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FXUS66 KSGX 152035
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
200 PM PDT THU MAY 15 2008
.SYNOPSIS...
STRONG HIGH PRESSURE ALONG THE WEST COAST AND WEAK OFFSHORE FLOW
WILL BRING HOT DAYS TO INLAND AREAS THROUGH THE WEEKEND WITH THE
HIGH TEMPERATURES EXTENDING NEARLY TO THE COAST ON FRIDAY AND
POSSIBLY SATURDAY. CONTINUED WARM SUNDAY AND MONDAY...THEN ONSHORE
FLOW WILL BRING A RETURN OF THE MARINE LAYER AND A COOLING TREND.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
STRONG UPPER LEVEL HIGH PRESSURE RIDGE CENTERED OVER THE WEST COAST
WILL SHIFT SLOWLY SOUTHWARD THROUGH SATURDAY. WEAK OFFSHORE FLOW
WILL BRING LOCALLY GUSTY WINDS THROUGH AND BELOW PASSES AND CANYONS
AT TIMES INTO SATURDAY. SUPPORT FOR WINDS SHIFTS INTO SOUTHERN AREAS
FOR FRIDAY...BUT ALSO ONLY BORDERLINE ADVISORY STRENGTH. WARMING
WILL CONTINUE TODAY WITH THE WEAK OFFSHORE FLOW BRINGING THE
GREATEST WARMING TO THE INLAND EMPIRE...ALTHOUGH IT WILL BE SOMEWHAT
MODERATED BY THE CIRRUS CLOUD COVER. THE OFFSHORE FLOW FOR FRIDAY
MAY ALLOW THE MUCH WARMER TEMPERATURES TO EXTEND NEARLY TO THE COAST
WITH HIGH TEMPERATURES WELL ABOVE SEASONAL AVERAGES FOR MOST AREAS
AND GREATEST DEPARTURES FROM SEASONAL AVERAGES FROM THE COAST INLAND
TO THE LOWER COASTAL VALLEYS. NOT MUCH CHANGE FOR SATURDAY EXCEPT
FOR SLIGHT COOLING POSSIBLE AT THE IMMEDIATE COAST AS WEAKER
OFFSHORE FLOW ALLOWS FOR MORE OF A SEA BREEZE. FOR MOST COASTAL
AREAS... HIGHEST TEMPERATURES WILL LIKELY BE EITHER FRIDAY OR
SATURDAY. NEAR RECORD HIGH TEMPERATURES ARE POSSIBLE FOR SOME
COASTAL AND VALLEY LOCATIONS...MAINLY FRIDAY AND SATURDAY WITH THE
STRONGEST OFFSHORE PRESSURE GRADIENTS.
MODELS INDICATE 850 MB TEMPERATURES SLOWLY WARM FOR SATURDAY AND
SUNDAY...PEAKING SUNDAY...ALTHOUGH A WEAK SEA BREEZE MAY BRING A
SLIGHT MODERATION IN THE HEAT NEAR THE COAST DURING THE
WEEKEND...AREAS FARTHER INLAND WILL CONTINUE TO WARM WITH
TEMPERATURES FOR THE FAR INLAND VALLEYS...MOUNTAINS...AND DESERTS
PROBABLY PEAKING ON SUNDAY AND REMAINING HIGH ON MONDAY BEFORE
LOWERING ON TUESDAY. WHILE IN LESS THAN GREAT AGREEMENT ON THE
DETAILS...THERE IS A GROWING MODEL CONSENSUS IN MOVING A TROUGH OF
LOW PRESSURE INLAND ALONG THE WEST COAST BYTHE MIDDLE OF NEXT WEEK.
CURRENT FORECAST SHOWS A GRADUAL RETURN TOWARD CLIMO (I.E. COOLING
AND A RETURN OF THE MARINE LAYER)...THE DETAILS OF WHICH WILL LIKELY
NEED TO BE MODIFIED AND PERHAPS ACCELERATED A BIT.
&&
.AVIATION...
151915Z...MDCRS SOUNDINGS FROM DEPARTURES FROM KSAN STILL SHOW THE
MARINE LAYER DEPTH AROUND 1000 FEET BUT SOUNDINGS FROM NEAR KSNA AND
KLAX SHOW THE DEPTH IN THOSE AREAS LESS THAN 500 FEET. EXPECT SOME
LOWERING OF THE DEPTH NEAR KSAN TONIGHT. NOT VERY CONFIDENT THAT
STRATUS WILL NOT BE A PROBLEM AT KSAN TONIGHT SO WILL MENTION FEW008
IN THE TAF FOR KSAN THROUGH THIS EVENING BUT BEST COURSE OF ACTION
MIGHT BE TO PLAN FOR SOME LOW CEILINGS SOMETIME TONIGHT. ANY CEILING
THAT DOES OCCUR SHOULD BE GONE SHORTLY AFTER SUNRISE ON FRIDAY.
NORTH OF KSAN NOT EXPECTING MUCH PROBLEM WITH STRATUS FOR TONIGHT AS
OFFSHORE FLOW SHOULD PREVAIL.
ABOVE THE MARINE LAYER...EXCEPT FOR CIRRUS AT OR ABOVE FL250...A
MOSTLY CLEAR SKY WITH UNRESTRICTED VISIBILITIES WILL CONTINUE
THROUGH FRIDAY.
THE MAIN PROBLEM WILL BE DENSITY ALTITUDE RELATED ISSUES AT MOST
AREA AIRPORT FOR FRIDAY. TEMPERATURES COULD REACH 30 TO 35C AT
KSNA...40C AT KONT AND VICINITY AIRPORT AND 40 TO 42C AT KPSP AND
KTRM.
&&
.FIRE WEATHER...
STRONG HIGH PRESSURE ALONG THE WEST COAST WILL BRING TEMPERATURES
WELL ABOVE SEASONAL AVERAGES THROUGH THE WEEKEND WITH HOT DAYTIME
CONDITIONS EXTENDING NEARLY TO THE COAST ON FRIDAY AND POSSIBLY
SATURDAY. WEAK OFFSHORE FLOW WILL BRING MUCH LOWER RELATIVE
HUMIDITIES TO INLAND AREAS TODAY AND FRIDAY WITH GUSTY WINDS THROUGH
AND BELOW PASSES AND CANYONS. A RED FLAG WARNING HAS BEEN ISSUED FOR
THE INLAND EMPIRE TODAY WITH A FIRE WEATHER WATCH FOR THE VALLEYS
FRIDAY. THE DAY SHIFT IN CONJUNCTION WITH THE GACC MAY WANT TO LOOK
MORE CLOSELY AT THE LOWER COASTAL SLOPES TO SEE IF FUEL MOISTURES
HAVE FALLEN LOW ENOUGH TO WARRANT A FIRE WEATHER WATCH FOR FRIDAY.
LONG DAYTIME DURATIONS OF LOW RELATIVE HUMIDITIES WILL CONTINUE INTO
THE WEEKEND FOR INLAND AREAS.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
FOR SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND
EMPIRE-SAN DIEGO COUNTY INLAND VALLEYS.
RED FLAG WARNING FROM 9 AM THIS MORNING TO 6 PM PDT THIS
AFTERNOON FOR SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-
THE INLAND EMPIRE.
PZ...NONE.
&&
$$
PUBLIC...PG
AVIATION/MARINE...HORTON
NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
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