Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 291632 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
930 AM PDT WED JUL 29 2015

.SYNOPSIS...APPROACHING HIGH PRESSURE ALLOWS FOR SOUTHEASTERLY
MONSOONAL FLOW ALOFT THROUGH THE WEEKEND. THUNDERSTORM POTENTIAL
SPREADS ACROSS THE AREA FROM SOUTH TO NORTH WEDNESDAY INTO THURSDAY.
THE POSSIBILITY OF THUNDERSTORMS LINGER INTO THE WEEKEND FOR
INTERIOR AREAS. BY EARLY NEXT WEEK DRY SOUTHWEST WINDS REMOVE ANY
THREAT OF THUNDERSTORMS.

&&

.SHORT TERM (TODAY-FRI)...

NO CHANGES NEEDED WITH THE MORNING UPDATE...SO NO ZONE/FORECAST
UPDATES WILL BE SENT OUT. MARINE LAYER DEPTH WAS AROUND 1400 FEET
THIS MORNING AT BOTH LAX AND VBG. LOW CLOUDS AND PATCHY FOG COVERED
MOST COASTAL AREAS AND SOME VALLEY AREAS THIS MORNING. EXPECTING ALL
LOW CLOUDS AND FOG TO CLEAR OUT BY LATER THIS MORNING OR EARLY THIS
AFTERNOON...SO SHOULD BE A MOSTLY SUNNY DAY FOR MUCH OF THE AREA.
TODAY SHOULD BE THE HOTTEST DAY...WITH SOME MID-LEVEL CLOUDS MOVING
INTO THE AREA TOMORROW IN ASSOCIATION WITH SURGE OF MONSOONAL
MOISTURE. STILL A SLIGHT CHANCE OF THUNDERSTORMS FOR THE LA/VENTURA
MOUNTAINS AND ANTELOPE VALLEY STARTING THIS AFTERNOON AS THE
"MONSOON FRONT" PUSHES INTO THE SOUTHERN HALF OF THE CWA. LIKELY NOT
ENOUGH MOISTURE FOR FLASH FLOODING TODAY. WILL HAVE TO LOOK AT THE
POSSIBILITY OF A FLASH FLOOD WATCH FOR TOMORROW AS PWATS INCREASE
ABOVE 1.7". LIMITING FACTOR FOR FLASH FLOODING TOMORROW WILL BE
FASTER STORM MOVEMENT...WITH SE STEARING WINDS OF 15-20 KTS...WHICH
IS USUALLY TOO FAST FOR WIDESPREAD FLASH FLOODING.

***FROM PREVIOUS DISCUSSION***

TOUGH FORECAST FOR MUCH OF THE REGION TONIGHT THROUGH FRI...AND
FORECAST CONFIDENCE IS BELOW NORMAL FOR THIS PORTION OF THE SHORT
TERM. SELY FLOW THROUGH THE MID AND UPPER LEVELS OF THE ATMOSPHERE
WILL TRANSPORT INCREASINGLY DEEP MOISTURE INTO THE REGION TONIGHT
AND THU. ALL MODELS SHOW A STRONG VORT ASSOCD WITH AN EASTERLY WAVE
APPROACHING THE REGION FROM THE SE TONIGHT...TRACKING ACROSS THE
AREA ON THU. THE SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS IN THE MTNS
THIS EVENING WILL SPREAD INTO COASTAL AND VALLEY AREAS OF L.A.
COUNTY BY LATE TONIGHT...INTO VTU COUNTY THU MORNING...AND THE
REMAINDER OF FORECAST AREA BY THU AFTERNOON. THIS CHANCE OF SHOWERS
AND SLIGHT CHANCE OF TSTMS WILL CONT THU NIGHT. PRECIPITABLE WATER
VALUES WILL CONT TO CLIMB...RISING TO AROUND 1.8 INCHES THU. ANY
THUNDERSTORM THU AND THU EVENING WILL HAVE THE POTENTIAL TO PRODUCE
HEAVY DOWNPOURS. MID AND UPPER LEVEL STEERING FLOW WILL BE A BIT
STRONGER ON THU...WHICH WOULD MITIGATE TO SOME EXTENT...THE THREAT
OF FLASH FLOODING. STILL...FLASH FLOOD WATCHES MAY BE NEEDED FOR
PORTIONS OF THE REGION DUE TO THE AVAILABLE MOISTURE AND THE
POTENTIAL FOR CELLS TO TRAIN OVER AN AREA. MAX TEMPS WILL BE VERY
TRICKY ON THU. THERE WILL PROBABLY BE ENOUGH CLOUD COVER TO KEEP
TEMPS DOWN A BIT...SO HAVE LOWERED TEMPS. HOWEVER...WITH THE
INCREASED HUMIDITY LEVELS...IT MAY FEEL MORE UNCOMFORTABLE. AND...IF
THERE IS MORE SUNSHINE THAN FORECAST...TEMPS WILL SKYROCKET IN THE
WARM AIR MASS ON THU.

LINGERING MOISTURE WILL KEEP A SLIGHT CHANCE OF SHOWERS AND TSTMS
ACROSS INTERIOR SECTIONS OF SLO AND SBA COUNTIES...THE MTNS OF L.A.
AND VTU COUNTIES AND THE ANTELOPE VALLEY ON FRI...BUT THE CHANCE OF
SHOWERS ELSEWHERE IS EXPECTED TO BE MINIMAL. HOWEVER...THE 06Z RUN
OF THE GFS BRINGS A DECENT VORT THROUGH THE REGION FROM THE S FRI
AFTERNOON...AND IF LATER RUNS CONT TO SHOW THIS FEATURE...AN
INCREASE IN POPS MAY HAVE TO BE CONSIDERED. MAX TEMPS MAY BE UP A
FEW DEGREES ON FRI...DUE TO AN EXPECTED INCREASE IN SUNSHINE.

.LONG TERM (SAT-TUE)...THE UPPER FLOW WILL TURN MORE SWLY OVER THE
WEEKEND...WHICH SHOULD BRING GRADUAL DRYING. HOWEVER...THERE SHOULD
BE ENOUGH LINGERING MOISTURE TO KEEP A SLIGHT CHANCE OF SHOWERS AND
TSTMS IN THE MTNS OF L.A. AND VTU COUNTIES AND THE ANTELOPE VALLEY
DURING THE AFTERNOON AND EVENING HOURS SATURDAY AND SUNDAY. NIGHT
THROUGH MORNING LOW CLOUDS MAY RETURN TO COASTAL AREAS BY EARLY NEXT
WEEK...BUT RATHER HIGH HEIGHTS SHOULD KEEP THE MARINE LAYER QUITE
SHALLOW. MAX TEMPS SHOULD BE NEAR TO SLIGHTLY ABOVE NORMAL ACROSS
THE REGION SAT THROUGH TUE.

&&

.AVIATION...29/1150Z...

AT 0807Z...THE MARINE INVERSION AT KLAX WAS BASED AT 1400 FEET. THE
TOP OF THE INVERSION WAS 4700 FEET WITH A TEMPERATURE OF 25 DEGREES
CELSIUS.

OVERALL...MODERATE CONFIDENCE IN 12Z TAF PACKAGE. IFR/LIFR CONDS
BLANKETING ALL COASTAL TAF SITES...WITH CLEAR SKIES ELSEWHERE.
CIG/VSBYS RESTRICTIONS WILL DISSIPATE BY AFTERNOON...WITH VFR CONDS
THROUGH EARLY THIS EVENING. FOR TONIGHT...MODERATE CONFIDENCE IN
RETURN OF IFR/LIFR CIGS TO CENTRAL COAST...BUT LOW CONFIDENCE IN
RETURN SOUTH OF POINT CONCEPTION.

KLAX...MODERATE CONFIDENCE IN 12Z TAF. DISSIPATION OF IFR CIGS COULD
BE +/- 2 HOURS OF CURRENT 17Z FORECAST. FOR TONIGHT...ANTICIPATE
HIGH CLOUDS WILL PREVENT ANY ORGANIZED STRATUS FROM DEVELOPING..BUT
LOW CONFIDENCE IN SAID FORECAST.

KBUR...HIGH CONFIDENCE IN 12Z FORECAST. THERE IS A 20% CHANCE OF IFR
CIGS 12Z-16Z THIS MORNING.

&&

.MARINE...29/900 AM...

HIGH CONFIDENCE IN GENERALLY LIGHT WINDS FOR AT LEAST THE NEXT 36
HOURS. FOG WITH SOME VISIBILITIES NEAR 1 MILE WILL CONTINUE THIS
MORNING AND MAY FOR AGAIN THURSDAY MORNING...ESPECIALLY NORTH OF
POINT CONCEPTION. MODERATE LONG PERIOD SWELL WILL CONTINUE TO IMPACT
THE AREA THROUGH THURSDAY. THUNDERSTORMS WILL BE POSSIBLE LATE
TONIGHT THROUGH EARLY FRIDAY MORNING. THE BEST CHANCE WILL BE
THURSDAY MORNING AS A DISTURBANCE MOVES THROUGH THE AREA FROM THE
SOUTH.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&

$$

PUBLIC...DB/SUKUP
AVIATION...RAT
MARINE...KITTELL
SYNOPSIS...RM

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