Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 290410
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
909 PM PDT SAT MAR 28 2015

.SYNOPSIS...

A WEAK TROUGH OF LOW PRESSURE WILL BRING A FEW DEGREES OF COOLING
SUNDAY AS IT DRIFTS ACROSS NORTHERN BAJA...BUT IT WILL STILL BE
QUITE WARM INLAND. A SHALLOW MARINE LAYER WILL BRING LOW CLOUDS AND
AREAS OF FOG BACK TO THE COASTAL ZONES TONIGHT. MILD AND DRY NEXT
WEEK WITH GUSTY WESTERLY WINDS IN THE MOUNTAINS AND DESERTS AT TIMES
AS STORMS PASS BY TO THE NORTH.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

EVEN THOUGH A SEA BREEZE KEPT COASTAL AREAS COOLER TODAY...IT WAS
ANOTHER RECORD BREAKER INLAND AS TEMPERATURES SOARED BACK INTO THE
UPPER 80S AND LOWER 90S. PALM SPRINGS HIT THE CENTURY MARK FOR THE
FIRST TIME THIS YEAR TO BREAK A RECORD SET BACK IN 1969.

AT 8 PM PDT...A COMPACT AREA OF LOW PRESSURE ABOUT 675 MILES SW OF
SAN DIEGO WAS SLINGING HIGH CLOUDS TOWARD THE REGION. LOWER CLOUDS
WERE BEGINNING TO DEVELOP ALONG THE IMMEDIATE COAST BASED ON SFC
OBSERVATIONS BUT THEY WERE NOT VISIBLE BELOW THE HIGH CLOUD DECK.
THE 00Z MIRAMAR SOUNDING HAD A 6.5 DEGREE C INVERSION BASED NEAR 500
FEET. THIS WAS SEVERAL HUNDRED FT LOWER THAN YESTERDAY EVENING.
SURFACE PRESSURE GRADIENTS HAD INCREASED TO 5-6 MBS ONSHORE TO THE
LOWER DESERTS...BUT WERE NEUTRAL TO WEAK OFFSHORE FROM NV.

BASED ON THE LATEST CEILING OBSERVATIONS ALONG THE COAST...FOG
DEVELOPMENT MAY BE CLOSE TO AREAS AFFECTED LAST NIGHT. BUT BASED ON
THE LOWER INVERSION HEIGHT FROM THE NKX SOUNDING...AND A DEVELOPING
OFFSHORE TREND FROM NV...THE FOG COULD DEVELOP CLOSER TO THE COAST.
MITIGATING FACTORS WILL BE THE THICKNESS OF THE HIGH CLOUD DECK...
WHICH COULD KEEP THE LOW CLOUDS/FOG MORE PATCHY IN NATURE. COASTAL
AIRPORTS WILL BE AT SOME RISK OF DENSE FOG OVERNIGHT. CONDITIONS
WILL BE MONITORED CLOSELY FOR THE POSSIBLE ISSUANCE OF A DENSE FOG
ADVISORY LATER.

FAIR TONIGHT INLAND BEYOND TEN MILES...AND ANY FOG/LOW CLOUDS THAT
DEVELOP OVERNIGHT CLOSE TO THE COAST SHOULD BURN OFF QUICKLY...
LEAVING FAIR AND MILD WEATHER AGAIN ON SUNDAY. IT SHOULD BE A COUPLE
OF DEGREES COOLER...MAINLY DUE TO THE PATCHY HIGH CLOUDS AND
SLIGHTLY LOWER THICKNESS AS THE WEAK TROUGH APPROACHES THE MEXICAN
COAST.

THE LATEST GFS/EC RUNS CARRY THE COMPACT LOW...CURRENTLY WELL
OFFSHORE...SE...BRINGING IT ONSHORE JUST SOUTH OF PUNTA EUGENIA TUE
MORNING. THIS WILL HAVE LITTLE AFFECT ON SOCAL WEATHER EXCEPT FOR
SOME HIGH CLOUDS AND A SLIGHT DROP IN HEIGHTS/THICKNESS. A STRONGER
SERIES OF TROUGHS WILL MOVE EAST OFF THE PACIFIC...ACROSS THE PACNW
AND INTO THE NORTHERN ROCKIES THROUGH FRI OF NEXT WEEK. THESE
SYSTEMS ARE TOO FAR NORTH TO BRING US ANY PRECIP...BUT THEY WILL
KEEP OUR SURFACE GRADIENTS ONSHORE WITH GUSTY WESTERLY WINDS IN THE
MTS/DESERTS AT TIMES. THERE WILL ALSO BE A MARINE LAYER WEST OF THE
MOUNTAINS...WITH PERIODS OF NIGHT AND MORNING LOW CLOUDS AND FOG.
TEMPERATURES WILL BE CLOSER TO AVERAGE NEXT WEEK UNDER MOSTLY ZONAL
FLOW ALOFT.

THE WEATHER FOR NEXT WEEKEND INTO THE FOLLOWING WEEK LOOKS
CONSIDERABLY DIFFERENT THAN THIS PAST WEEKEND AS A LARGE TROUGH
DEVELOPS OVER THE WEST. DETAILS AND TIMING ARE NOT CERTAIN...BUT
SEVERAL OF THE PAST EC/GFS DETERMINISTIC RUNS LOOK SIMILAR ENOUGH
WITH THE LONGWAVE PATTERN TO BEGIN BUILDING CONFIDENCE IN THIS
CHANGE. EXPECT STRONGER WESTERLY WINDS OVER THE MTS/DESERTS AND MUCH
COOLER WEATHER THEN.

&&

.AVIATION... 290300Z...COASTAL AREAS...LOW CLOUDS AND FOG ARE MOVING
ONTO THE BEACHES AT THIS TIME AND WILL PUSH ABOUT 5 MILES INLAND
OVERNIGHT...WITH CIGS 200-600 FEET MSL. PATCHY FOG IS LIKELY AGAIN
TONIGHT WITH VIS 1-3 SM WHERE CLOUDS INTERSECT TERRAIN. LOCAL DENSE
FOG IS POSSIBLE AS WELL...ESPECIALLY ON THE COASTAL MESAS...INCL
KCRQ. LOW CLOUDS AND FOG EXPECTED TO CLEAR OFF THE COAST BY 16Z SUN.

VALLEYS/MOUNTAINS/DESERTS...SCT CLOUDS AOA 15000 FEET WITH
UNRESTRICTED VIS THROUGH SUNDAY.

&&

.MARINE...

800 PM...PATCHY DENSE FOG POSSIBLE AGAIN TONIGHT THROUGH SUNDAY
MORNING...OTHERWISE NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH
TUESDAY.

&&

.BEACHES...

800 PM...A SOUTH SWELL WITH A LONG PERIOD WILL CREATE STRONG RIP AND
LONGSHORE CURRENTS INTO SUNDAY AFTERNOON...AS WELL AS ELEVATED SURF
ALONG SOUTH-FACING BEACHES. FOR DETAILS SEE THE BEACH HAZARDS
STATEMENT...LAXCFWSGX.

&&

.SKYWARN...
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...BEACH HAZARDS STATEMENT THROUGH SUNDAY AFTERNOON FOR ORANGE
     COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.

PZ...NONE.
&&

$$

PUBLIC...JAD
AVIATION/MARINE...PG



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