouds moving into swrn
CA tonight thru Tue to keep mostly cloudy skies for the most part
over the region, except some clearing should develop over SLO/SBA
Counties Tue afternoon.

Onshore gradients will decrease thru Tue, but there will still be
breezy SW-NW onshore winds each afternoon and evening for many
areas. The NAM was also forecasting gradients from SBA-SMX to peak
at -2.9 mb at 06Z this evening. This will contribute to gusty sub-
advisory NW to N sundowner winds for the SBA County S coast and
Santa Ynez Mtns mainly W of Goleta this evening.

Temps are forecast to turn even warmer Mon thru Tue despite the
presence of mid and hi level clouds over the region. This is due to
a combination of weaker onshore gradients and increased boundary
layer/950 mb temps. It looks like highs in the warmest vlys and
lower mtns will reach the Mid 80s to near 90 on Mon, and upper 80s
to low 90s on Tue. High temps by Tue will be about 3-8 deg above
normal away from the coast.

.LONG TERM (WED-SAT)...31/347 AM.

Both the GFS and the EC agree the upper low will not move much on
Wednesday. But the mid and high level clouds should move away and
it should be a sunny day. The sunshine will add another 3 to 6
degrees of warming to the area and Wednesday will be warmest day
of the next 7 with all of the vlys in the 90s and coastal areas
mostly in the 80s away from the beaches.

On Thursday both models promise to move the upper low to the east
towards Baja. There are still differences however. The GFS places
the center of the low about 100 miles further east than the EC
does. Whichever mdl is correct or if it a compromise between the
two it probably will not make too much of a difference in the
forecast for Srn CA. Look for partly cloudy skies everywhere and
morning low clouds across the coasts. The hgts will lower through
the day and this will kick off a cooling trend.

Both mdls now suggest that the upper low be pulled up to the north
and east as it becomes entwined in the flow around a large PacNW
low. This will move the upper low over the area Thursday night
(GFS) or Friday morning (EC). This passage will generate a slight
chc of mtn showers again earlier GFS and later EC. Friday will
start out a little cloudy but will then clear in the afternoon the
lower hgts will accelerate the cooling trend and max temps should drop
5 to 10 degrees. Max temps will end up only 1 to 3 degrees above
normal across the coasts and 2 to 5 degrees blo normal over the
vlys and interior.

Dry WSW flow on tap for next Saturday. Look for mostly sunny skies
as the low`s passage will likely disrupt the marine layer. max
temps will warm a few degrees with rising hgts.

&&

.AVIATION...31/1837Z.

At 1730z at KLAX... The inversion was around 2450 feet. The top of
the inversion was around 3600 feet with a temperature of 16 degrees
Celsius.

Overall... Moderate confidence in the current TAFs. Lingering MVFR
CIGs along both coasts of Santa Barbara County will scatter out
by early afternoon. However all coastal terminals have a seventy
percent chance of at least IFR/MVFR conditions returning after
06z and along the Central Coast VLIFR/LIFR conditions may return
as early as 03z. There is a sixty percent chance of MVFR conditions
at KPRB 06z-17z and a twenty percent chance of IFR/MVFR conditions
at KBUR and KVNY 09z-16z. Otherwise and elsewhere, VFR conditions
will prevail.

KLAX... Moderate confidence in the current TAF. There is a seventy
percent chance of IFR/MVFR conditions returning 08z-18z.
Otherwise, VFR conditions will prevail. There will be no east
winds greater than 8 kts during the forecast period.

KBUR... Moderate confidence in the current TAF. There is a twenty
percent chance of IFR/MVFR conditions 09z-16z. Otherwise, VFR
conditions will prevail through the forecast period.

&&

.MARINE...31/800 AM.

Across the outer waters... Winds will be elevated and gusty to Small
Craft Advisory (SCA) level beginning this morning near Point
Conception and across all of the outer waters by this afternoon.
The winds will diminish after midnight to below SCA level then
will increase to SCA level again tomorrow with similar timing.
Conditions across all of the outer waters will be below SCA levels
Tuesday through at least Wednesday then there is a sixty percent
chance of the wind increasing to SCA level again on Thursday.

Across the nearshore waters of the Central Coast... Winds will
increase to SCA level this afternoon and evening, otherwise
conditions will be below SCA levels through at least Thursday.

Across the inner waters south of Point Conception... Winds will
increase to SCA level from Point Conception to Point Mugu this
afternoon and evening and will be elevated but below SCA level
south of Point Mugu during the same period. Otherwise, conditions
will be below SCA levels through at least Thursday.

A long period south swell will gradually subside but will increase
again later in the week.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect until 2 PM PDT this
      afternoon for zones 40-41-87. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9
      PM PDT this evening for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Monday for zones 650-670-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Monday for zone
      673. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (TUE-SAT).

No significant hazards expected.

&&
$$

PUBLIC...Sirard/Rorke
AVIATION...Kj
MARINE...Kj
SYNOPSIS...Sirard

weather.gov/losangeles


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