Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 020340 CCA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
830 PM PDT WED JUL 1 2015

.SYNOPSIS...

A SURGE OF MONSOONAL MOISTURE WILL BRING ISOLATED SHOWERS AND THUNDERSTORMS
TO THE REGION TONIGHT THROUGH THURSDAY MORNING...SHIFTING TO THE MOUNTAINS
AND DESERTS ON THURSDAY AFTERNOON AND FRIDAY AFTERNOON.
AS THE HOLIDAY WEEKEND APPROACHES...COOLING IS EXPECTED WITH A TROUGH
OF LOW PRESSURE TO OUR NORTH.

&&

.SHORT TERM (TONIGHT-SAT)...
AMPLE MONSOONAL MOISTURE CONTINUES TO STREAM INTO SOUTHERN CALIFORNIA
TONIGHT, LATEST RADAR IMAGERY IS FAIRLY QUIET ACROSS OUR
FORECAST AREA THIS EVENING...BUT THERE REMAINS ISOLATED THUNDERSTORM
ACTIVITY ACROSS THE SAN JOAQUIN VALLEY AND DESERTS OF
SAN BERNARDINO COUNTY...AS WELL AS LIGHT SHOWERS OFF THE COAST OF SOUTHERN
ORANGE COUNTY. ESRL PRECIPITABLE WATER SENSORS SHOWING VALUES GENERALLY
BETWEEN 1.4 AND 1.6 INCHES ACROSS THE FORECAST AREA THIS EVENING...WITH
EVEN HIGHER VALUES UP TO 1.8 INCHES UPSTREAM ACROSS THE COAST OF SAN DIEGO COUNTY.

LATEST 00Z NAM MODEL CONTINUES TO SHOW A GOOD AMOUNT OF MOISTURE FROM
THE 750 MB LEVEL ALL THE WAY UP TO 300 MB. IN THIS TYPE OF PATTERN...ISOLATED
LIGHT SHOWERS AND SPRINKLES COULD HAPPEN JUST ABOUT ANYWHERE. HOWEVER...
00Z MODEL AND HIGH RESOLUTION MODELS ARE FOCUSING BEST MID LEVEL MOISTURE AND
ELEVATED INSTABILITY/CAPE OVER THE MOUNTAINS AND DESERTS...AS WELL AS
ALL OF SLO COUNTY OVERNIGHT INTO THURSDAY MORNING. IN FACT 00Z NAM MODEL SHOWING
MU CAPE VALUES OF 300-600 J/KG ACROSS THE ABOVE MENTIONED AREAS.
THESE FACTORS COMBINED WITH SOME MID LEVEL LIFT NOTED IN THE CROSS SECTIONS
WARRANTS THE ADDITION OF A SLIGHT CHANCE OF THUNDERSTORMS IN EVENING UPDATE
FOR THE MOUNTAINS...ANTELOPE VALLEY...AND ALL OF SLO COUNTY.
CERTAINLY NOT A SURE THING...BUT ENOUGH FACTORS TO AT LEAST INCLUDE A SLIGHT
CHANCE OF CONVECTION.

OTHERWISE...DRYING TREND STARTS TO DEVELOP ACROSS THE FORECAST AREA
BY THURSDAY AFTERNOON. HOWEVER...THERE IS ENOUGH RESIDUAL MOISTURE AND
INSTABILITY TO WARRANT A SLIGHT CHANCE OF THUNDERSTORMS FOR THE MOUNTAINS
AND ANTELOPE VALLEY DURING THE AFTERNOON HOURS. WHILE THERE WILL BE MORE
SUNSHINE ON THURSDAY...ONSHORE FLOW WILL BE ON THE INCREASE...KEEPING
TEMPERATURES A BIT COOLER FOR COASTAL AND VALLEY AREAS THAN MOST OF THIS
WEEK. THIS COOLING TREND WILL CONTINUE INTO SATURDAY...WITH A RETURN OF
MORE TYPICAL NIGHT AND MORNING LOW CLOUDS AND FOG BY TOMORROW NIGHT.

*** FROM PREVIOUS DISCUSSION ***

.LONG TERM (SUN-WED)...WEATHER RETURNING TO MORE TYPICAL EARLY
SUMMER CONDITIONS AS A TROF SETS UP ACROSS NRN CALIFORNIA AND THE 4
CORNERS HIGH SHIFTS EAST. BY MID WEEK THERE IS A FAIR AMOUNT OF
MODEL DISAGREEMENT WITH THE ECMWF NOW SHOWING THE TROF DEEPENING
ACROSS THE WEST COAST WHILE THE THE GFS SHOWS THE RIDGE EXPANDING
WEST AGAIN WITH A SIGNIFICANT WARMING TREND. THIS IS A REVERSAL OF
ROLES FROM YESTERDAY WHEN THE EC WAS THE MUCH WARMER MODEL FOR THE
LATTER HALF OF NEXT WEEK. EITHER WAY, THERE`S NO INDICATION OF
MONSOON FLOW RETURNING NEXT WEEK.

&&

.AVIATION...01/2330Z...

AT 2300Z...THE MARINE INVERSION AT KLAX WAS BASED AT 650 FEET. THE
TOP OF THE INVERSION WAS 2600 FEET WITH A TEMPERATURE OF 26 DEGREES.

OVERALL...LOW TO MODERATE CONFIDENCE IN THE 00Z TAF PACKAGE. ALL TAF
SITES WILL LIKELY REMAIN VFR FOR MOST OF THE NEXT 24+ HOURS...BUT
THERE IS A CHANCE FOR IFR/LIFR CONDITIONS FOR COASTAL SITES TONIGHT.
THE BEST CHANCE FOR IFR/LIFR CONDITIONS ARE FROM 10-14Z...BUT THE
FORMATION OF THE STRATUS DECK WILL LIKELY BE SPOTTY AND RANDOM DUE
TO THE MID AND HIGH-LEVEL CLOUDS. ISOLATED SHOWERS AND SPRINKLES
WILL CONTINUE THROUGH THURSDAY MORNING. THERE IS A VERY SLIGHT
CHANCE (LESS THAN 10%) OF THUNDERSTORMS AT KPMD OR KWJF THIS EVENING.

KLAX...MODERATE CONFIDENCE IN 00Z TAF. THERE IS A 30 PERCENT CHANCE
OF IFR/LIFR CIGS TONIGHT FROM 10-14Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN 00Z TAF. THERE IS A 10 PERCENT
CHANCE OF IFR/LIFR CIGS TONIGHT FROM 10-14Z.

&&

.MARINE...01/830 PM...

HIGH CONFIDENCE THAT WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT
ADVISORY (SCA) CRITERIA THROUGH THE EARLY AFTERNOON ON THURSDAY.
THERE IS A CHANCE FOR SOME LOCAL SCA CONDITIONS AROUND POINT
CONCEPTION AND IN THE VICINITY OF THE CHANNEL ISLANDS LATE THURSDAY
AFTERNOON AND THURSDAY NIGHT...BUT LIKELY NOT WIDESPREAD ENOUGH TO
ISSUE A SCA. THERE IS A BETTER CHANCE FOR SCA CONDITIONS BY FRIDAY
AFTERNOON AND FRIDAY NIGHT FOR THE AREAS MENTIONED ABOVE.

THERE IS A SLIGHT CHANCE OF THUNDERSTORMS LATE TONIGHT INTO THURSDAY
MORNING FOR ZONES P645/670.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...GOMBERG/MW
AVIATION/MARINE...SUKUP/GOMBERG
SYNOPSIS...B

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