Area Forecast Discussion
Issued by NWS Los Angeles, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KLOX 220441
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
940 PM PDT THU MAY 21 2015

.SYNOPSIS...

A CLOUDY AND SHOWERY WEATHER PATTERN WILL DEVELOP OVER THE AREA AS A
TROUGH OF LOW PRESSURE OFF THE CALIFORNIA COAST MOVES OVER THE
REGION THROUGH FRIDAY NIGHT. CONTINUED COOL CONDITIONS WILL OCCUR
THROUGH SATURDAY...BUT DEVELOPING HIGH PRESSURE WILL BRING A WARMING
AND DRYING TREND FOR EARLY NEXT WEEK.

&&

.UPDATE...

INFRARED IMAGERY INDICATES A COLD BUT DISORGANIZED TROUGH OF LOW
PRESSURE SPINNING ABOUT 125 MILES SOUTHWEST OF POINT CONCEPTION.
THIS TROUGH WILL CONTINUE TO SPIN SOUTH AND EAST INTO THE SOUTHERN
CALIFORNIA BIGHT THROUGH FRIDAY. A COLD AIR MASS ALOFT WILL BRING
THE THREAT OF CONVECTIVE SHOWERS AND ISOLATED THUNDERSTORMS FROM
LATE TONIGHT THROUGH FRIDAY. POPS WILL BE NUDGED SLIGHTLY HIGHER AS
NAM BUFR TIME HEIGHT SECTIONS INDICATE SOME LIFT FOR PRECIPITATION
INTO THE DESERT. THE BEST CHANCE FOR SHOWERS WILL BE FROM LOS
ANGELES COUNTY SOUTHWARD. ORANGE AND SAN DIEGO COUNTIES WILL DO MUCH
BETTER FOR RAIN AMOUNTS. MOST LOCATIONS ACROSS THE AREA WILL SEE
0.10 INCH OR LESS. LOCAL AMOUNTS UP TO 0.25 INCH ARE POSSIBLE ALONG
THE SOUTH AND WEST FACING SLOPES OF THE MOUNTAINS. SHOWERS...IF
ANY...SHOULD START AFTER MIDNIGHT...AND CONTINUE INTO THE MORNING
COMMUTE. A DIFFLUENT PATTERN ALOFT SHOULD AID IN THE DEVELOPMENT OF
CONVECTION OVER THE SOUTH COAST BASIN.

A COOL WEATHER PATTERN WILL LINGER INTO FRIDAY. A MOSTLY CLOUDY DAY
IS SETTING UP FOR FRIDAY. THE BEST CHANCE FOR SUN WILL BE FOR THE
SAN LUIS OBISPO COUNTY COASTAL AREAS ON FRIDAY. SHOWERS COULD LINGER
ACROSS THE INTERIOR PORTIONS OF THE AREA AND THE MOUNTAINS INTO THE
AFTERNOON.

A WIND ADVISORY MAY BE NEEDED FOR THE SOUTH COAST PORTION OF SANTA
BARBARA COUNTY AND THE SANTZ YNEZ RANGE ON FRIDAY AFTERNOON AND
EVENING AS MODEL SOLUTIONS ARE DEVELOPING MARGINALLY STRONG WINDS
ACROSS THE AREA. THERE IS A CHANCE THAT COULD CAUSE SOME ISSUES FOR
THE REFUGIO OIL SPILL INCIDENT.

&&

.PREV DISCUSSION...

SHORT TERM...PRECIP POTENTIAL WILL DROP OFF FRIDAY EVENING AND NO
PRECIP IS EXPECTED SAT. SKY FORECAST WILL BE TRICKY AS THERE WILL
AGAIN BE A WEAK INVERSION IN PLACE BUT AMPLE MOISTURE SO CLOUD
COVERAGE WILL LIKELY BE RATHER HAPHAZARD, AND POSSIBLY MUCH LESS
THAN CURRENT FORECAST INDICATES.

LOW CONFIDENCE FORECAST FOR SUNDAY, THOUGH MINIMAL IMPACTS. NAM/EC
FAVOR A REBUILDING RIDGE WITH MORE WARMING WHILE THE GFS DELAYS THIS
UNTIL MONDAY. WILL CONTINUE WITH THE SLOW WARMING TREND PER THE GFS
FOR NOW.

LONG TERM...RATHER POOR MODEL CONSENSUS WITH THE UPPER PATTERN NEXT
WEEK AS WELL, BUT AGAIN MINIMAL IMPACTS AS THE FORECAST WILL REMAIN
DRY REGARDLESS OF WHICH MODEL VERIFIES CLOSEST. A SLIGHT WARMUP IS
EXPECTED THROUGH THE MIDDLE OF THE WEEK WITH HIGHS FLOATING AROUND
NORMAL LEVELS. THEN POSSIBLY POKING UP A BIT ABOVE NORMAL BY THE END
OF THE WEEK BUT ONLY IF THE WARMER ECMWF IS CORRECT. OTHERWISE, A
PRETTY QUIET WEEK OF WEATHER EXPECTED NEXT WEEK WITH NO PRECIP, NO
TEMPERATURE EXTREMES EITHER WAY, AND JUST STANDARD ONSHORE WINDS.

&&

.AVIATION...22/0000Z.

AT 00Z...THERE WAS A WEAK MARINE LAYER AROUND 5800 FEET DEEP. THE
TOP OF THE INVERSION WAS NEAR 7500 FEET WITH A TEMPERATURES OF 4
DEGREES CELSIUS.

MVFR TO VFR CONDITIONS WITH CEILINGS AT OR BELOW 5000 FEET WILL
LIKELY DEVELOP THROUGH 12Z AT ALL TERMINALS AS A TROUGH OF LOW
PRESSURE APPROACHES THE AREA. THERE IS A 20 PERCENT CHANCE OF LOW
MVFR CONDITIONS BETWEEN 05Z AND 12Z...AND IN ANY HEAVIER SHOWERS.

KLAX...MODERATE CONFIDENCE IN THE FORECAST. THERE IS A 60 PERCENT
CHANCE OF MVFR CONDITIONS. THE TIME OF ARRIVAL COULD BE AS SOON AS
08Z...BUT MORE LIKELY BETWEEN 10Z AND 12Z. THERE IS A 10 PERCENT
CHANCE OF SOUTH CROSS WINDS GREATER THAN 10 KNOTS BETWEEN 10Z AND
16Z.

KBUR...MODERATE CONFIDENCE IN THE FORECAST. THERE IS A 60 PERCENT
CHANCE OF MVFR CONDITIONS. THE TIME OF ARRIVALS COULD BE AS SOON AS
06Z...BUT MORE LIKELY BETWEEN 08Z AND 10Z.

&&

.MARINE...21/900 PM.

SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE OUTER WATERS SOUTH OF
POINT SAL AND THE WESTERN PORTION OF THE SANTA BARBARA. THERE IS A
80 PERCENT CHANCE THAT WINDS WILL INCREASE TO SMALL CRAFT LEVELS ON
FRIDAY AFTERNOON AND CONTINUE INTO FRIDAY NIGHT.

THE STRONGEST WINDS IN THE SANTA BARBARA CHANNEL WILL BE ACROSS THE
WESTERN PORTION AND MAY IMPACT THE REFUGIO OIL SPILL INCIDENT WITH
WIND WAVES UP TO 4 FEET. WIND GUSTS COULD APPROACH 25 KNOTS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...HALL/MW
AVIATION...HALL
MARINE...HALL
SYNOPSIS...HAL

WWW.WEATHER.GOV/LOSANGELES


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.