729  
FXUS66 KLOX 291336  
AFDLOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA  
536 AM PST THU FEB 29 2024  
   
SYNOPSIS
 
29/505 AM.  
 
A DEEP MARINE LAYER AND STRENGTHENING ONSHORE FLOW WILL MAKE FOR A  
CLOUDY AND MUCH COOLER DAY TODAY, WITH SOME PATCHY DRIZZLE THIS  
MORNING. A COLD STORM SYSTEM WILL MOVE INTO SOUTHERN CALIFORNIA  
FRIDAY THROUGH SATURDAY NIGHT WITH PERIODS OF RAIN AND MOUNTAIN  
SNOW EXPECTED. DRY AND COOL WEATHER IS EXPECTED SUNDAY THROUGH AT  
LEAST TUESDAY, WITH A CHANCE OF SOME RAIN BY MIDWEEK.  
 

 
   
SHORT TERM (TDY-SAT)
 
29/503 AM.  
 
THE MARINE LAYER HAS DEEPENED SIGNIFICANTLY SINCE LAST EVENING,  
AND WAS NOW ABOUT 3000 FT. CLOUDS HAVE BECOME WIDESPREAD IN ALL  
COASTAL AND VALLEY AREAS, AND WERE BEGINNING TO PUSH INTO THE  
COASTAL SLOPES. EXPECT THE MARINE LAYER TO DEEPEN ADDITIONALLY  
THIS MORNING, WITH CLOUDS EXTENDING FARTHER INTO THE MOUNTAINS. IN  
ADDITION, WITH THE DEEPENING MARINE LAYER AND WEAKLY CYCLONIC FLOW  
ALOFT, EXPECT SOME DRIZZLE THIS MORNING, ESPECIALLY SOUTH OF PT.  
CONCEPTION. THERE IS A SLIGHT CHANCE OF MEASURABLE RAIN THIS  
MORNING, ESPECIALLY ACROSS EASTERN VTU COUNTY AND L.A. COUNTY.  
THERE IS A SLIGHT CHANCE THAT LIGHT RAIN COULD LINGER INTO THE  
AFTERNOON IN THE FOOTHILLS OF EASTERN L.A. COUNTY.  
 
WITH STRONG ONSHORE FLOW AND A TROUGH DIGGING THROUGH EASTERN  
PACIFIC, EXPECT LITTLE CLEARING TODAY FROM THE COASTAL SLOPES  
SOUTHWARD AND WESTWARD TO THE COAST. HOWEVER, THERE MAY BE SOME  
BREAKS IN THE CLOUDS FROM TIME TO TIME, ESPECIALLY NEAR THE COAST.  
GUSTY SW TO W WINDS COULD GET CLOSE TO ADVISORY LEVELS IN THE  
ANTELOPE VALLEY AND FOOTHILLS, AND THRU THE HIGHWAY 14 CORRIDOR.  
THERE IS A SLIGHT CHANCE OF LIGHT RAIN THIS AFTERNOON NORTH OF  
PT. CONCEPTION, ASSOCIATED WITH THE DIGGING TROUGH. THERE WILL BE  
SIGNIFICANT COOLING ACROSS THE REGION TODAY, WITH MAX TEMPS DOWN  
5 TO 10 DEGREES IN MANY AREAS. SOME LOCATIONS, ESPECIALLY IN THE  
VALLEYS COULD HAVE HIGHS ALMOST 15 DEGREES LOWER THAN ON WED.  
 
SYNOPTICALLY, A VERY COLD UPPER LOW WAS LOCATED IN THE GULF OF  
ALASKA EARLY THIS MORNING, WITH A LARGE TROUGH EXTENDING TO ITS  
SOUTH. THIS UPPER LOW WILL DROP SOUTHWARD THRU FRI, REACHING A  
POSITION ABOUT 400 NM W OF VANCOUVER BY LATE FRI AFTERNOON. AS IT  
DOES THIS, THE ASSOCIATED TROUGH EXTENDING TO ITS SOUTH WILL  
CONTINUE TO DIG THRU THE EASTERN PACIFIC, AND IT WILL SHARPEN  
SOMEWHAT. DEEP LAYERED WESTERLY FLOW ALOFT WILL PUMP INCREASING  
MOISTURE INTO THE REGION TONIGHT AND FRI, AND THE FLOW ALOFT WILL  
BECOME INCREASINGLY CYCLONIC. HEIGHT FALLS AND THE DIGGING TROUGH  
WILL HELP TO PROVIDE INCREASING LIFT THRU THE ATMOSPHERE. WHILE  
THIS SYSTEM WILL NOT HAVE ANY CONNECTION TO THE SUBTROPICS (WITH  
PW VALUES ABOUT 0.8 INCHES OR LESS), MID LEVEL HEIGHT FALLS WILL  
HELP TO WRING OUT AVAILABLE MOISTURE. THERE WILL BE A CHANCE OF  
RAIN ACROSS MUCH OF SBA AND SLO COUNTIES TONIGHT, WITH RAIN  
BECOMING LIKELY IN FAR NORTHERN AREAS OVERNIGHT. THERE IS A  
SLIGHT CHANCE OF RAIN REACHING L.A. COUNTY LATE TONIGHT, BUT EVEN  
IF RAIN DOES NOT MAKE IT ALL THE WAY SOUTHWARD ACROSS THE AREA  
TONIGHT, THERE WILL PROBABLY BE SOME DRIZZLE TONIGHT/FRI MORNING.  
 
ON FRI, THE CHANCE OF RAIN WILL INCREASE THRU THE DAY, WITH RAIN  
LIKELY NORTH OF PT. CONCEPTION, AND A CHANCE OF RAIN ELSEWHERE,  
ESPECIALLY IN THE AFTERNOON. IT WILL BE A CLOUDY AND RATHER COLD  
DAY FOR THE FIRST DAY OF MARCH, WITH MAX TEMPS 6 TO 12 DEGREES  
BELOW NORMAL IN MOST AREAS. RAINFALL THRU FRI SHOULD BE ONE TENTH  
OF AN INCH OR LESS SOUTH OF PT. CONCEPTION, AND A QUARTER TO ONE  
HALF INCH NORTH, WITH LOCALLY HIGHER TOTALS IN NORTHWESTERN SLO  
COUNTY. SNOW LEVELS WILL BE MOSTLY ABOVE 6000 FT THRU FRI, AND  
WITH LOWER PRECIP TOTALS SOUTH OF PT. CONCEPTION, EXPECT ONLY  
LIGHT SNOW ACCUMULATIONS IN THE MTNS THRU FRI. WINDS COULD  
REACH ADVISORY LEVELS IN THE ANTELOPE VALLEY AND ADJACENT FOOTHILLS,  
IN THE MOUNTAINS, AND POSSIBLY IN HIGHER TERRAIN OF SLO AND SBA  
COUNTIES FRI AFTERNOON.  
 
THE UPPER LOW WILL REMAIN ANCHORED TO THE WEST OF VANCOUVER ISLAND  
FRI NIGHT AND SAT, BUT A FAIRLY STRONG SHORT WAVE TROUGH ROTATING  
AROUND ITS SOUTHERN SIDE WILL MOVE INTO THE PAC NW FRI NIGHT AND  
SAT. ITS ASSOCIATED FRONTAL SYSTEM WILL MOVE ACROSS THE REGION FRI  
NIGHT AND SAT, BRINGING PERIODS OF RAIN. RAIN WILL BE MOSTLY ON  
THE LIGHT SIDE, BUT COULD BE MODERATE TO BRIEFLY HEAVY AT TIMES AS  
INSTABILITY INCREASES DUE TO COOLING ALOFT. AT THIS POINT, IT  
APPEARS THAT THE PORTION OF THE FRONT THAT WILL AFFECT THE  
FORECAST AREA WILL BE TOO FAR FROM THE PARENT LOW, AND TOO  
REMOVED FROM ITS BEST DYNAMICS TO BRING MUCH IN THE WAY OF HEAVY  
RAIN TO THE REGION, BUT BRIEFLY HEAVIER SHOWERS ARE POSSIBLE,  
ESPECIALLY SAT. IN FACT, A THUNDERSTORM OR TWO IS NOT OUT OF THE  
QUESTION LATE FRI NIGHT AND SAT. EVEN ABSENT THAT, BRIEFLY HEAVY  
CONVECTIVE SHOWERS COULD PRODUCE LOCAL RAINFALL RATES TO ONE HALF  
INCH PER HOUR. GUSTY SOUTH WINDS FRI NIGHT AND EARLY SAT WILL  
SHIFT TO WEST BEHIND THE FRONT. THE FRONT WILL MOVE TO THE EAST OF  
THE REGION SAT NIGHT, AND RAIN WILL TURN TO SCATTERED SHOWERS.  
 
WHEN ALL IS SAID AND DONE, RAINFALL TOTALS SHOULD AVERAGE 0.50 TO  
0.75 INCHES SOUTH OF PT. CONCEPTION, WITH LOCAL TOTALS OF 1 TO  
1.5 INCHES IN THE MTNS AND FOOTHILLS, ESPECIALLY IN EASTERN L.A.  
COUNTY. NORTH OF PT. CONCEPTION, EXPECT 0.75 TO 1.50 INCHES OF  
RAIN, WITH LOCAL TOTALS OVER 2 INCHES ACROSS NORTHWESTERN SLO  
COUNTY.  
 
SNOW LEVELS WILL DROP TO 5000 TO 5500 FT OR SO BY LATE FRI NIGHT  
AND SAT, AND TO 4000 TO 4500 FT BY SAT NIGHT. THAT COULD CAUSE  
PROBLEMS ON HIGHER PORTIONS OF INTERSTATE 5. WINTER WEATHER  
ADVISORIES (AT LEAST) WILL LIKELY BE NEEDED FOR THE MTNS. THE  
LATEST SNOWFALL ESTIMATES ARE FOR 5 TO 10 INCHES ABOVE 7000 FT  
AND 2 TO 5 INCHES BETWEEN 5500 AND 7000 FT. LIGHTER ACCUMULATIONS  
ARE POSSIBLE DOWN TO 4500 FT. AT THIS TIME, IT APPEARS TRAVEL ON  
I-5 OVER THE GRAPEVINE SHOULD BE MINIMALLY AFFECTED BY SNOW.  
   
LONG TERM (SUN-WED)
 
29/455 AM.  
 
MOIST WEST TO NORTHWESTERLY FLOW BEHIND THE FRONT WILL KEEP A  
CHANCE OF SHOWERS SUN MORNING, ESPECIALLY IN THE MTNS AND IN  
L.A COUNTY. PARTIAL CLEARING IS POSSIBLE SUN AFTERNOON. IT WILL BE  
COOL AND BREEZY SUN, AND NW WINDS COULD REACH ADVISORY LEVELS  
ACROSS SOUTHWESTERN SBA COUNTY AND THRU THE I-5 CORRIDOR.  
 
BROAD WESTERLY FLOW ALOFT WILL SETTLE OVER THE REGION MON,  
BRINGING DRY WEATHER, WITH PARTLY CLOUDY SKIES. IT WILL REMAIN  
COOL, BUT THERE SHOULD BE A COUPLE OF DEGREES OF WARMING.  
 
A TROUGH DROPPING THRU THE PAC NW INTO THE GREAT BASIN MON NIGHT  
AND TUE WILL CAUSE HEIGHTS TO FALL A BIT ACROSS THE FORECAST AREA.  
IT WILL BE COOL, BUT WILL LIKELY REMAIN DRY. GUSTY NW WINDS MAY  
CONTINUE TO AFFECT PORTIONS OF SOUTHERN SBA COUNTY AND THE I-5  
CORRIDOR MON THRU TUE.  
 
A COMPACT UPPER LOW WILL DROP SOUTHEASTWARD THRU THE PAC LATE TUE  
AND TUE NIGHT, THEN IT WILL OPEN UP INTO A TROUGH AS IT MOVES  
ACROSS NORTHERN CA WED. THE SOUTHERN END OF ITS FRONTAL SYSTEM  
MAY BRING A CHANCE OF RAIN TO THE REGION AGAIN WED, MAINLY NORTH  
OF PT. CONCEPTION, WHERE IT COULD START AS EARLY AS TUE NIGHT.  
 

 
   
AVIATION
 
29/1334Z.  
 
AROUND 12Z, THE MARINE LAYER DEPTH WAS AROUND 3100 FEET DEEP AT  
KLAX. THE TOP OF THE INVERSION WAS NEAR 4200 FEET WITH A  
TEMPERATURE NEAR 9 DEGREES CELSIUS.  
 
MODERATE CONFIDENCE IN THE CURRENT FORECAST. LOWER CONFIDENCE IN  
IFR CEILINGS IN DRIZZLE THROUGH 18Z AND FOR TIMING OF CONDITIONS  
IMPROVING TO THE VFR CATEGORY AFTER 18Z. THERE IS A MODERATE  
CHANCE THAT MVFR CONDITIONS COULD LINGER AT SOME TERMINALS THROUGH  
THE PERIOD. HIGHER CONFIDENCE OF MVFR CONDITIONS RETURNING AFTER  
03Z, BUT THERE IS A MODERATE CHANCE THAT ARRIVAL COULD BE UP TO  
TWO HOURS EARLIER THAN FORECAST.  
 
KLAX...THERE IS A 30 PERCENT CHANCE OF IFR CONDITIONS DEVELOPING  
IN DRIZZLE THROUGH 16Z. VFR CONDITIONS WITH CEILINGS AT OR BELOW  
6000 FEET ARE LIKELY TO DEVELOP BETWEEN 19Z AND 22Z, BUT THERE IS  
A 30 PERCENT CHANCE THAT MVFR CONDITIONS MAY LINGER THROUGH THE  
PERIOD. MVFR CONDITIONS WILL SPREAD INTO KLAX AS SOON AS 01Z, OR  
AS LATE AS 04Z.  
 
KBUR...THERE IS A 40 PERCENT CHANCE OF IFR CONDITIONS DEVELOPING  
IN DRIZZLE THROUGH 16Z. VFR CONDITIONS WITH CEILINGS AT OR BELOW  
6000 FEET ARE LIKELY TO DEVELOP BETWEEN 19Z AND 22Z, BUT THERE IS  
A 30 PERCENT CHANCE THAT MVFR CONDITIONS MAY LINGER THROUGH THE  
PERIOD. MVFR CONDITIONS WILL SPREAD INTO KBUR AROUND 03Z.  
 

 
   
MARINE
 
29/517 AM.  
 
MODERATE-TO-HIGH CONFIDENCE IN THE CURRENT FORECAST. HIGHER  
CONFIDENCE IN SEAS RELATIVE TO WINDS.  
 
WIND AND SEAS WILL VERY LIKELY REMAIN BELOW SMALL CRAFT ADVISORY  
(SCA) LEVELS THROUGH EARLY FRIDAY, THEN THERE IS A LIKELY-TO-VERY  
LIKELY (60-90 PERCENT) CHANCE OF WIDESPREAD SCA CONDITIONS  
SPREADING INTO THE COASTAL WATERS FROM NORTHWEST TO SOUTHEAST  
BETWEEN EARLY FRIDAY AND EARLY SATURDAY. WIDESPREAD SCA CONDITIONS  
WILL LIKELY AFFECT THE WATERS THROUGH EARLY SUNDAY WITH HAZARDOUS  
SEAS BEING COMMON ACROSS MOST OF THE COASTAL WATERS.  
 
WINDS WILL DIMINISH BETWEEN SUNDAY NIGHT AND MONDAY, BUT  
HAZARDOUS SEAS MAY LINGER A LITTLE LONGER FOR THE WATERS SOUTHWEST  
THROUGH NORTHWEST OF THE CHANNEL ISLANDS BEYOND 10 NM OFFSHORE.  
 

 
   
BEACHES
 
29/533 AM.  
 
A BUILDING WEST TO NORTHWEST SWELL ACROSS THE COASTAL WATERS WILL  
RAPIDLY INCREASE SURF BETWEEN FRIDAY AND SATURDAY, AND THEN  
REMAIN HIGH THROUGHOUT THE WEEKEND. SURF HEIGHTS WILL BUILD  
THROUGH FRIDAY, LIKELY PEAKING ON SATURDAY FOR BEACHES ALONG THE  
CENTRAL COAST AND ON SUNDAY FOR BEACHES SOUTH OF POINT CONCEPTION.  
THE LATEST MODELS INCREASE SWELL HEIGHTS SLIGHTLY OVER THE  
PREVIOUS FORECAST TO 12 TO 17 FEET ALONG THE CENTRAL COAST WITH A  
WAVE PERIOD BETWEEN 12 AND 15 SECONDS. SURF HEIGHTS BETWEEN 10 AND  
16 FEET ARE POSSIBLE OVER THE WEEKEND WITH LOCAL SETS POSSIBLE  
REACHING 20 FEET AT WEST AND NORTHWEST FACING SHORES.  
 
SWELL ENERGY DOES SUBSIDE MUCH AS IT MOVES INTO THE SOUTHERN  
CALIFORNIA BIGHT, BUT THERE IS A MODERATE CHANCE SWELL COULD REACH  
10 FEET AT 13-14 SECONDS, PRODUCING LOCAL SETS AS HIGH AS 13 FEET  
AT WEST FACING SHORES. HIGH SURF ADVISORIES REMAIN IN EFFECT FOR  
SECTIONS OF THE COAST MOST SUSCEPTIBLE TO WEST THROUGH NORTHWEST  
NORTHWEST WAVE ENERGY. THE HIGH SURF ADVISORY INCLUDES THE  
CENTRAL COAST STARTING EARLY FRIDAY MORNING, AND THE VENTURA  
COUNTY COAST STARTING LATE FRIDAY AFTERNOON, AND THEN CONTINUING  
IN THESE AREAS THROUGH THE WEEKEND.  
 
IN ADDITION, ROUGH SEAS ARE EXPECTED TO MATERIALIZE, AS A RESULT  
OF LONGER-PERIOD SWELL AND SHORTER-PERIOD WIND WAVES CAUSED BY  
BREEZY WINDS. THESE FACTORS WILL CREATE DANGEROUS CONDITIONS AT  
AREA BEACHES, INCLUDING A HIGH RIP-CURRENT RISK. WHILE THE STEEP  
WIND WAVES WILL CONTRIBUTE TO DANGEROUS AND CHAOTIC SEAS, THEY  
WILL ALSO DISRUPT ENERGY FROM LONGER-PERIOD SWELL. THIS WILL CAUSE  
THE COASTAL-FLOODING POTENTIAL TO BE LIMITED. ALSO, ASTRONOMICAL  
HIGH TIDES WILL BE MODEST, AROUND 5 FEET, WHICH WILL REDUCE THE  
RISK FOR COASTAL FLOODING. NEVERTHELESS, VERY MINOR COASTAL  
FLOODING ALONG THE IMMEDIATE COASTLINE CANNOT BE RULED OUT AROUND  
THE TIME OF OVERNIGHT HIGH TIDE (MIDNIGHT-2AM) FRIDAY NIGHT AND  
SATURDAY NIGHT. THIS WOULD PRIMARILY BE FOR BEACHES MOST  
SUSCEPTIBLE TO WEST TO NORTHWESTERLY WAVE ENERGY, SUCH AS  
PORTIONS OF THE MORRO BAY AND VENTURA PIER AREAS.  
 
IN THE EXTENDED OUTLOOK, THERE IS THE POTENTIAL FOR A MORE  
SUBSTANTIAL SWELL EVENT DURING MIDDLE TO LATTER PARTS OF NEXT  
WEEK, CAPABLE OF PRODUCING EVEN HIGHER SURF AND GREATER COASTAL  
FLOODING POTENTIAL. HOWEVER, THE EVOLUTION OF THE ASSOCIATED  
STORM SYSTEM ALOFT IS ESPECIALLY UNCERTAIN AT THIS TIME RANGE, AND  
THIS UNCERTAINTY EXTENDS TO HIGH-SURF AND COASTAL-FLOODING  
POTENTIAL. NEVERTHELESS, THOSE WITH BEACH INTERESTS FOR MIDDLE TO  
LATTER PARTS OF NEXT WEEK SHOULD CONTINUE TO MONITOR THE LATEST  
INFORMATION FROM THE NATIONAL WEATHER SERVICE.  
 

 
   
LOX WATCHES/WARNINGS/ADVISORIES
 
 
CA...HIGH SURF ADVISORY IN EFFECT FROM 4 AM FRIDAY TO 4 AM PST  
MONDAY FOR ZONES 340-346. (SEE LAXCFWLOX).  
HIGH SURF ADVISORY IN EFFECT FROM 4 PM FRIDAY TO 4 AM PST  
MONDAY FOR ZONE 354. (SEE LAXCFWLOX).  
PZ...SMALL CRAFT ADVISORY IN EFFECT FROM 9 AM FRIDAY TO 4 AM PST  
MONDAY FOR ZONES 645-673. (SEE LAXMWWLOX).  
SMALL CRAFT ADVISORY IN EFFECT FROM 9 PM FRIDAY TO 4 AM PST  
MONDAY FOR ZONE 650. (SEE LAXMWWLOX).  
SMALL CRAFT ADVISORY IN EFFECT FROM 3 AM SATURDAY TO 4 AM PST  
MONDAY FOR ZONE 655. (SEE LAXMWWLOX).  
SMALL CRAFT ADVISORY IN EFFECT FROM 3 AM FRIDAY TO 4 AM PST  
MONDAY FOR ZONE 670. (SEE LAXMWWLOX).  
SMALL CRAFT ADVISORY IN EFFECT FROM 3 PM FRIDAY TO 4 AM PST  
MONDAY FOR ZONE 676. (SEE LAXMWWLOX).  
 

 
 

 
 
PUBLIC...DB  
AVIATION...HALL  
MARINE...HALL  
BEACHES...HALL/COHEN  
SYNOPSIS...DB  
 
WEATHER.GOV/LOSANGELES  
 
EXPERIMENTAL GRAPHICAL HAZARDOUS WEATHER OUTLOOK AT:  
HTTPS://WWW.WEATHER.GOV/ERH/GHWO?WFO=LOX  
 
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