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AREA FORECAST DISCUSSION

 
 FXUS66 KSGX 251133 CCA
 AFDSGX
 
 AREA FORECAST DISCUSSION...UPDATED
 NATIONAL WEATHER SERVICE SAN DIEGO CA
 330 AM PST WED NOV 25 2009
 
 .SYNOPSIS...HIGH PRESSURE ALOFT AND WEAK OFFSHORE FLOW WILL BRING 
 CLEAR SKIES AND WARMER DAYS THROUGH THURSDAY WITH LOCAL GUSTY WINDS 
 THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES. COOLER WITH MORE 
 CLOUDS AND A SLIGHT CHANCE OF RAIN SATURDAY AS UPPER LEVEL LOW 
 PRESSURE MOVES THROUGH. POTENTIALLY STRONG OFFSHORE FLOW ON SUNDAY 
 AND MONDAY WITH GUSTY WINDS BELOW THE PASSES AND CANYONS.
 
 &&
 
 .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... 
 ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
 
 .SHORT TERM (TODAY-FRIDAY)...SKIES WERE CLEAR THIS MORNING WITH 
 LOCALLY GUSTY WINDS BELOW THE PASSES AND CANYONS. WIND GUSTS WERE 
 GENERALLY LESS THAN 25 MPH...EXCEPT NEAR THE ANAHEIM HILLS FIRE 
 WHERE GUSTS TO 50 MPH HAVE BEEN OBSERVED. OFFSHORE GRADIENTS WITH 
 ABOUT -10 MB SAN-TPH.
 
 THE RIDGE ALOFT WILL SLOWLY SHIFT E AND OFFSHORE GRADIENTS WILL 
 GRADUALLY WEAKEN THROUGH THURSDAY. THIS WILL CONTINUE CLEAR SKIES 
 WITH A LITTLE WARMING IN MOST AREAS. THE WARMEST DAY IN MOST AREAS 
 WILL BE THURSDAY WITH MAX TEMPS ABOUT 6 TO 12 DEGREES ABOVE SEASONAL 
 AVERAGES INLAND FROM THE IMMEDIATE COAST. OFFSHORE WINDS WILL MAINLY 
 BE GRADIENT DRIVEN WITH LITTLE UPPER OR THERMAL SUPPORT. MOST WINDS 
 WILL REMAIN BELOW ADVISORY STRENGTH WITH GUSTS TO ABOUT 35 MPH AT 
 TIMES THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES. HOWEVER...THERE 
 COULD BE ISOLATED STRONGER GUSTS TO 50 MPH THIS MORNING IN THE WIND 
 PRONE AREAS OF THE SANTA ANA MOUNTAINS AND FOOTHILLS AND BELOW THE 
 CAJON PASS. THE WARM...DRY OFFSHORE WINDS WILL MAINTAIN AN ELEVATED 
 FIRE WEATHER HAZARD. COOL AT NIGHT IN AREAS PROTECTED FROM THE 
 WINDS. 
 
 ONSHORE FLOW WILL RETURN AHEAD OF AN APPROACHING TROUGH. THIS WILL 
 BRING COOLER WEATHER AND A RETURN OF SOME MARINE LAYER CLOUDS AND 
 HIGH CLOUDINESS FRIDAY. THE MARINE LAYER WILL INITIALLY BE QUITE 
 SHALLOW WITH PATCHY DENSE FOG POSSIBLE AT THE COAST DURING THE DAY. 
 THE MARINE LAYER SHOULD BEGIN TO DEEPEN FRIDAY NIGHT.
 
 &&
 
 .LONG TERM (SATURDAY-TUESDAY)...LATEST GUIDANCE INDICATES THAT A 550 
 DM UPPER LOW WILL MOVE OVER SOUTHERN CALIFORNIA ON SATURDAY WITH A 
 100+ KT JET TO OUR SOUTH. THIS WILL BRING A MUCH DEEPER MARINE 
 LAYER...COOLER WEATHER...AND A SLIGHT CHANCE OF RAIN AND MOUNTAIN 
 SNOW. STRONG OFFSHORE FLOW MAY DEVELOP IN THE WAKE OF THIS UPPER LOW 
 SUNDAY AND MONDAY. THE LATEST ECMWF...GFS AND DGEX INDICATE NE WINDS 
 OF 30-40 KT AT 850 MB WITH MODEST OFFSHORE PRESSURE GRADIENTS. IT 
 WILL STILL BE COOL THOUGH DUE TO COLD ADVECTION FROM THE NORTH. 
 MOSTLY CLEAR AND WARMER MONDAY AND TUESDAY. 
 
 &&
 
 .AVIATION...
 250930Z...CLEAR SKIES AND UNRESTRICTED VISIBILITY EXCEPT FOR SMOKE 
 FROM WILDFIRE BELOW FL020 VICINITY SANTA ANA RIVER CANYON SOUTHWEST 
 TOWARDS KSNA. GAP WINDS EAST TO NORTHEAST 15-25KT WITH GUSTS 35-45KT 
 THROUGH MOUNTAIN PASSES AND ALIGNED CANYONS UNTIL 26/1800 UTC WILL 
 CREATE AREAS OF TURBULENCE AND LLWS...MAINLY BELOW THE CAJON 
 PASS...AND OVER THE ORANGE COUNTY COASTAL PLAIN INCLUDING KSNA.
 
 &&
 
 .MARINE...
 MODERATE TO LARGE WNW SWELL TO ARRIVE THURSDAY NIGHT AND CONTINUE 
 THROUGH SATURDAY. WAMIII MODEL FOR SEVERAL DAYS HAS BEEN ADVERTISING 
 A RAPID INCREASE IN SWELL HEIGHTS LATE THURSDAY AFTERNOON/EVENING 
 REACHING 8 FT AT 16 SECONDS FROM 295 DEGREES OVERNIGHT/EARLY FRIDAY 
 MORNING. THE CURRENT OFFSHORE WIND FLOW PATTERN ENDS SHORTLY BEFORE 
 THIS AND CLIMATOLOGY FAVORS DENSE FOG NEAR SHORE AS FLOW RETURNS TO 
 ONSHORE. CONDITIONS COULD BE QUITE HAZARDOUS LATE THURSDAY THROUGH 
 FRIDAY MORNING ENTERING AND EXITING HARBORS AND BAYS. CONFIDENCE 
 FAIRLY HIGH IN HIGH SURF EVENT FRIDAY AND SATURDAY
 
 &&
 
 .SGX WATCHES/WARNINGS/ADVISORIES...
 
 RED FLAG WARNING UNTIL 10 AM PST THURSDAY FOR THE SANTA ANA 
 MOUNTAINS AND FOOTHILLS. SEE LAXRFWSGX. 
 
 &&
 
 

 
 PUBLIC...SCV
 AVIATION/MARINE...BALFOUR
 
 
 
 
 
 
 
 
 

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