Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 200017
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
517 PM PDT SUN APR 19 2015

UPDATED AVIATION SECTION

.SYNOPSIS...
EXPECT A STEADY COOLING TREND THROUGH THE MIDDLE OF THE WEEK WITH
LOW CLOUDS AND FOG IN THE COASTAL AND VALLEY AREAS. THERE WILL BE A
SLIGHT CHANCE OF THUNDERSTORMS OVER SOME OF THE MOUNTAINS EARLY IN
THE WEEK. PERSISTENT LOW PRESSURE OFF THE COAST WILL BRING A SLIGHT
CHANCE OF SHOWERS TO MUCH OF THE AREA WEDNESDAY THROUGH FRIDAY.


&&

.SHORT TERM (TODAY-WED)...AN UPPER LOW 400 MILES WEST OF SFO WILL
SLIDE SOUTH ALONG 130W AND ONSHORE NEAR TJ TUE MORNING. A SECOND AND
COLDER UPPER LOW WILL FOLLOW ON WED AND TAKE A SIMILAR TRACK
INITIALLY, BUT THEN TURN INLAND EVEN FARTHER SOUTH ACROSS CENTRAL
BAJA. THIS IS MUCH FURTHER WEST AND SOUTH THAN MODELS HAD PREDICTED
A FEW DAYS AGO AND IS NOT GOOD FOR OUR RAIN CHANCES THIS WEEK. FOR
MOST OF THE AREA THE BIGGEST IMPACT WILL BE COOLER TEMPS WITH A
DEEPER MARINE LYR. HOWEVER, WITH THE FIRST UPPER LOW THERE WILL BE
SOME UNSTABLE AIR OVER THE MTNS MON AND TUE, PARTICULARLY OVER
VENTURA COUNTY, AND THERE COULD SOME ISOLATED THUNDERSTORMS THERE.
NOT A LOT OF MOISTURE TO WORK WITH BUT THE STEERING WINDS AREN`T ALL
THAT STRONG SO WE`LL HAVE TO KEEP AN EYE ON POSSIBLE FLASH FLOODING
ALONG WITH GUSTY WINDS AND HAIL. MONDAY APPEARS TO HAVE BETTER
CONVECTIVE PARAMETERS THAN TUESDAY. LOCAL WRF RUN ALSO SHOWS SOME
INSTABILITY OVER THE WRIGHTWOOD AREA BUT IT`S A PRETTY SMALL AREA
AND FOR NOW WILL JUST INDICATE SOME AFTERNOON BUILDUPS THERE.

HIGHS WILL COOL EACH DAY THROUGH WED, BOTTOMING OUT IN THE 60S TO
LOW 70S FOR MOST COAST/VALLEY AREAS. CAN`T RULE OUT A LITTLE DRIZZLE
WED MORNING WITH THE DEEPENING MARINE LYR, AND HAVE LEFT IN THE LOW
POPS FOR THE AFTERNOON AS THE SECOND UPPER LOW MOVES DOWN THE COAST
AND BOTH THE GFS AND EC SHOWS SOME LIGHT PRECIP THAT DAY. BUT THIS
IS LOOKING LESS AND LESS LIKELY WITH EACH RUN.

.LONG TERM (THU-SUN)...THE UPPER LOW WILL CONTINUE ITS MARCH WELL
OFF THE COAST AND SOUTH OF 30N BEFORE TURNING EAST INTO CENTRAL BAJA
ON THU. THE GFS CONTINUES TO HANG ON TO SOME LIGHT PRECIP ACROSS
MOSTLY THE SRN PORTION OF THE FORECAST AREA THU AND FRI WHILE THE EC
SEEMS TO BE SHIFTING IT EAST AND SOUTH WHICH LOOKS BETTER GIVEN THE
LOW TRACK. EITHER WAY, JUST VERY LIGHT AMOUNTS AT BEST AND PROBABLY
NOTHING FOR MANY AREAS EXCEPT POSSIBLE NIGHT AND MORNING MARINE LYR
DRIZZLE. HIGH TEMPS TO REMAIN A FEW DEGREES BELOW NORMAL THROUGH
FRIDAY. THEN TURNING A BIT WARMER SAT AND MORE SO SUNDAY AS WEAK
RIDGING DEVELOPS.

&&

.AVIATION...20/0017Z.

AT 2250Z...THE MARINE LAYER AT KLAX WAS AROUND 1000 FEET DEEP. THE
INVERSION TOP IS AT 3000 FEET WITH A TEMP OF 18 DEGREES C.

IFR TO MVFR CONDITIONS WILL SPREAD INTO COASTAL TERMINALS THROUGH
08Z...THEN INTO VALLEY TERMINALS BETWEEN 08Z AND 13Z. THE MARINE
LAYER DEPTH SHOULD LIFT SOUTH OF POINT CONCEPTION TO NEAR 2000 FEET
AND ALLOW MOST TERMINALS SOUTH OF POINT CONCEPTION TO LIFT INTO THE
MVFR CATEGORY. THERE IS A CHANCE OF A LATER CLEARING THAN FORECAST
AT COASTAL TERMINALS ON MONDAY.

KLAX...IFR CONDITIONS SHOULD SPREAD INTO KLAX BETWEEN 02Z AND 07Z.
THERE IS A 30 PERCENT CHANCE OF AN EARLIER ARRIVAL UP TO TWO HOURS
EARLIER. CONDITIONS SHOULD IMPROVE TO MVFR BETWEEN 07Z AND 10Z AND
LINGER THROUGH AT LEAST 18Z. THERE IS A 30 PERCENT CHANCE THAT
CLEARING COULD DELAYED BY UP TO TWO HOURS ON MONDAY.

KBUR...VFR CONDITIONS ARE EXPECTED THROUGH AT LEAST 07Z. THERE IS A
30 PERCENT CHANCE OF IFR CONDITIONS BETWEEN 07Z AND 10Z...THEN
PREDOMINANT MVFR CONDITIONS SHOULD DEVELOP BETWEEN 10Z AND 14Z. VFR
CONDITIONS SHOULD DEVELOP AROUND 16Z.

&&

.MARINE...19/200 PM.

SMALL CRAFT ADVISORY CONDITIONS ARE NOT EXPECTED THROUGH TUESDAY.
THERE IS A CHANCE SCA CONDITIONS WILL EXIST WEDNESDAY MORNING
THROUGH THURSDAY FROM PIEDRAS BLANCAS TO POINT SAL 10-60NM AND FROM
POINT SAL TO SAN MIGUEL ISLAND. PATCHY DENSE FOG WILL DISSIPATE
THROUGH THE REMAINDER OF THE MORNING AND THERE IS A CHANCE PATCHY
DENSE FOG WILL REDEVELOP NEAR SHORE FROM PIEDRAS BLANCAS TO THE SAN
PEDRO BASIN EARLY MONDAY MORNING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

PUBLIC...MW
AVIATION...HALL
MARINE...30
SYNOPSIS...SWEET

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