FXUS66 KSEW 252134
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
235 PM PDT THU SEP 25 2003

.SYNOPSIS...A STRONG UPPER LEVEL HIGH PRESSURE SYSTEM WILL BUILD 
TONIGHT AND FRIDAY AND REMAIN OVER THE AREA THROUGH EARLY NEXT WEEK. 
THERMAL LOW PRESSURE WILL DEVELOP ALONG THE COAST LATE FRIDAY WITH 
THE RESULTING OFFSHORE FLOW PUSHING HIGH TEMPERATURES TO NEAR RECORD 
READINGS BY SUNDAY. THE RIDGE WILL MOVE EAST THE FIRST PART OF NEXT 
WEEK BRINGING ABOUT AN END TO THE OFFSHORE FLOW. THIS WILL LEAD TO 
HIGH TEMPERATURES CLOSER TO NORMAL THE FIRST PART OF NEXT WEEK.   

.DISCUSSION...SATELLITE IMAGERY SHOWS MOST OF THE CLOUD COVER HAS 
DISSIPATED OVER WESTERN WASHINGTON THIS AFTERNOON. SURFACE GRADIENTS 
HAVE GONE NORTHERLY AND STRATUS ALONG THE COAST SHOWING SIGNS OF 
PULLING OFFSHORE. WARM WEEKEND STILL ON TRACK WITH UPPER LEVEL RIDGE 
BUILDING AND THERMAL LOW PRESSURE EXPANDING UP THE COAST TOMORROW. 
850 MB WINDS COMING AROUND TO EAST 00Z-06Z SAT AND PROGGED TO BE 
NEAR 20 KNOTS ON SATURDAY. MODEL 850 MB TEMPS STILL RUNNING IN THE 
HIGH TEENS CELSIUS FOR THE WEEKEND. THIS IS A GOOD COMBINATION FOR 
RECORD TEMPERATURES OVER THE CWA. SATURDAYS RECORD HIGHS ARE NEAR 
90 IN MANY PLACES WHICH WILL MAKE IT TOUGH TO BEAT BUT SUNDAYS 
RECORD HIGHS ARE CLOSER TO 80. WITH THE UPPER LEVEL RIDGE AXIS AND 
THE THERMAL RIDGE AXIS RIGHT OVER WESTERN WASHINGTON ON SUNDAY THIS 
LOOKS TO BE THE WARMEST DAY EVEN WITH THE LOW LEVEL EASTERLIES 
DECREASING. IN THE HISTORY OF SEATAC AIRPORT THERE HAVE ONLY BEEN 13 
DAYS WHERE THE HIGH HAS REACHED 80 DEGREES THE LAST WEEK OF 
SEPTEMBER. WE HAVE A SHOT AT TWO IN A ROW SATURDAY AND SUNDAY.
.EXTENDED...ONCE AGAIN NOT MUCH CONSISTENCY IN THE EXTENDED MODELS. 
GFS STILL WANTS TO KICK THE UPPER LOW WELL OFF THE CALIFORNIA COAST 
TOWARD OREGON INITIALLY THEN HAVE IT TURN NORTH ALONG 130W. THE 
CANADIAN MEANWHILE KEEPS A STRONG RIDGE OVER THE AREA. MORE 
AGREEMENT ON SOLUTIONS AT THE SURFACE WITH THE THERMALLY INDUCED 
TROUGH MOVING EAST OF THE CASCADES MONDAY. TEMPERATURES ALOFT COOL 
AS THE THERMAL RIDGE ALSO SHIFTS EAST BUT STILL WARM FOR THIS TIME 
OF YEAR. FOR NOW WILL GO WITH COOLER MAX TEMPS ON MONDAY WITH A 
MARINE PUSH BUT STILL NEAR OR A BIT ABOVE NORMAL FOR THIS TIME OF 
YEAR. BEYOND MONDAY WILL STAY WITH THE WEAK ONSHORE PATTERN AND NOT 
BITE OFF ON THE GFS SOLUTION WHICH UNDERCUTS THE RIDGE AND BRINGS 
PRECIP INTO THE AREA TUESDAY AND THURSDAY. FELTON

.SEW...NONE.

.KATX...VCP31/CSR32...OPERATIONAL.

$$