348  
FXUS66 KLOX 141220  
AFDLOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA  
420 AM PST SAT DEC 14 2019  
   
SYNOPSIS
 
14/334 AM.  
 
LOW PRESSURE WILL BRING A CHANCE OF RAIN AND SNOW SHOWERS TO THE  
MOUNTAINS THROUGH EARLY SUNDAY, AREAS OF GUSTY WINDS, AND MUCH  
COOLER WEATHER TO THE REGION THIS WEEKEND. SOME WARMING IS  
EXPECTED MONDAY AND TUESDAY WITH DRY WEATHER AND SOME GUSTY SANTA  
ANA WINDS. A STORM SYSTEM MAY BRING SOME RAIN TO THE REGION  
WEDNESDAY INTO EARLY THU, FOLLOWED BY DRY AND COOL WEATHER FOR THE  
END OF THE WEEK.  
 

 
   
SHORT TERM (TDY-MON)
 
14/420 AM.  
 
WEAKENING FRONTAL SYSTEM WAS PUSHING ACROSS MONTEREY COUNTY  
EARLY THIS MORNING, BRINGING SOME SCATTERED SHOWER ACTIVITY  
WITH IT. THIS FRONT MAY HOLD TOGETHER ENOUGH TO BRING A FEW  
SHOWERS TO SLO COUNTY AND NORTHERN SBA COUNTY THIS MORNING.  
ELSEWHERE, A DEEP MARINE LAYER HAS DEVELOPED ACROSS L.A. AND VTU  
COUNTIES, WITH CLOUDS WIDESPREAD IN ALL COASTAL AND VALLEY AREAS  
EXCEPT FOR THE SANTA CLARITA VALLEY. CLOUDS MAY PUSH INTO THE  
SANTA CLARITA VALLEY AND INTO THE COASTAL SLOPES BY DAYBREAK.  
THERE COULD BE SOME DRIZZLE AS WELL, ESPECIALLY IN THE FOOTHILLS.  
GUSTY NORTHWEST TO NORTH WINDS CONTINUED ACROSS SOUTHERN SBA  
COUNTY, AND THAT HAS KEPT THE SOUTH COAST OF SBA COUNTY CLEAR SO  
FAR, BUT IF THE WINDS DROP OFF, CLOUDS SHOULD SNEAK NORTHWARD FROM  
VTU COUNTY AROUND OR SHORTLY AFTER DAYBREAK.  
 
KIND OF A COMPLICATED FORECAST FOR TODAY. NORTHWESTERLY TO NORTH  
FLOW WILL INCREASE ACROSS THE REGION LATER TODAY BEHIND THE  
WEAKENING FRONTAL SYSTEM. EXPECT ADVISORY LEVEL NW WINDS ON THE  
CENTRAL COAST THIS AFTERNOON, AND W TO NW WINDS ACROSS THE  
ANTELOPE VALLEY LATE THIS MORNING THROUGH TONIGHT. NW WINDS WILL  
LIKELY ALSO REACH ADVISORY LEVELS THRU AND BELOW PASSES AND  
CANYONS OF THE SANTA YNEZ RANGE AND THE ADJACENT SOUTH COAST OF  
SBA COUNTY, LATE THIS AFTERNOON OR EVENING THROUGH LATE TONIGHT,  
AND THROUGH THE INTERSTATE 5 CORRIDOR AND THE SANTA CLARITA  
VALLEY THIS EVENING THROUGH SUN MORNING. WIND ADVISORIES HAVE BEEN  
ISSUED FOR THESE AREAS. ADVISORIES MAY HAVE TO BE EXPANDED TO  
INCLUDE THE SAN FERNANDO VALLEY, THE SANTA MONICA MOUNTAINS, AND  
THE L.A. COUNTY COAST BELOW PASSES AND CANYONS FROM MALIBU TO THE  
HOLLYWOOD HILLS, BUT AT THIS TIME, IT APPEARS THAT WINDS WILL  
REMAIN JUST BELOW ADVISORY LEVELS IN THOSE AREAS.  
 
SKIES SHOULD BECOME PARTLY CLOUDY THIS AFTERNOON, EXCEPT REMAIN  
MOSTLY CLOUDY IN THE MOUNTAINS, AND POSSIBLY ACROSS MUCH OF L.A.  
COUNTY. MOIST CYCLONIC WESTERLY FLOW COULD BRING A FEW SHOWERS TO  
THE EASTERN SAN GABRIEL MOUNTAINS AND POSSIBLY EVEN THE SAN  
GABRIEL VALLEY THIS AFTERNOON AND EVENING. TODAY WILL BE  
SIGNIFICANTLY COOLER THAN IT WAS ON FRI IN ALL AREAS, WITH TEMPS  
DOWN TO BELOW NORMAL LEVELS IN MOST AREAS.  
 
MOIST NORTHERLY FLOW WILL BRING A CHANCE OF SHOWERS TO  
INTERIOR SECTIONS OF SERN SLO AND NERN SBA COUNTY, AND TO THE  
NORTHERN MOUNTAINS OF VTU COUNTY AND NWRN L.A. COUNTY THIS  
AFTERNOON INTO TONIGHT, LINGERING ACROSS THE NORTHERN SLOPES OF  
VTU COUNTY THROUGH SUNDAY MORNING.  
 
WHILE PRECIPITATION TOTALS IN THE MOUNTAINS ARE NOT EXPECTED TO  
BE EXCESSIVE, SNOW COULD CAUSE SOME TRAVEL PROBLEMS ON PORTIONS OF  
INTERSTATE 5 LATE TONIGHT/SUN MORNING. A WINTER WEATHER ADVISORY  
MAY HAVE TO BE CONSIDERED FOR THE MOUNTAINS DUE TO POTENTIAL  
IMPACTS FOR INTERSTATE 5.  
 
SKIES WILL BECOME MOSTLY SUNNY ACROSS THE REGION ON SUNDAY, BUT IT  
SHOULD ACTUALLY EVEN BE A FEW DEGREES COOLER THAN TODAY IN MOST  
AREAS. EXPECT NW-N TO REMAIN MOSTLY BELOW ADVISORY LEVELS SUNDAY  
EVENING. HOWEVER, WINDS WILL SHIFT TO A MORE NORTHEASTERLY  
DIRECTIONS LATE SUN NIGHT AND MONDAY MORNING. OFFSHORE GRADIENTS  
AND UPPER SUPPORT LOOK TO BE SUFFICIENT FOR AT LEAST LOW END WIND  
ADVISORY LEVEL NORTHEAST WINDS ACROSS THE MTNS AND VALLEYS OF L.A.  
AND VTU COUNTIES, AND THE VTU COUNTY COASTAL PLAIN MONDAY  
MORNING. MONDAY SHOULD BE SEVERAL DEGREES WARMER, ESPECIALLY WEST  
OF THE MOUNTAINS, BUT IT WILL NOT BE A PARTICULARLY WARM SANTA ANA  
WIND EVENT, WITH WARMEST LOCATIONS LIKELY TOPPING OUT IN THE  
LOWER 70S ON MON.  
   
LONG TERM (TUE-FRI)
 
13/206 PM.  
 
ONE MORE DAY OF SANTA ANAS/OFFSHORE FLOW TUESDAY. THE EC HAS BEEN  
CONSISTENT SHOWING THE STRONGEST GRADIENTS TUESDAY MORNING BUT  
WOULD HAVE TO THINK THAT UPPER SUPPORT WOULD BE WEAKER WITH THE  
RIDGE RIGHT OVERHEAD. EC ENSEMBLES HAVE BEEN FAVORING TUESDAY AS  
THE STRONGEST DAY FOR SANTA ANA WINDS BUT WOULD NOT BE SURPRISED  
IF THAT'S REVERSED OR AT THE VERY LEAST SIMILAR. EITHER WAY  
PROBABLY A SECOND DAY OF LOW END ADVISORY LEVEL WINDS IN  
LA/VENTURA COUNTIES WITH SIMILAR OR SLIGHTLY WARMER TEMPS.  
 
FORECAST CONFIDENCE DROPS QUITE A BIT FOR MID WEEK AS MODELS HAVE  
NOT BEEN IN GOOD AGREEMENT ON THE PATTERN EVOLUTION AND TIMING OF  
THE NEXT TROUGH. GFS AND EC ARE IN BETTER AGREEMENT TODAY ON THE  
PATTERN BUT THE GFS IS FINDING A MUCH DEEPER SOURCE OF MOISTURE  
THAN THE EC IS. SO STILL A CHANCE OF RAIN WED INTO THU WITH BEST  
ODDS ACROSS SLO/SB COUNTIES. RAINFALL AMOUNTS PROBABLY UNDER A  
HALF INCH EITHER WAY, AND POSSIBLY MUCH LESS.  
 
GOOD CONFIDENCE IN DRY AND SLIGHTLY WARMER WEATHER THE LAST PART  
OF THURSDAY AND FRIDAY WITH AN UPPER RIDGE RETURNING.  
 

 
   
AVIATION
 
13/2313Z.  
 
AT 2245Z, THE MARINE INVERSION AT KLAX WAS BASED AT 1400 FEET.  
THE TOP OF THE INVERSION WAS 3600 FEET WITH A TEMPERATURE OF  
18 DEGREES CELSIUS.  
 
OVERALL, MODERATE CONFIDENCE IN 00Z TAF PACKAGE. HIGH CONFIDENCE  
IN CIG/VSBY RESTRICTIONS AT ALL COASTAL/VALLEY SITES, BUT LOW  
CONFIDENCE IN FLIGHT CATEGORIES AND TIMING OF FLIGHT CATEGORY  
CHANGES. MOST SITES WILL HAVE CIGS START OUT AT IFR/LIFR LEVELS,  
BUT WILL INCREASE TO MVFR LEVELS OVERNIGHT AND INTO SATURDAY  
MORNING.  
 
KLAX...OVERALL, MODERATE CONFIDENCE IN 00Z TAF. TIMING OF CHANGE  
FROM IFR TO MVFR CONDITIONS COULD BE +/- 3 HOURS OF CURRENT 09Z  
FORECAST. TIMING OF DISSIPATION OF MVFR CIGS COULD BE +/- 2 HOURS  
OF CURRENT 22Z FORECAST. NO SIGNIFICANT EASTERLY WIND COMPONENT  
IS EXPECTED.  
 
KBUR...OVERALL, MODERATE CONFIDENCE IN 00Z TAF. TIMING OF ARRIVAL  
OF MVFR CIGS COULD BE +/- 3 HOURS OF CURRENT 10Z FORECAST WITH A  
30% CHANCE OF CIGS STARTING AT IFR LEVELS. TIMING OF DISSIPATION  
OF MVFR CIGS COULD BE +/- 2 HOURS OF CURRENT 22Z FORECAST.  
 

 
   
MARINE
 
14/303 AM.  
 
FOR THE OUTER WATERS, MODERATE TO HIGH CONFIDENCE IN CURRENT  
FORECAST. SMALL CRAFT ADVISORY (SCA) LEVEL WINDS AND/OR SEAS WILL  
CONTINUE THROUGH AT LEAST LATE SUN NIGHT. THE GALE WARNING IS IN  
EFFECT FOR THIS AFTERNOON AND TONIGHT NIGHT FOR PZZ676 AND NOW  
PZZ673. MAINLY NEAR POINT CONCEPTION AND AREAS SOUTH. WITH THE  
GUSTY WINDS, SHORT-PERIOD, CHOPPY SEAS WILL BE LIKELY. HIGH SEAS  
OVER 10 FEET WILL CONTINUE THROUGH LATE SUN NIGHT, THEREFORE A  
SMALL CRAFT ADVISORY IS NOT ONLY IN EFFECT FOR WINDS, BUT FOR  
HAZARDOUS SEAS. ON TUESDAY AND WEDNESDAY, THERE IS A 50% CHANCE  
OF SCA LEVEL EAST TO SOUTHEAST WINDS.  
 
FOR THE INNER WATERS NORTH OF POINT SAL, MODERATE TO HIGH  
CONFIDENCE IN CURRENT FORECAST. SCA LEVEL WINDS ARE EXPECTED  
TODAY AND TONIGHT WITH SHORT-PERIOD, CHOPPY SEAS. ADDITIONALLY,  
SCA LEVEL SEAS WILL CONTINUE THROUGH TONIGHT. ON TUESDAY, THERE  
IS A 50% CHANCE OF SCA LEVEL SOUTHEAST WINDS.  
 
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION, MODERATE TO HIGH  
CONFIDENCE IN CURRENT FORECAST. FOR THIS MORNING, SCA LEVEL WEST  
TO NORTHWEST WINDS ARE EXPECTED. A GALE WARNING BECOMES VALID THIS  
AFTERNOON THROUGH TONIGHT (WITH THE STRONGEST WINDS ACROSS  
WESTERN SECTIONS). FROM SUNDAY NIGHT THROUGH WEDNESDAY, THE WINDS  
WILL SHIFT TO THE NORTHEAST WITH SCA LEVEL WINDS LIKELY SUNDAY  
NIGHT THROUGH TUESDAY.  
 
A LARGE AND LONG PERIOD WEST TO NORTHWEST SWELL WILL IMPACT THE  
COASTAL WATERS THROUGH AT LEAST LATE SUNDAY NIGHT, RESULTING IN  
HAZARDOUS SEA CONDITIONS AND LARGE BREAKING WAVES NEAR SHORE,  
ESPECIALLY WITH A LARGE SHORT PERIOD WIND SWELL ON TOP OF THAT.  
BREAKING WAVES AT THE MORRO BAY AND VENTURA HARBOR ENTRANCES WILL  
BE POSSIBLE.  
 

 
   
BEACHES
 
13/806 PM.  
 
A LARGE LONG-PERIOD WEST TO NORTHWEST SWELL WILL CONTINUE ACROSS  
THE COASTAL WATERS OF SOUTHWEST CALIFORNIA, PEAKING THROUGH  
SATURDAY MORNING, THEN SLOWLY DIMINISH OVER THE REMAINDER OF THE  
WEEKEND.  
 
SURF WILL LIKELY PEAK BETWEEN 12 AND 16 FEET FOR THE CENTRAL  
COAST. A HIGH SURF ADVISORY IS IN EFFECT FOR THE CENTRAL COAST  
THROUGH MONDAY MORNING.  
 
A HIGH SURF ADVISORY IS ALSO IN EFFECT THROUGH NOON SUNDAY FOR  
THE BEACHES SOUTH OF POINT CONCEPTION WITH SURF BETWEEN 6 AND 10  
FEET POSSIBLE. HIGHEST SURF WILL OCCUR ACROSS EXPOSED WEST FACING  
BEACHES. STRONG RIP CURRENTS AND DANGEROUS BREAKING WAVES ARE  
EXPECTED.  
 
WITH HIGH TIDES AROUND 6.5 FEET SATURDAY, MINOR COASTAL FLOODING  
IS POSSIBLE DURING THE LATE MORNING HIGH TIDE. ANY COASTAL  
FLOODING IMPACTS SHOULD BE CONFINED TO THE BEACHES, WITH FLOODING  
POSSIBLE IN THE MOST VULNERABLE PARKING LOTS, BIKE PATHS, AND  
WALKWAYS.  
 

 
   
LOX WATCHES/WARNINGS/ADVISORIES
 
 
CA...HIGH SURF ADVISORY IN EFFECT UNTIL NOON PST MONDAY FOR ZONES  
34-35. (SEE LAXCFWLOX).  
WIND ADVISORY IN EFFECT FROM NOON TODAY TO 7 PM PST THIS  
EVENING FOR ZONES 34-35. (SEE LAXNPWLOX).  
HIGH SURF ADVISORY IN EFFECT UNTIL 4 AM PST SUNDAY FOR ZONE  
39. (SEE LAXCFWLOX).  
WIND ADVISORY IN EFFECT UNTIL 3 AM PST SUNDAY FOR ZONES  
39-52. (SEE LAXNPWLOX).  
HIGH SURF ADVISORY IN EFFECT UNTIL NOON PST SUNDAY FOR ZONES  
40-41-87. (SEE LAXCFWLOX).  
WIND ADVISORY IN EFFECT FROM 4 PM THIS AFTERNOON TO NOON PST  
SUNDAY FOR ZONES 53-54. (SEE LAXNPWLOX).  
WIND ADVISORY IN EFFECT FROM 10 AM THIS MORNING TO 3 AM PST  
SUNDAY FOR ZONE 59. (SEE LAXNPWLOX).  
WIND ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO NOON PST  
SUNDAY FOR ZONE 88. (SEE LAXNPWLOX).  
PZ...SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 AM PST SUNDAY FOR ZONE  
645. (SEE LAXMWWLOX).  
SMALL CRAFT ADVISORY IN EFFECT UNTIL NOON PST TODAY FOR ZONES  
650-655-673-676. (SEE LAXMWWLOX).  
GALE WARNING IN EFFECT FROM NOON TODAY TO 3 AM PST SUNDAY FOR  
ZONES 650-655-673-676. (SEE LAXMWWLOX).  
SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 AM PST MONDAY FOR ZONE  
670. (SEE LAXMWWLOX).  
 

 
 
.HAZARD POTENTIAL OUTLOOK (MON-FRI).  
 
GUSTY NORTHEAST WINDS POSSIBLE ACROSS PARTS OF LA/VENTURA  
COUNTIES MONDAY AND TUESDAY.  
 

 
 

 
 
PUBLIC...DB/MW  
AVIATION...RAT  
MARINE...KAPLAN  
BEACHES...SIRARD  
SYNOPSIS...DB  
 
WEATHER.GOV/LOSANGELES  
 
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