FXUS66 KSGX 060434
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
900 PM PST SAT DEC 5 2009
.SYNOPSIS...A COLD LOW PRESSURE SYSTEM FROM THE NORTH WILL BRING
COOL AND MOSTLY CLOUDY WEATHER SUNDAY WITH A FEW SHOWERS. THIS
SYSTEM WILL MOVE ACROSS SOUTHERN CALIFORNIA MONDAY INTO TUESDAY
BRINGING RAIN...HEAVY AT TIMES...A LOT OF MOUNTAIN SNOW AND STRONG
WINDS MONDAY INTO TUESDAY. A SECOND...WARMER STORM WILL BRING MORE
RAIN WEDNESDAY NIGHT THROUGH FRIDAY.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
THE HIGHER CLOUDS CLEARED OUT LATE THIS AFTERNOON WHILE THE LOWER
CLOUDS HAVE DEEPENED UP TO 7000 FEET. A DEEP LOW PRESSURE TROUGH
COMING DOWN THE COAST WILL KEEP THESE LOWER CLOUDS IN THE FORECAST
BUT WITH ADDITIONAL INSTABILITY WHICH COULD WRING OUT A FEW SHOWERS
TONIGHT THROUGH SUNDAY. ANY SHOWERS THAT OCCUR WILL BE LIGHT AND
MOST LIKELY IN THE INLAND VALLEYS OR MOUNTAINS. THEN THE REAL STORM
HITS. THE MAIN CONCERNS WITH THE MONDAY STORM WILL BE THE HEAVY
MOUNTAIN SNOW AND STRONG WINDS. MOISTURE FROM THE PACIFIC WILL ENTER
THE PICTURE SUNDAY NIGHT AND INCREASE MONDAY AS THE MAIN TROUGH AXIS
MOVES THROUGH SOUTHERN CALIFORNIA. REALLY STRONG WINDS WILL COME
WITH IT. INITIALLY THE LOW SNOW LEVELS WILL RISE MONDAY...THEN DROP
QUICKLY MONDAY NIGHT AS THE FINAL FRONT MOVES THROUGH. THIS COLD
FRONT LOOKS LIKE THE ONES IN THE METEOROLOGY TEXTBOOKS COMPLETE WITH
A WARM FRONT AND DROPPING PRESSURE AHEAD OF IT...THEN A SUDDEN WIND
SHIFT AND PRESSURE RISE BEHIND IT. BY SUNRISE TUESDAY THE RAIN WILL
BE GONE PRETTY MUCH. THE REST OF TUESDAY AND MOST OF WEDNESDAY
APPEAR DRY FOR NOW UNDER A WEAK TRANSITORY RIDGE. ZONAL FLOW BRINGS
IN A DEEPLY SATURATED AIR MASS OF TROPICAL ORIGIN AROUND
THURSDAY...BUT THE EXACT TIMING OF ITS ARRIVAL IS UNCERTAIN. THERE
ARE NOT A LOT OF DYNAMICS WITH THIS SYSTEM...BUT WITH ALL THE
MOISTURE AVAILABLE THE DYNAMICS WILL NOT BE NEEDED TO PRODUCE A LOT
OF RAIN. THIS WARMER SYSTEM WILL KEEP THE SNOW LEVEL QUITE HIGH AT
OR ABOVE RESORT LEVELS. ON FRIDAY SHOWERS WILL DECREASE. THERE ARE
HINTS THAT ON SATURDAY WE COULD GET THE NEXT WAVE OF RAIN...OR NOT.
THE MODELS ARE VERY INCONCLUSIVE ABOUT THAT.
&&
.AVIATION...
060330Z...STRATUS WITH BASES BETWEEN 3500 AND 5000 FT MSL AND TOPS
TO OVER 7000 FT MSL SHOULD REMAIN MOSTLY BKN TO OVC THROUGH SUNDAY.
FOG...LOCALLY DENSE...WILL OBSCURE THE COASTAL SLOPES OF THE
MOUNTAINS THROUGH SUNDAY. DRIZZLE AND LIGHT RAIN IS POSSIBLE OVER
AND WEST OF THE MOUNTAINS SUNDAY...WITH CIGS LOWERING TO AROUND 2000
FT MSL AT TIMES.
ABOVE THE MARINE LAYER...CIRRUS AND ALTOSTRATUS AOA FL150 WILL BEGIN
TO MOVE OVER THE AREA SUNDAY MORNING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
SPECIAL WEATHER STATEMENT...SEE LAXSPSSGX.
EXTENDED HYDROLOGIC FORECAST...SEE LAXESFSGX.
WINTER STORM WATCH...SEE LAXWSWSGX.
&&
$$
PUBLIC...MM
AVIATION...SULLIVAN
