Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 311147
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
447 AM PDT TUE MAY 31 2016

.SYNOPSIS...

High pressure will gradually build over the area through the
week. This will result in a noticeable warming trend for areas
away from the coast through Friday with night and morning low
clouds and fog retreating to the beaches. For the weekend, low
pressure will move across the area, bringing cooler temperatures
and an increase in low clouds and fog for coastal and valley
areas.
&&

.SHORT TERM...(TDY-THU)

Overall, 00Z models in good synoptic agreement through the period.
At upper levels, ridge will gradually build over the area. Near
the surface, weak to moderate onshore flow will continue.

Forecast-wise, main issues through the short term will be the
marine layer stratus and temperatures. With regard to the marine
layer stratus, current AMDAR soundings indicate marine inversion
based around 1500 feet. With decent onshore flow, stratus should
continue to develop this morning and push into the coastal
valleys. Stratus should dissipate nicely by this afternoon,
although clouds could linger at some beaches. For tonight through
Thursday, the marine inversion will become more shallow and
exhibit less inland extent as upper ridge builds overhead. However
the inversion should strengthen, so clearing near the beaches
could be rather limited Wednesday and Thursday. Other than the
marine layer stratus, skies should remain mostly clear through the
period.

As for temperatures, with ridge building in overhead and less
extensive marine influence, afternoon highs will exhibit a
noticeable warming trend (especially away from the beaches). In
fact by Thursday, most coastal valleys will be in the upper 80s to
lower 90s while interior valleys and the deserts will climb to
around 100 degrees.

.LONG TERM...(FRI-MON)

For the extended, 00Z models continue to exhibit good synoptic
agreement. At upper levels, ridge will peak in strength on Friday
then will weaken and move eastward as an upper low moves
toward/inland over the area Saturday through Monday. Near the
surface, onshore flow will gradually strengthen through the
weekend.

Forecast-wise, Friday is expected to be the warmest day with ridge
peaking in strength (with most coastal valleys in the 90s). For
Saturday through Monday, a noticeable cooling trend is anticipated
as well as an increase in marine layer stratus coverage as the
upper low swings through the area. Looking at all moisture progs
this upper low looks to be very moisture starved. However, given
the time of year, this low`s potential cannot be discounted as it
will bring some increase in instability. So, there is a non-zero
chance of showers/thunderstorms over the mountains Saturday/Sunday
but not high enough to warrant any mention in the official
forecast. This feature will need to be watched as we get closer to
the weekend.

&&

.AVIATION...31/12Z...

AT 08Z AT KLAX... THE INVERSION WAS ABOUT 3450 FEET DEEP. THE TOP
OF THE MARINE INVERSION WAS NEAR 4800 FEET WITH A TEMPERATURE OF
22 DEGREES CELSIUS.

OVERALL... MODERATE TO HIGH CONFIDENCE IN THE 12Z TAFS. THE
REDUCED CONFIDENCE IS DUE TO THE GENERAL UNCERTAINTY IN MARINE
INCURSION BEHAVIOR AND BECAUSE THE CATEGORY CHANGES AND
CLEARING TIMES MAY BE OFF BY +/- 2 HOURS. CIGS MOSTLY LIFR/IFR
OVERNIGHT NORTH OF POINT CONCEPTION AND MOSTLY MVFR TO THE SOUTH.
ONSHORE GRADIENTS ARE TRENDING WEAKER OVER THE NEXT 24 HOURS SO
THERE IS A 40 PERCENT CHANCE THAT CIGS COULD SCOUR OUT EARLY WITH
SCATTERED STRATUS LINGERING ACROSS SOME COASTAL AREAS. OTHERWISE
AND ELSEWHERE VFR CONDITIONS ARE EXPECTED.

KLAX... MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THE REDUCED
CONFIDENCE IS DUE TO THE GENERAL UNCERTAINTY IN MARINE INCURSION
BEHAVIOR AND BECAUSE THE CATEGORY CHANGES AND CLEARING TIMES MAY
BE OFF BY +/- 2 HOURS. CIGS MOSTLY MVFR WITH PERIODS DIPPING DOWN
TO IFR. ONSHORE GRADIENTS ARE TRENDING WEAKER OVER THE NEXT 24
HOURS SO THERE IS A 30 PERCENT CHANCE THAT CIGS COULD SCOUR OUT
EARLY TO SCATTERED STRATUS.

KBUR... MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THE REDUCED
CONFIDENCE IS DUE TO THE GENERAL UNCERTAINTY IN MARINE INCURSION
BEHAVIOR. ONSHORE GRADIENTS ARE TRENDING WEAKER OVER THE NEXT 24
HOURS SO THERE IS A 40 PERCENT CHANCE THAT CIGS COULD SCOUR OUT
EARLY TO SCATTERED STRATUS.

&&

.MARINE...31/230 AM...

Small Craft Advisory level winds will flow across the central and
southern portions of the outer coastal waters through mid morning
and there is a chance of them increasing again tonight. Northwest
swell across the coastal waters will continue to diminish through
the middle of the week. A long period south swell will reach the
coastal waters by late today then peak on Wednesday and Thursday
before subsiding. The swells will likely remain below advisory
criteria but there will be extra surging and currents along
exposed south facing beaches.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect from Wednesday morning
      through Thursday evening For zones 40-41-87. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 9 AM PDT this morning
      For zones 673-676. (See LAXMWWLOX).

&&
$$

PUBLIC...RAT
AVIATION...KJ
MARINE...KJ
SYNOPSIS...RAT

weather.gov/losangeles


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