527  
FXUS66 KLOX 281155  
AFDLOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA  
455 AM PDT SUN MAY 28 2017  
   
..AVIATION DISCUSSION UPDATED
 
 
   
SYNOPSIS
 
 
AN UPPER LEVEL RIDGE OF HIGH PRESSURE AND A LOWERING MARINE LAYER  
WILL SUPPORT A WARMING TREND THROUGH EARLY NEXT WEEK. THE HIGH WILL  
BE REPLACED BY A WEAK UPPER LEVEL TROUGH OF LOW PRESSURE BY THE  
MIDDLE OF NEXT WEEK PROVIDING A COOLING TREND WITH MORE WIDESPREAD  
NIGHT AND MORNING LOW CLOUDS FOR THE COAST AND VALLEYS.  
 

 
   
SHORT TERM
 
(TDY-TUE)  
 
PLEASANT BUT RATHER DULL ON TAP FOR THE NEXT THREE DAYS. ALL MDLS  
AGREE THAT A 582 DM RIDGE WILL PERSIST OVER THE AREA TODAY AND  
MONDAY WITH A TROF MOVING INTO THE AREA MONDAY NIGHT AND LASTING  
INTO TUESDAY.  
 
MARINE LAYER STRATUS IS STRUGGLING TO DEVELOP DUE TO A WEAK  
INVERSION AND OFFSHORE TRENDS. THE ONLY EXCEPTION IS WESTERN SBA  
COUNTY WHERE WESTERLY FLOW HAS PRODUCED A BACKWARDS BUILDING  
STRATUS DECK. PATCHY STRATUS WILL DEVELOP TOWARDS DAWN OVER THE LA  
AND VTA COASTS AND THE SAN GABRIEL VLY AS CONTINUED RADIATIONAL  
COOLING INCREASES THE LOW LEVEL HUMIDITIES CLOSE TO 100%.  
 
WHATEVER THE MORNING STRATUS PATTERN SKIES EVERYWHERE WILL BE  
SUNNY BY MID TO LATE MORNING. THE INCREASING HGTS...OFFSHORE  
TRENDS AND ABUNDANT SUNSHINE WILL ALL CONTRIBUTE TO 3 TO 6 DEGREES  
OF WARMING ACROSS THE AREA AND MOST MAX TEMPS WILL END UP 2 TO 4  
DEGREES ABOVE NORMAL.  
 
NOT MUCH CHANGE IN THE WEATHER FOR MONDAY. THE STRATUS MAY BE A  
LITTLE BETTER DEVELOPED AS THE INVERSION WILL BE STRONGER. MAX  
TEMPS WILL BE UP 1 TO 2 DEGREES FROM TODAYS READINGS.  
 
TUESDAY WILL SEE THE ARRIVAL OF A WEAK TROF ALONG WITH AN INCREASE  
IN THE ONSHORE FLOW BOTH TO THE WEST AND NORTH. THIS WILL LIKELY  
SPIN UP AN EDDY. LOOK FOR SIGNIFICANT INCREASE IN MORNING LOW  
CLOUD COVERAGE ESP FOR THE VLYS. STILL THE ONSHORE FLOW AND THE  
INVERSION WILL NOT BE STRONG ENOUGH TO PREVENT TOTAL CLEARING MAX  
TEMPS WILL FALL WITH THE BIGGEST DROPS IN THE VLYS AND THE  
SMALLEST INLAND.  
   
LONG TERM
 
(WED-SAT)  
 
THE GFS AND EC AGREE THAT A FAIRLY SHARP (AT LEAST FOR THIS TIME  
OF YEAR) UPPER LEVEL TROUGH WILL MOVE ACROSS THE FORECAST AREA ON  
WEDNESDAY. THIS SYSTEM WILL CONTINUE TO DEEPEN THE MARINE LAYER  
WHICH WILL CONTINUE TO COOL THE COASTS AND VLYS. LOWERING HGTS  
WILL ALLOW SOME COOLING INLAND ALSO. THE PVA WITH THIS TROF MOVES  
ACROSS DURING MAX HEATING AND WHILE IT IS STILL ON THE DRY SIDE  
THERE IS A 20 PERCENT CHC OF A TSTM.  
 
A LITTLE RIDGE WILL BRING A DECREASE IN MARINE LAYER COVERAGE AS  
WELL AS A NOTICEABLE BUMP UP IN TEMPS ON THURSDAY.  
 
THE FORECAST IS A LITTLE MUDDLED FOR FRIDAY AND SATURDAY AS THE  
GFS CONTINUES THE RIDGE WHILE THE EC BRINGS IN A WEAK TROF. THE  
NIGHT THROUGH MORNING LOW CLOUD PATTERN SHOULD CONTINUE BUT TO  
WHAT DEGREE WILL BE DEPENDENT ON WHICH PATTERN ACTUALLY DEVELOPS.  
 

 
   
AVIATION
 
28/12Z.  
 
AT 09Z AT KLAX... THE INVERSION WAS BASED NEAR 500 FEET. THE TOP  
OF THE INVERSION WAS NEAR 4900 FEET WITH A TEMPERATURE OF ABOUT  
17 DEGREES CELSIUS.  
 
OVERALL... MODERATE CONFIDENCE IN THE CURRENT TAFS. LIFR/IFR  
CONDITIONS WILL DEVELOP AT SOME COASTAL LOCATIONS BY 14Z THEN  
WILL CLEAR BY 18Z. THERE IS A FIFTEEN PERCENT CHANCE OF LIFR/IFR  
CONDITIONS AT KBUR AND KVNY IN THE 13Z-17Z PERIOD AND A TEN PERCENT  
CHANCE AT KPRB AND KSBA IN THE 14Z-17Z PERIOD. LIFR/IFR CONDITIONS  
WILL LIKELY DEVELOP AT MOST COASTAL AND ADJACENT VALLEY LOCATIONS  
AFTER 29/04Z. OTHERWISE AND ELSEWHERE VFR CONDITIONS WILL  
PREVAIL.  
 
KLAX... MODERATE CONFIDENCE IN THE CURRENT TAF. THERE IS A THIRTY  
PERCENT CHANCE OF LIFR/IFR CONDITIONS IN THE 13Z-17Z PERIOD THEN A  
SEVENTY PERCENT CHANCE IN THE 29/05Z-17Z PERIOD. OTHERWISE VFR  
CONDITIONS WILL PREVAIL. NO EAST WINDS ABOVE 7 KNOTS ARE EXPECTED.  
 
KBUR... MODERATE CONFIDENCE THE CURRENT TAF. THERE IS A FIFTEEN  
PERCENT CHANCE OF LIFR/IFR CONDITIONS IN THE 13Z-17Z PERIOD THEN A  
SIXTY PERCENT CHANCE AFTER 29/05Z. OTHERWISE VFR CONDITIONS WILL  
PREVAIL.  
 

 
   
MARINE
 
28/200 AM.  
 
SMALL CRAFT ADVISORY (SCA) CONDITIONS CONTINUE ACROSS THE OUTER  
WATERS INTO AT LEAST TUESDAY THOUGH THERE WILL BE PERIODS DURING  
OVERNIGHT AND EARLY MORNING HOURS WHEN WINDS DIP BELOW SCA LEVELS.  
 
SCA CONDITIONS WILL BEGIN IN THE NEARSHORE WATERS OF THE CENTRAL  
COAST THIS AFTERNOON AND CONTINUE INTO AT LEAST TUESDAY. THERE  
WILL BE PERIODS DURING THE OVERNIGHT AND EARLY MORNING HOURS WHEN  
CONDITIONS WILL DIP BELOW SCA LEVELS. THE STRONGER WINDS WILL  
SPILL INTO THE WESTERN HALF OF THE SANTA BARBARA CHANNEL EACH  
EVENING BUT NOT FAR ENOUGH TO WARRANT A SCA FOR THE ENTIRE  
CHANNEL.  
 
THE ELEVATED WINDS WILL CREATE A SHORT PERIOD CHOP OVER ALL  
WATERS INCLUDING THE SANTA BARBARA CHANNEL AND SANTA MONICA BASIN  
IN THE INNER WATERS. THE WINDS PEAK MONDAY AND TUESDAY AND THERE  
IS A THIRTY PERCENT CHANCE THAT GALE CONDITIONS FORM BEYOND 30 NM  
OF THE CENTRAL COAST.  
 

 
   
LOX WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
PZ...SMALL CRAFT ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO 9  
AM PDT TUESDAY FOR ZONE 645. (SEE LAXMWWLOX).  
SMALL CRAFT ADVISORY IN EFFECT UNTIL 9 AM PDT TUESDAY FOR  
ZONES 670-673-676. (SEE LAXMWWLOX).  
 

 
   
HAZARD POTENTIAL OUTLOOK
 
(TUE-SAT)  
NO SIGNIFICANT HAZARDS EXPECTED.  
 

 

 
 
PUBLIC...RORKE  
AVIATION...KJ  
MARINE...KJ  
SYNOPSIS...SIRARD  
 
WEATHER.GOV/LOSANGELES  
 
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