Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 300054 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
555 PM PDT MON JUN 29 2015

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

A WARM AND HUMID AIR MASS WILL OCCUR ACROSS THE AREA THROUGH THE
WEEK AS A HIGH PRESSURE REMAINS ANCHORED OVER THE GREAT BASIN.
SOUTHEAST FLOW ALOFT WILL BRING ENOUGH MOISTURE AND UNSTABLE AIR TO
CREATE A SLIGHT CHANCE OF THUNDERSTORMS AND SHOWERS THIS
WEEK...MAINLY IN THE MOUNTAINS AND DESERTS. A COOLING TREND WILL
OCCUR FOR THE HOLIDAY WEEKEND AS A LOW PRESSURE APPROACHES.

&&

.SHORT TERM (TODAY-THU)...

MIDDLE AND HIGH LEVEL CLOUDINESS CONTINUES TO STREAM OVER THE AREA
THIS AFTERNOON AS HIGH PRESSURE REMAINS ANCHORED OVER THE GREAT
BASIN. SOUTHEAST FLOW ALOFT CONTINUES TO PUMP MIDDLE AND HIGH LEVEL
MOISTURE OVER THE AREA. A VERY WARM AND HUMID AIR MASS REMAINS OVER
THE AREA. TEMPERATURES WARMED SLIGHTLY...UP ABOUT 2-4 DEGREES OVER
THIS YESTERDAY. LOCAL HEAT INDEX VALUES...THE TEMPERATURE THAT THE
HUMAN BODY PERCEIVES...ARE HOVERING NEAR 100 DEGREES OVER THE
VALLEYS AND FOOTHILLS. NO ISSUANCE OF AN EXCESSIVE HEAT WARNING IS
EXPECTED...ALTHOUGH LOCAL CRITERIA MAY BE REACHED. VERY SLIGHT
COOLING...BY A DEGREE OR TWO...SHOULD OCCUR ON TUESDAY AS ONSHORE
STRENGTHENS SOMEWHAT. THIS COOLING TREND SHOULD OCCUR INTO THURSDAY
AS A TROUGH OF LOW PRESSURE NEAR 25N AND 125W INCHES CLOSER TO THE
AREA THROUGH LATE WEEK.

SHOWER ACTIVITY HAS REMAINED RATHER ISOLATED TODAY AS
EXPECTED...WITH MOST ACTIVITY OCCURRING OVER THE MOUNTAINS AND
DESERT. A FEW SHOWERS HAVE BEEN STREAMING OVER THE SAN GABRIEL
VALLEY AND LOS ANGELES COUNTY COAST WITH ONLY SPRINKLES OCCURRING AT
THIS TIME. POPS REMAIN UNCHANGED AT THIS TIME AS SHOWERS CONTINUE TO
STREAM NORTH OUT OF SAN DIEGO AND ORANGE COUNTIES.

MARINE LAYER STRATUS COVERAGE WILL CONTINUE TO BE PROBLEMATIC FOR
THE PERIOD. LOCAL 2-KM WRF SOLUTIONS SUGGEST LITTLE TO NO MARINE
LAYER COVERAGE AND NAM BUFR TIME HEIGHT SECTIONS KEEP HUMIDITIES IN
THE MARINE LAYER RATHER DRY FOR THE NEXT COUPLE OF DAYS. FORECAST
KEEPS MARINE LAYER IN PLACE AS VISIBLE IMAGERY KEEPS SHOWS SOME
STRATUS LINGERING ALONG THE CENTRAL COAST THIS AFTERNOON.
HOWEVER...IT MAY NOT BE SURPRISING TO SEE CLOUDS SCOUR OUT THIS
EVENING. MODEL SOLUTIONS DO HINT AT A POSSIBLE MARINE LAYER STRATUS
EXPANSION ON THURSDAY BUT CONFIDENCE REMAINS LOW AT THIS TIME DUE
ANOTHER POSSIBLE SURGE OF MONSOONAL MOISTURE.

POPS AND WEATHER REMAIN IN THE FORECAST ACROSS THE INTERIOR PORTIONS
OF THE AREA...ESPECIALLY FOR THE MOUNTAINS AND DESERT. CONFIDENCE IS
WANING A BIT IN THE POPS AND WEATHER OVER THE NEXT SEVERAL
DAYS...BUT ENOUGH MOISTURE REMAINS IN PLACE TO KEEP SLIGHT CHANCE
POPS IN THE FORECAST. MODEL SOLUTIONS CONTINUE TO REMAIN AGGRESSIVE
FOR THURSDAY IN PUSHING ANOTHER WAVE OF INSTABILITY AND MONSOONAL
MOISTURE OVER THE AREA.

.LONG TERM (FRI-MON)...

RIDGING SHOULD START TO WEAKEN FOR LATE WEEK AND INTO THE WEEKEND AS
THE TROUGH OF LOW PRESSURE OFF BAJA CALIFORNIA DRIFT NORTH INTO THE
AREA. THE FLOW PATTERN WILL GRADUALLY VEER FROM SOUTHEAST TO
SOUTHWEST OVER THE WEEKEND. A COOLING TREND SHOULD TAKE SHAPE OVER
THE WEEKEND ALONG WITH A RETURN OF LOW CLOUDS AND FOG TO THE COAST
AND LOWER VALLEYS.

&&

.AVIATION...30/0030Z...

AT 2350Z...THE MARINE INVERSION AT KLAX WAS 700 FT DEEP. THE TOP OF
THE INVERSION WAS AT 2400 FT WITH A TEMPERATURE OF 30 DEG C.

GENERALLY HI CONFIDENCE IN THE 00Z TAFS. LOW CLOUDS WITH LIFR/IFR
CONDITIONS ARE EXPECTED AT KSMX FROM ABOUT 10Z-17Z. THERE IS ALSO A
20 PERCENT CHANCE OF LOW CLOUDS AND IFR CONDITIONS AT TIMES LATE
TONIGHT AND TUE MORNING AT KSBP...KOXR AND KLAX. OTHERWISE...VFR
CONDITIONS SHOULD PREVAIL FOR THE MOST PART AT THE AIRFIELDS THRU
TUE. THERE IS ALSO A SLIGHT CHANCE OF THUNDERSTORMS AT KWJF AND KPMD
THIS EVENING AND AGAIN TUE AFTERNOON.

KLAX...GENERALLY HI CONFIDENCE IN THE 00Z TAF WITH VFR CONDITIONS
EXPECTED FOR THE MOST PART THROUGH TUE EVENING. HOWEVER...THERE IS A
20 PERCENT CHANCE OF LOW CLOUDS AND IFR CONDITIONS LATE TONIGHT
AND TUE MORNING.

KBUR...HI CONFIDENCE IN THE 00Z TAF WITH MVFR CONDITIONS EXPECTED
THRU TUE AFTERNOON.

&&

.MARINE...29/200 PM.

SMALL CRAFT ADVISORY CONDITIONS WILL LIKELY CONTINUE FROM PIEDRAS
BLANCAS EXCLUDING THE AREA FROM POINT SAL NORTH 0-10 NM TO NW OF SAN
NICOLAS ISLAND THROUGH LATE TONIGHT. OTHERWISE THERE IS A CHANCE
SHOWERS WILL DEVELOP NEAR SHORE SOUTH OF POINT MUGU THIS AFTERNOON.
THROUGH EARLY WEDNESDAY TWO STORM SYSTEMS WITH GALE TO STORM FORCE
WINDS AND WITH A FETCH BETWEEN 200-220 DEGREES RELATIVE TO VENTURA
COAST WILL GENERATE SEAS 30-40 FEET SOUTHEAST OF NEW ZEALAND. THE
SWELLS WILL BEGIN TO ARRIVE A WEEK FROM TODAY AND BUILD THROUGH
TUESDAY.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...HALL
AVIATION...SIRARD
MARINE...30
SYNOPSIS...SETO/HALL

WWW.WEATHER.GOV/LOSANGELES


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