Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 250516 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1015 PM PDT THU APR 24 2014

UPDATED AVIATION SECTION

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL BRING BREEZY WINDS...POSSIBLE
PRECIPITATION AND A DROP IN TEMPERATURES TO BELOW NORMAL FROM FRIDAY
TO SATURDAY. A HIGH PRESSURE SYSTEM WILL TAKE HOLD OF THE REGION
NEXT WEEK AND WITH OFFSHORE WINDS WILL BRING A SIGNIFICANT WARM UP.
TEMPERATURES WILL BE FAR ABOVE NORMAL WITH THE WARMEST DAYS ON
TUESDAY AND WEDNESDAY.

&&

.SHORT TERM (TONIGHT-SUN)...A WEAK MARINE INVERSION WAS AROUND 700
FT DEEP EARLY THIS EVENING AT LAX. WITH AN EDDY EXPECTED TO SPIN UP
OVERNIGHT ACROSS THE SOCAL BIGHT...THE MARINE LAYER SHOULD GRADUALLY
DEEPEN THRU THE NIGHT. PATCHY LOW CLOUDS WERE ALONG THE CENTRAL
COAST THIS EVENING AND SHOULD EXPAND SOME THERE TONIGHT. LOW CLOUDS
ARE FORECAST TO DEVELOP OVER THE SOCAL BIGHT AND MOVE TO THE
L.A./VTU COUNTY COASTAL AREAS LATER TONIGHT...WITH THE LOW CLOUDS
EXPANDING INTO THE ADJACENT VLYS BY DAYBREAK. THERE WILL ALSO BE AN
INCREASE IN MAINLY HI CLOUD COVER OVERNIGHT FOR PARTLY CLOUDY SKIES
ACROSS INLAND AREAS.

A BROAD UPPER LEVEL TROUGH OF LOW PRESSURE WILL BE MOVING INTO THE
EASTERN PAC ON FRI THEN DEEPEN FRI NIGHT BEFORE MOVING QUICKLY E ON
SAT. WEAK UPPER LEVEL RIDGING WILL THEN BUILD INTO THE E PAC FOR
SUN...WITH A BROAD NW FLOW ALOFT OVER SRN CA. THE UPPER TROF WILL
BRING A COLD FRONT INTO SLO/SBA COUNTIES FRI AFTERNOON WITH A CHANCE
OF SHOWERS INCREASING THRU THE DAY. THE FRONT WILL MOVE QUICKLY S
THRU VTU/L.A. COUNTIES FRI NIGHT ALONG WITH SCATTERED SHOWERS AND
MOUNTAIN SNOW SHOWERS. IT LOOKS LIKE THE SHOWERS WILL END EARLY SAT
FOR MOST AREAS...EXCEPT LINGERING ON THE N MOUNTAIN SLOPES INTO LATE
SAT MORNING. ANOTHER WEAKENING COLD FRONT WILL APPROACH SLO/SBA
COUNTIES WHILE DISSIPATING ON SUN...BUT DRY CONDITIONS SHOULD
PREVAIL IN ALL AREAS FROM SAT AFTERNOON THRU SUN. RAINFALL AMOUNTS
FROM THE WEATHER SYSTEM SHOULD RANGE FROM 0.15 INCH OR LESS FOR THE
COAST AND VLYS...TO A TENTH TO THIRD OF AN INCH FOR THE MTNS...ALTHO
LOCAL HIGHER AMOUNTS UP TO A HALF INCH WILL BE POSSIBLE MAINLY ON
THE WEST TO NORTH SLOPES. THE LATEST NAM ACTUALLY CRANKS OUT UP TO
AN INCH OF PRECIPITATION ON THE NORTH SLOPES. AT ANY RATE...SNOW
LEVELS SHOULD START OUT ABOUT 7500 FEET THRU EARLY FRI EVENING THEN
DROP TO 4500 TO 5000 FEET BY LATE FRI NIGHT INTO SAT MORNING. SOME
ACCUMULATING SNOW WILL BE POSSIBLE ABOVE 5000 FEET...POSSIBLY 1 TO 3
INCHES ESPECIALLY HIGHER ELEVATIONS. HOWEVER...IF THE NAM IS
CORRECT...THEN THE NORTH SLOPES OF VTU/L.A. COUNTIES COULD RECEIVE A
BIT MORE SNOWFALL THAN IS CURRENTLY FORECAST...AND IS SOMETHING
WORTH WATCHING ON THE NEXT COUPLE OF MODEL RUNS.

ANOTHER EFFECT OF THIS QUICK MOVING WEATHER SYSTEM IN AN INCREASE IN
THE WINDS ACROSS MUCH OF THE AREA. THE STRONGEST WINDS ARE EXPECTED
IN THE ANTELOPE VLY FRI AFTERNOON AND EVENING AND IN THE L.A./VTU
COUNTY MTNS LATER FRI NIGHT AND AGAIN SAT AFTERNOON AND SAT NIGHT
WHERE GUSTS UP TO 50 MPH WILL BE POSSIBLE. OTHER AREAS WITH WIND
GUSTS OF 35 TO 40 MPH AT TIMES LATE FRI THRU SAT EVENING INCLUDE
MANY COASTAL AREAS...AND THE SBA COUNTY MTNS. WIND ADVISORIES WILL
LIKELY BE NEEDED FOR MANY OF THESE LOCATIONS AS WE DRAW CLOSER TO
THE EVENT.

MOSTLY CLOUDY SKIES FRI INTO SAT MORNING WILL GIVE WAY TO PARTLY
CLOUDY SKIES SAT AFTERNOON AND SAT NIGHT...THEN MOSTLY CLEAR SKIES
FOR SUN. TEMPS WILL TURN COOLER FOR FRI BACK TO NEAR NORMAL TO
SLIGHTLY BELOW NORMAL...THEN COOL FURTHER FOR SAT TO SEVERAL DEGREES
BELOW NORMAL FOR MOST AREAS. TEMPS WILL REBOUND ON SUN TO NEAR
NORMAL OVERALL.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (MON-THU)...A SIGNIFICANT WARM UP IS STILL ON TRACK FOR
MOST OF NEXT WEEK. DOES NOT LOOK LIKE IT WILL BE AS WARM AS
PREVIOUSLY THOUGHT WITH 950 TEMPERATURES NOW STAYING UNDER 30 DEG C
AS WAS PREVIOUSLY FORECAST BY THE GFS...BUT DOES LOOK LIKE IT WILL
NOW LAST A LITTLE LONGER. HIGH TEMPERATURES WILL WARM EACH DAY
STARTING MONDAY AND TUESDAY...THEN LEVEL OFF SLIGHTLY ON WEDNESDAY
AND COOL JUST A BIT MORE ON THURSDAY. TOUGH TO TELL IF TUESDAY OR
WEDNESDAY WILL BE THE WARMEST DAY AT THIS POINT...BUT EXPECTING
HIGHS IN UPPER 80S AND LOW 90S COAST AND VALLEYS BY TUESDAY AND
WEDNESDAY...AND EVEN WITH A COUPLE OF DEGREES COOLING ON THURSDAY WE
SHOULD CONTINUE TO REPORT SOME LOW 90 DEGREE READINGS ON THURSDAY IN
THE VALLEYS.  THIS IS 15 TO 20 DEGREES ABOVE NORMAL FOR THIS TIME OF
YEAR. OFFSHORE WINDS WILL BE STRONGEST ON WEDNESDAY AND WEAKEN SOME
ON THURSDAY. THESE HEAT EVENTS TEND TO LAST A LITTLE LONGER THAN
MODELS FORECAST AND OFTENTIMES SOME OF THE WARMEST DAYS OF THE EVENT
ARE WHEN THE OFFSHORE WINDS WEAKEN ON THE TAIL END OF IT.

&&

.AVIATION...25/0515Z...EXPECT WIDESPREAD CIGS TO DEVELOP IN ALL
COASTAL AND VALLEY AREAS OVERNIGHT...WITH THE EXCEPTION OF THE S
COAST OF SBA COUNTY WHICH SHOULD REMAIN CLEAR. EXPECT CONDS TO BE
MOSTLY MVFR...EXCEPT LOCALLY IFR ON THE CENTRAL COAST. EXPECT LITTLE
CLEARING ON FRI...ALTHOUGH CIGS WILL LIKELY RISE INTO THE VFR
CATEGORY IN MOST AREAS. FRONTAL SYSTEM WILL APPROACH SLO AND SBA
COUNTIES LATE IN THE AFTERNOON OR EVENING...BRINGING SOME SHOWERS
POSSIBLY AS EARLY AS 22Z. GUSTY WINDS THRU AND BELOW PASSES AND
CANYONS OF SRN SBA COUNTY THROUGH LATE TONIGHT...WITH SOME LLWS
LIKELY.

KLAX...MODERATE CONFIDENCE IN THE 06Z TAF. THERE IS A 20 PERCENT
CHANCE THAT MVFR CIGS WILL NOT ARRIVE UNTIL 13Z. THERE IS A 20
PERCENT CHANCE THAT CONDS WILL REMAIN MVFR THROUGH THE AFTERNOON ON
FRI. THERE IS A 20 PERCENT CHANCE THAT E TO SE WINDS COULD REACH 10
KT BETWEEN 13Z AND 17Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20 TO
30 PERCENT CHANCE THAT CIGS WILL IMPROVE TO VFR LEVELS AS EARLY AS
21Z.

&&

.MARINE...25/900 PM PDT...GENERALLY HI CONFIDENCE OF GALE FORCE
WINDS DEVELOPING OVER THE MUCH OF THE COASTAL WATERS BY LATE FRI
AFTERNOON AND CONTINUING INTO LATE SAT NIGHT. THE STRONGEST WINDS
MAY AFFECT PARTS OF THE INNER WATERS AT TIMES. SEAS WILL BUILD TO 7
TO 11 FEET OVERALL DUE TO THE STRONG WINDS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
GALE WARNING (SEE LAXMWWLOX).
GALE WATCH (SEE LAXMWWLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&
$$

PUBLIC...SIRARD/JACKSON
AVIATION...DB
MARINE...SIRARD
SYNOPSIS...SETO

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