Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 250521 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1020 PM PDT THU JUL 24 2014

UPDATED AVIATION SECTION

.SYNOPSIS...
A WARM AIR MASS WILL REMAIN OVER THE REGION THROUGH LATE NEXT WEEK
AS HIGH PRESSURE REMAINS ANCHORED OVER THE DESERT SOUTHWEST. A WEAK
DISTURBANCE MOVING AROUND THE HIGH PRESSURE SYSTEM COULD BRING A
RETURN OF MONSOONAL MOISTURE TO THE MOUNTAINS AND DESERTS THIS
WEEKEND. ANY NIGHT THROUGH MORNING LOW CLOUDS AND FOG WILL MAINLY
REMAIN CONFINED TO THE COASTAL AREAS THROUGH THE PERIOD.

&&

.SHORT TERM (TONIGHT-SAT)...
STRONG UPPER LEVEL HIGH PRESSURE SYSTEM CENTERED OVER THE DESERT
SOUTHWEST COMBINED WITH OFFSHORE PRESSURE GRADIENTS TO THE NORTH
PROVIDED SIGNIFICANT WARMING ACROSS MUCH OF THE REGION TODAY. SOME
OF THE HOT SPOTS TODAY INCLUDED ACTON AT 108 DEGREES...PALMDALE AT
107 DEGREES...LANCASTER AND SAUGUS AT 106 DEGREES...AS WELL AS
CHATSWORTH AND WOODLAND HILLS AT 105 DEGREES. IN EVENING
UPDATE...HAVE BUMPED UP WIND SPEEDS SLIGHTLY FOR SBA SOUTH COAST
THIS EVENING WHERE LOCALIZED GUSTS UP TO 35 MPH WILL CONTINUE THIS
EVENING. SBA-SMX GRADIENT HAS CLIMBED UP TO -4.2 MB BUT UPPER LEVEL
WIND SUPPORT IS RATHER MINIMAL. THE NORTHWEST FLOW AROUND POINT
CONCEPTION COMBINED WITH ONSHORE TRENDS WILL HELP TO SPIN UP AN EDDY
CIRCULATION OVERNIGHT INTO FRIDAY MORNING. SATELLITE IMAGERY NOT
SHOWING MUCH IN THE WAY OF LOW CLOUDS FORMING OFF THE SOUTHERN
COASTAL WATERS THIS EVENING...BUT SHOULD BEGIN TO FORM LATER
TONIGHT. AT THIS POINT...THINKING THAT LOW CLOUDS AND FOG WILL
MOSTLY AFFECT COASTAL AREAS OF ORANGE AND SAN DIEGO COUNTIES AS WELL
AS THE ADJACENT COASTAL WATERS...HOWEVER THERE IS A SLIGHT CHANCE
THAT IT COULD SURGE NORTHWARD INTO THE LA COUNTY COASTAL AREAS BY
MORNING. WITH ACARS DATA SHOWING A LOW AND STRONG MARINE INVERSION
(CURRENTLY AROUND 600 FEET DEEP)...THERE WILL BE THE POTENTIAL FOR
DENSE FOG FORMATION ANYWHERE CLOUDS DO FORM. HIGHER PROBABILITY OF
LOW CLOUDS AND DENSE FOG FORMING ACROSS THE CENTRAL COAST TONIGHT.

INFRARED SATELLITE IMAGERY SHOWING A FAIRLY GOOD SURGE OF MID LEVEL
MONSOONAL MOISTURE MOVING INTO NORTHERN BAJA AND SAN DIEGO COUNTY
THIS EVENING. LATEST 00Z NAM MODEL SEEMS TO HAVE PRETTY GOOD HANDLE
ON THIS MID LEVEL MOISTURE AND ADVECTS IT NORTHWARD TOWARDS LOS
ANGELES COUNTY ON FRIDAY. IN EVENING UPDATE...HAVE INCLUDED PARTLY
CLOUDY CONDITIONS FOR LA COUNTY ON FRIDAY DUE TO THIS INFLUX OF MID
LEVEL MOISTURE. WHILE MODEL SOUNDINGS DO SHOW A GOOD INVERTED-V
STRUCTURE OVER THE LA COUNTY MOUNTAINS (GOOD MID LEVEL MOISTURE
COMBINED WITH VERY DRY LOW LEVELS)...THERE IS NOT MUCH IN THE WAY OF
INSTABILITY. FOR NOW...HAVE INCLUDED SOME LOW GRADE POPS (IN 5-10
PERCENT RANGE OVER LA COUNTY MOUNTAINS)...BUT PROBABLY WILL JUST SEE
SOME CLOUDS AND PERHAPS A FEW SPRINKLES.

THE COMBINATION OF THE WEAK EDDY CIRCULATION...STRENGTHENING ONSHORE
FLOW...AND SOME MID LEVEL CLOUDS WILL BRING SOME COOLING TO MUCH OF
THE REGION TOMORROW...ESPECIALLY COASTAL AND VALLEY AREAS. WITH THAT
BEING SAID...STILL VERY WARM CONDITIONS WITH WARMEST VALLEYS LIKELY
CLIMBING TO BETWEEN 95 AND 100 DEGREES ON FRIDAY. THE LOWER MOUNTAINS
AND ANTELOPE VALLEY WILL LIKELY SEE TRIPLE DIGIT READINGS AGAIN ON
FRIDAY...HOWEVER EVEN THESE AREAS WILL BE DOWN A FEW DEGREES FROM
TODAY`S READINGS.

PLEASE REFER TO FIRE WEATHER DISCUSSION BELOW FOR ELEVATED FIRE
DANGER CONCERNS ACROSS INTERIOR SECTIONS TOMORROW.

*** FROM PREVIOUS DISCUSSION ***
ON FRIDAY NIGHT AND SATURDAY MORNING THE NAM INCREASES THE MARINE
LAYER MOISTURE ENOUGH TO JUSTIFY SOME LOW CLOUDS AND FOG INTO LONG
BEACH SATURDAY MORNING. MODEL RELATIVE HUMIDITY CROSS SECTIONS SHOW
QUITE A BIT OF MID AND UPPER LEVEL MOISTURE STREAMING NORTHWARD IN
THE SOUTH TO SOUTHWEST FLOW ON SATURDAY FOR SOME MAINLY HIGH LEVEL
CLOUDS. TEMPERATURES AGAIN ARE EXPECTED TO BE FAIRLY PERSISTENT FROM
FRIDAY`S HIGHS...MAYBE A DEGREE OR SO COOLER DEPENDING ON HIGH CLOUD
COVER.

STILL ENOUGH OF A THREAT...ALTHOUGH MINIMAL...TO LEAVE THE GOING TRW
CHANCES ON SUNDAY UNCHANGED. INSTABILITY IS NOT THAT GREAT...BUT
MODELS CONTINUE TO SHOW ENOUGH INCREASE IN MOISTURE AND HINTS AT A
KICKER ROTATING NORTHWARD AROUND THE HIGH TO CONTINUE WITH THE GOING
SLIGHT CHANCE POPS THERE SUNDAY AFTERNOON. NOT AT ALL A SLAMDUNK AT
THIS POINT...HOWEVER. AFTERNOON TEMPERATURES ONCE AGAIN EXPECTED TO
BE MUCH THE SAME AS FRIDAY AND SATURDAY.

.LONG TERM (MON-THU)...
NOT MUCH CHANGE AT ALL FOR NEXT WEEK. THE UPPER LEVEL HIGH REMAINS
GENERALLY OVER THE SOUTHWEST UNITED STATES THROUGH THE PERIOD. NOT
THAT IMPRESSED WITH MODEL FORECASTS OF THE MARINE LAYER NEXT WEEK
BUT KEPT THE FORECAST UNCHANGED. MODELS KEEPING MOST OF THE MONSOON
MOISTURE FAR ENOUGH TO OUR EAST TO INHIBIT ANY THUNDERSTORM CHANCES.
DO NOT EXPECT MUCH DAY TO DAY CHANGE IN MAX TEMPERATURES THROUGH THE
PERIOD...GENERALLY REMAINING AROUND NORMAL TO JUST BELOW COASTAL
AREAS...AND ABOVE NORMAL FURTHER INLAND.

&&

.AVIATION...25/0520Z...
CLEAR SKIES ACROSS THE REGION ATTM WITH JUST SOME HIGH CLOUDS MOVING
INTO SRN SXNS. EXEPCT IFR CONDS TO DEVELOP ON THE CENTRAL
COAST...BUT EXPECT MAINLY VFR CONDS ELSEWHERE...WITH JUST A CHANGE
OF IFR CONDS ACROSS CSTL SECTIONS OF L.A. AND VTU COUNTIES.

KLAX...LOW TO MODERATE CONFIDENCE IN TAF. THERE IS A 30 TO 40 PERCENT
CHANCE IF IFR CONDS BETWEEN 09Z AND 15Z.

KBUR...HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE FORECAST PERIOD.

&&

.MARINE...24/830 PM.

FOR THE OUTER WATERS...HIGH CONFIDENCE IN SMALL CRAFT CONDITIONS
INTO EARLY FRIDAY MORNING...WITH ISOLATED GUSTS TO 35 KNOTS AROUND
POINT CONCEPTION. FOR THE INNER WATERS...SMALL CRAFT CONDITIONS
THROUGH EARLY FRIDAY MORNING FOR THE WESTERN PORTION OF THE SANTA
BARBARA CHANNEL. WEST TO NORTHWEST FLOW WILL WEAKEN ON FRIDAY.

PATCHY DENSE FOG WITH VISIBILITY 1 NM OR LESS MAY IMPACT PORTIONS OF
THE COASTAL WATERS FROM LATE TONIGHT THROUGH FRIDAY MORNING.

NO SIGNIFICANT MARINE ISSUES ARE EXPECTED THIS WEEKEND.

&&

.FIRE WEATHER...24/830 PM.
ELEVATED FIRE DANGER ACROSS INTERIOR SECTIONS OF FORECAST AREA ON
FRIDAY AFTERNOON AND EVENING DUE TO COMBINATION OF GUSTY ONSHORE
WINDS...VERY WARM TEMPERATURES...AND LOW HUMIDITIES. ONSHORE WINDS
GUSTING BETWEEN 25 AND 35 MPH WILL BE COMMON ACROSS THE INTERIOR
VALLEYS...MOUNTAINS...AND DESERTS...WITH LOCAL GUSTS AS HIGH AS 45
MPH ACROSS THE FAVORED FOOTHILLS OF THE ANTELOPE VALLEY.
MEANWHILE...MANY OF THESE SAME AREAS WILL SEE HUMIDITIES FALLING
INTO THE TEENS DURING THE AFTERNOON HOURS...WITH ISOLATED SINGLE
DIGIT READINGS IN THE MOUNTAINS AND ANTELOPE VALLEY. WHILE BRIEF
CRITICAL FIRE WEATHER CONDITIONS WILL BE POSSIBLE IN THE MOUNTAINS
AND ANTELOPE VALLEY ON FRIDAY...THERE WILL NOT BE A SUFFICIENTLY
LONG DURATION TO WARRANT A RED FLAG WARNING.

&&


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

&&
$$

PUBLIC...GOMBERG/JACKSON
AVIATION...DB
MARINE...HALL
FIRE...GOMBERG
SYNOPSIS...HALL

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