Small Craft Advisory 99, NWS Los Angeles, CA

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
840 PM PDT WED AUG 17 2011

.SYNOPSIS...
AN UPPER HIGH WILL BRING FAIR WEATHER INTO THURSDAY...EXCEPT WHERE
THE ONSHORE FLOW BRINGS OVERNIGHT CLOUDS AND FOG TO COASTAL PLAIN.
AFTERNOON TEMPERATURES WILL BE ABOVE NORMAL INTO FRIDAY...WITH THE
HOTTEST DAY ON THURSDAY. AT THE END OF THE WEEK...AN UPPER LOW WILL
APPROACH TO DEEPEN THE MARINE LAYER AND BRING A SLIGHT COOLING TREND
INTO THE WEEKEND. NEXT WEEK...THE UPPER HIGH WILL RETURN FOR MORE
FAIR WEATHER WITH ABOVE NORMAL TEMPERATURES.

&&

.SHORT TERM (TONIGHT-SAT)...MARINE LAYER DEPTH AT LAX EARLY THIS
EVENING WAS AROUND 700 FT OR SO. LOW CLOUDS AND FOG HAVE MOVED INTO
PORTIONS OF THE CENTRAL COAST THIS EVENING...AND SHOULD LINGER OVER
THE COASTAL PLAIN THRU THE NIGHT. OVER THE SOCAL BIGHT...LOW CLOUDS
HAVE LINGERED ALONG PORTIONS OF THE SAN COUNTY COAST. HOWEVER...AN
EDDY IS FORECAST TO DEVELOP WHICH SHOULD DRAW THE LOW CLOUDS
NORTHWARD...REACHING THE L.A. COUNTY COAST MAINLY AFTER MIDNIGHT...
AND THE VTU COAST BY MORNING. IN ADDITION...PATCHY DENSE FOG WILL BE
POSSIBLE WITH ANY LOW CLOUDS. OTHERWISE...MOSTLY CLEAR SKIES CAN BE
EXPECTED OVERNIGHT. THE GUSTY W TO SW WINDS IN THE ANTELOPE VALLEY
THIS EVENING WILL DIMINISH AS THE NIGHT PROGRESSES. ALSO...LOCAL
GUSTY NORTHERLY CANYON WINDS ALONG THE SBA S COAST AND SANTA YNEZ
RANGE WILL PERSIST THRU THE EVENING.

UPPER LEVEL RIDGING FROM THE E WILL LINGER OVER SRN CA THRU THU
NIGHT. A BROAD UPPER LEVEL TROF WILL APPROACH THE AREA FROM THE ERN
PAC BY FRI...THEN LINGER OFF THE CENTRAL CA COAST THRU SAT. THE
MARINE LAYER WILL REMAIN RATHER SHALLOW THRU FRI...GENERALLY LESS
THAN 1000 FT DEEP...THEN DEEPEN FRI NIGHT INTO SAT IN RESPONSE TO
THE UPPER LEVEL TROF AND INCREASING ONSHORE FLOW. VARYING AMOUNTS OF
LOW CLOUDS AND FOG WILL CONTINUE TO BE POSSIBLE NIGHT AND MORNING
HOURS FOR SOME COASTAL AREAS...ESPECIALLY FOR THE CENTRAL COAST AND
THE L.A. COUNTY COAST...WITH ANY LOW CLOUDS CONFINED TO THE COASTAL
PLAIN THRU FRI MORNING. THE LOW CLOUDS ARE EXPECTED TO BECOME MORE
WIDESPREAD ALONG THE COASTAL PLAIN AND INTO SOME OF THE ADJACENT
VALLEYS FRI NIGHT INTO SAT MORNING. OTHERWISE...MOSTLY CLEAR SKIES
ARE EXPECTED FOR THE MOST PART OVER THE FORECAST AREA THRU SAT.
GUSTY AFTERNOON AND EVENING WINDS WILL PERSIST IN THE ANTELOPE
VALLEY THRU THE PERIOD THANKS TO DECENT ONSHORE GRADIENTS. GUSTY
NORTHERLY CANYON WINDS CAN ALSO BE EXPECTED EACH EVENING FOR THE SBA
S COAST AND MTNS...ESPECIALLY IN THE VICINITY OF GAVIOTA PASS. TEMPS
ACROSS THE REGION ARE FORECAST TO REMAIN SEVERAL DEGREES ABOVE
NORMAL THU...WITH TRIPLE DIGIT HEAT EXPECTED IN THE WARMEST VALLEYS.
SLIGHT COOLING SHOULD TAKE PLACE FRIDAY...THEN FURTHER COOLING BACK
TO NEAR NORMAL IS EXPECTED FOR SAT.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (SUN-WED)...
BOTH GFS AND ECMWF SOLUTIONS AGREE THAT THE UPPER-LEVEL RIDGE
WILL BUILD WEST BETWEEN SUNDAY AND NEXT WEDNESDAY. 500 MB HEIGHTS
INCREASE GRADUALLY THROUGH MONDAY NIGHT...BUT LIFT MORE
DRAMATICALLY BY NEXT TUESDAY AND WEDNESDAY. WITH 850 MB
TEMPERATURES AND 1000-500 MB THICKNESS VALUES DEEPENING...A
WARMING TREND SHOULD TAKE SHAPE FOR THE PERIOD...BECOMING MOST
PRONOUNCED NEXT TUESDAY AND WEDNESDAY.

ONE WRINKLE IN THE FORECAST THAT COULD DEVELOP IS A POSSIBLE SURGE
OF MID-LEVEL MOISTURE INTO THE AREA FROM THE SOUTH NEAR THE END OF
THE FORECAST PERIOD. CURRENT MODEL SOLUTIONS DO NOT INDICATE
MUCH...IF ANY...SUB-TROPICAL MOISTURE BEING TRANSPORTED NORTH IN THE
SOUTHEAST FLOW PATTERN AT UPPER AND MIDDLE LEVELS. HOWEVER...A FEW
PERTURBATIONS OF THE GFS SOLUTIONS DO INDICATE A FAVORABLE HIGH
CENTER FOR A RETURN OF MONSOONAL FLOW TO THE AREA. FOR THE CURRENT
TIME...THE PACKAGE REMAINS CLOUD AND POP FREE...BUT THE SCENARIO
WILL BE MONITORED OVER THE COMING DAYS FOR FURTHER DEVELOPMENT.

&&

.AVIATION...18/0000Z...GENERALLY HI CONFIDENCE IN THE CURRENT TAF
PACKAGE...EXCEPT MODERATE CONFIDENCE FOR THE KOXR TAF. LIFR/IFR
CONDITIONS WILL MOVE INTO KSMX BY 05Z AND KSBP BY 08Z...AND
KOXR...KLAX AND KLGB AROUND 10Z-11Z. THE LOW CLOUDS AND FOG WILL
LIKELY CLEAR AWAY FROM THESE AIRFIELDS BY LATE THU MORNING WITH VFR
CONDITIONS THE REST OF THE DAY. THERE IS A 40-50 PERCENT CHANCE THE
LOW CLOUDS MAY NOT DEVELOP TONIGHT AT KOXR. ELSEWHERE...VFR
CONDITIONS WILL PREVAIL THRU THU.

KLAX...GENERALLY HI CONFIDENCE IN THE CURRENT TAF. LOW CLOUDS WITH
LIFR CIGS ARE EXPECTED TO AFFECT THE AIRFIELD FROM ABOUT 10Z-17Z.
OTHERWISE...VFR CONDITIONS ARE EXPECTED THRU THU EVENING.

KBUR...GENERALLY HI CONFIDENCE IN THE CURRENT TAF. VFR CONDITIONS
ARE EXPECTED THRU THU.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&

PUBLIC...SIRARD/GOMBERG/HALL/SMITH
AVIATION...SIRARD
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
249 PM PDT WED AUG 17 2011

CAZ034>041-044>046-051>054-059-087-088-547-548-181300-
SAN LUIS OBISPO COUNTY CENTRAL COAST-
SANTA BARBARA COUNTY CENTRAL COAST-SANTA YNEZ VALLEY-
SAN LUIS OBISPO COUNTY INTERIOR VALLEYS-CUYAMA VALLEY-
SANTA BARBARA COUNTY SOUTH COAST-VENTURA COUNTY COAST-
LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES-
VENTURA COUNTY INTERIOR VALLEYS-VENTURA COUNTY COASTAL VALLEYS-
SANTA MONICA MOUNTAINS RECREATIONAL AREA-
SAN LUIS OBISPO COUNTY MOUNTAINS-
SANTA BARBARA COUNTY MOUNTAINS-VENTURA COUNTY MOUNTAINS-
LOS ANGELES COUNTY MOUNTAINS EXCLUDING THE SANTA MONICA RANGE-
ANTELOPE VALLEY-CATALINA ISLAND-SANTA CLARITA VALLEY-
LOS ANGELES COUNTY SAN FERNANDO VALLEY-
LOS ANGELES COUNTY SAN GABRIEL VALLEY-
249 PM PDT WED AUG 17 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA.

.DAY ONE... THIS AFTERNOON AND TONIGHT

PATCHY DENSE FOG WILL REDUCE VISIBILITIES TO ONE QUARTER MILE OR
LESS IN COASTAL AREAS EXCEPT FOR SANTA BARBARA SOUTH COAST AFTER
MIDNIGHT. A MIX OF LONG PERIOD SOUTH SWELL WITH A WESTERLY WIND
SWELL WILL PRODUCE A POTENTIAL FOR HIGH RIP CURRENTS AT AREA
BEACHES.

* HIGH RIP CURRENT RISK......SEE FZUS56 KLOX - SRFLOX FOR DETAILS *

.DAYS TWO THROUGH SEVEN... THURSDAY THROUGH TUESDAY

PATCHY DENSE FOG WILL REDUCE VISIBILITIES TO ONE QUARTER MILE OR
LESS IN COASTAL AREAS EXCEPT FOR SANTA BARBARA SOUTH COAST THURSDAY
MORNING. A MIX OF LONG PERIOD SOUTH SWELL WITH A WESTERLY WIND SWELL
WILL PRODUCE A POTENTIAL FOR HIGH RIP CURRENTS AT AREA BEACHES
THURSDAY.

* HIGH RIP CURRENT RISK......SEE FZUS56 KLOX - SRFLOX FOR DETAILS *

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

HALL