Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 210004 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
504 PM PDT SAT SEP 20 2014

UPDATED AVIATION SECTION

.SYNOPSIS...

ONSHORE FLOW WILL KEEP TEMPERATURES AROUND NORMAL ON SUNDAY WITH A
LINGERING MARINE LAYER. TEMPERATURES WILL BE ABOVE NORMAL MONDAY
THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS IN. A TROUGH OF LOW
PRESSURE MOVES IN FROM THE NORTH THURSDAY TO INCREASE THE MARINE
LAYER AND BRING A COOLING TREND INTO THE WEEKEND.

&&

.SHORT TERM (SUN-TUE)...STRATUS HELD ON LONGER THAN EXPECTED OVER
THE LA COUNTY COAST AND VALLEYS SO TEMPS WERE LOWERED AND SKY COVER
ADJUSTED TO REFLECT THIS CLOUD COVER...SAME FOR SBA COUNTY SOUTH
COAST. CUMULUS BUILDUP HAS BEEN QUITE WEAK SO FAR AND DO NOT
ANTICIPATE MUCH CHANGE IN THAT THROUGH THE DAY. THE UPPER LOW IS
JUST ABOUT ON TOP OF THE AREA AND ANY DYNAMIC SUPPORT IS GONE. WATER
VAPOR IMAGERY ALSO SHOWING QUITE A BIT OF DRYING OVER VTU AND LA
COUNTY. LA COUNTY MOUNTAINS ONLY SEEING A FEW VERY SMALL CUMULUS AT
THIS TIME AND IT`S A STRETCH EVEN AT THAT. LEFT THE SLIGHT CHANCE OF
PRECIP IN THE VTU AND SBA MOUNTAINS FOR THIS EVENING TO ACCOUNT FOR
THE SLIGHT CHANCE A WEAK CELL OR TWO DEVELOPING...BUT DID REMOVE
POPS FROM THE EVENING FORECAST FOR LA COUNTY MOUNTAINS AND THE AV.

UPPER LOW IS EAST OF THE AREA TOMORROW WITH HEIGHT RISES IN ITS WAKE
HELPING TO BRING A WEAK WARMING TREND AND ABSENCE OF ANY MOUNTAIN
PRECIP CHANCES. AM EXPECTING A FAIRLY SIMILAR MARINE LAYER TOMORROW
BUT FOR NOW WILL GO FOR BETTER AFTERNOON CLEARING AND WARMING
THROUGH LA COUNTY COAST AND VALLEYS...BUT THAT MAY HAVE TO BE
ADJUSTED LATER TONIGHT IF IT LOOKS LIKE THE STRATUS DECK MIGHT
LINGER INTO THE AFTERNOON.  RIDGING ON MONDAY AND TUESDAY WILL BRING
LESS OF A MARINE LAYER...A WEAKER ONSHORE PRESSURE GRADIENT...AND
MORE WARMING.

.LONG TERM (WED-SAT)...
LITTLE CHANGE EXPECTED FROM TUESDAY TO WEDNESDAY. RIDGE AXIS HAS
SLID BY A BIT TO OUR EAST BUT STILL UNDER ITS INFLUENCE FOR ABOVE
NORMAL TEMPERATURES ALL BUT THE IMMEDIATE CENTRAL COAST. LITTLE
CHANGE IN THE MARINE LAYER EXPECTED. THEN ON THURSDAY THE DEEP UPPER
TROUGH MODELS HAVE BEEN FORECASTING FOR THE END OF THE WEEK SHOULD
BEGIN TO SHOW SOME INFLUENCE BY WAY OF SLIGHTLY COOLER TEMPERATURES
OVER SLO COUNTY. GFS AND ECMWF DIFFER ON BOTH SPEED AND INTENSITY
WITH THIS TROUGH AFTER THURSDAY. THE GFS IS NOT AS DEEP WHILE ALSO
MOVING IT THROUGH FASTER...BRUSHING THE TROUGH AXIS BY THE AREA BY
SATURDAY. MEANWHILE THE DEEPER AND SLOWER ECMWF HAS THE TROUGH STILL
WEST OF THE AREA ON SATURDAY. ECMWF SOLUTION WOULD RESULT IN COOLER
TEMPS ON SATURDAY. THE GFS APPEARS TO HAVE BETTER RUN TO RUN
CONSISTENCY SO IT`S FAVORED. BOTH GFS AND ECMWF ESSENTIALLY SHOW A
DRY TROUGH PASSAGE AS BOTH KEEP PRECIP WELL EAST OF THE AREA. WOULD
BE HARD TO IMAGINE AT LEAST SOME SHOWERS SNEAKING INTO NORTHERN SLO
COUNTY IF THE ECMWF VERIFIES BUT KEPT ANY POPS OUT FOR NOW. HAVE PUT
FRIDAY AS THE COOLEST DAY AND SATURDAY`S TEMPS ARE A COMPROMISE
BETWEEN THE ECMWF AND GFS SOLUTION.

&&

.AVIATION...21/0004Z.

NORTH OF POINT CONCEPTION...MVFR CONDITIONS WILL SPREAD INTO COASTAL
TERMINALS THROUGH 08Z...THEN LOWER TO THE IFR CATEGORY THROUGH 11Z.
AT KPRB...THERE IS A CHANCE OF IFR CONDITIONS BETWEEN 10Z AND 16Z.
THERE IS A CHANCE OF LIFR CONDITIONS BETWEEN 11Z AND 15Z. VFR
CONDITIONS SHOULD REDEVELOP BETWEEN 16Z AND 18Z.

SOUTH OF POINT CONCEPTION...MVFR CONDITIONS WILL LIKELY SPREAD
THROUGH 08Z...OR 13Z AT THE LATEST. THERE IS A CHANCE OF IFR
CONDITIONS AT KSBA. VFR CONDITIONS SHOULD REDEVELOP BETWEEN 16Z AND
20Z.

KLAX...THERE IS A 90 PERCENT CHANCE OF MVFR CONDITIONS BETWEEN 05Z
AND 20Z.  MVFR CONDITIONS SHOULD ESTABLISH BY 10Z AT THE LATEST.

KBUR...THERE IS A 70 PERCENT CHANCE OF MVFR CONDITIONS BETWEEN 08Z
AND 18Z. MVFR CONDITIONS SHOULD ESTABLISH BY 13Z AT THE LATEST.

&&

.MARINE...20/900 AM

THERE IS A CHANCE SMALL CRAFT ADVISORY CONDITIONS WILL DEVELOP INT
HE VICINITY OF THE CHANNEL ISLANDS EACH EVENING AND EXIST SEVERAL
HOURS SUNDAY THROUGH TUESDAY. THERE IS A CHANCE THE NORTHWEST WINDS
WILL INCREASE TO GALES FRIDAY IN THE VICINITY OF THE NORTHERN
ISLANDS TO SAN NICOLAS ISLAND. A MIXED WEST NORTHWEST SWELL AND
SOUTH SOUTHWEST SWELL WILL CONTINUE TO SUBSIDE TODAY. SWELLS
ORIGINATING FROM A FAST MOVING AND SHORT LIVED GULF OF ALASKA STORM
A COUPLE DAYS AGO ON THURSDAY ARE EXPECTED TO ARRIVE SUNDAY FROM
295-305. THERE IS A CHANCE THE SWELL WILL PEAK SUNDAY NIGHT AND
LINGER THROUGH TUESDAY. A LOW PRESSURE SYSTEM IS LIKELY TO DEVELOP
OVER THE EASTERN PACIFIC NEXT WEEK MONDAY THROUGH TUESDAY AND
GUIDANCE HAD TRENDED DEEPER WITH THE SYSTEM. SWELLS GENERATED BY
STORM FORCE WINDS ARE EXPECTED TO ARRIVE FROM 300-310 DEGREES
WEDNESDAY EVENING AND PEAK THURSDAY AND LINGER THROUGH FRIDAY AND
SMALL CRAFT ADVISORY CONDITIONS FRO HAZARDOUS SEAS WILL LIKELY
EXIST.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...JACKSON
AVIATION/MARINE...30
SYNOPSIS...SETO

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