Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 261040
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
340 AM PDT SAT JUL 26 2014

.SYNOPSIS...HIGH PRESSURE ALOFT AND WEAK LOW LEVEL ONSHORE FLOW WILL
PREVAIL FOR THE NEXT WEEK. THIS WILL GIVE A STRETCH OF SUNNY AND
WARM WEATHER TO WESTERN WASHINGTON.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS FLAT UPPER LEVEL RIDGE OVER
WESTERN WASHINGTON EARLY THIS MORNING WITH AN UPPER LEVEL TROUGH
BACK NEAR 150W. LOW CLOUDS HAVE DEVELOPED ALONG THE CASCADE
FOOTHILLS EXTENDING NORTH NORTHWEST TO NEAR THE SAN JUANS. LOW
CLOUDS HAVE ALSO DEVELOPED ALONG THE NORTH COAST. ELSEWHERE JUST A
FEW HIGH CLOUDS. TEMPERATURES AT 10Z/3 AM WERE IN THE UPPER 40S TO
NEAR 60.

UPPER LEVEL TROUGH WELL OFFSHORE WILL DIG SOUTH TODAY. THIS IN TURN
WILL START INCREASING THE AMPLITUDE OF THE UPPER LEVEL RIDGE OVER
WESTERN WASHINGTON. 500 MB HEIGHTS START THE DAY IN THE MID TO
UPPER 570 DMS AND INCREASE THROUGHOUT THE DAY ENDING UP IN THE LOW
580S DMS BY 00Z SUN/5 PM SAT. AT THE SURFACE GRADIENTS ARE FLAT THIS
MORNING AND WILL REMAIN LIGHT DURING THE DAY WITH A LITTLE INCREASE
IN THE WESTERLY GRADIENT THROUGH THE STRAIT LATE THIS AFTERNOON AND
TONIGHT. WITH THE FLAT SURFACE GRADIENTS NO EXPECTING MUCH MORE IN
THE WAY OF LOW CLOUD DEVELOPMENT THIS MORNING. MODEL 850
TEMPERATURES RISE FROM PLUS 8 TO 10C EARLY THIS MORNING TO PLUS 10
TO 14C BY LATE THIS AFTERNOON. WITH THE RIDGE BUILDING AND WARMER
TEMPERATURES ALOFT HIGHS TODAY WILL BE ABOUT 5 DEGREES WARMER THAN
FRIDAY WITH 70S AND LOWER 80S COMMON OVER THE INTERIOR AND AROUND 70
ON THE COAST.

LITTLE CHANGE IN THE SURFACE PATTERN ON SUNDAY WITH THE UPPER RIDGE
CONTINUING TO BUILD WITH THE TROUGH DIGGING WELL OFFSHORE. 500 MB
HEIGHTS RISE INTO THE MID 580 DMS BY 00Z MON/5 PM SUN WITH 850 MB
TEMPERATURES WARMING ANOTHER 3 OR 4 DEGREES C. EXPECT ANOTHER 5
DEGREES OR SO OF WARMING FOR THE INTERIOR WHICH WILL PUSH THE
WARMEST LOCATIONS NEAR 90 DEGREES WITH 80S COMMON OVER MOST OF THE
INTERIOR. WITH THE WEAK NORTHWESTERLY SURFACE GRADIENTS HIGHS ALONG
THE COAST WILL REMAIN IN THE LOWER 70S.

LITTLE CHANGE IN THE PATTERN ON MONDAY WITH THE 500 MB HEIGHTS
REMAINING IN THE MID 580 DMS AND THE SURFACE GRADIENTS LIGHT
NORTHWESTERLY. TEMPERATURES ALOFT WARM SLIGHTLY SO THERE COULD BE
ANOTHER COUPLE OF DEGREES OF WARMING FOR THE INTERIOR. FOR THE MOST
PART HIGHS ONCE AGAIN WILL BE IN THE 80S FOR THE INTERIOR WITH
TEMPERATURES IN THE LOWER 780S ALONG THE COAST.

.LONG TERM...00Z EXTENDED MODELS RUNS IN GOOD AGREEMENT THAT THERE
WILL BE LITTLE CHANGE IN THE PATTERN...BOTH SURFACE AND ALOFT
THROUGH THE END OF NEXT WEEK. THE FLOW ALOFT BECOMES A BIT MORE
SOUTHERLY LATE IN THE PERIOD WHICH BRINGS UP THE POSSIBILITY OF
LATE DAY CONVECTION IN THE CASCADES BUT WILL LEAVE THIS OUT OF THE
FORECAST FOR NOW. WILL STAY WITH THE IDEA OF HIGH TEMPERATURES 5 TO
10 DEGREES ABOVE NORMAL FOR THE INTERIOR. THE NORTHWESTERLY SURFACE
GRADIENTS WILL KEEP THE AFTERNOON SEABREEZE IN PLAY ALONG THE COAST
KEEPING HIGHS THERE AROUND 70 DEGREES. WHAT LITTLE IN THE WAY OF LOW
CLOUDS THAT WILL DEVELOP WILL BE MOSTLY CONFINED TO THE COAST. FELTON

&&

.AVIATION...WEAK UPPER LEVEL RIDGING AND LOW LEVEL ONSHORE FLOW WILL
PERSIST THROUGH THE WEEKEND. MODERATE WESTERLY FLOW ALOFT WILL
BECOME SOUTHWESTERLY THIS AFTERNOON AS THE UPPER LEVEL RIDGE AXIS
SHIFTS EAST AND AMPLIFIES.

THE AIR MASS OVER WESTERN WASHINGTON WILL REMAIN GENERALLY DRY AND
STABLE THROUGH THE WEEKEND. LOW CLOUDS HAVE BEEN SLOW TO REFORM
OVERNIGHT...AIDED BY THE LIGHT SURFACE GRADIENTS AND OVERALL DRYING
TREND OVER THE LAST 24 HOURS. SATELLITE IMAGERY HINTING AT STRATUS
DEVELOPING ALONG THE NORTH COAST AND WEST ENTRANCE OF THE STRAIT AS
OF 10Z. EXPECT LOW CLOUDS TO DEVELOP OVER THE COAST...CHEHALIS GAP
AND STRAIT AROUND DAYBREAK AND PERSIST INTO MID MORNING BEFORE
SCATTERING OUT TO SUNNY SKIES DURING THE AFTERNOON. CLOUDS WILL
REFORM AGAIN EARLY SUNDAY MORNING...REMAINING SIMILARLY CONSTRAINED
TO THE COAST AND STRAIT...BURNING OFF BY LATE MORNING.


KSEA...VFR CONDITIONS WILL PERSIST THROUGH THE DAY. NORTHEASTERLY
WINDS 6 TO 8 KTS WILL WEAKEN SOMEWHAT AROUND SUNRISE...BECOMING
NORTHWESTERLY 6 TO 8 KTS AROUND 18Z.

&&

.MARINE...A PERSISTENT PATTERN OF HIGH PRESSURE OVER THE COASTAL
WATERS AND LOWER PRESSURE INLAND WILL SUPPORT ONSHORE FLOW THROUGH
EARLY NEXT WEEK. AS IS TYPICAL WITH THIS SORT OF PATTERN...EXPECT
STRONGEST WINDS THROUGH THE CENTRAL AND EAST STRAIT...POSSIBLY
REACHING SMALL CRAFT ADVISORY LEVELS AT TIMES ESPECIALLY DURING THE
LATE AFTERNOON AND EVENING HOURS. WEST TO NORTHWESTERLY SWELL 3 TO 4
FEET AT AROUND 8 SECONDS WILL PERSIST THROUGH EARLY NEXT WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML








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