031  
FXUS66 KLOX 192016  
AFDLOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA  
116 PM PDT THU APR 19 2018  
   
SYNOPSIS
 
19/1150 AM.  
 
GUSTY WINDS ARE FORECAST INTO EARLY FRIDAY. HIGH PRESSURE AND  
OFFSHORE FLOW WILL BRING ABOVE NORMAL TEMPERATURES FROM FRIDAY INTO  
MONDAY. AN EDDY WILL USHER IN OVERNIGHT COASTAL LOW CLOUDS AND FOG  
FROM SATURDAY INTO MONDAY. THEN A LOW SHOULD ARRIVE BY TUESDAY FOR  
INCREASING ONSHORE FLOW AND A COOLING TREND THROUGH THURSDAY.  
 

 
   
SHORT TERM (TDY-SUN)
 
19/115 PM.  
 
THE UPPER LOW HAS DEPARTED AND A RIDGE WILL MOVE IN TONIGHT AND  
FRIDAY AND REMAIN IN PLACE AT LEAST THROUGH EARLY SUNDAY FOR A  
WARMING TREND, MAINLY INLAND. FOR TODAY GUSTY WEST TO NORTHWEST  
WINDS THAT DEVELOPED BEHIND THE DEPARTED COLD FRONT WILL CONTINUE  
INTO THE OVERNIGHT HOURS BEFORE WEAKENING. COASTAL AREAS, THE I5  
CORRIDOR, AND THE ANTELOPE VALLEY WILL BEAR THE BRUNT OF THESE  
WINDS WITH NOT AS MUCH REACHING THE COASTAL VALLEYS. OVERALL A  
WEAKER POST-FRONTAL WIND EVENT THAN WHAT WE SAW MONDAY BUT STILL  
AT LEAST LOW END ADVISORY FOR THE ABOVE MENTIONED AREAS.  
 
LATER TONIGHT AN EDDY CIRCULATION IS EXPECTED TO DEVELOP THAT WILL  
HELP PULL IN SOME LOW CLOUDS INTO SRN LA COUNTY. FORECAST  
SOUNDINGS INDICATE JUST ENOUGH OF AN INVERSION BELOW 1000' TO  
SUPPORT IT BUT PROBABLY NOT A REAL SOLID COVERAGE. SOME LOW CLOUDS  
ALSO EXPECTED TO DEVELOP ALONG PARTS OF THE CENTRAL COAST AND IN  
THE SOUTHERN SALINAS VALLEY WHERE THERE COULD ALSO BE SOME DENSE  
FOG.  
 
WITH THE RIDGE BUILDING IN FRIDAY AND SATURDAY EXPECTING TEMPS  
INLAND TO JUMP SEVERAL DEGREES, BACK UP INTO THE 80S. COASTAL  
AREAS WILL STILL HAVE ENOUGH OF AN ONSHORE FLOW AND LIKELY SOME  
MARINE LAYER CLOUDS DURING THE MORNING HOURS AT LEAST TO KEEP  
TEMPS QUITE A BIT COOLER THERE.  
 
A LITTLE COOLING TREND EXPECTED FOR SUNDAY IN MOST AREAS AS THE  
RIDGE SHIFTS EAST AND A WEAK TROUGH MOVES INTO THE PAC NW. PRETTY  
DECENT ONSHORE TREND BY AFTERNOON SO A STRONGER AND EARLIER SEA  
BREEZE EXPECTED.  
   
LONG TERM (MON-THU)
 
19/116 PM.  
 
MODELS STILL IN A BIT OF FLUX NEXT WEEK WITH THE EXPECTED  
DEVELOPMENT OF A CUTOFF LOW AT SOME POINT SEVERAL HUNDRED MILES  
WEST OF THE COAST. TODAY'S GFS SOLUTION SHIFTED TO YESTERDAY'S  
ECMWF, KEEPING THE LOW WEST OF 130W THROUGH AT LEAST THURSDAY THEN  
SLOWLY MOVING IT TOWARDS THE COAST NEXT WEEKEND. MEANWHILE, THE  
ECMWF ACTUALLY DID THE OPPOSITE AND LOOKS A LITTLE CLOSER TO  
YESTERDAY'S GFS. SO NOT A LOT OF CONFIDENCE ESPECIALLY AROUND MID  
WEEK. EARLY IN THE WEEK NOT EXPECTING A LOT OF CHANGE FROM SUNDAY.  
SLIGHTLY COOLER PERHAPS WITH THE ONSHORE TRENDS BUT HEIGHTS STAY  
FAIRLY HIGH AT LEAST THROUGH TUESDAY SO MOST INLAND AREAS SHOULD  
REMAIN AT LEAST A FEW DEGREES ABOVE NORMAL. AFTER THAT IT JUST  
DEPENDS ON THE SPEED AND MAGNITUDE OF THE UPPER LOW AND WHERE IT  
ENDS UP MOVING INLAND. CAN'T RULE OUT SOME SHOWER CHANCES WHEN  
THAT HAPPENS BUT RIGHT NOW THE MODELS ARE HOLDING ANY OF THAT OFF  
UNTIL AT LEAST FRIDAY. LIKELY STILL A LOT OF BACK AND FORTH IN THE  
SOLUTIONS BEFORE THERE IS ANY REAL CONFIDENCE BEYOND EARLY NEXT  
WEEK.  
 

 
   
AVIATION
 
19/1857Z.  
 
AT 1655Z AT KLAX, THERE WAS NO MARINE LAYER OR INVERSION AT KLAX.  
 
THE COLD FRONT HAS NOW EXITED THE REGION AND THE CLOUDS WILL  
GRADUALLY DECREASE JUST AS THE NORTHWEST WINDS BEGIN TO INCREASE  
THROUGHOUT THE AFTERNOON. GUSTY WEST TO NORTHWEST WINDS WILL  
AFFECT MUCH OF THE REGION THROUGH THIS AFTERNOON, WITH WINDS  
SHIFTING TO THE NORTH AND REMAINING GUSTY TONIGHT. THERE WILL BE  
AREAS OF LLWS AND MODERATE UDDF THROUGH TONIGHT.  
 
KLAX...MODERATE TO HIGH CONFIDENCE IN THE 18Z TAF. THERE IS A  
20-30% CHANCE OF LOW LEVEL WIND SHEAR THROUGH 02Z.  
 
KBUR...MODERATE TO HIGH CONFIDENCE IN THE 18Z TAF. THERE IS A  
20-30% CHANCE OF LOW LEVEL WIND SHEAR THROUGH 02Z.  
 

 
   
MARINE
 
19/1256 PM.  
 
HIGH CONFIDENCE IN AT LEAST SMALL CRAFT ADVISORY (SCA) LEVEL  
WINDS AND POSSIBLY SEAS DEVELOPING ACROSS ALL COASTAL WATERS  
TODAY, THEN CONTINUING THRU LATE TONIGHT BEFORE SUBSIDING. THERE  
IS A 20-30% CHANCE OF GALE FORCE WINDS LATE THIS AFTERNOON AND  
EVENING ACROSS THE OUTER WATERS AND WESTERN PORTIONS OF THE INNER  
WATERS AND SBA CHANNEL. STEEP SHORT-PERIOD SEAS ARE EXPECTED  
ACROSS THE WATERS THRU TONIGHT.  
 
SCA LEVEL WINDS ARE EXPECTED ACROSS THE OUTER WATER FRI AFTERNOON  
INTO FRI NIGHT. THERE IS A 30-40% CHANCE OF SCA LEVEL WINDS  
ACROSS THE NORTHERN INNER WATERS FRI AFTERNOON AND EVENING, AND A  
20% CHANCE OF SCA LEVEL WINDS ACROSS THE SBA CHANNEL.  
 
THERE IS A 20-30% CHANCE OF SCA LEVEL WINDS ACROSS THE OUTER  
WATERS SAT THROUGH SUN. SCA LEVEL WINDS ARE LIKELY ACROSS THE  
OUTER WATERS AND NORTHERN INNER WATERS MON.  
 

 
   
LOX WATCHES/WARNINGS/ADVISORIES
 
 
CA...WIND ADVISORY IN EFFECT UNTIL 9 PM PDT THIS EVENING FOR ZONES  
34>36-51. (SEE LAXNPWLOX).  
WIND ADVISORY IN EFFECT UNTIL 3 AM PDT FRIDAY FOR ZONES  
39>41-52>54-59-87. (SEE LAXNPWLOX).  
PZ...SMALL CRAFT ADVISORY IN EFFECT UNTIL 3 AM PDT FRIDAY FOR  
ZONES 645-650-655-670-673-676. (SEE LAXMWWLOX).  
 

 
 
.HAZARD POTENTIAL OUTLOOK (SUN-THU).  
 
NO SIGNIFICANT HAZARDS EXPECTED.  
 

 
 

 
 
PUBLIC...MW  
AVIATION...SWEET  
MARINE...SWEET  
SYNOPSIS...STU  
 
WEATHER.GOV/LOSANGELES  
 
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