Wildfire and High Wind in California, May 2 to 11, 2013

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1045 PM PDT WED MAY 1 2013

NEW AVIATION DISCUSSION

...SANTA ANA WINDS TO BRING EXTREME FIRE DANGER FOR MUCH OF LOS
   ANGELES AND VENTURA COUNTIES THROUGH FRIDAY...

.SYNOPSIS...

HOT...DRY AND GUSTY CONDITIONS ARE EXPECTED OVER THE AREA THROUGH
FRIDAY. A COOLING TREND IS EXPECTED TO BEGIN SATURDAY WITH ISOLATED
SHOWERS POSSIBLE SUNDAY AFTERNOON THROUGH TUESDAY.

&&

.SHORT TERM (TONIGHT-SAT)...OFFSHORE FLOW CONTINUES TO INCREASE OVER
THE FORECAST AREA THIS EVENING...WITH A 24 HOUR GRADIENT CHANGE OF
-9.3 MB LAX-DAG AND -11.9 MB LAX-TPH. BY LATE TONIGHT...THE LATEST
NAM IS FORECASTING 850 MB WINDS UP TO 50 KT IN THE MTNS AND UP TO 55
KT AT 950 MB (1500 FT) OVER VTU COUNTY COAST. WITH DECENT COLD AIR
ADVECTION AND OFFSHORE GRADIENTS...HIGH WINDS ARE EXPECTED IN THE
MTNS OF L.A./VTU COUNTIES INCLUDING THE SANTA MONICA MTNS AND IN THE
SANTA CLARITA VALLEY...WHERE HIGH WIND WARNINGS ARE IN EFFECT LATER
TONIGHT INTO THU. GUSTY NE WINDS WILL ALSO SPREAD INTO THE VTU
COUNTY VLYS...SAN FERNANDO VALLEY...AND THE COAST FROM MALIBU TO VTU
WHERE WIND ADVISORIES ARE IN EFFECT AS WELL. PLEASE SEE THE LATEST
NON PRECIPITATION WEATHER MESSAGE (LAXNPWLOX) FOR FURTHER DETAILS.
THERE ARE ALSO SIGNIFICANT FIRE WEATHER CONCERNS WITH THE WINDS
COMBINED WITH EXTREMELY LOW HUMIDITIES. PLEASE SEE THE FIRE WEATHER
DISCUSSION BELOW FOR ADDITIONAL INFORMATION.

UPPER LEVEL RIDGING WILL PREVAIL OVER SWRN CA THRU THU...THEN SLOWLY
WEAKEN THRU FRI BEFORE AN UPPER LEVEL TROF MOVES INTO THE AREA FOR
SAT. THE OFFSHORE FLOW WILL WEAKEN SOME FOR LATER THU THRU FRI BUT
HUMIDITIES WILL REMAIN VERY DRY WITH THE FIRE WEATHER CONCERNS
CONTINUING. THE OFFSHORE FLOW WILL WEAKEN FURTHER FRI NIGHT THEN
TURN ONSHORE IN ALL AREAS FOR SAT. CLEAR SKIES WILL PREVAIL THRU THE
PERIOD EXCEPT FOR POSSIBLE LOW CLOUDS AND FOG ALONG THE COASTAL
PLAIN LATER FRI NIGHT AND SAT MORNING. TEMPS WILL SOAR ACROSS MUCH
FOR THE REGION THU AND FRI...WITH HIGHS MUCH ABOVE NORMAL EVEN FOR
MANY COASTAL AREAS. TEMPS WILL COOL OFF SOME FOR SAT BUT REMAIN
SEVERAL DEGREES ABOVE NORMAL FOR MANY AREAS.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (SUN-WED)...A BROAD LONG WAVE RIDGE WITH AN EMBEDDED
CYCLONIC CIRCULATION IS EXPECTED TO SHIFT NORTHEAST OVER THE AREA
SUNDAY THROUGH TUESDAY. LATEST GUIDANCE INDICATED THE BULK OF THE
MOISTURE LIMITED IN THE MID LEVELS WITHIN A MARGINAL CONVECTIVE
UNSTABLE AIR MASS. WILL CONTINUE WITH LOW POPS SUNDAY AFTERNOON
THROUGH TUESDAY MORNING AS THE SYSTEM GRADUALLY SHIFTS OVER THE
AREA. BUT THE BULK OF THE MOISTURE AND ASCENDING FLOW IS EXPECTED
SUNDAY EVENING AND HAVE ADJUSTED POPS UP ONE CATEGORY SUNDAY NIGHT.
OTHERWISE A COOLING TREND IS EXPECTED THROUGH THE PERIOD AND THERE
IS A CHANCE TEMPERATURES WILL RANGE 5 TO 10 DEGREES BELOW NORMAL
WITH THE COOLEST TEMPERATURES AT THE COAST MONDAY THROUGH WEDNESDAY.

&&

.AVIATION...

02/0545Z

HI CONFIDENCE IN THE CURRENT TAFS WITH VFR CONDITIONS AT ALL
AIRFIELDS THROUGH THU EXCEPT FOR KLGB WHERE THERE IS A 30 PERCENT
CHANCE OF MVFR CIGS 11Z-15Z. GUSTY NE WINDS ARE EXPECTED LATE
TONIGHT AND THU MORNING FOR KOXR...KBUR AND KVNY. THERE IS A 20
PERCENT CHANCE OF LOW LEVEL WIND SHEAR CONDITIONS AT KVNY AND KBUR.
GUSTY NE WINDS ARE ALSO EXPECTED AT KWJF AND KPMD BY THU AFTERNOON.

KLAX...HI CONFIDENCE IN THE CURRENT TAF. THERE IS A 30 PERCENT
CHANCE OF AN 8 KT EAST WIND COMPONENT FROM 11Z-18Z.

KBUR...HI CONFIDENCE IN THE CURRENT TAF. LGT-OCNL MDT TURBC SFC TO
070 AND A SLIGHT CHC OF LLWS THROUGH THE PERIOD.

&&

.FIRE WEATHER...
RED FLAG WARNINGS IN EFFECT FOR MUCH OF LOS ANGELES AND VENTURA
COUNTIES THROUGH FRIDAY...WHERE EXTREME FIRE DANGER EXISTS. GUSTY
OFFSHORE WINDS HAVE ALREADY BROUGHT SIGNIFICANT WARMING AND DRYING
TO THE MOUNTAINS AND SANTA CLARITA VALLEY TODAY. WIDESPREAD SINGLE
DIGIT HUMIDITIES ALREADY IMPACTING THESE AREAS...WITH HUMIDITIES AS
LOW AS 2 PERCENT BEING OBSERVED!

THE MARINE INVERSION PREVENTED THE OFFSHORE WINDS FROM SPREADING
INTO THE REMAINING VALLEYS TODAY. AS SURFACE HIGH PRESSURE BUILDS
OVER THE GREAT BASIN OVERNIGHT INTO THURSDAY MORNING...OFFSHORE FLOW
FROM THE SURFACE TO THE 850 MB LEVEL WILL INCREASE SHARPLY. IN
FACT...LATEST NAM MODEL SHOWS LAX-DAGGETT GRADIENT PEAKING AT -8 MB
EARLY THURSDAY MORNING...WHICH IS VERY IMPRESSIVE FOR THIS TIME OF
YEAR. AS A RESULT...SANTA ANA WINDS ARE EXPECTED TO STRENGTHEN AND
BECOME MORE WIDESPREAD OVERNIGHT INTO THURSDAY...LEADING TO A LARGER
AREA OF EXTREME FIRE DANGER. THE PEAK OF THE WINDS ARE EXPECTED TO
BE FROM 2 AM TONIGHT THROUGH 2 PM THURSDAY...WITH THE MOUNTAINS OF
LOS ANGELES AND VENTURA COUNTIES EXPECTED TO SEE WIND GUSTS IN THE
60 TO 70 MPH RANGE. COASTAL AND VALLEY AREAS ARE EXPECTED TO SEE
GUSTS IN THE 40 TO 60 MPH RANGE...WITH THE STRONGEST WINDS FOCUSED
ACROSS THE SANTA CLARITA VALLEY AND EASTERN VENTURA COUNTY VALLEYS.

THE SANTA ANA WINDS ARE EXPECTED TO BRING IN SOME OF THE DRIEST AIR
WE HAVE SEEN IN SOME TIME...WITH LONG DURATIONS OF SINGLE DIGIT
HUMIDITIES EXPECTED THROUGH FRIDAY. WE WILL LIKELY SEE MANY STATIONS
REPORT HUMIDITIES UNDER 5 PERCENT DURING THE NEXT COUPLE OF DAYS.
WIND PRONE AREAS WILL SEE LITTLE OR NO HUMIDITY RECOVERY TONIGHT AND
AGAIN THURSDAY NIGHT. DUE TO THE LOW SEASONAL PRECIPITATION...IT IS
ALSO IMPORTANT TO NOTE THAT A LARGE PORTION OF LOS ANGELES AND
VENTURA COUNTIES HAVE LIVE FUEL MOISTURE LEVELS THAT ARE 2 TO 3
MONTHS AHEAD OF SCHEDULE...RESEMBLING READINGS TYPICALLY SEEN IN
JULY OR AUGUST.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING (SEE LAXNPWLOX).
RED FLAG WARNING (SEE LAXRFWLOX).
WIND ADVISORY (SEE LAXNPWLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

PUBLIC...SIRARD/30
FIRE WEATHER...GOMBERG
AVIATION...ASR
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
257 PM PDT WED MAY 1 2013

CAZ034>041-044>046-051>054-059-087-088-547-548-021300-
SAN LUIS OBISPO COUNTY CENTRAL COAST-
SANTA BARBARA COUNTY CENTRAL COAST-SANTA YNEZ VALLEY-
SAN LUIS OBISPO COUNTY INTERIOR VALLEYS-CUYAMA VALLEY-
SANTA BARBARA COUNTY SOUTH COAST-VENTURA COUNTY COAST-
LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES-
VENTURA COUNTY INTERIOR VALLEYS-VENTURA COUNTY COASTAL VALLEYS-
SANTA MONICA MOUNTAINS RECREATIONAL AREA-
SAN LUIS OBISPO COUNTY MOUNTAINS-
SANTA BARBARA COUNTY MOUNTAINS-VENTURA COUNTY MOUNTAINS-
LOS ANGELES COUNTY MOUNTAINS EXCLUDING THE SANTA MONICA RANGE-
ANTELOPE VALLEY-CATALINA ISLAND-SANTA CLARITA VALLEY-
LOS ANGELES COUNTY SAN FERNANDO VALLEY-
LOS ANGELES COUNTY SAN GABRIEL VALLEY-
257 PM PDT WED MAY 1 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA.

.DAY ONE... TODAY AND TONIGHT

GUSTY OFFSHORE WINDS WILL DEVELOP AND INCREASE OVER VENTURA AND LOS
ANGELES COUNTIES TONIGHT. A HIGH WIND WARNING IS IN EFFECT OVER
AREAS OF LOS ANGELES AND VENTURA COUNTIES AFTER MIDNIGHT. EXTREMELY
DRY AND WARM CONDITIONS WILL COMBINE WITH THE GUSTY WINDS TO BRING
CRITICAL FIRE WEATHER CONDITIONS TO INLAND LOCATIONS.

* HIGH WIND WARNING..........SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* RED FLAG WARNING...........SEE WWUS86 KLOX - RFWLOX FOR DETAILS *

* WIND ADVISORY..............SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* SPECIAL WEATHER STATEMENT..SEE WWUS86 KLOX - SPSLOX FOR DETAILS *

.DAYS TWO THROUGH SEVEN... THURSDAY THROUGH TUESDAY

HIGH WIND WARNING FOR AREAS OF LOS ANGELES AND VENTURA COUNTIES WILL
END THURSDAY AFTERNOON. GUSTY OFFSHORE WINDS AND EXTREMELY DRY AND
WARM CONDITIONS WILL BRING CRITICAL FIRE WEATHER CONDITIONS TO
INLAND LOCATIONS THROUGH FRIDAY. UNSEASONABLY HIGH AFTERNOON
TEMPERATURES WILL BE NEAR RECORD LEVELS IN MANY LOCATIONS THROUGH
FRIDAY.

* HIGH WIND WARNING..........SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* RED FLAG WARNING...........SEE WWUS86 KLOX - RFWLOX FOR DETAILS *

* WIND ADVISORY..............SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* SPECIAL WEATHER STATEMENT..SEE WWUS86 KLOX - SPSLOX FOR DETAILS *

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.