FXUS66 KSGX 050540
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
940 PM PST SAT FEB 4 2012

.SYNOPSIS...
HIGH PRESSURE ALOFT ALONG THE WEST COAST AND SURFACE HIGH PRESSURE
OVER THE GREAT BASIN WILL CONTINUE FAIR DRY WEATHER THROUGH TUESDAY
MORNING. FOR TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING...A LOW
PRESSURE SYSTEM TRACKING SOUTHEAST OFF THE SOUTHERN CALIFORNIA AND
BAJA CALIFORNIA COAST WILL BRING A CHANCE OF PRECIPITATION. HIGH
PRESSURE BUILDING LATE WEDNESDAY THROUGH FRIDAY WILL BRING WARMER
WEATHER AND A RETURN TO DRY OFFSHORE FLOW.

&&

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

TODAY WOUND UP BEING A DEGREE OR TWO WARMER THAN YESTERDAY...THE
WARMEST BEING 79 AT SANTA ANA. HOWEVER...MANY COASTAL AND VALLEY
AREAS SAW HIGHS IN THE MID 70S...AND WERE WARMER THAN THE LOWER
DESERTS.

THIS STATIC OFFSHORE PATTERN WILL REMAIN IN PLACE SUNDAY FOR ANOTHER
SUNNY...MILD DAY AND BREEZY OFFSHORE WINDS IN THE EAST-WEST ORIENTED
PASSES. THE AIRMASS WILL REMAIN VERY DRY WITH AFTERNOON HUMIDITIES
FROM 15-25% ONCE AGAIN TOMORROW.

THE FIRST SIGN IF AIRMASS MODIFICATION TAKES PLACE SUNDAY NIGHT AND
MONDAY AS WE TRANSITION TO STRONGER ONSHORE FLOW PATTERN. IT WILL BE
A GRADUAL PROCESS THOUGH...WITH THE FIRST HINT OF LOW LEVEL MOISTURE
AND A SHALLOW MARINE LAYER ARRIVING AT THE COASTLINE MONDAY MORNING.
COASTAL HIGHS WILL BE LOWER MONDAY FROM THE MARINE LAYER
INFLUENCE...BUT FARTHER INLAND MONDAY WILL BE ANOTHER MILD DAY IN
THE VALLEYS...MOUNTAINS AND DESERTS. ON MONDAY NIGHT THE COOL MARINE
AIR WILL SPREAD INTO THE VALLEYS AND TUESDAY WILL BE NOTICEABLY
COOLER WEST OF THE MTNS.

ALL THE MODELS HAVE TRENDED A LITTLE CLOSER TO THE COAST WITH TROUGH
APPROACHING THE WEST COAST TUESDAY...EVEN THE ECMWF. THE 00Z NAM12
AND GFS ARE CLOSEST TO THE COAST WITH TRACK OF THE UPPER LOW OVER
THE OUTER ISLANDS TUESDAY NIGHT. THE CANADIAN MODEL IS A LITTLE
FARTHER WEST...BUT STILL CLOSE ENOUGH TO GENERATE SMALL QPF. THE 12Z
ECMWF REMAINS THE FARTHER WEST WITH THE TRACK...BUT IT TOO IS CLOSE
ENOUGH TO BRUSH COASTAL SOCAL WITH SMALL QPF. THIS IS THE SECOND RUN
OF THE ECMWF THAT HAS GENERATED PRECIP OVER LAND...A TREND THAT ADDS
GREATER CONFIDENCE THAT WE WILL IN FACT GET PRECIP FROM THIS SYSTEM
SOMETIME TUESDAY INTO TUESDAY NIGHT.

.LONG TERM...
WEDNESDAY THROUGH SATURDAY...ON WEDNESDAY THE UPPER LOW WILL MOVE
SOUTHEAST TOWARD NORTHERN BAJA. A WIND SHIFT FROM THE SOUTHWEST TO
THE NORTHEAST WILL TAKE PLACE WITH THE PASSAGE OF THE TROUGH AXIS.
THERE IS A CHANCE FOR WRAP AROUND MOISTURE WEDNESDAY MORNING TO
PRODUCE LIGHT PRECIP ON THE EAST FACING MTN SLOPES...BUT TOO SMALL
TO MENTION AT THIS TIME. THAT WILL ULTIMATELY DEPEND OF THE TRACK OF
THE UPPER LOW...HOW MUCH MOISTURE GETS INTO THE SYSTEM...AND HOW
TIGHT THE CIRCULATION IS.

BY WEDNESDAY AFTERNOON THE MODELS HAVE THE CLOSED LOW AND ITS
REMNANT MOISTURE WELL TO THE SOUTHEAST. DRY NORTHEAST FLOW FROM HIGH
PRESSURE BUILDING ALOFT ALONG THE WEST COAST WILL BRING DRY...MILD
WEATHER AND WEAK OFFSHORE FLOW TO SOCAL THU AND FRI.

&&

.AVIATION...
050525Z...VFR CONDS WITH FEW-SCT CLDS AOA FL200 WILL PREVAIL THROUGH
SUNDAY AFTERNOON. STRATUS THAT HAS DEVELOPED OVER THE SOUTHERN
CALIFORNIA BIGHT THIS EVENING WILL REMAIN SOUTH AND WEST OF SAN
CLEMENTE ISLAND TONIGHT. STRATUS WITH BASES AROUND 500 FT MSL WILL
LIKELY RETURN TO COASTAL AREAS AFTER 06/02Z SUNDAY EVENING. VIS OF
3-5SM WILL ACCOMPANY THE STRATUS WITH LOCALLY LOWER VIS IN THE
COASTAL MESAS. KSAN...KCRQ AND KSNA WILL LIKELY BE IMPACTED...BUT
KONT WILL REMAIN VFR.

&&

.MARINE...
A LARGE WEST-NORTHWEST SWELL WILL LIKELY MOVE INTO THE AREA LATE
TUESDAY INTO THURSDAY. THIS SWELL WILL BRING HIGH SURF TO THE COAST
AND SEAS ABOVE 10 FEET OVER THE COASTAL WATERS. THE SWELL WILL BE
LARGEST SOUTH OF A LINE FROM THE SOUTHERN TIP OF SAN CLEMENTE ISLAND
TO DEL MAR.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC/FIRE WEATHER...MOEDE
AVIATION/MARINE...MOKER




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