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000
FXUS66 KLOX 180435
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
935 PM PDT MON JUN 17 2013

.SYNOPSIS...

A NORTHERLY SURFACE GRADIENT WILL CONTINUE GUSTY NORTHERLY WINDS
FOR THE MOUNTAINS AND SANTA BARBARA SOUTH COAST THROUGH WEDNESDAY
NIGHT. TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH MID
WEEK...FOLLOWED BY A SLIGHT WARM UP INTO NEXT WEEKEND AS THE UPPER
LOW CURRENTLY OFF THE WASHINGTON COAST SHIFTS EASTWARD. AREAS OF
NIGHT THROUGH MORNING LOW CLOUDS AND FOG WILL CONTINUE FOR PARTS
OF THE COASTAL PLAIN INTO THE WEEKEND.

&&

.UPDATE...

A NORTHERLY SURFACE PRESSURE GRADIENT CONTINUES TO TIGHTEN ACROSS
THE AREA THIS EVENING. KSBA-KSMX SURFACE PRESSURE GRADIENTS SURGED
TO -5.2 MB THIS HOUR. WITH GRADIENTS STILL STRENGTHENING...A HIGH
WIND WARNING IS BEING CONSIDERED AT THIS TIME. FOR NOW...A WIND
ADVISORY REMAINS IN EFFECT THROUGH 3 AM PDT TUESDAY MORNING. WITH
GUSTY WINDS DEVELOPING THROUGH THE INTERSTATE 5 CORRIDOR LAST
NIGHT...A WIND ADVISORY WAS ADDED FOR THE LOS ANGELES AND VENTURA
COUNTY MOUNTAINS THROUGH 3 AM PDT TUESDAY.

WIND ADVISORIES MAY NEED TO BE EXTENDED OR EXPANDED FOR TUESDAY
AFTERNOON THROUGH TUESDAY NIGHT. ADVISORY LEVEL WINDS COULD
DEVELOP ALONG THE CENTRAL COAST...THE ANTELOPE VALLEY...SAN LUIS
OBISPO COUNTY INTERIOR VALLEYS...IN ADDITION TO...SOUTHERN SANTA
BARBARA COUNTY AND THE INTERSTATE 5 CORRIDOR. THE THERMAL PATTERN
IS MUCH MORE CONDUCIVE FOR SUNDOWNER WINDS BETWEEN TUESDAY AND
TUESDAY NIGHT...WITH 950 MB KSBA-KSMX 950 MB THERMAL GRADIENTS
EXCEEDING 10 DEGREES CELSIUS IN NAM-WRF SOLUTIONS. LOCAL 4-KM WRF
SOLUTIONS MAY ALSO ADD ADDITIONAL CLARITY IN A COUPLE OF HOURS
AFTER 00Z RUN IS FINISHED. WITH GRADIENTS HEALTHY TONIGHT AND THE
THERMAL PATTERN TIGHTER ON TUESDAY AND TUESDAY NIGHT...A HIGH
WIND WATCH/WARNING IS BEING CONSIDERED AT THIS TIME FOR THE SANTA
BARBARA SOUTH COAST AND MOUNTAINS. AN UPDATE HAS BEEN ISSUED TO
INCREASE WINDS THROUGH TUESDAY NIGHT.

&&

.PREV DISCUSSION...

SHORT TERM...HEIGHTS/THICKNESSES ARE EXPECTED TO FALL/DECREASE
OVER THE AREA AS THE CYCLONIC CENTER OFF THE WA/OR COAST SHIFTS
INLAND TUESDAY NIGHT AND PATCHY LOW CLOUDS WILL LIKELY MIX OUT
RELATIVELY EARLY WEDNESDAY. A COOLING TREND IS EXPECTED TUE WITH
THE TEMPERATURES ON THE CENTRAL COAST DIFFERING BY 5 TO 10
DEGREES...OTHERWISE TEMPERATURES WILL DIFFER BY MINUS 2 TO 5
DEGREES ELSEWHERE. A SLIGHT WARMING TREND IS THEN EXPECTED
WEDNESDAY THROUGH THURSDAY WHERE TEMPERATURES WILL LIKELY WARM TO
AROUND NORMAL BY THURSDAY.

LONG TERM...REASONABLE HIGH CONFIDENCE THROUGH THE PERIOD.
ONSHORE PRESSURE GRADIENT IS EXPECTED TO PERSIST OVER THE AREA
WHILE A BROAD LOW AMPLITUDE LONG WAVE TROUGH GRADUALLY DEVELOPS
OVER THE EASTERN PACIFIC THROUGH THE PERIOD. SLIGHT TEMPERATURES
CHANGES ARE EXPECTED THROUGH THE PERIOD. COASTAL TEMPERATURES WILL
LIKELY REMAIN A FEW DEGREES BELOW NORMAL WHILE INLAND TEMPERATURES
REMAIN AROUND NORMAL.

&&

.AVIATION...18/0014Z.

VFR CONDITIONS WILL PERSIST AT MOST TERMINALS EXCEPT FOR A CHANCE OF
IFR TO MVFR CONDITIONS AT COASTAL TERMINALS SOUTH OF POINT
CONCEPTION...AND LIFR TO IFR CONDITIONS AT COASTAL TERMINALS NORTH
OF POINT CONCEPTION. PERIODS OF MODERATE TO STRONG LOW-LEVEL WIND
SHEAR AND TURBULENCE ARE POSSIBLE THROUGH 08Z AT KSBA...WITH A
CHANCE OF LOW-LEVEL WIND SHEAR AND TURBULENCE AT TERMINALS NORTH OF
POINT CONCEPTION.

KLAX...VFR CONDITIONS WILL PERSIST THROUGH AT LEAST 04Z...THEN THERE
IS A 60 PERCENT CHANCE OF IFR TO MVFR CONDITIONS AT KLAX THROUGH
10Z. BY 10Z...THERE IS A 80 PERCENT CHANCE OF MVFR CONDITIONS. VFR
CONDITIONS SHOULD REDEVELOP BETWEEN 16Z AND 17Z.

KBUR...VFR CONDITIONS WILL PERSIST THROUGHOUT THE PERIOD EXCEPT FOR
A 20 PERCENT OF IFR TO MVFR CONDITIONS BETWEEN 13Z AND 16Z.

&&

.FIRE WEATHER...

INCREASING NORTHWEST FLOW THROUGH THURSDAY ACROSS THE SANTA BARBARA
COUNTY MOUNTAINS AND SOUTH COAST...AS WELL AS THE INTERSTATE 5
CORRIDOR AND ANTELOPE VALLEY. GUSTY SUNDOWNER WINDS WILL AFFECT THE
SANTA BARBARA COUNTY MOUNTAINS AND SOUTH COAST...STRONGEST DURING
THE LATE AFTERNOON AND NIGHTTIME HOURS...WHEN GUSTS BETWEEN 35 AND
45 MPH WILL BE COMMON. TEMPERATURES ARE EXPECTED TO SOAR INTO THE
80S THROUGH EARLY EVENING WITH HUMIDITIES POTENTIALLY FALLING BELOW
20 PERCENT. CONDITIONS ARE NOT EXPECTED TO BE QUITE AS HOT OR DRY ON
TUESDAY. GUSTY WINDS WILL ALSO IMPACT THE ANTELOPE VALLEY AND LOS
ANGELES COUNTY MOUNTAINS DURING THE NEXT FEW DAYS...ESPECIALLY
THROUGH THE INTERSTATE 5 CORRIDOR. THESE AREAS WILL GENERALLY SEE
GUSTS IN THE 35 TO 45 MPH RANGE WITH ISOLATED GUSTS AS HIGH AS 50
MPH NEAR WHITAKER PEAK. HUMIDITIES WILL FALL TO BETWEEN 10 AND 20
PERCENT ACROSS THE MOUNTAINS WITH POOR OVERNIGHT RECOVERIES.
MEANWHILE...SINGLE DIGIT HUMIDITIES WILL BE COMMON ACROSS THE
ANTELOPE VALLEY EACH AFTERNOON. THE GUSTY WINDS AND LOW HUMIDITIES
WILL MAINTAIN ELEVATED FIRE DANGER THROUGH THURSDAY ACROSS THE
MOUNTAINS...ANTELOPE VALLEY...AND SANTA BARBARA SOUTH COAST.

OF PARTICULAR CONCERN WILL BE LATE WEDNESDAY MORNING THROUGH THURSDAY
MORNING WHEN EVEN DRIER AIR IS EXPECTED TO SURGE INTO INLAND AREAS.
DURING THIS TIME...THERE WILL BE THE POTENTIAL FOR A PROLONGED PERIOD
OF HUMIDITIES IN THE TEENS AND SINGLE DIGITS ACROSS THE MOUNTAINS OF
LOS ANGELES...VENTURA...AND SANTA BARBARA COUNTIES. THESE VERY LOW
HUMIDITIES COUPLED WITH THE CONTINUED GUSTY NORTHWEST TO NORTH WINDS
AND VERY DRY FUELS WILL BRING THE POTENTIAL FOR CRITICAL FIRE WEATHER
CONDITIONS IN THE MOUNTAINS. AS A RESULT...A FIRE WEATHER WATCH HAS
BEEN POSTED FOR THE MOUNTAINS VALID LATE WEDNESDAY MORNING THROUGH
THURSDAY MORNING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
GALE WARNING (SEE LAXMWWLOX).
GALE WATCH (SEE LAXMWWLOX).
FIRE WEATHER WATCH (SEE LAXRFWLOX).
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...HALL/30
AVIATION...HALL
FIRE WEATHER...GOMBERG
SYNOPSIS...SUKUP/HALL

WWW.WEATHER.GOV/LOSANGELES