Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 281145
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
445 AM PDT THU MAY 28 2015

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

THE ONSHORE FLOW WILL BRING NIGHT THROUGH MORNING LOW CLOUDS ACROSS
THE COAST AND SOME VALLEYS...OTHERWISE FAIR SKIES WITH ABOVE NORMAL
TEMPERATURES INTO THE WEEKEND. A LOW SYSTEM WILL APPROACH ON SUNDAY
TO INCREASE CLOUDS AND COOL TEMPERATURES TO NORMAL FOR NEXT WEEK.

&&

.SHORT TERM (TODAY-SAT)... THE MARINE LAYER HAS SHRUNK TO ABOUT 1300
FEET AS HIGH PRESSURE ALOFT SQUASHES IT DOWN. GRADIENTS ARE TRENDING
OFFSHORE AHEAD OF THE BUILDING HIGH PRESSURE AND THESE TWO THINGS
ARE SLOWING THE MARINE LAYER CLOUD DEVELOPMENT. THE VLYS WILL ONLY
SEE PATCHY CLOUDS. GOING FOR A TOTAL CLEARING DAY BUT THIS IS NOT
FOR SURE AS THE HIGH PRESSURE BUILDS IN THE INVERSION WILL STRENGTHEN
WHICH WILL MAKE CLEARING HARDER. RIGHT NOW THINK THE OFFSHORE TRENDS
WILL BE ENOUGH TO COUNTERACT IT. MARINE LAYER IS LOWER AND STRONGER
NORTH OF POINT CONCEPTION AND LOW CLOUDS COVER ALL THE COAST AND THE
SANTA YNEZ VLY LOW CLOUDS WILL ALSO MOVE INTO THE PASO ROBLES AREA
FROM THE SALINAS VLY. THE BIGGEST EFFECT OF THE SHRINKING MARINE
LAYER WILL BE THE WARMING IN THE VLYS. LOOK FOR PLENTY OF MAX TEMPS
IN THE UPPER 70S AND LOWER 80S TODAY. THE BUILDING HGTS WILL ALSO
ALLOW THE DESERTS TO REACH THE 90 DEGREE MARK. WHILE THERE MAY BE
DEGREE OR TWO OF WARMING ACROSS THE COAST IT WILL NOT BE THAT
NOTICABLE AS THE MARINE LAYER WILL HAVE A LARGE MODERATING EFFECT.

REALLY NOT MUCH CHANGE FOR FRIDAY. THE RIDGE AXIS MOVES OVERHEAD AND
INLAND TEMPS WILL JUMP AGAIN. LOOK FOR 3 TO 6 DEGREES OF ADDITIONAL
WARMING. THE VLYS WILL ALMOST ALL BE THE 80S WITH A COUPLE 90 DEGREE
READINGS LIKELY. THERE IS A CHANCE THAT WEAK NORTH FLOW WILL KEEP
THE SBA SOUTH COAST LOW CLOUD FREE. THE VLYS WILL ALSO BE LARGELY
LOW CLOUD FREE (SAVE THE SANTA YNEZ VLY WHICH WILL BE SOCKED IN)
ONLY THE SAN GABRIEL VLY HAS A DECENT CHC OF SOME LOW CLOUDS.

NOT MUCH REAL CHANGE FOR SATURDAY. THE RIDGE WILL START TO MOVE TO
THE EAST BUT NOT IN TIME TO AFFECT THE TEMPERATURES. THE AIR MASS
WILL START OFF A DEGREE OR TWO WARMER THAN FRIDAY MORNING AND THIS
WILL TRANSLATE INTO A DEGREE OR TWO OF WARMING FOR THE MAX TEMPS.
THERE WILL LIKELY BE QUITE A LARGE TEMPERATURE GRADIENT BETWEEN THE
BEACHES AND THE INLAND PORTION OF THE COASTAL ZONES...10 OR MORE
DEGREES FROM LAX TO THE USC CAMPUS. SATURDAY WILL BE THE WARMEST DAY
OF THE NEXT 7.

.LONG TERM (SUN-WED)... BY SATURDAY NIGHT THE RIDGE WILL BE TO THE
EAST OF THE AREA AND A TROF WILL BE MOVING INTO THE WEST COAST. THIS
TROF WILL SLOWLY MOVE INTO THE AREA AND INTENSIFY SUNDAY THROUGH
TUESDAY. THE MARINE LAYER CLOUD PATTERN WILL INCREASE EACH DAY AND
MAX TEMPS WILL COOL EACH DAY AS WELL. THE MARINE LAYER WILL MOVE
INTO THE VLYS IN EARNEST ON MONDAY AND THIS WILL BE DAY WITH THE
BIGGEST COOL DOWN.

THE TROF MOVES OUT ON WEDNESDAY AND THIS WILL KICK OFF A DECREASE IN
THE LOW CLOUDS AND AN INCREASE IN MAX TEMPS.

&&

.AVIATION...

28/1140Z

AT 0544Z THE MARINE LAYER DEPTH AT KLAX WAS AROUND 1200 FT DEEP. THE
TOP OF THE INVERSION WAS NEAR 3500 FEET WITH A TEMPERATURE OF 18
DEGREES CELSIUS.

N OF POINT CONCEPTION...MODERATE CONFIDENCE WITH IFR CIGS THIS
MORNING...EXCEPT FOR LIFR AT KPRB. CIGS WILL SCOUR OUT WITHIN +/-1
HOUR FROM TAFS. MODERATE CONFIDENCE FOR CIGS TO REDEVELOP TONIGHT
INTO FRIDAY MORNING. 30 PERCENT CHANCE THAT LIFR/IFR CIGS WILL COME
IN A FEW HOURS EARLIER FOR COASTAL TAFS.

S OF POINT CONCEPTION...MODERATE CONFIDENCE FOR HIGH IFR OR LOW MVFR
CIGS ALONG COASTAL TAF SITES. HIGHER CONFIDENCE FOR VFR CONDS FOR
KSBUR AND KVNY TODAY. 30 PERCENT CHANCE  FOR MVFR VSBYS FOR VALLEY
TAFS THIS MORNING. LOWER CONFIDENCE WITH TIMING OF IFR CIGS OR LOW
MVFR CIGS FOR COASTAL TAFS TONIGHT INTO FRIDAY MORNING. 20 PERCENT
CHANCE FOR IFR CIGS AT KBUR/KVNY TONIGHT AFTER 09Z.

KLAX...GOOD CONFIDENCE IN CIGS SCOURING OUT +/- 1 HOUR FROM TAF
TIME.  A 30 PERCENT CHC OF A 21Z BURN OFF AND A 20 PERCENT CHC OF
5SM HZ CONDS AT THE TERMINAL FROM 16Z-23Z.

KBUR...FAIR CONFIDENCE IN TAF. THERE IS A 30 PERCENT CHC OF CIGS
ARRIVING AFTER 13Z. THERE IS A HIGH CHANCE THAT CIGS WILL NOT OCCUR
THIS MORNING. NOT TOO CONFIDENT FOR IFR CIGS TO DEVELOP TONIGHT INTO
FRIDAY MORING. A 30 PERCENT CHC OF IFR CIGS TO DEVELOP BY 10Z FRI
MORNING THROUGH 16Z.

&&

.MARINE...

28/315 AM

OUTER WATERS...EXPECT NORTH TO NORTHWEST WINDS GENERALLY 10 TO 20
KNOTS OVER THE OUTER ZONES THIS MORNING. 70 PERCENT CHANCE SMALL
CRAFT ADVISORY LEVEL WINDS WILL DEVELOP THIS AFTERNOON AND CONTINUE
THROUGH THE OVERNIGHT HOURS INTO EARLY FRIDAY MORNING. SLIGHTLY LESS
CONFIDENCE FOR SMALL CRAFT ADVISORY WINDS FOR THE OUTER WATERS FOR
FRIDAY AFTERNOON/EVE.  THE MARINE LAYER WILL BECOME MORE SHALLOW
FRIDAY AND SATURDAY NIGHT AND MORNINGS. A 40 PERCENT CHANCE FOR A
DENSE FOG ADVISORY FOR THE COASTAL WATERS N OF POINT CONCEPTION WILL
BE POSSIBLE.

INNER WATERS...WINDS ARE EXPECTED TO REMAIN WELL BELOW SMALL CRAFT
ADVISORY LEVELS THROUGH THE WEEKEND...EXCEPT FOR THE WESTERN PORTION
OF THE SANTA BARBARA CHANNEL WHERE GUSTS TO 20 KNOTS ARE EXPECTED
THIS EVENING AND POSSIBLY ONCE AGAIN LATE FRIDAY EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...CK
SYNOPSIS...SETO

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