000
FXUS66 KSGX 271713
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
915 AM PST MON DEC 27 2010
.SYNOPSIS...WEAK HIGH PRESSURE WILL BRING DRY AND MILD WEATHER WITH
A FEW CLOUDS TODAY AND TUESDAY. A STORM APPROACHING FROM THE
NORTHWEST WILL LIKELY BRING RAIN...MOUNTAIN SNOW AND LOCAL STRONG
GUSTY WINDS WEDNESDAY. DRY AND VERY COLD THURSDAY AND FRIDAY.
ANOTHER UPPER LOW COULD BRING MORE SHOWERS TOWARD THE BEGINNING OF
NEXT WEEK.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
PATCHY SHALLOW FOG IN THE INLAND VALLEYS THIS MORNING IS BURNING OFF
AND THE OFFSHORE FLOW IS PRODUCING LOCAL WINDS GUSTING TO 25
MPH...MOSTLY IN THE CANYONS AND PASSES.
WEAK HIGH PRESSURE WILL BRING GENERALLY FAIR WEATHER AND NEAR TO
SLIGHTLY BELOW SEASONAL TEMPERATURES TODAY AND TUESDAY. THERE WILL
BE VARIABLE HIGH CLOUDINESS AND PATCHY EARLY MORNING GROUND FOG.
WEAK OFFSHORE FLOW WILL CAUSE LOCAL BREEZY CONDITIONS THROUGH AND
BELOW MOUNTAIN CANYONS AND PASSES THIS MORNING...AND TO A LESSER
EXTENT TUESDAY MORNING.
A FAST MOVING STORM APPROACHING FROM THE NW WILL MOVE THROUGH SW CA
LATE TUESDAY NIGHT AND EARLY WEDNESDAY. THE STORM WILL LIKELY TAP
INTO DEEP MOISTURE RESULTING IN A PERIOD OF MODERATE TO HEAVY PRECIP
WITH THE FRONTAL PASSAGE WEDNESDAY MORNING. THE SNOW LEVEL WILL BE
NEAR 6000 FT N TO 6500 FT S ON WED MORNING...THEN LOWER RAPIDLY
BEHIND THE COLD FRONT TO ABOUT 4000 FT BY WED NIGHT. HOWEVER...MOST
OF THE SIGNIFICANT PRECIP WILL BE OVER BY THE TIME THE SNOW LEVEL
LOWERS TO 4000 FT. MOST AREAS WILL BE ABOUT 6 TO 12 DEGREES BELOW
SEASONAL AVERAGES WEDNESDAY...REMAINING BELOW SEASONAL AVERAGES ON
THURSDAY.
RAINFALL TOTALS SHOULD RANGE FROM ABOUT A THIRD TO TWO THIRDS OF AN
INCH IN THE COASTAL AND VALLEY AREAS WITH THREE QUARTERS OF AN INCH
TO ONE AND A QUARTER INCH ON THE COASTAL MOUNTAIN SLOPES. THERE WILL
BE GENERALLY MORE PRECIP IN THE N AND LESS TO THE S. THE HIGH
DESERTS SHOULD GET UP TO HALF AN INCH WITH LESS THAN A QUARTER OF AN
INCH OF RAIN IN THE LOWER DESERTS.
SAN BERNARDINO COUNTY MOUNTAIN RESORT LEVELS AND THE HIGHER
RIVERSIDE COUNTY MOUNTAINS SHOULD GET ABOUT 3 TO 8 INCHES OF SNOW.
HOWEVER...THERE COULD LOCALLY BE NEAR A FOOT OF SNOW ON THE HIGHEST
PEAKS. THE HIGHER SAN DIEGO COUNTY MOUNTAINS COULD GET AN INCH OR
TWO OF SNOW. COLD AIR DAMMING COULD ALSO PRODUCE SNOW FLURRIES IN
THE HIGH DESERTS.
STRONG GUSTY W TO NW WINDS WILL ACCOMPANY THIS SYSTEM INCREASING
BEHIND THE FRONT WEDNESDAY NIGHT. THE STRONGEST WINDS WILL BE IN THE
MOUNTAINS AND HIGH DESERTS.
THE TROUGH MOVES E LEAVING DRY COLD NW FLOW ALOFT THURSDAY AND
FRIDAY. MAX TEMPS WILL BE ABOUT 10 TO 20 DEGREES BELOW SEASONAL
AVERAGES. COLD AT NIGHT WITH WIDESPREAD FROST LIKELY IN THE INLAND
VALLEYS.
INCREASING CLOUDINESS BUT DRY MOST OF THE DAY SATURDAY WITH A LITTLE
WARMING AS THE AIR MASS MODERATES UNDER A WEAK RIDGE. ANOTHER LOW
PRESSURE SYSTEM MAY BRING SHOWERS LATE SUNDAY NIGHT AND MONDAY.
HOWEVER...MODELS CONTINUE TO BE INCONSISTENT FOR THE WEEKEND AND
LOTS OF UNCERTAINTY REMAINS IN THE DETAILS OF THE FORECAST THAT FAR
OUT.
&&
.AVIATION...
271500Z...PATCHY GROUND FOG WITH VIS BELOW 1 SM WILL DISSIPATE FROM
THE VALLEYS BY 1630Z. VERY LOCAL VALLEY FOG COULD RETURN TONIGHT.
OTHERWISE...VFR CONDITIONS WILL PREVAIL WITH ONLY A FEW HIGH CLOUDS
ABOVE FL200 THROUGH TUESDAY.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
SPECIAL WEATHER STATEMENT. SEE LAXSPSSGX.
&&
$$
PUBLIC...PG
AVIATION...MAXWELL
