Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 020552
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1030 PM PDT SAT AUG 1 2015

NEW AVIATION DISCUSSION

.SYNOPSIS...A TROUGH OF LOW PRESSURE OFF THE COAST AND A RIDGE OF
HIGH PRESSURE OVER THE FOUR CORNERS REGION WILL RESULT IN NEAR
NORMAL TEMPERATURES IN MOST LOCATIONS THROUGH NEXT WEEK...ALONG WITH
NIGHT THROUGH MORNING LOW CLOUDS AND FOG WEST OF THE MOUNTAINS.
SLIGHT COOLING IS POSSIBLE BY LATE NEXT WEEK AS LOW PRESSURE OFF THE
COAST MOVES EAST.

&&

.UPDATE...

SOUTHWEST FLOW ALOFT CONTINUES TO ESTABLISH BETWEEN A TROUGH OF LOW
PRESSURE OVER THE EASTERN PACIFIC OCEAN NEAR 36N AND 135W...AND A
RIDGE OF HIGH PRESSURE OVER WEST TEXAS. A PERSISTENT ONSHORE FLOW
WILL REMAIN IN PLACE THROUGH AT LEAST TUESDAY AND KEEP NIGHT THROUGH
MORNING LOW CLOUDS AND FOG IN THE FORECAST FOR THE COAST AND LOWER
VALLEYS. TEMPERATURES WILL REMAIN SEASONAL FOR THIS TIME OF YEAR
ACROSS SOUTHWEST CALIFORNIA. LOCALLY WINDY CONDITIONS WILL DEVELOP
EACH AFTERNOON AND EVENING IN THE ANTELOPE VALLEY AS THE SEABREEZE
ARRIVES AND PUSHES INTO THE DESERT.

LOCALLY GUSTY SUNDOWNER WINDS HAVE DEVELOPED ACROSS THE SANTA
BARBARA SOUTH COAST AND ADJACENT SANTA YNEZ MOUNTAINS THIS EVENING.
WINDS ARE RIDING NEAR ADVISORY LEVELS CURRENTLY. KSBA-KSMX SURFACE
PRESSURE GRADIENTS HAVE SURGED TO -3.8 MB LAST HOUR...BUT MINIMAL
STRENGTHENING IS NOT EXPECTED AT THIS TIME. LOCAL 2-KM WRF MSL
PRESSURE PATTERN REVEALS LITTLE CHANGE IN THE SURFACE PRESSURE
GRADIENTS FROM NOW THROUGH MIDNIGHT TONIGHT. WINDS WILL BE MONITORED
CLOSELY BUT NO WIND ADVISORY ISSUANCE IS EXPECTED AT THIS TIME.

&&

.PREV DISCUSSION...

SHORT TERM...THE FORECAST AREA WILL STAY UNDER THE INFLUENCE OF
SOUTHWESTERLY FLOW ALOFT WITH VERY LITTLE DAY TO DAY CHANGES IN THE
STRENGTH OF THE ONSHORE PRESSURE GRADIENTS. MARINE LAYER DEPTH MAY
FLUCTUATE EACH NIGHT BUT FOR THE MOST PART EXPECT SIMILAR OVERNIGHT
AND MORNING STRATUS COVERAGE THIS PERIOD WITH IT LIKELY EXTENDING
INTO THE VALLEYS. A BUMP UP IN NORTHWESTERLY FLOW OFFSHORE AT THE
SURFACE SHOULD HELP EDDY FORMATION AND KEEP THE SBA SOUTH COAST IN
THE OVERNIGHT CLEAR BY MONDAY NIGHT. SOME HIGH CLOUDS MAY BE
STREAMING ACROSS IN THE SOUTHWEST UPPER FLOW ON TUESDAY...OTHERWISE
SKIES WILL BE MOSTLY SUNNY IN THE AFTERNOONS. TEMPERATURES WILL STAY
JUST BELOW NORMAL THROUGH THE PERIOD WITH NO PRECIPITATION.

LONG TERM...NOT MUCH CHANGE AT ALL IN THE FIRST PART OF THE EXTENDED
PERIOD...WITH CONTINUED NIGHTTIME-MORNING STRATUS...CLEARING DURING
THE DAY AND TEMPERATURES STAYING JUST BELOW NORMAL. BOTH THE GFS AND
ECMWF FORECAST A DRY CLOSED UPPER LOW DROPPING DOWN OFF THE COAST BY
LATER IN THE PERIOD. ONCE IT DOES MOVE THROUGH THE MAIN IMPACTS WILL
BE INCREASING WINDS MOUNTAINS AND FAR INTERIOR SECTIONS...AND COOL
OUR AFTERNOON HIGH TEMPS...MORE NOTABLY IN THE MOUNTAINS...THE
ANTELOPE VALLEY AND FAR INTERIOR SLO COUNTY.

&&

.AVIATION...

02/0545Z

AT 05Z...THE MARINE LAYER AT KLAX WAS AROUND 1300 FEET DEEP. THE TOP
OF THE INVERSION IS AROUND 2700 FEET WITH A TEMPERATURE OF 26
DEGREES CELSIUS.

GOOD CONFIDENCE THAT THERE WILL BE CIGS AT ALL CSTL/VLY XCP KSBA
TERMINALS BY 13Z. BUT LOWER CONFIDENCE IN EXACT ARRIVAL TIME WHICH
COULD BE OFF BY 2 HOURS. GOOD CONFIDENCE IN BURN OFF TIMES. THERE IS
A 40 PERCENT CHC OF IFR CIGS AT KSBA 12Z-17Z.

KLAX...LOW CONFIDENCE IN EXACT ARRIVAL TIME OF CIGS AND COULD HAPPEN
ANYTIME 08Z-12Z. THERE IS A 40 PERCENT CHC CIGS WILL REMAIN IFR
UNTIL 16Z. GOOD CONFIDENCE IN CLEARING AND REST OF FCST THRU 03/06Z.
LOWER CONFIDENCE IN RETURN OF MARINE LAYER TOMORROW EVENING.

KBUR...LOW CONFIDENCE IN EXACT ARRIVAL TIME OF CIGS AND COULD HAPPEN
ANYTIME 09Z-13Z. GOOD CONFIDENCE IN CLEARING AND REST OF FCST THRU
03/06Z.

&&

.MARINE...01/900 PM.

THE SMALL CRAFT ADVISORY HAS BEEN EXPANDED FOR ALL OUTER WATERS THIS
EVENING. WINDS COULD DROP BELOW SMALL CRAFT ADVISORY LEVELS LATE
TONIGHT AND EARLY SUNDAY MORNING ACROSS THE NORTHERN PORTION OF THE
OUTER WATERS...BUT WINDS WILL DEVELOP FAIRLY RAPIDLY ON SUNDAY
MORNING AS A BUMP IN THE NORTHERLY GRADIENT DEVELOPS. WITH A SLIGHT
INCREASE IN NORTHWEST WINDS EXPECTED ON SUNDAY...A SMALL CRAFT
ADVISORY HAVE BEEN ADDED FOR THE NEARSHORE WATERS ALONG THE CENTRAL
COAST...AND ACROSS THE EAST SANTA BARBARA CHANNEL. WINDS SHOULD
START DIMINISHING EARLY MONDAY MORNING.

&&

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

&&

$$

PUBLIC...HALL/MJ
AVIATION/MARINE...ASR/HALL
SYNOPSIS...SUKUP

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