FXUS66 KSGX 231110
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
310 AM PST WED DEC 23 2009

.SYNOPSIS...
FAIR...DRY...AND WARMER THROUGH FRIDAY AS HIGH PRESSURE ALOFT BUILDS 
OFF THE WEST COAST. SURFACE HIGH PRESSURE OVER THE GREAT BASIN WILL 
BRING LOCAL OFFSHORE WINDS AT TIME THE NEXT FEW DAYS. FOR SUNDAY 
THROUGH EARLY NEXT WEEK...LOW PRESSURE FROM THE PACIFIC WILL BRING 
COOLER WEATHER AND A CHANCE OF PRECIPITATION.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

.SHORT TERM (TODAY THROUGH FRIDAY)...
THE STRONG...COLD TROUGH OF LOW PRESSURE THAT BROUGHT SHOWERS AND 
STRONG WINDS YESTERDAY IS MOVING EASTWARD...NOW CENTERED ALONG THE 
ARIZONA...NEW MEXICO BORDER. SURFACE HIGH PRESSURE OVER THE GREAT 
BASIN...BEHIND THIS UPPER TROUGH OF LOW PRESSURE...WILL BRING 
LOCALLY GUSTY NORTH TO NORTHEAST WINDS THIS MORNING BELOW PASSES AND 
CANYONS. IT IS STILL VERY MUCH A NORTH FLOW EVENT EARLY THIS MORNING 
BASED ON WHERE THE GUSTS ARE STRONGEST WITH STRONGEST GUSTS OF 40 TO 
45 MPH IN THE INLAND EMPIRE AND IN THE SANTA ANA MOUNTAINS.

SURFACE HIGH PRESSURE WILL LINGER OVER THE GREAT BASIN TONIGHT INTO 
SATURDAY BRINGING MOSTLY WEAK OFFSHORE WINDS AT TIMES. BUILDING HIGH 
PRESSURE ALONG AND OFF THE CALIFORNIA COAST WILL BRING WARMING TO 
NEAR SEASONAL LEVELS THROUGH FRIDAY. IN THE COLDER...DRIER AIR MASS 
BEHIND THE DEPARTING TROUGH OF LOW PRESSURE...PATCHY FROST IS 
POSSIBLE IN COLDER...WIND SHELTERED PORTIONS OF THE VALLEYS EARLY 
THIS MORNING AND AGAIN LATE TONIGHT THROUGH EARLY THURSDAY MORNING.

&&

.LONG TERM (SATURDAY THROUGH TUESDAY)...
HIGH CLOUDS WILL INCREASE AND TEMPERATURES WILL BEGIN TO COOL 
SATURDAY AS HIGH PRESSURE ALONG THE WEST COAST BEGINS TO WEAKEN. 
MORE COOLING AND INCREASING CHANCES FOR PRECIPITATION FOR SUNDAY 
INTO EARLY NEXT WEEK AS FLOW ACROSS THE PACIFIC UNDERCUTS THE 
WESTERN U.S. RIDGE. CONTINUING MODEL TO MODEL AND RUN TO RUN 
DIFFERENCES WITH PRECIPITATION DETAILS DURING THIS PERIOD.

&&

.AVIATION...
231000Z...AREAS OF 15 TO 20 MPH NORTH WINDS OVER THE COASTAL WATERS 
AND BELOW MOUNTAIN PASSES THIS MORNING...OTHERWISE CLEAR WITH LIGHT 
WINDS THROUGH FRIDAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FROST ADVISORY UNTIL 9 AM PST THIS MORNING FOR SAN BERNARDINO 
     AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO 
     COUNTY VALLEYS.

     FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PST THURSDAY FOR 
     SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND 
     EMPIRE-SAN DIEGO COUNTY VALLEYS.

     WIND ADVISORY UNTIL NOON PST TODAY FOR SAN BERNARDINO AND 
     RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SANTA ANA 
     MOUNTAINS AND FOOTHILLS.

PZ...GALE WARNING UNTIL 2 AM PST EARLY THIS MORNING FOR WATERS FROM 
     SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM 
     OUT INCLUDING SAN CLEMENTE ISLAND.

     SMALL CRAFT ADVISORY UNTIL 2 AM PST EARLY THIS MORNING FOR 
     COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER 
     AND OUT 30 NM.

&&

$$

PUBLIC...MARTIN
AVIATION/MARINE...MACKECHNIE

NWS ON THE WEB AT WEATHER.GOV/SANDIEGO