AREA FORECAST DISCUSSION

 
 FXUS66 KSGX 170440
 AFDSGX
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SAN DIEGO CA
 940 PM PDT FRI MAY 16 2008
 
 .SYNOPSIS...
 STRONG HIGH PRESSURE OVER CALIFORNIA WILL BRING UNSEASONABLY HOT 
 WEATHER THIS WEEKEND. HIGH TEMPERATURES WILL EXCEED 100 DEGREES IN 
 THE INLAND AREAS AND IN THE DESERTS. IT WILL NOT BE QUITE AS HOT 
 NEAR THE COAST DUE TO THE COOLING EFFECTS OF THE AFTERNOON SEA 
 BREEZE. A LOW PRESSURE TROUGH WILL BRING GRADUAL COOLING EARLY NEXT 
 WEEK WITH A RETURN TO SEASONAL TEMPERATURES WEDNESDAY AND THURSDAY. 
 
 &&
 
 .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
 SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
 COUNTIES...
 
 OFFSHORE SUBSIDENCE WARMING FROM GUSTY NE WINDS SENT COASTAL HIGHS 
 INTO THE 80S AND 90S THIS AFTERNOON...10 TO 15 DEGREES HIGHER THAN 
 YESTERDAY. VALLEY TEMPS WERE ABOUT THE SAME AS YESTERDAY WITH 100 
 DEGREE HIGHS IN THE INLAND EMPIRE. MOUNTAIN TEMPS WERE LOWER BY A 
 FEW DEGREES. 
 
 A LIST OF RECORD MAXES AND MINS ARE HEADLINED ON OUR WEBPAGE.
 
 THE OFFSHORE SUPPORT HAS WEAKENED AND THE NORTHEAST WINDS WILL BE 
 LIGHTER SATURDAY AND SUNDAY. BUT THE HOT AIRMASS IS ALREADY IN PLACE 
 AND TEMPS THIS WEEKEND WILL REFLECT THIS. IN FACT THE 850 MB TEMPS 
 ACTUALLY INCREASE IN THE MTNS AND DESERTS FROM 23C THIS EVENING TO 
 AROUND 31C SUNDAY. IT IS LIKELY THAT THE HIGH DESERTS WILL REACH 100 
 SUNDAY...AND THE LOWER DESERTS WILL EXCEED 110. THE MOUNTAINS WILL 
 ALSO BE 10 TO 15 DEGREES HIGHER THAN TODAY. 
 
 A THERMAL LOW DEVELOPS IN RESPONSE TO THE DESERT HEAT. THIS WILL 
 INCREASE THE ONSHORE FLOW EACH AFTERNOON. THE LATEST 00Z MODEL 
 GUIDANCE FORECASTS THIS COOL MARINE AIR TO BEGIN COOLING THE 
 IMMEDIATE COAST SUNDAY AFTERNOON...THEN REACH THE INLAND VALLEYS 
 MONDAY. HOWEVER THE COOLING WILL NOT REACH THE MOUNTAINS AND DESERTS 
 UNTIL TUESDAY...SO THEY WILL REMAIN WARM/HOT MONDAY.
 
 LONG TERM...A MAJOR PATTERN CHANGE IN FORECAST NEXT TUESDAY THROUGH 
 FRIDAY WITH A HIGH AMPLITUDE LONG WAVE TROUGH OVER THE WEST HALF OF 
 THE NATION. COOL NORTHERLY FLOW EXTENDING FROM BRITISH COLUMBIA 
 SOUTHWARD INTO CALIFORNIA WILL BRING COOLER WEATHER WEDNESDAY TROUGH 
 FRIDAY WITH BREEZY NORTHEAST WINDS AT TIMES. 
 
 &&
 
 .AVIATION...170400Z
 MARINE INVERSION WAS IN THE 200-400 FT MSL RANGE. STRATUS WITH VERY 
 LOW CIGS...BELOW 300 FT...AND FOG WITH LOW VSBYS...BELOW 1 
 MILE...POSSIBLY EVEN BELOW 1/4 MILE...WILL LIKELY IMPACT THE 
 SOUTHERN PART OF THE SAN DIEGO COUNTY COAST AFT 08Z AND CONTINUE 
 THROUGH 15Z SAT. THERE IS ABOUT A 60% CHANCE THIS WILL REACH 
 LINDBERGH FIELD...THOUGH THE DURATION IS LIKELY TO BE SHORT. RAPID 
 CLEARING IS EXPECTED SAT WITH MOSTLY VFR CONDITIONS AFTER 15 OR 16Z. 
 WINDS THROUGH CANYONS/PASSES SHOULD MOSTLY REMAIN UNDER 25 KNOTS 
 SAT. STRATUS/FOG COULD RETURN TO THE COASTAL WATERS/IMMEDIATE COAST 
 LATE SAT NIGHT. 
 
 HIGH TEMPS DURING PEAK HEATING SAT WILL CAUSE DENSITY ALTITUDE 
 CONCERNS FOR MAINLY INLAND AIRPORTS.
 
 &&
 
 .SGX WATCHES/WARNINGS/ADVISORIES.
 
 SPECIAL WEATHER STATEMENT FOR THE HOT WEEKEND WEATHER...SEE 
 LAXSPSSGX.
 
 &&
 
 

 
 PUBLIC...MOEDE
 AVIATION/MARINE...MAXWELL
 
 NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
 
 
 
 
 

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