Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 301632 CCA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
930 AM PDT THU OCT 30 2014

.SYNOPSIS...

IT WILL BE PARTLY TO MOSTLY CLOUDY TODAY WITH TEMPERATURES NEAR
NORMAL. SKIES WILL TURN CLOUDY TONIGHT. THERE COULD BE MORNING
DRIZZLE ACROSS THE COASTS AND VALLEYS FRIDAY MORNING. RAIN WILL
OVERSPREAD THE AREA STARTING FRIDAY AFTERNOON OVER THE CENTRAL COAST
AND MOVING INTO AREAS SOUTH OF POINT CONCEPTION LATER IN THE
EVENING. TEMPERATURES WILL FALL BELOW NORMAL ON FRIDAY AND
SATURDAY.

&&

.SHORT TERM (TODAY-SAT)...

FORECAST FOR TODAY IS IN GOOD SHAPE. A WEAK UPPER LOW TO THE SW IS
SPREADING SOME MID AND HIGH CLOUDS ACROSS THE REGION AHEAD OF THE
TROUGH OF LOW PRESSURE TO THE NW. SKIES TODAY WILL BE PARTLY CLOUDY
AND AT TIMES MOSTLY CLOUDY. WITH THE TROUGH OF LOW PRESSURE
APPROACHING AND THE RETURN OF ONSHORE FLOW...HIGHS TODAY WILL BE A
GOOD 5-10 DEGREES COOLER THAN YESTERDAY FOR MUCH OF THE AREA...AND
10-15 DEGREES COOLER ON THE CENTRAL COAST.

THE MAIN FOCUS FOR TODAY WILL CONTINUE TO BE FINE TUNING THE RAIN
FORECAST FOR FRIDAY AFTERNOON THROUGH SATURDAY WITH THE APPROACHING
TROUGH. MODELS CONTINUE TO TREND WETTER...WITH THE SYSTEM COMING A
LITTLE FURTHER SOUTH. HIGH CONFIDENCE THAT EVERYONE IN OUR AREA WILL
GET SOME RAIN WITH THIS SYSTEM...EXCEPT MAYBE THE ANTELOPE VALLEY.
WILL PROBABLY BE INCREASING THE RAINFALL AMOUNTS WITH THE AFTERNOON
UPDATE BASED UPON THE 12Z MODELS RUNS.

***FROM PREVIOUS DISCUSSION***

A LARGE TROF WILL APPROACH THE AREA TONIGHT. THE LIFT ASSOC WITH
THIS TROF SHOULD FINALLY PRODUCE LOW CLOUDS. IT WILL IN FACT PRODUCE
ENOUGH LOW CLOUDS TO COVER THE COASTS AND VLYS AND EVEN THE COASTAL
SLOPES. TOWARDS DAWN THE LOWER ATMOS WILL BE MOIST ENOUGH THAT THE
LIFT WITH THE TROF WILL PRODUCE SOME DRIZZLE. NEAR THE FOOTHILLS
WHERE THE OROGRAPHICS WILL GIVE THE LIFT JUST A LITTLE MORE OOMPH
THERE COULD EVEN BE A COUPLE HUNDREDTHS OF PRECIPITATION.

SPEAKING OF PRECIPITATION THE FIRST RAIN FALL OF THE RAIN SEASON IS
STILL ON TRACK FOR FRIDAY AND SATURDAY. THE SFC FRONT ASSOC WITH THE
BIG EAST PAC TROF WILL MOVE CLOSE THE CENTRAL COAST FRIDAY MORNING.
IT WILL BRING A SLIGHT CHC OF RAIN TO WESTERN SLO COUNTY BUT REALLY
IT LOOKS LIKE THE RAIN WILL HOLD OFF UNTIL THE AFTERNOON. RAIN WILL
OVERSPREAD THE CENTRAL COAST FRIDAY AFTERNOON AND IT LOOKS LIKE
HALLOWEEN IS GOING TO BE WASH OUT FOR TRICK OR TREATERS IN SLO AND
WESTERN SBA COUNTIES.

ALL THE REAL ACTION HAPPENS FRIDAY NIGHT AND EARLY SATURDAY MORNING
AS THE ONE TWO PUNCH OF THE SFC FRONT AND THE POST FRONTAL TROF MOVE
ACROSS THE AREA. RAIN IS LIKELY EVERYWHERE EXCEPT THE ANTELOPE VLY
WHERE THERE IS ONLY A CHC OF RAIN. THERE IS A VERY NICE VORT MAX
ALONG WITH A COLD POOL OF AIR ALOFT BEHIND THE FRONT AND THESE TWO
THINGS WILL COMBINE TO BRING A SLIGHT CHC OF TSTMS TO SLO AND SBA
COUNTIES. THE REST OF THE AREA WILL BE COVERED IN SHOWERS AND SOME
MAY BE HEAVY.

THE VORT MAX EXITS THE AREA SATURDAY MORNING AND SHOWER ACTIVITY
WILL DIMINISH FROM THE NW TO THE SE THROUGH THE DAY. BY AFTERNOON
THE BEST CHC OF RAIN WILL BE ACROSS THE SAN GABRIEL FOOTHILLS WHERE
THERE IS ALWAYS A LITTLE POST FRONTAL CONVERGENCE AND UPSLOPE AS
WELL AS THE NORTH SLOPES OF THE VTA AND LA MTNS DUE TO UPSLOPE
CREATED BY NORTHERLY POST FRONTAL WINDS. ONE LAST SHOT OF VORTICITY
WILL ALSO CREATE A SLIGHT CHC OF SHOWER ACTIVITY ACROSS THE CENTRAL
COAST.

SHOWERS WILL LINGER INTO THE EVENING ACROSS THE NORTH SLOPES AND THE
SAN GABRIEL COASTAL SLOPES BUT THEY WILL DIMINISH TO ZERO OVERNIGHT.

SNOW LEVELS WILL START OUT OVER 7000 FEET BUT WILL FALL TO AROUND
6000 FEET BY SATURDAY. SNOWFALL IS REALLY NOT AN ISSUE BUT THERE
WILL BE SOME LIGHT ACCUMULATIONS AT ELEVATIONS OVER 6000 FEET ACROSS
THE NORTH SLOPES AND THE EASTERN SAN GABRIELS.

RAINFALL AMOUNTS KEEP IN RAMPING UP WITH EACH MDL RUN. NOW IT LOOKS
LIKE THE CENTRAL COAST WILL SEE .75 INCHES TO AROUND AN INCH. THE
REST OF THE NON-DESERT AREAS SHOULD RECEIVE ABOUT A QUARTER TO A
HALF INCH OF RAIN...EXCEPT FOR THE FOOTHILL AREAS OF THE SAN
GABRIELS COULD SEE UP TO AN INCH OF RAIN.

MAX TEMPS WILL FALL EACH DAY. FRIDAY WILL SEE MAX TEMPS 3 TO 6
DEGREE BLO NORMAL. SATURDAYS HIGHS WILL BE 6 TO 12 DEGREES BLO
NORMAL WITH NO READINGS IN THE 70S ANYWHERE.

THERE WILL BE SOME WINDS SATURDAY BEHIND THE FRONT AND MTNS AND THE
ANTELOPE VLY MAY NEED A LOW END WIND ADVISORY.

.LONG TERM (SUN-WED)...
AND THEN ITS GONE. ALL MDLS FORECAST THAT A RIDGE WILL BEGIN TO
BUILD INTO THE AREA STARTING SUNDAY AND THEN BUILDING EACH DAY
THROUGH WEDNESDAY. HIGH PRESSURE IN THE INTERIOR WILL PRODUCE ENOUGH
OFFSHORE FLOW TO KEEP THE LOW CLOUDS AWAY. THERE MAY BE ENOUGH MID
LEVEL LEFT OVER CLOUDS SUNDAY TO CREATE PARTLY CLOUDY SKIES BUT
MONDAY THROUGH WEDNESDAY WILL BE MOSTLY CLEAR.

MAX TEMPS WILL RISE EACH DAY. MAX TEMPS SUNDAY WILL STILL BE BLO
NORMAL BUT WILL RISE TO ABOVE NORMAL MONDAY AND BY WEDNESDAY MAX
TEMPS WILL BE 4 TO 8 DEGREES ABOVE NORMAL.

&&

.AVIATION...

30/1215Z

THE MARINE LAYER AT KLAX AT 1200Z WAS NEAR 1100 FT DEEP. THE
INVERSION TOP WAS NEAR 3200 FEET WITH A TEMPERATURE OF 21 DEGREES C.

OVERALL VFR BKN LEVELS JUST ABOUT EVERYWHERE...WITH LOWER CONFIDENCE
FOR LOW MVFR CIGS FOR LA COUNTY COAST. MODERATE CONFIDENCE AFTER 02Z
THIS EVE THAT MVFR CIGS WILL DEVELOP ACROSS MANY COASTAL
SITES...THEN SPREAD INTO VALLEYS AFTER MIDNIGHT. 30 PERCENT CHANCE
FOR IFR CONDS FOR FEW VALLEY TAF SITES.

KLAX...LOW CONFIDENCE IN TAF. THERE IS A 30 PERCENT CHANCE OF MVFR
CIGS 12Z-17Z.

KBUR...GOOD CONFIDENCE IN TAF. THERE IS A 10 PERCENT CHANCE OF MVFR
CONDITIONS BETWEEN 12Z AND 16Z. BETTER CHANCE FOR MVFR CIGS AFTER
10Z-11Z FRI MORNING.

&&

.MARINE...

30/900 AM

NO SIGNIFICANT MARINE ISSUES ARE EXPECTED THROUGH FRIDAY
MORNING...EXCEPT FOR A 30 PERCENT CHANCE OF PATCHY DENSE FOG WITH
VISIBILITY ONE NAUTICAL MILE OR LESS. EXPECT PERIODS OF SMALL CRAFT
ADVISORY LEVELS WHEN WINDS SHIFT TO THE WEST TO NORTHWEST BEHIND THE
FRONT EARLY SATURDAY...ALTHOUGH THE LATEST RUNS OF THE MODELS ARE
SHOWING A STRONGER SYSTEM...SO A GALE WARNING IS NOT OUT OF THE
QUESTION...ABOUT A 30 PERCENT CHANCE RIGHT NOW. THERE WILL ALSO BE
AN INCREASING NORTHWEST SWELL BETWEEN 10 AND 12 FEET SATURDAY AND
SUNDAY WHICH WILL QUICKLY DIMINISH EARLY NEXT WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&

$$

PUBLIC...SUKUP/RORKE
AVIATION/MARINE...KAPLAN
SYNOPSIS...B

WWW.WEATHER.GOV/LOSANGELES





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