000
FXUS66 KSEW 101548
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
850 AM PDT FRI OCT 10 2008
.SYNOPSIS...STRONG HIGH PRESS ALOFT OFFSHORE IS EXPECTED TO SLOWLY
DRIFT EAST INTO THE PACIFIC NORTHWEST THROUGH THE WEEKEND. THIS
WEATHER PATTERN WILL PROVIDE GENERALLY CLEAR SKIES..CRISP MORNINGS..
AND AREAS OF NIGHT AND MORNING FOG AND LOW CLOUDS. THE HIGH PRESSURE
ALOFT IS FORECAST TO MOVE EAST OF THE CASCADES MONDAY AS A WEAK WARM
FRONT APPROACHES FOR A THREAT OF RAIN. WESTERLY FLOW ALOFT WILL
PREVAIL NEXT WEEK BRINGING A FEW WEAK PACIFIC FRONTS THROUGH THE
REGION.
&&
.SHORT TERM...GOSH..IT FEELS LIKE FALL ALREADY. THE HIGH AMPLITUDE
UPPER RIDGE IS NOW INCHING INSIDE 140W WHILE OUR PESKY UPPER LOW HAS
NOW SAGGED SE INTO THE GREAT BASIN. COOL NORTHERLY FLOW ALOFT AND AT
THE SURFACE HAS DEVELOPED OVER OUR AREA.
MORNING SATELLITE IMAGES AND SURFACE OBSERVATIONS SHOW AREAS OF LOW
CLOUDS AND SOME FOG FROM MAINLY ARLINGTON AND EVERETT SOUTHWARD THRU
PUGET SOUND AND DOWN TO THE COLUMBIA RIVER. UPSLOPE FLOW ON THE
OLYMPICS ALSO PRODUCING SOME CLOUDS NEAR PORT ANGELES AND SEQUIM.
THE REST OF THE AREA IS GENERALLY CLEAR AND COOL THIS MORNING AND
THE MORNING CLOUDS AND FOG SHOULD DISSIPATE BY MIDDAY FOR LOTS OF
SUNSHINE BUT HIGH TEMPS REMAINING BELOW SEASONAL NORMS.
THEN THERE IS TONIGHT. WITH THE CLEARING SKIES..COOL AIR MASS AND
EASING NORTHERLY WINDS..LOOK FOR OUR FIRST MORE WIDESPREAD NIGHT OF
NEAR OR BELOW FREEZING TEMPS. THE EXCEPTIONS WILL BE AREAS NEAR
BODIES OF WATER LIKE PUGET SOUND..THE STRAIT AND COASTAL WATERS.
LOOK FOR A STATEMENT TO BE ISSUED ON THIS LATER SITUATION TODAY. CAN
YOU SAY FROST ON THE PUMPKIN?
THE UPPER RIDGE WILL DOMINATE THE WEATHER THROUGH SUNDAY AS IT
SLIDES EAST OVER THE PACIFIC NORTHWEST. SO CLEAR SKIES WITH THE
EXCEPTION OF SOME NIGHT AND MORNING FOG OR LOW CLOUDS. TEMPS WILL
MODERATE A BIT EACH DAY..CLIMBING CLOSE TO AVERAGE BY SUNDAY.
BY LATE SUN..FRESH FORECAST GUIDANCE THIS MORNING CONTINUES THE
TREND OF EASING THE UPPER RIDGE INLAND AS A WEAK PACIFIC WARM FRONT
APPROACHES THE COAST. ANTICIPATE AN INCREASE IN CLOUD COVER ALONG
THE COAST AND OLYMPIC PENINSULA FOLLOWED BY A THREAT OF RAINFALL SUN
NIGHT. FALL IS HERE. BUEHNER
.LONG TERM...FROM PREVIOUS DISCUSSION..WESTERLY FLOW ALOFT WILL
FOLLOW THE UPPER RIDGE AND PREVAIL ACROSS THE FORECAST AREA MONDAY
THROUGH THURSDAY. BEST GUESS IS THAT TWO WEAK FRONTAL SYSTEMS
EMBEDDED IN THE ZONAL FLOW WILL MOVE THROUGH WESTERN WASHINGTON
DURING THAT FOUR DAY PERIOD...BUT LONGER RANGE MODELS CONTINUE TO
SHOW POOR AGREEMENT AND CONSISTENCY ON THE TIMING. THE CURRENT
TIMING IN THE EXTENDED FORECAST DOES NOT AGREE TOO WELL WITH THE
MOST RECENT GFS...BUT GIVEN THE UNCERTAINTY IT IS FINE FOR NOW.
MCDONNAL
&&
.AVIATION...AN OFFSHORE UPPER LEVEL RIDGE OF HIGH PRESSURE PRODUCING
MOSTLY DRY NORTHERLY FLOW ACROSS WESTERN WASHINGTON TODAY. EXCEPTION
THIS MORNING IS MOISTURE NEAR THE SURFACE RESULTING IN AREAS OF LOW
CLOUDS AND FOG ESPECIALLY NEAR THE TYPICAL WATER SOURCES. FALL
MORNING SUN WEAKER IN INTENSITY...SO BURNOFF TIME WILL TAKE A LITTLE
LONGER PROBABLY NEAR 18-20Z FOR A MOSTLY SUNNY FALL AFTERNOON. NEXT
PROBLEM IS TOMORROW...SATURDAY..MORNING. WITH WIDESPREAD FREEZING OR
NEAR FREEZING EARLY MORNING TEMPERATURES...FROST OUT OF MOISTURE
LIKELY SO MORNING FOG FORMATION COULD BE DELAYED TO LATER IN
THE MORNING OR NOT AT ALL. WILL LOOK CLOSER AT THIS ISSUE FOR
AFTERNOON PACKAGE. WINDS TO REMAIN NORTHERLY TODAY...DECREASING
OVER THE WEEKEND AS THE RIDGE MOVES FURTHER INLAND OVER WESTERN
WASHINGTON. PRANGE
KSEA...MVFR LOW CLOUDS WILL PERSIST THROUGH 18-20Z...AND
NLY WINDS 5 TO 10 KT. SKIES WILL CLEAR OUT THIS AFTERNOON. PATCHY
FOG IS EXPECTED SAT MORNING. PRANGE
&&
.MARINE...A STRONG 1034 MB RIDGE OF HIGH PRES CENTERED OFFSHORE
ALONG 135W WILL CONTINUE TO PRODUCE NORTHERLY FLOW ACROSS W WA
TODAY. SEAS THIS MORNING AT BUOY 041 WERE AROUND 10 FT BUT SHOULD
SEE SWELLS BEGIN TO SUBSIDE LATE THIS AFTERNOON. NORTHERLY WIND
COMPONENT TODAY AND THROUGH THE WEEKEND. WIND SPEEDS SHOULD BEGIN TO
DIMINISH AS PRESSURE GRADIENTS RELAX LATER TODAY AND INTO THE
WEEKEND. ONSHORE FLOW WILL INCREASE EARLY NEXT WEEK. PRANGE
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY COAST AND GRAYS HARBOR BAR.
$$
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