FXUS66 KSGX 060942
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
145 AM PST SUN DEC 6 2009
.SYNOPSIS...A COLD...DEVELOPING LOW PRESSURE SYSTEM FROM THE NORTH
WILL BRING COOL AND MOSTLY CLOUDY WEATHER TODAY 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 WARMER...WEAKER STORM WILL BRING
LIGHTER AMOUNTS OF RAIN ON THURSDAY. MOSTLY CLOUDY NEXT WEEKEND WITH
CHANCES OF PRECIPITATION AS A SYSTEM MOVES BY MOSTLY TO THE NORTH OF
THE AREA.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
MARINE LAYER 6000 FT DEEP...BUT THE STRATUS BASE HAS RISEN TO 4000
FEET. THE THINNING STRATOCU LAYER IS EVIDENT IN THE SATELLITE LOOP.
BENEATH THE CLOUDS THE AIR IS COLD AND DRY. SO NOT EXPECTING MUCH
PRECIP TODAY. WILL KEEP SLIGHT CHANCE IN TO COVER PATCHY DRIZZLE OR
ISOLATED SHOWERS PARTICULARLY FOR MT SLOPES AND FOOTHILLS.
MODELS CONSISTENT WITH CARVING A COLD 525 POSITIVE TILT TROF OVER N
CALIF BY THIS EVENING. THAT PUTS US IN STRONG MOIST 555 W FLOW ALOFT
WHICH WILL THICKEN THE CLOUDS OVERNIGHT WITH INCREASING CHANCES OF
PRECIP. THE TROF INTENSIFIES...DEVELOPING A 150 KT JET MAX AND
STRONG COLD FRONT...THAT COME THROUGH ALL OF SOCAL ON MON. S-SW FLOW
AT THE SURFACE AND STRONG W FLOW ALOFT...ALONG WITH INSTABILITY...
WILL PRODUCE HEAVY RAIN AND MT SNOW MON-MON NIGHT...SO THE WINTER
STORM WATCH LOOKS GOOD. MIGHT NEED A FLASH FLOOD WATCH WEST OF THE
MTS. STORM TOTALS SHOULD RANGE FROM 3/4 TO 1.5 INCHES IN COASTS AND
VALLEYS TO 3 INCHES IN THE LOWER ELEVATION OF THE MTS. THE SNOW
LEVEL WILL BE AROUND 5000 FT MON PM...LOWERING TO 4000 FT MON
NIGHT...WITH 1 FT OF SNOW AT RESORT LEVEL AND 2-3 FEET AT HIGHER
ELEVATIONS. EVEN SAN DIEGO MTS SHOULD GET 1/2 FT OF SNOW. STRONG
WINDS COULD CAUSE NEAR BLIZZARD CONDITIONS AT TIMES WITH THAT STRONG
JET MAX COMING THROUGH. WILL LIKELY NEED HIGH WIND WARNINGS IN LOWER
MTS AND DES...PARTICULARLY IN SAN DIEGO COUNTY MON NIGHT INTO TUE.
LINGERING SHOWERS TUE MORNING. PARTLY CLOUDY AND BREEZY TUE PM WITH
564 WNW FLOW ALOFT. WARMER AND CLEARER WED UNDER WEAK 567 RIDGE...
WHICH IS A CHANGE FROM PREVIOUS MODELS. THE NEXT SYSTEM IS NOW
PROGGED TO ARRIVE THU MORNING. IT WILL BE A FAST MOVING WEAK COLD
FRONT WITH 1/4 TO 1/2 INCH OF RAIN ON THE FLATS. WITH 564 WNW FLOW
ALOFT DURING FRONTAL PASSAGE...EXPECT SNOW LEVELS TO BE ABOVE 6500
FT WITH 4 TO INCHES OF SNOW. COOL MOIST FLOW WILL LIKELY KEEP
SCATTERED LIGHT SHOWERS GOING INTO FRIDAY MORNING...THEN CLEARING
UNDER A WEAK 570 RIDGE FOR MOST OF FRIDAY.
STRONG ZONAL FLOW PATTERN SETS UP BY NEXT WEEKEND...WITH A LOT OF
MOISTURE STAYING NORTH OF US. LOOKS LIKE WE WILL BE ON THE DRY
SOUTHERN SIDE OF THE JET STREAM UNDER MOSTLY 570 WEST FLOW ALOFT.
MAY MANAGE TO GET 1/4 TO 1/2 INCH OF RAIN ON THE FLATS DUE TO THICK
MID AND HIGH CLOUDS.
CLEARING MON DEC 14...THEN WARMER WITH WEAK-MOD 12 MB OFFSHORE FLOW
UNDER A 575 UPPER HIGH BY TUE DEC 15.
&&
.AVIATION...
060830Z...VERY DEEP MARINE LAYER. BASES AROUND 4-5K FT MSL WITH THE
TOP ABOUT 7-8K FT. VSBY ABOVE 7SM. LOCAL DRIZZLE AND LIGHT RAIN AT
TIMES THROUGH THIS MORNING AND POSSIBLY THROUGH TONIGHT. MAJOR COLD
FRONT MOVING IN LATE TONIGHT THROUGH MONDAY WITH HEAVY RAIN AT TIMES
AND VERY WINDY. BASES WILL BE LOWERING LATE TONIGHT...DOWN TO AROUND
1K FT AND LOWER IN HEAVY RAIN WITH VSBY BELOW 1SM AT TIMES. HEAVY
RAIN MOVING IN THE AREA EARLY TO MID MORNING MONDAY.
&&
.MARINE...
060830Z...A STRONG COLD FRONT WILL MOVE INTO THE AREA LATE SUNDAY
NIGHT THROUGH MONDAY. IT WILL BE VERY WINDY MONDAY AND SEAS WILL BE
HAZARDOUS. SMALL CRAFT ADVISORY FOR INNER AND OUTER WATERS OFF SAN
DIEGO COUNTY FROM MID MONDAY MORNING THROUGH MID TUESDAY MORNING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
SPECIAL WEATHER STATEMENT...SEE LAXSPSSGX.
EXTENDED HYDROLOGIC FORECAST...SEE LAXESFSGX.
WINTER STORM WATCH...SEE LAXWSWSGX.
SMALL CRAFT ADVISORY...SEE LAXMWWSGX.
&&
$$
PUBLIC...MACKECHNIE
AVIATION...WHITLOW
