AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 200 PM PST THU NOV 6 2008
.SYNOPSIS...HIGH PRESSURE AND OFFSHORE FLOW WILL BRING CLEAR SKIES AND LOCAL GUSTY WINDS BELOW PASSES THROUGH FRIDAY. A WEAK LOW PRESSURE SYSTEM WILL BRING COOLER WEATHER WITH MORE CLOUDS SATURDAY THROUGH WEDNESDAY. HIGH PRESSURE WILL RETURN NEXT THURSDAY WITH FAIR AND WARMER WEATHER.
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.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
SPARKLING CLEAR WEATHER...WITH WARM DAYS AND COOL NIGHTS WILL CONTINUE THROUGH FRIDAY. HIGH PRESSURE ALOFT AND OFFSHORE FLOW WILL MAKE IT SO ONE MORE DAY. TODAY OFFSHORE WINDS ARE QUITE LOCALIZED AND NOT TOO STRONG WITH NOT MUCH MORE THAN A SURFACE OFFSHORE PRESSURE GRADIENT TO PUSH THEM. TOP WINDS TONIGHT AND FRIDAY MORNING WILL PEAK OUT AT AROUND 40-45 MPH AT THE FAVORED SPOTS...AND THAT SHOULD KEEP US SHY OF THE WIND ADVISORY CRITERIA. IT WILL BE VERY SIMILAR TO THE WINDS OF TODAY...WITH ONLY A SLIGHT EASTERLY SHIFT IN DIRECTION OF FLOW. TEMPERATURES WILL CLIMB A LITTLE MORE FRIDAY. LOWS AT NIGHT WILL CONTINUE ON THE COOL SIDE WITH THE DRY AIR IN MOST AREAS WHERE THE WIND WILL BE CALM. AN UPPER TROUGH OF LOW PRESSURE WILL HEAD INTO THE WEST COAST ON SATURDAY AND THROUGH CA SATURDAY NIGHT AND SUNDAY MORNING. MODELS HAVE BEEN INCONSISTENT OR AT LEAST IN DISAGREEMENT ON WHETHER THERE WILL BE PRECIPITATION OR NOT...BUT RIGHT NOW IT APPEARS TO REMAIN JUST BARELY ON THE DRY SIDE. THE MOISTURE IS VERY LIMITED AND A DEEP BUT DISRUPTED MARINE LAYER LOOKS LIKE THE BEST FORECAST FOR NOW. COOL NORTHWEST FLOW WILL CONTINUE FOR A FEW DAYS BEFORE THE UPPER RIDGE BUILDS AGAIN THE SECOND HALF OF NEXT WEEK FOR FAIR AND WARMER WEATHER.
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.AVIATION... 062100Z...CLEAR THROUGH FRIDAY. OFFSHORE FLOW WILL CAUSE LOCAL GUSTY NORTHEAST WINDS IN AND BELOW PASSES AND CANYONS...ESPECIALLY OVERNIGHT INTO TOMORROW MORNING. WIND GUSTS WILL GENERALLY REMAIN BELOW 30 KT WITH LOCALLY HIGHER GUSTS POSSIBLE NEAR THE SANTA ANA MOUNTAINS...IMMEDIATELY BELOW THE CAJON PASS...AND BELOW THE SAN DIEGO MOUNTAINS.
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.FIRE WEATHER... NO CHANGE FROM PREVIOUS FORECAST REASONING. CURRENT OBSERVATIONS OF WINDS...RELATIVE HUMIDITY...AND 10 HOUR DEAD FUEL MOISTURE LEVELS ARE ABOUT WHAT WAS EXPECTED. TEMPERATURES ONLY HAVE ABOUT ANOTHER HALF HOUR BEFORE SOLAR HEATING WANES. RELATIVE HUMIDITY RECOVERY WILL BE POOR OVERNIGHT AND EAST TO NORTHEAST WINDS WILL INCREASE AGAIN THIS EVENING INTO EARLY FRIDAY MORNING WITH SUSTAINED WINDS 20 MPH GUSTS 35-40 MPH MOST WIND PRONE AREAS EXCEPT THE EAST TO WEST ALIGNED CANYONS AND PASSES IN EASTERN SAN DIEGO COUNTY/WESTERN RIVERSIDE COUNTY MAY HAVE GUSTS CLOSER TO 50 MPH. FOR FRIDAY...TEMPERATURES WILL BE UP ANOTHER 5 DEGREES ALL AREAS...AND RELATIVE HUMIDITY WILL DROP INTO THE 5 TO 10 PERCENT RANGE...BUT WINDS WILL BE DIMINISHING AS THE DAY PROGRESSES...WITH PEAK GUSTS MID TO LATE MORNING IN THE 30 TO 40 MPH RANGE. FRIDAY NIGHT WILL AGAIN HAVE POOR HUMIDITY RECOVERY OVER THE VALLEYS AND COASTAL SLOPES...AND LINGERING DRY AIR SATURDAY WILL LIKELY LOWER RELATIVE HUMIDITY BELOW 15 PERCENT OVER MOST OF THE MOUNTAIN AND DESERT AREAS. THE INCREASE IN SOUTHWEST WINDS AHEAD OF THE APPROACHING TROUGH SATURDAY MAY CREATE SEVERAL HOURS OF CRITICAL FIRE WEATHER CONDITIONS FOR THE DESERTS SATURDAY AFTERNOON AND EVENING AND WILL HIGHLITE THIS WITH HEADLINES IN THE APPROPRIATE ZONES. AS BEFORE...NO RED FLAG WARNINGS OR FIRE WEATHER WATCHES FOR THIS.
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