000
FXUS66 KSEW 042142
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PDT FRI JUL 4 2008
.SYNOPSIS...A CHANCE OF SHOWERS WILL LINGER INTO THE EVENING...THEN
THE TAIL END OF ANOTHER SYSTEM WILL BRING A LITTLE RAIN TO THE AREA
ON SATURDAY. LOOK FOR DRY WEATHER WITH NEAR OR SLIGHTLY ABOVE NORMAL
DAYTIME TEMPERATURES ON SUNDAY UNDER WEAK HIGH PRESSURE ALOFT. A
WARMING TREND WILL KEEP SKIES MAINLY SUNNY NEXT WEEK.
&&
.SHORT TERM...SOME BREAKS IN THE CLOUDS BUT BASICALLY A MOSTLY
CLOUDY AFTERNOON. HIGHS LOOK LIKE THEY WILL BE 65 TO 75...COOLER ON
THE COAST. WILL KEEP A SMALL CHANCE OF SHOWERS GOING THIS EVENING
EVEN THOUGH SO FAR NOTHING HAS HAPPENED...THERE HAVE BEEN CUMULUS
CLOUDS FILLING THE HOLES AND A SHOWER IS STILL POSSIBLE.
NEXT UP IS A WEAK SYSTEM ON SATURDAY. THIS MOVES IN DURING THE DAY
AND DOES NOT SEEM TO HAVE MUCH PUNCH. THERE WILL PROBABLY BE A
LITTLE RAIN ON THE COAST AND PERHAPS NORTH AND HAVE PUT KEPT LIKELY
POPS THERE. NOT GOING TO BE MUCH IN THE INTERIOR AND EVEN THAT WILL
HAVE TO WAIT UNTIL THE AFTERNOON. SMALL CHANCE OF SHOWERS CONTINUES
INTO SATURDAY EVENING. WITH THE CLOUDS AND THE LOWER HEIGHTS
ASSOCIATED WITH AN UPPER TROUGH...TEMPS WILL BE SLIGHTLY LOWER ON
SATURDAY.
HEIGHTS COMMENCE BUILDING ON SUNDAY. SHOULD BE SEVERAL DEGREES
WARMER SUNDAY AS CLOUDS EVAPORATE AND EARLY JULY SUN BEATS DOWN AND
HAVE GONE FOR MID 70S. STILL MIGHT BE A LINGERING SHOWER OR TWO IN
THE CASCADES BUT EVERYWHERE ELSE WILL BE DRY. MONDAY LOOKS EVEN
WARMER WITH HEIGHTS IN THE 580S...HOWEVER PERSISTENT ONSHORE LOW
LEVEL FLOW WILL KEEP THINGS COOLER THAN THEY OTHERWISE WOULD BE.
STILL HAVE GONE WITH THE HIGH END OF ENSEMBLES AS FAR AS TEMPS.
.LONG TERM...WITH ONSHORE FLOW HAVE INDICATED A BROAD BRUSH TYPICAL
DIURNALLY VARYING SUMMER PATTERN...WITH AREAS OF LATE NIGHT AND
MORNING CLOUDS...AND MOSTLY SUNNY IN THE AFTERNOON. AGAIN HAVE
FORECAST TEMPS AT THE HIGH END OF THE ENSEMBLES. HEIGHTS REMAIN IN
THE 580S AND THERE SHOULD BE NO PROBLEM GETTING WELL INTO THE 70S
EACH DAY. MODELS INDICATE A WEAK TROUGH ON FRIDAY DEPRESSING HEIGHTS
AND HAVE GONE SLIGHTLY COOLER THEN. BURKE
&&
.AVIATION...AN UPPER LEVEL TROUGH JUST OFFSHORE WILL MAINTAIN SW
FLOW ALOFT AND A MOIST LOW LEVEL AIR MASS OVER WESTERN WA THROUGH
THIS EVENING. SOME SHOWER ACTIVITY GOING ON IN THE WEAKLY UNSTABLE
AIR MASS...BUT NOTHING EXCITING. VFR CIGS RUNNING GENERALLY
BKN050-060 AND THAT SHOULD CONTINUE THROUGH THE EVENING. EXPECT
NORMAL OVERNIGHT LOWERING OF CIGS TO BKN015-025 AHEAD OF THE COLD
FRONT.
A WEAK COLD FRONT WILL MOVE THROUGH THE AREA SATURDAY. GFS IS A
LITTLE FASTER THAN NAM. WILL FOLLOW THE MORE PESSIMISTIC NAM AT THIS
POINT...SO FROPA COAST AROUND 21Z AND PUGET SOUND AROUND 01Z. WILL
HANG ON TO MVFR CIGS THROUGH THE DAY.
KSEA...EXPECT CURRENT CONDITIONS TO CONTINUE THROUGH THE EVENING...
SO WILL KEEP CIGS AROUND BKN050-060. BOTH MAV/MET MOS SHOW CIGS
010-020 LATE TONIGHT SO WILL GO WITH PERSISTENCE FORECAST THERE AS
WELL. NO CHANGE TO S WINDS. KAM
&&
.MARINE...THE SURFACE RIDGE OVER WESTERN WA WILL KEEP PRESSURE
GRADIENTS AND WINDS WEAK THROUGH THIS EVENING. THE APPROACHING COLD
FRONT JUST INSIDE 135W IS MORE ORGANIZED THAT WE`VE SEEN FOR QUITE A
WHILE...BUT IS STILL RATHER WEAK. SHOULD BEGIN AFFECTING THE COASTAL
WATERS AFTER MIDNIGHT...WITH WINDS OVER THE COASTAL WATERS REACHING
LOW END SCA AFTER MIDNIGHT. UPSTREAM BUOY 36 HASN`T REACTED STRONGLY
YET SO WILL WAIT ON THE ADVISORY AND LET THE MIDSHIFT PUT IT UP.
GFS/NAM AGREE ON A SATURDAY MORNING FROPA ON THE COAST. HAVE DECIDED
TO GO WITH WRF-GFS WINDS...SO FORECAST HAS LOW END SCA S WINDS
AROUND MIDDAY SATURDAY FOR THE E STRAIT AND N INLAND WATERS.
SHOULD HAVE A SCA IN THE CENTRAL/EAST STRAIT LATE SATURDAY BEHIND
THE FRONT. THE SURFACE RIDGE SLOWLY SHIFTS FARTHER AND FARTHER
OFFSHORE SATURDAY AFTERNOON THROUGH MONDAY...WITH GRADUALLY
INCREASING ONSHORE FLOW ACROSS THAT PERIOD. SHOULD BE BACK TO THE
NORMAL DIURNAL SCA`S IN THE STRAIT. KAM
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
NONE.
$$
WEATHER.GOV/SEATTLE
