FXUS66 KSGX 252107
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
105 PM PST FRI DEC 25 2009
.SYNOPSIS...PATCHY FOG IS POSSIBLE ALONG THE COAST TONIGHT...AND
HIGH CLOUDS WILL INCREASE SATURDAY AND SUNDAY...BUT OTHERWISE FAIR
WEATHER WILL CONTINUE OVER THE WEEKEND. THE DAYS WILL BE SLIGHTLY
COOLER...BUT THE NIGHTS WILL BE A BIT WARMER. UPPER LEVEL LOW
PRESSURE APPROACHING FROM THE NORTHWEST WILL BRING A SLIGHT CHANCE
OF SHOWERS AROUND MONDAY. A FEW PERIODS OF WEAK TO MODERATE OFFSHORE
FLOW WILL OCCUR NEXT WEEK AS THE UPPER LEVEL LOW FOR MONDAY MOVES BY
TO OUR SOUTH...AND OTHER SYSTEMS GO BY TO OUR NORTHEAST.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
SKIES WERE MOSTLY CLEAR TODAY...THOUGH A FEW PATCHES OF FOG/STRATUS
WERE OVER THE COASTAL WATERS THIS MORNING. A FEW PATCHES OF FOG
COULD MAKE IT TO THE COAST OVERNIGHT...AND GIVEN THE SURFACE-BASED
MARINE INVERSION...IF IT ARRIVES...IT WILL BE DENSE. IT SHOULD BE
LOCAL...AT BEST. THE LOCAL EAST WINDS THROUGH E-W
PASSES/CANYONS...SUCH AS THE CAMPO AREA...WERE MOSTLY 20 MPH OR LESS
AND SHOULD GRADUALLY WANE LATER THIS AFTERNOON.
A BROAD AREA OF LOW PRESSURE REMAINS OVER THE NE PACIFIC...WITH A
CENTER AROUND 48N/155W AT PRETTY MUCH ALL HEIGHT LEVELS WITH A
SURFACE LOW OF 971 MB. A DECENT 160 KT JET WAS ON THE SOUTH SIDE
WHICH WILL HELP STEER A WAVE ON THE SOUTH SIDE OF THE LOW TOWARDS
CALIFORNIA...EXCEPT THAT BEFORE IT ARRIVES...THAT WAVE WILL TURN
INTO A CLOSED LOW AND SINK TOWARDS BAJA CALIFORNIA. SO...PRECIP
CHANCES LOOK QUITE LOW FOR HERE...AND I WILL PROBABLY LOWER THEM TO
JUST A SLIGHT CHANCE AROUND MONDAY. WE ACTUALLY STILL HAVE RIDGING
ON SUNDAY...SO PRECIP CHANCES WILL BE REMOVED FOR THEN. THE SURFACE
LOW WILL BE FAIRLY DEEP...IN THE 1002-1004 MB RANGE AS IT DRIFTS BY
TO THE SW...BUT WITH THE SOUTHERLY TRACK TOWARDS BAJA...THAT WILL
ACTUALLY WORK TO INCREASE THE OFFSHORE FLOW. ANY SORT OF CANYON/PASS
WIND FOR MONDAY WILL BE SURFACE-BASED WITH POSSIBLY 8 MB OFFSHORE
FLOW FROM SOUTHERN NEVADA TO THE COAST AS THE 850-700 MB COLD AIR
ADVECTION WILL BE MINIMAL DUE TO E-SE FLOW VERSUS NE. IF PRECIP
OCCURS...AMOUNTS WILL BE A FEW HUNDREDTHS DUE TO LIMITED
MOISTURE...AND SNOW LEVELS WILL BE AROUND 5000-6000 FEET.
AROUND TUE/WED NEXT WEEK...HIGH PRESSURE ALOFT WILL BUILD OVER THE E
PAC AND RESULT IN NW FLOW ALOFT HERE. A COUPLE OF SYSTEMS WILL PASS
BY TO THE N/NE...BUT MOST LIKELY WILL BE TOO FAR INLAND FOR PRECIP
HERE. OFFSHORE FLOW COULD REOCCUR AFTER THE SYSTEMS PASS BY. TEMPS
SHOULD START OUT BELOW NORMAL EARLY IN THE WEEK...THEN RECOVER TO
NEAR NORMAL THE 2ND HALF OF THE WEEK...AT LEAST BASED ON CURRENT
GUIDANCE.
&&
.AVIATION...
252100Z...VFR THROUGH THIS EVENING. PATCHY IFR/LIFR CIGS VIS
POSSIBLE BY SAT MORNING ALONG THE COAST.
.MARINE...
252100Z...A LARGE LONG PERIOD WEST SWELL IS FORECAST TO MOVE INTO
THE COASTAL WATERS SUNDAY...INCREASING THROUGH THE DAY...THEN
DECREASING LATE TUESDAY. HIGH SURF CONDITIONS APPEAR LIKELY FOR
EXPOSED WEST FACING BEACHES BY SUN AFTERNOON.
&&
$$
PUBLIC...MAXWELL
AVIATION/MARINE...SCV
