FXUS66 KSGX 280547
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
945 PM PST FRI NOV 27 2009
.SYNOPSIS...AN UPPER LEVEL TROUGH AND STRONG SURFACE COLD FRONT WILL
MOVE ACROSS RAPIDLY SOUTHERN CALIFORNIA TONIGHT. THIS EARLY SEASON
STORM WILL BRING SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS...AND
ALSO BRING SHARPLY COLDER WEATHER TOMORROW. SNOW LEVELS WILL FALL TO
NEAR 5000 FEET SATURDAY MORNING...AND SEVERAL INCHES OF SNOW ARE
LIKELY IN THE SAN BERNARDINO MOUNTAINS. THE SHOWERS WILL TAPER OFF
SATURDAY NIGHT AS THE UPPER LOW MOVES SOUTHEAST. GRADUAL WARMING
SUNDAY AND MONDAY WITH GUSTY OFFSHORE WINDS BEHIND THE DEPARTING
TROUGH.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
INCREDIBLY RAPID MARINE LAYER DEEPENING OCCURRED THIS EVENING AND IT
WILL CONTINUE OVERNIGHT...REACHING A DEPTH OF 5000-6000 FEET
SATURDAY MORNING.
POTENT UPPER LOW CENTERED OVER THE CENTRAL VALLEY PLOWING RAPIDLY
SOUTHWARD TONIGHT. THE 00Z NAM MODEL IS STRONGER THAN IT PREDECESSOR
AND IS THE MOST AMBITIOUS MODEL RUN YET WITH ITS QPF OUTPUT. ITS
COMPACT CIRCULATION CENTER IS PACKING A LOT OF ENERGY WITH STRONG
PVA REACHING SOUTHERN CALIFORNIA BTWN 09Z AND 18Z SATURDAY. IT IS
ALSO A VERY COLD SYSTEM WITH 500 MB TEMPERATURES FALLING TO -27C
TOMORROW MORNING...REALIZING A VERY UNSTABLE ATMOSPHERE. FACTOR IN
LOW AND MID LEVEL MOISTURE ADVECTION TONIGHT AND THERE IS EVIDENCE
TO SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS. HOWEVER...I HAVE
TEMPERED THE RAIN AMOUNTS SLIGHTLY LOWER THAN THE NAM OUTPUT AS THEY
SEEM A BIT OVERDONE.
SINCE THIS WILL BE THE FIRST COLD...WINTER STORM THAT WILL BRING
ACCUMULATION SNOW TO THE SAN BERNARDINO MOUNTAINS...I HAVE ISSUED A
WINTER WEATHER ADVISORY FOR THIS AREA THIS 3 PM SATURDAY. THE SNOW
LEVELS WILL DROP RAPIDLY TONIGHT BEHIND THE COLD FRONT TONIGHT TO
AROUND 4500 FEET TOMORROW MORNING. WITH DEEP MOISTURE AND
INSTABILITY IN PLACE SEVERAL INCHES OF SNOW ARE LIKELY AT RESORT
LEVELS. THUNDERSNOW IS ALSO POSSIBLE.
TEMPERATURES WILL BE 10 TO 15 DEGREES LOWER TOMORROW AS THE COLD
CORE LOW TRACKS DIRECTLY OVERHEAD. TEMPS WILL LIKELY REMAIN IN THE
30S ABOVE 6000 FEET...IN THE 40S IN LOWER MTN ELEVATIONS...AND THE
50S AND LOW 60S COAST AND VALLEYS AND HIGH DESERTS. LOWER DESERTS
WILL BE IN THE LOW TO MID 60S.
THIS COLD UPPER LOW WILL MOVE SOUTHEAST OVER NORTHERN BAJA EARLY
SUNDAY MORNING. WRAP AROUND MOISTURE AND NORTHEAST FLOW WILL BRING
CLOUDS AND POSSIBLE SHOWERS TO THE NORTHEAST FACING SLOPES OF THE
MOUNTAINS THROUGH SUNDAY MORNING.
AS THE LOW MOVES FARTHER SOUTHEAST SUNDAY AFTERNOON IT WILL DRAW IN
A WARMER...DRIER AIRMASS. GRADIENT WINDS BETWEEN THE DEPARTING UPPER
LOW AND THE BUILDING HIGH OVER THE GREAT BASIN WILL RESULT IN GUSTY
NORTHEAST WINDS ACROSS THE MOUNTAINS AND THROUGH PASSES AND CANYONS
SUNDAY AND MONDAY.
MEDIUM RANGE MODELS CONTINUE TO SHOW DRY CONDITIONS THROUGH THE
MIDDLE OF NEXT WEEK BEFORE ANOTHER SHORTWAVE MOVING SOUTH LATE IN
THE WEEK.
&&
.AVIATION...
280445Z...MARINE LAYER RAPIDLY DEEPENING THIS EVENING WITH CURRENT
BASES AROUND 2500 FT MSL. EXPECT WIDESPREAD CLOUDS TO CONTINUE OVER
AND WEST OF THE MOUNTAINS WITH BASES BETWEEN 2500-3500 FT THROUGH
SATURDAY. THERE IS A CHANCE OF RAIN SHOWERS AND TSTORMS BETWEEN
12Z-00Z...MAINLY IN SAN DIEGO COUNTY AND OVER THE SAN BERNARDINO
COUNTY MOUNTAINS/VALLEYS. PARTIAL CLEARING IS EXPECTED SATURDAY
AFTERNOON TO THE NORTHWEST...INCLUDING AT KSNA. STRONG WINDS ALOFT
WILL CAUSE MOUNTAIN WAVE ACTIVITY AND TURBULENCE OVER DESERTS. SKIES
WILL CLEAR MOST AREAS SATURDAY NIGHT THROUGH SUNDAY. LINGERING
SHOWERS ARE POSSIBLE OVER THE HIGH DESERTS AND SAN BERNARDINO
MOUNTAINS ON SUNDAY MORNING. SCV
&&
.MARINE...
A LONG PERIOD 10 FT NW SWELL HAS ARRIVED AT THE SAN CLEMENTE BASIN
BUOY THIS EVENING. THE SWELL IS EXPECTED TO BUILD TONIGHT THROUGH
SATURDAY...PEAK SATURDAY EVENING...THEN DECREASE THROUGH SUNDAY.
THIS WILL BRING HIGH SURF AND DANGEROUS RIP CURRENTS TO THE BEACHES
THROUGH SUNDAY MORNING...WITH THE LARGEST SURF ON SAN DIEGO COUNTY
BEACHES SOUTH OF DEL MAR. HIGH SURF ADVISORIES ARE IN EFFECT UNTIL 2
PM SUNDAY FOR BOTH ORANGE COUNTY AND SAN DIEGO COUNTY COASTS. SMALL
CRAFT ADVISORIES ARE ALSO IN EFFECT TONIGHT THROUGH SATURDAY NIGHT
FOR COASTAL WATERS DUE TO 10-15 FOOT COMBINED SEAS IN OUTER WATERS
AND AROUND 10 FEET INNER WATERS.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WINTER WEATHER ADVISORY FOR THE SAN BERNARDINO MOUNTAINS FROM 3
AM TO 3 PM SATURDAY.
HIGH SURF ADVISORY UNTIL 2 PM PST SUNDAY FOR ORANGE COUNTY
COASTAL AREAS.
HIGH SURF ADVISORY UNTIL 2 PM PST SUNDAY FOR SAN DIEGO COUNTY
COASTAL AREAS.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS TO 8 AM PST SUNDAY FOR
WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 30
TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM MIDNIGHT
TONIGHT TO MIDNIGHT PST SATURDAY NIGHT FOR COASTAL WATERS
FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT 30 NM.
&&
$$
PUBLIC...MOEDE
AVIATION/MARINE...SCV
