AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 845 PM PST SAT NOV 13 1999
SATELLITE IMAGERY SHOWS WEAK RIDGING FINALLY BEGINNING TO DEVELOP
OVER WESTERN WASHINGTON AFTER A DRIPPY DAY. SURFACE OBS HAVE SKIES
SCATTERING OUT AS FAR NORTH AS KTDO WHILE LIGHT RAIN CONTINUES IN
WHATCOM COUNTY AS WARM FRONT REMAINS HUNG UP ALONG THE CANADIAN
BORDER. AS RIDGE CONTINUES TO BUILD TONIGHT THIS SHOULD PUSH PRECIP
NORTH OF THE BORDER IN THE NEXT COUPLE OF HOURS. WITH THE CONSTANT
PRECIP TODAY LOW LEVELS OF THE AMS ARE EXTREMELY MOIST WITH DEWPTS
ANYWHERE FROM TWO TO NINE DEGREES ABOVE LAST NIGHT...IN THE MID 40S
TO MID 50S. REASON FOR THE CLEARING TO THE SOUTH IS EVIDENT IN THE
ACARS SOUNDINGS WITH MULTIPLE REPORTS SOUTHEAST OF SEA-TAC REPORTING
WINDS AT 2000 FEET SSW AT 20-25 KT. CONTRAST THIS WITH VAD WIND
PROFILER ON WSR-88D WHICH HAS LIGHT WINDS UP TO 6000 FEET. EVEN WITH
THE MIXING TO THE SOUTH SURFACE GRADIENTS ARE LIGHT AND FOG ALREADY
FORMING. THIS WILL BE THE STORY OVER ALL OF WESTERN WASHINGTON
TOMORROW MORNING WITH MODELS SHOWING INVERSIONS STILL IN PLACE AND
LIGHT SURFACE GRADIENTS. RECORD MAX TEMPS TO THE SOUTH IN PORTLAND
SATURDAY AND 850 MB TEMPS AT SALEM +12C AT 00Z. WITH UPPER LEVEL
RIDGE BUILDING THIS WARM AIR WILL MOVE NORTHWARD SO EVEN THOUGH NOT
EXPECTING MUCH SUNSHINE UNTIL THE AFTERNOON TEMPERATURES WILL CLIMB
QUICKLY ONCE THE SUN BREAKS THROUGH. FIRST LOOK AT NEW MODEL RUNS
SHOWS LITTLE CHANGE FROM 00Z RUN SO FAR. WILL ADD SOME FOG TO THE
SUNDAY MORNING FORECAST OTHERWISE NO CHANGES. FELTON
UIL 9311 SEA 2101 OLM 2101
.KATX...VCP21/CSR21...OPERATIONAL...
.SEW...SCA W ENTRANCE STRT JDF.