073  
FXUS66 KLOX 271005  
AFDLOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA  
305 AM PDT THU JUN 27 2019  
   
SYNOPSIS
 
26/612 PM.  
 
OVERNIGHT AND MORNING LOW CLOUDS WILL CONTINUE ALONG MUCH OF THE  
COAST AND ADJACENT VALLEYS THROUGH THE WEEK. BREEZY AFTERNOON AND  
EVENING WINDS WILL DEVELOP EACH DAY IN THE MOUNTAINS AND DESERTS  
THROUGH THURSDAY. TEMPERATURES WILL REMAIN RELATIVELY COOL THROUGH  
FRIDAY THEN WARM A BIT THIS WEEKEND.  
 

 
   
SHORT TERM (TDY-SAT)
 
27/247 AM.  
 
LATEST GOES-17 FOG PRODUCT IMAGERY INDICATED MUCH LESS AREAL  
COVERAGE OF STRATUS COMPARED TO THE LAST SEVERAL NIGHTS. AT THIS  
POINT, THE SOUTHERN HALF L.A. COUNTY COAST AND VALLEYS WERE  
AFFECTED BY THE MARINE LAYER STRATUS, AS WELL AS THE CENTRAL COAST  
AND SANTA YNEZ VALLEY. LATEST SOUNDINGS NEAR LAX INDICATED THE  
MARINE LAYER DEPTH IS ABOUT HALF OF WHAT IT WAS THE LAST FEW DAYS  
AT 1900 FT THIS MORNING. EXPECTING LOW CLOUDS TO EVENTUALLY FILL  
IN ACROSS ALL OF L.A. COUNTY COAST AND VALLEYS, AND EVENTUALLY  
ACROSS THE VENTURA COUNTY AND PORTIONS OF THE VALLEYS. CONFIDENCE  
IS NOT AS HIGH FOR MAKING IT TO THE SANTA BARBARA SOUTH COAST BY  
DAYBREAK, BUT EVENTUALLY SHOULD CREEP UP INTO THE CITY OF SANTA  
BARBARA THIS MORNING.  
 
SYNOPTICALLY, A 566 DM UPPER LOW WAS LOCATED JUST NORTH OF THE  
CALIF/OREGON BORDER. THIS LOW WILL SLOWLY PIVOT SLIGHTLY NORTH  
INTO WASH ST. THROUGH THE WEEKEND. ALTHOUGH THERE WILL CONTINUE TO  
BE AN ASSOCIATED TROUGH ACROSS MUCH OF CALIFORNIA THROUGH THE  
WEEKEND, HIGH PRESSURE ALOFT ACROSS THE SOUTHWEST WILL STRENGTHEN  
AND NUDGE FARTHER WEST CAUSING H5 HEIGHTS TO RISE. THE COMBINATION  
OF RISING HEIGHTS, AND WEAKER ONSHORE GRADIENTS WILL CAUSE THE  
MARINE LAYER TO CONTINUE TO SHRINK DUE TO THE SUBSIDENCE ALOFT.  
 
THIS SHOULD TRANSLATE TO A SLIGHT WARMING TREND THROUGH SATURDAY  
WITH LESS MARINE LAYER STRATUS INTRUSION FOR SOME VALLEYS AND A  
QUICKER SCOUR OUT TIME EACH DAY THROUGH SATURDAY. HIGH TEMPS  
SHOULD BE 2-5 DEGREES WARMER TODAY AND A FEW MORE DEGREES WARMER  
FRIDAY, WITH SIMILAR HIGH TEMPS ON SATURDAY. (HIGH TEMPS SHOULD  
BE AROUND NORMAL OR SLIGHTLY HIGHER THAN NORMAL BY FRIDAY.)  
 
WITH WEAKER ONSHORE GRADIENTS EXPECTED, SW WINDS SHOULD NOT BE AS  
STRONG ACROSS THE ANTELOPE VALLEY, ESPECIALLY NEAR LAKE PALMDALE.  
HOWEVER, WITH A STRENGTHENING NW-N GRADIENT BETWEEN SBA-SMX AND  
SBA-BFL, THERE WILL BE GUSTY LOCALIZED SUNDOWNER WINDS ACROSS THE  
WESTERN PORTION OF THE SBA SOUTH COAST, MAINLY WEST OF REFUGIO  
EACH LATE AFTERNOON AND EVENING HOURS THROUGH SAT. WINDS SHOULD  
REMAIN JUST UNDER WIND ADVISORY THRESHOLDS AS IT SHOULD NOT BE  
WIDESPREAD. WEAK OFFSHORE WINDS OFF THE SAN LUCIA MTNS TO THE  
CENTRAL COAST EACH MORNING WILL BRING A FEW DEGREES OF WARMING  
ACROSS THE CENTRAL COAST BEFORE THE SEABREEZE KICKS IN EACH  
AFTERNOON.  
 
THE TRICKY PART OF THE FORECAST WILL BE HOW STRONG THE CATALINA  
EDDY WILL GET. THERE WILL CONTINUE TO BE GUSTY NW WINDS ACROSS THE  
OUTER WATERS WHICH SHOULD HELP THE EDDY STRENGTHEN INSIDE THE  
SOCAL BIGHT EACH EVENING THROUGH EARLY MORNING HOURS. THE  
THINKING IS THAT THERE WILL ONLY BE PATCHY LOW CLOUDS N OF POINT  
CONCEPTION FRI/SAT MORNINGS, BUT THE EDDY SHOULD CONTINUE TO BRING  
NIGHT THROUGH MORNING LOW CLOUDS ACROSS THE COAST AND PORTIONS OF  
THE COASTAL VALLEYS THROUGH AT LEAST SATURDAY TO L.A. AND VENTURA  
COUNTIES. THE BEST CHANCE FOR THE SBA SOUTH COAST TO DEVELOP LOW  
CLOUDS WILL BE AROUND DAWN EACH MORNING DUE TO THE EARLIER NW  
WINDS EXPECTED.  
 
ALSO, MODELS ARE PICKING UP ON A SLUG OF MID LEVEL SUB-TROPIC  
MOISTURE OFF OF BAJA CALIF FRIDAY NIGHT BEING DRAWN UP TO OUR  
SOUTH WITH THE UPPER TROUGH TO THE NW AND UPPER HIGH TO THE EAST  
INTO THE VERY SOUTHERN PORTION OF CALIFORNIA/AZ BY SATURDAY. IT IS  
A VERY SHARP BOUNDARY THAT REMAINS TO THE SOUTH OF THE FORECAST  
AREA, BUT WILL HAVE TO BE MONITORED IN CASE IT PUSHES FARTHER  
NORTH. MODELS HAVE A TOUGH TIME RENDERING SOLUTIONS AT TIMES WITH  
THESE TYPES OF SCENARIOS IN RESPECT TO PRECIP.  
   
LONG TERM (SUN-WED)
 
27/304 AM.  
 
OVERALL, THE GFS AND ECMWF ARE IN GOOD AGREEMENT WITH LARGE SCALE  
SYNOPTIC FEATURES SUN-WED. THIS IS THE TIME OF YEAR WHEN A  
PERSISTENT UPPER TROUGH WILL LINGER TO THE NW OF SOUTHERN  
CALIFORNIA AND HIGH PRESSURE ACROSS THE SOUTHWEST SETS UP AND  
SOUTHERN CALIFORNIA IS STUCK IN BETWEEN THE TWO. SOMETIMES THE  
UPPER TROUGH WILL DIG FURTHER SOUTH ALLOWING FOR WIDESPREAD  
COOLING, AND OTHER TIMES, THE UPPER RIDGE WILL NUDGE WEST AND  
CAUSE WARMING AND LESS LOW CLOUD INTRUSION. IN THIS CASE, THE  
FORECAST WILL CHANGE VERY LITTLE THROUGH THE EXTENDED PERIOD. HIGH  
TEMPS INLAND WILL BE JUST ABOVE NORMAL FOR THE MOST PART WITH  
NIGHT THROUGH MORNING LOW CLOUDS ACROSS COASTAL AREAS AND SOME  
COASTAL VALLEY LOCATIONS. THERE WILL BE SOME LOCAL GUSTY SUB-  
ADVISORY SUNDOWNER WINDS ACROSS THE WESTERN PORTION OF THE SBA  
SOUTH COAST, MAINLY WEST OF REFUGIO MON-WED LATE  
AFTERNOONS/EVENINGS.  
 

 
   
AVIATION
 
27/0528Z.  
 
AT 04Z, THE MARINE LAYER DEPTH WAS AROUND 1950 FEET DEEP AT KLAX.  
THE TOP OF THE MARINE INVERSION AROUND 2600 FEET WITH A  
TEMPERATURE NEAR 18 DEGREES CELSIUS. THERE WAS ANOTHER INVERSION  
ABOVE UP TO AROUND 4300 FEET.  
 
LOW-TO-MODERATE CONFIDENCE IN THE CURRENT FORECAST. HIGHER  
CONFIDENCE IN TIMING, LESS CONFIDENCE IN FLIGHT CATEGORIES.  
 
IFR TO MVFR CONDITIONS WILL LIKELY SPREAD INTO COASTAL AND VALLEY  
TERMINALS THROUGH 13Z. THERE IS A CHANCE THAT CONDITIONS COULD BE  
ONE CATEGORY LOWER, ESPECIALLY NORTH OF POINT CONCEPTION. BETTER  
CLEARING IS EXPECTED FOR THE VALLEY TERMINALS ON THURSDAY. COASTAL  
TERMINALS COULD CLEAR UP TO 1 HOUR EARLIER/LATER THAN FORECAST.  
 
KLAX...MVFR CONDITIONS WILL BECOME PREVALENT THROUGH 08Z. VFR  
CONDITIONS COULD DEVELOP AS SOON AS 19Z OR AS LATE AS 21Z. MVFR  
CONDITIONS SHOULD SPREAD INTO KLAX BETWEEN 05Z AND 08Z. THERE IS A  
BETTER CHANCE OF IFR CONDITIONS ON THURSDAY NIGHT.  
 
KBUR...MVFR CONDITIONS WILL SPREAD INTO KBUR BETWEEN 08Z AND 12Z.  
THERE IS A 50 PERCENT CHANCE OF IFR CONDITIONS. VFR CONDITIONS  
COULD DEVELOP AS SOON AS 17Z OR AS LATE AS 19Z.  
 

 
   
MARINE
 
27/223 AM.  
 
FOR THE OUTER WATERS... SMALL CRAFT ADVISORY (SCA) LEVEL WINDS  
WILL CONTINUE THROUGH AT LEAST LATE FRIDAY NIGHT WITH A SIXTY  
PERCENT CHANCE OF BEING EXTENDED THROUGH AT LEAST SATURDAY. THERE  
IS A THIRTY PERCENT CHANCE OF GALES DURING THE THURSDAY AFTERNOON  
THROUGH FRIDAY NIGHT PERIOD.  
 
FOR THE INNER WATERS NORTH OF POINT SAL... SCA WINDS WILL DEVELOP  
THIS AFTERNOON AND CONTINUE INTO EARLY FRIDAY MORNING. THERE IS A  
SIXTY PERCENT CHANCE OF SCA LEVEL WINDS EACH AFTERNOON AND EVENING  
THROUGH AT LEAST SATURDAY.  
 
FOR THE INNER WATERS SOUTH OF POINT CONCEPTION... SCA WINDS WILL  
DEVELOP THIS AFTERNOON AND CONTINUE INTO EARLY FRIDAY MORNING  
ACROSS THE WESTERN PORTION OF THE SANTA BARBARA CHANNEL WITH  
CONDITIONS ELSEWHERE BEING ELEVATED BUT REMAINING BELOW SCA  
CRITERIA. THERE IS A SIXTY PERCENT CHANCE OF SIMILAR CONDITIONS  
EACH AFTERNOON AND EVENING THROUGH AT LEAST SATURDAY.  
 

 
   
LOX WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
PZ...SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 AM PDT SATURDAY FOR  
ZONES 670-673. (SEE LAXMWWLOX).  
SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 AM PDT FRIDAY FOR ZONE  
676. (SEE LAXMWWLOX).  
 

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

 
 

 
 
PUBLIC...KAPLAN  
AVIATION...HALL  
MARINE...KJ  
SYNOPSIS...KJ  
 
WEATHER.GOV/LOSANGELES  
 
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