FXUS66 KSGX 241312
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
500 AM PST THU DEC 24 2009

.SYNOPSIS...COLD INLAND THIS MORNING WITH PATCHY FROST. HIGH 
PRESSURE ALOFT AND WEAK OFFSHORE FLOW WILL CONTINUE FAIR SKIES 
THROUGH FRIDAY. A COUPLE OF UPPER LEVEL LOW PRESSURE SYSTEMS WILL 
BRING MORE CLOUDS AND COOLING SATURDAY INTO NEXT WEEK. CHANCE OF 
SHOWERS SUNDAY AND MONDAY. 

&&

.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... 
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.

.SHORT TERM (TODAY-SATURDAY)...SKIES WERE CLEAR EARLY THIS MORNING 
EXCEPT FOR A FEW HIGH CLOUDS. AIRCRAFT SOUNDINGS SHOWED INCREASING 
NW WINDS ALOFT. OFFSHORE GRADIENTS FROM THE N WITH ABOUT -7 MB 
SAN-TPH AND WEAK ONSHORE TO THE E. 

COOL THIS MORNING WITH PATCHY FROST INLAND. A HIGH AMPLITUDE UPPER 
RIDGE WILL MOVE ACROSS THE W COAST TODAY AND FRIDAY AND THEN WEAKEN 
SATURDAY. A SURFACE HIGH CENTERED IN NRN NV WILL SLOWLY SHIFT E AND 
WEAKEN THROUGH SATURDAY CAUSING OFFSHORE FLOW. WINDS WILL BE MOSTLY 
GRADIENT DRIVEN WITH WEAK UPPER AND THERMAL SUPPORT. AS A 
RESULT...LOCAL GUSTY WINDS THROUGH AND BELOW MOUNTAIN CANYONS AND 
PASSES WILL GENERALLY REMAIN BELOW ADVISORY STRENGTH. 
HOWEVER...THERE COULD BE BRIEF GUSTS TO NEAR 40 MPH NEAR THE CAJON 
PASS AND IN THE SANTA ANA MOUNTAIN CANYONS THIS MORNING. SKIES WILL 
BE MOSTLY CLEAR TODAY AND FRIDAY EXCEPT FOR A FEW HIGH CLOUDS. HIGH 
CLOUDINESS WILL INCREASE ENOUGH FOR PARTLY CLOUDY SKIES SATURDAY AS 
THE UPPER HIGH WEAKENS AND A TROUGH APPROACHES FROM WNW. A LITTLE 
WARMER TODAY AND FRIDAY WITH MAX TEMPS NEAR OR JUST A LITTLE BELOW 
SEASONAL AVERAGES. COOLER SATURDAY. 

&&

.LONG TERM (SUNDAY-WEDNESDAY)...MODELS REMAIN INCONSISTENT WITH THE 
TROUGH MOVING THROUGH EARLY NEXT WEEK. THE TROUGH SHOULD MOVE 
THROUGH FAIRLY SLOWLY WITH SOME THREAT OF PRECIP AS EARLY AS LATE 
SATURDAY NIGHT AND CONTINUING INTO MONDAY EVENING. DRIER NW FLOW 
SHOULD DEVELOP TUESDAY INTO WEDNESDAY. ANOTHER TROUGH WILL CAUSE A 
SMALL CHANCE OF SHOWERS WEDNESDAY AFTERNOON AND NIGHT. MAX TEMPS 
SHOULD BE ABOUT 5 TO 10 DEGREES BELOW SEASONAL AVERAGES IN MOST 
AREAS. 

&&

.AVIATION...
240900Z...MOSTLY CLEAR SKIES AND UNRESTRICTED VISIBILITIES WILL 
CONTINUE THROUGH FRIDAY. LOCAL GUSTY NE WINDS WILL OCCUR NEAR THE 
PASSES IN THE MORNINGS. 

&&

.MARINE
241300Z...A LARGE 10 FT...17 SECOND WEST SWELL WILL LIKELY BRING 
HIGH SURF AND POSSIBLE MINOR COASTAL FLOODING SUNDAY THROUGH TUESDAY 
OF NEXT WEEK. 

.SGX WATCHES/WARNINGS/ADVISORIES...

FROST ADVISORY FOR THE INLAND VALLEYS UNTIL 9 AM PST TODAY...SEE 
LAXNPWSGX.

&&

$$

PUBLIC...ATKIN  
AVIATION/MARINE...MACKECHNIE