Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 120524
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1025 PM PDT FRI JUL 11 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...
HIGH PRESSURE WILL EXPAND WEST OVER THE WEEKEND...RESULTING IN A
SIGNIFICANT WARMING TREND...ESPECIALLY FOR INLAND AREAS. SOME
MONSOONAL MOISTURE WILL RETURN BY SUNDAY...BRINGING A SLIGHT CHANCE
OF THUNDERSTORMS FOR THE MOUNTAINS AND DESERTS FOR MUCH OF NEXT WEEK.

&&

.SHORT TERM (TONIGHT-MON)...
UPPER LEVEL RIDGE OF HIGH PRESSURE CURRENTLY CENTERED OVER THE GREAT
PLAINS WILL EXPAND WESTWARD AND BECOME CENTERED OVER NEVADA THIS
WEEKEND. RISING HEIGHTS COMBINED WITH EASTERLY FLOW ALOFT WILL BRING
A SIGNIFICANT WARMING TREND TO INTERIOR SECTIONS OF SOUTHWEST
CALIFORNIA THIS WEEKEND. CURRENT SATELLITE IMAGERY SHOWING SOME
PATCHY LOW CLOUDS AND FOG RETURNING TO SOME COASTAL AREAS THIS
EVENING WHILE A BAND OF HIGHER LEVEL CLOUDS MOVE INTO LOS ANGELES
COUNTY FROM THE SOUTH.

AS HIGH PRESSURE EXPANDS WESTWARD...THE MARINE LAYER DEPTH IS
EXPECTED TO LOWER TO AROUND 1500 FEET LATER TONIGHT INTO SATURDAY
MORNING. AS A RESULT...LOW CLOUDS AND FOG ARE NOT EXPECTED TO SPREAD
AS FAR INLAND AS THE PAST COUPLE OF NIGHTS...BUT WILL STILL LIKELY
REACH SOME OF THE COASTAL VALLEYS. TEMPERATURES WILL BEGIN THEIR
SHARP TREND UPWARD ON SATURDAY...ESPECIALLY ACROSS INLAND AREAS ABOVE
THE MARINE INFLUENCE. WARMEST LOCATIONS IN THE MOUNTAINS...ANTELOPE
VALLEY...AND INTERIOR SLO COUNTY VALLEYS ARE EXPECTED TO TOP OFF AROUND
100 DEGREES ON SATURDAY. 00Z NAM CONTINUES TO SHOW ANOTHER SHARP UPWARD
TREND IN BOUNDARY LAYER TEMPERATURES FOR SUNDAY...WITH TRIPLE DIGIT
READINGS MORE COMMON ACROSS THE MOUNTAINS...DESERTS...AND INTERIOR
VALLEYS. IN FACT...PASO ROBLES AND LANCASTER ARE EXPECTED TO CLIMB
TO AROUND 105 DEGREES!

IN ADDITION TO THE HOT TEMPERATURES THIS WEEKEND...THE OTHER NOTABLE
WEATHER STORY WILL BE THE RETURN OF MONSOONAL MOISTURE ON SUNDAY
AND MONDAY. AS THE EASTERLY FLOW DEEPENS ON SUNDAY...SOME MID LEVEL
MOISTURE WILL BEGIN TO MOVE INTO EASTERN LOS ANGELES COUNTY BY
SUNDAY AFTERNOON...WITH A SLIGHT CHANCE OF ELEVATED THUNDERSTORMS
FOR THE EASTERN SAN GABRIELS. MOST OF THE MOISTURE AND ASSOCIATED
THUNDERSTORM THREAT IS STILL EXPECTED TO REMAIN TO OUR EAST ON
SUNDAY. ON SUNDAY NIGHT...MODEL CROSS SECTIONS SHOWING INCREASING
MID LEVEL MOISTURE ASSOCIATED WITH AN EASTERLY WAVE TRACKING ACROSS
BAJA AND SOUTHEAST CALIFORNIA. IN FACT PRECIPITABLE WATER VALUES ARE
PROJECTED TO INCREASE TO AROUND 1.5 INCHES BY LATE SUNDAY NIGHT
ACROSS COASTAL AREAS OF LOS ANGELES AND VENTURA COUNTIES. 18Z AND
00Z NAM HAVE BEEN SHOWING A WELL DEFINED VORTICITY AREA ASSOCIATED
WITH THE EASTERLY WAVE...FIRST MOVING THROUGH THE INLAND EMPIRE LATE
SUNDAY NIGHT...REACHING LA AND  VENTURA COUNTIES ON MONDAY MORNING.
IF THIS FEATURE PANS OUT...IT COULD PROVIDE NECESSARY DYNAMICS FOR
CONVECTION ACROSS COASTAL AND VALLEY AREAS (IN ADDITION TO MOUNTAINS
AND DESERTS) FOR LATE SUNDAY NIGHT INTO MONDAY. AT THIS
POINT...STILL A FAIRLY SLIM CHANCE OF THUNDERSTORMS FOR COASTAL AND
VALLEY AREAS (LESS THAN 15 PERCENT)...BUT LATER SHIFTS WILL NEED TO
MONITOR THIS CLOSELY.  NOT OUT OF THE QUESTION THAT INITIAL SURGE OF
CONVECTION COULD HAVE SOME ISOLATED DRY LIGHTNING...BUT ATMOSPHERE
SHOULD MOISTEN ON MONDAY WITH STORMS BECOMING WETTER WITH TIME. A BETTER
CHANCE OF THUNDERSTORMS REMAINS ACROSS THE MOUNTAINS OF LOS ANGELES
AND VENTURA COUNTIES AS WELL AS THE ANTELOPE VALLEY ON MONDAY.

*** FROM PREVIOUS DISCUSSION ***

.LONG TERM (TUE-FRI)...MADE MINOR CHANGES THROUGH THE PERIOD.
GUIDANCE WAS CONSISTENT WITH PREVIOUS RUNS AND THE LONG WAVE RIDGE
CONTINUES TO SHIFT WEST OVER THE EASTERN PACIFIC THROUGH THE PERIOD.
THE BULK OF THE TROPICAL MOISTURE AND STEEPEST LAPSE RATES ARE
CENTERED OVER THE AREA TUESDAY. WILL CONTINUE WITH A CHANCE OF
THUNDERSTORMS TUESDAY AFTERNOON AND EVENING AND SLIGHT CHANCE EACH
AFTERNOON WEDNESDAY THROUGH THURSDAY. A SLIGHT COOLING TREND WILL
CONTINUE THROUGH WEDNESDAY AND TEMPERATURES WILL DIFFER BY MINUS 2-3
DEGREES EACH DAY FROM THE PREVIOUS DAY. LITTLE TEMPERATURE CHANGE IS
EXPECTED THURSDAY THROUGH FRIDAY AND TEMPERATURES MAY RANGE FROM 3
DEGREES BELOW NORMAL IN THE LOWER ELEVATIONS TO 2 DEGREES ABOVE
NORMAL INLAND AND THE HIGHER ELEVATIONS.


&&

.AVIATION...12/0525Z...

OVERALL...MODERATE CONFIDENCE IN 06Z TAF PACKAGE. LATEST AMDAR
SOUNDINGS INDICATE MARINE INVERSION AROUND 1000 FEET ACROSS THE LAX
BASIN...AND BASED ON SURFACE OBS THE INVERSION NORTH OF POINT
CONCEPTION IS AROUND 1500 FEET. OVERNIGHT AS UPPER RIDGE BEGINS TO
BUILD IN FROM THE EAST...THE INVERSION SHOULD REMAIN THE SAME IF NOT
SHRINK A LITTLE. SO...BEST CHANCES FOR IFR/MVFR CIGS WILL BE AT THE
COASTAL TAF SITES. ANY CIGS THAT DEVELOP SHOULD DISSIPATE BY LATE
SATURDAY MORNING.

KLAX...MODERATE CONFIDENCE IN 06Z TAF. TIMING OF RETURN OF IFR CIGS
COULD BE AN HOUR OR TWO LATER THAN CURRENT 08Z FORECAST.

KBUR...LOW CONFIDENCE IN 06Z TAF. THERE IS A 40% CHANCE OF IFR/LIFR
CIGS DEVELOPING AFTER 10Z.

&&

.MARINE...11/845 PM...

GOOD CONFIDENCE IN SMALL CRAFT ADVISORIES FOR PZZ673 AND PZZ676
THROUGH TONIGHT...AS SUPPORTED BY CURRENT OBSERVATIONS. AFTER
SATURDAY MORNING...HIGH CONFIDENCE IN AN EXTENDED PERIOD OF STRONG
SMALL CRAFT ADVISORY CONDITIONS THROUGH LATE SUNDAY NIGHT FOR ALL
OUTER WATERS...AS NW FLOW IS EXPECTED TO STRENGTHEN. NW WINDS MAY
APPROACH GALE FORCE FOR THE NORTHERN OUTER WATERS LATE SUNDAY
AFTERNOON AND EVENING.

WITH THE 900 PM UPDATE...A SMALL CRAFT ADVISORY WAS ADDED FOR THE
INNER WATERS N OF POINT SAL FOR SATURDAY AFTERNOON AND NIGHT.
ANOTHER SMALL CRAFT ADVISORY MAY EVENTUALLY BE NEEDED FOR SUNDAY
AFTERNOON AND NIGHT.

GOOD CONFIDENCE THAT WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT
CRITERIA FOR THE INNER WATERS S OF POINT CONCEPTION THROUGH THE
WEEKEND...OTHER THAN SOME LOCAL GUSTS TO 25 KT FOR THE WESTERN
PORTION OF THE SANTA BARBARA CHANNEL EACH AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
BEACH HAZARDS STATEMENT (SEE LAXCFWLOX).

&&

$$

PUBLIC...GOMBERG/30
AVIATION...GOMBERG
MARINE...SUKUP
SYNOPSIS...SUKUP

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