Duarte Weather

000
FXUS66 KLOX 302346
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
446 PM PDT Sat May 30 2020

.SYNOPSIS...30/205 PM.

Partly to mostly cloudy skies will prevail across southwestern
California through this afternoon, with a few leftover showers
over San Luis Obispo and Santa Barbara Counties. Night and
morning low clouds and fog should affect the coast and valleys
tonight into early next week, otherwise partly to mostly cloudy
skies will continue. Temperatures will be several degrees below
normal today, then turn warmer to near normal Sunday and to
several degrees above normal early next week.

&&

.SHORT TERM (TDY-TUE)...30/202 PM.

A 564 dm H5 low was inland over nrn CA early this afternoon, with
a broad WSW flow aloft over swrn CA. The tail end of a weak
frontal system pushed into the Central Coast with a few showers
down to Point Conception. Further N, steady rain occurred in the
hills of NW SLO County, with up to 0.63 inch of rain reported at
Rocky Butte from last night thru today. There will be a few
leftover showers over parts of SLO/SBA Counties thru mid
afternoon. Otherwise, partly to mostly cloudy skies will prevail
N of Point Conception thru sunset, with sunny to partly cloudy
skies elsewhere.

Decent onshore gradients should continue this afternoon (e.g.,
NAM fcst LAX-DAG +8.2 mb at 00Z) which will contribute to breezy
to gusty W to SW winds for much of the forecast area into early
this evening. Temps will be about 3-10 deg below normal across
the region, with afternoon highs in the warmest vlys and lower
mtns expected to be in the mid to upper 70s, except into the low
80s in the Antelope Vly

For tonight through Sun night, a broad upper level trof will develop
over the E Pac just off of the CA coast with S to SW flow aloft over
the forecast area. On Mon, a 570 dm H5 low will develop at the base
of the upper trof about 200 NM SW of Point Conception. The upper
trof should then drift S and away from srn CA to a position about
300 NM SSW of Point Conception by late Tue afternoon. This
will allow H5 heights to increase over swrn CA from about 572-577
dm Mon afternoon to around 577-579 dm Tue afternoon.

A weak marine inversion around 1000 ft deep is expected to form
tonight. Low clouds are expected to develop along the coast and
move into some of the adjacent vlys late tonight and Sun morning.
The generally weak inversion will continue Sun night 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 into
some adjacent vlys altho there should be northerly canyon winds
along the SBA County S coast which should keep the low clouds
away. Marine layer clouds will continue to affect most coastal
areas Mon night into Tue morning as well. Otherwise, there will be
plenty of mid and hi level clouds moving into swrn CA Sun 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 some thru Tue, but there will
still be breezy SW-NW onshore winds each afternoon and evening
for many areas. For Sun evening, the NAM was also forecasting
gradients from SBA-SMX to peak at -3.6 mb at 06Z. This will
contribute to gusty NW to N sundowner winds for the SBA County S
coast and Santa Ynez Mtns mainly W of Goleta, with some gusts
possibly approaching Advisory levels.

Temps are forecast to turn warmer Sun 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 lower to mid 80s Sun, Mid 80s
to near 90 on Mon, and mid 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)...30/202 PM.

The GFS and EC have the upper level low remaining about 300 to 350
NM SW of Point Conception on Wed, then the models differ in the
movement of the upper low Thu and Fri. The GFS is quicker to
eject the upper low NE Thu and into srn CA Thu night and early Fri
morning. The EC is slower and keeps the upper level low nearly
stationary thru Thu then pushes it NE and into srn CA by midday on
Fri. The GFS also develops showers over much of the forecast area
Thu night and early Fri while the EC remains dry for the most
part. The GFS and EC ensembles pretty much follow the thinking of
their respective operational runs thru this period. By Sat,
however, both models are consistent with a large upper level trof
moving into the E Pac giving srn CA a broad SW flow aloft.

The NBM does have less than 15 percent POPs over the area
Wednesday evening and again Thursday evening, too low to mention
pcpn (the Wednesday evening POPs do not make sense anyway). Due
to model uncertainties, kept dry weather over the forecast area
thru the extended period. The marine layer pattern should continue
with night and morning low clouds and fog mostly for the coast
except minor intrusion into the adjacent valleys at times.
Otherwise, mostly clear skies can be expected across the region.
Forecast confidence this period is moderate at best due to model
inconsistencies.

Temps should be several degrees warmer than normal on Wed then a
gradual cooling trend should take place thru the end of the week.
It should be noted the EC has decent offshore gradients Wed with
temps much warmer than what is currently forecast.

&&

.AVIATION...30/2345Z.

At 2340Z at KLAX, the marine layer was 2000 feet deep. The top of
the weak inversion was at 2500 feet with a temperature of 15
degrees C.

Low to moderate confidence in TAFs. Plenty of residual low
level moisture will likely bring areas of low clouds to
coastal and some valley locations overnight into Sunday
morning, however there is reduced confidence due to weak
marine inversion and increasing stream of mid and high level
clouds from the southwest.

KLAX...Low to moderate confidence in TAF. MVFR cigs likely
to develop late tonight into early Sunday morning, however
timing of onset is +/- 2 hours from current TAF.

KBUR...Low to moderate confidence in TAF. While there is
the potential of IFR/MVFR cigs to develop briefly Sunday
morning, there is a 30 percent chance of no cigs.

&&

.MARINE...30/128 PM.

Good confidence that winds and seas will largely remain below
Small Craft Advisory (SCA) level today. Widespread SCA level
northwest winds are likely across the waters from the Central
Coast to San Nicolas Island Sunday afternoon through Monday night.

Short period seas will build Sunday night into Tuesday due to the
increased northwest winds. Long period south swell will persist
through next week.

&&

.BEACHES...30/128 PM.

Beach hazards for elevated surf and high rip current risk
continues through Sunday afternoon.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect through Sunday afternoon
      for zones 40-41-87. (See LAXCFWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK (TUE-SAT).

No significant hazards expected.

&&

$$

PUBLIC...Sirard
AVIATION...Gomberg
MARINE...Sweet
BEACHES...Sweet
SYNOPSIS...Sirard

weather.gov/losangeles

NWS LOX Office Area Forecast Discussion