Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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598
FXUS66 KSEW 081645
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
845 AM PST MON FEB 8 2016

.SYNOPSIS...AN UPPER LEVEL RIDGE OVER THE AREA TODAY WILL SHIFT EAST
ON TUESDAY. LOW LEVEL OFFSHORE FLOW TODAY WILL CONTINUE THROUGH
TUESDAY. THE HIGH WILL WEAKEN AND CONTINUE TO MOVE EAST ON WEDNESDAY
WITH A WEAK FRONT REACHING THE COAST. WEATHER SYSTEMS EMBEDDED IN
THE SOUTHWESTERLY FLOW ALOFT WILL MOVE THROUGH WESTERN WASHINGTON
WEDNESDAY NIGHT THROUGH SATURDAY.

&&

.SHORT TERM...EXCEPT FOR THIN CIRRUS SKIES ARE CLEAR OVER WESTERN
WASHINGTON THIS MORNING. THERE IS PATCHY FOG BUT THIS SHOULD BE GONE
BY 10 AM OR SO. A STRONG UPPER LEVEL RIDGE IS FORECAST TO REMAIN
OVER THE AREA THROUGH TUESDAY. HIGHS WILL BE IN THE MID 50S TO MID
60S WITH OFFSHORE SURFACE FLOW. PATCHY FOG IS LIKELY AGAIN LATE
TONIGHT AND EARLY TUESDAY MORNING.

THE UPPER RIDGE WILL MOVE EAST AND WEAKEN TUESDAY NIGHT WITH
SOUTHWESTERLY FLOW ALOFT INCREASING OFF THE COAST. A WEAK WEATHER
SYSTEM WILL MOVE ONTO THE COAST LATE TUESDAY NIGHT AND INTO
THE INTERIOR WEDNESDAY. MODEL SOLUTIONS CONTINUE TO BE INCONSISTENT
WIT WITH THE ECMWF AND CANADIAN LEAVING THIS FEATURE OFFSHORE WHILE
THE NAM AND THE GFS BRING PRECIPITATION INTO THE AREA MAINLY NORTH
OF A HOQUIAM TO SEATTLE LINE. WILL KEEP THE RAIN CHANCE ALONG THE
COAST WEDNESDAY FOR NOW. BURKE

.LONG TERM...PREVIOUS DISCUSSION...THERE IS GOOD AGREEMENT IN THE
UPPER LEVEL PATTERN FOR THE EXTENDED PERIOD IN THE 00Z MODEL RUNS
WITH AN UPPER LEVEL RIDGE TO THE EAST AND SOUTHWESTERLY FLOW ALOFT
OVER THE AREA THROUGH FRIDAY NIGHT. ONCE AGAIN THE TIMING OF WHEN
THE SYSTEMS EMBEDDED IN THE SOUTHWESTERLY FLOW ALOFT MOVE THROUGH
WESTERN WASHINGTON IS INCONSISTENT. IN GENERAL THERE IS ONE IN THE
WEDNESDAY NIGHT AND THURSDAY TIME FRAME AND ANOTHER ONE IN THE
FRIDAY/FRIDAY NIGHT TIME FRAME. THE MODELS HAVE BEEN MOST CONSISTENT
WITH THE FRIDAY/FRIDAY NIGHT SYSTEM SO WILL STAY WITH THE HIGHER
POPS WHILE KEEPING CHANCE POPS IN THE FORECAST FOR WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT OVER THE INTERIOR. WILL BUMP THE POPS INTO
THE LIKELY CATEGORY FOR THE COAST WEDNESDAY NIGHT AND THURSDAY.
UPPER LEVEL TROUGH MOVING THROUGH ON SATURDAY KEEPING AT LEAST
CHANCE POPS IN THE FORECAST. ON SUNDAY THE ECMWF AND CANADIAN BRING
A FAIRLY MOIST WARM FRONT INTO THE AREA WHILE THE GFS IS A LITTLE
STRONGER WITH THE UPPER LEVEL RIDGE TO THE SOUTH KEEPING MOST OF THE
WARM FRONT TO THE NORTH. FELTON

&&

.HYDROLOGY...RIVER FLOODING IS UNLIKELY OVER THE NEXT 7 DAYS.

&&

.AVIATION...AN UPPER LEVEL RIDGE WILL REMAIN OVER WESTERN
WASHINGTON THROUGH TONIGHT. HIGH PRES E OF THE CASCADES COMBINED
WITH LOWER PRES OFFSHORE WILL GIVE LOW LEVEL OFFSHORE FLOW. THE AIR
MASS IS DRY AND STABLE WITH PATCHY MORNING AND LATE NIGHT FOG.

LOCATIONS FROM ABOUT KTCM AND KSHN SOUTHWARD ARE SEEING FOG WHILE
SKIES ARE MAINLY CLEAR WITH GOOD VFR CONDITIONS AND ONLY SOME THIN
HIGH MOISTURE NORTH OF THERE AND ALONG THE COAST. THE FOG WILL BURN
OFF BY 19Z THIS MORNING...THEN REFORM AFTER 08Z TONIGHT IN ABOUT THE
SAME SPOTS AS THIS MORNING.  ALBRECHT

KSEA...NORTH WIND 5 8 KNOTS. GOOD VISIBILITIES WITH ONLY THIN CIRRUS
THROUGH TONIGHT. ALBRECHT

&&

.MARINE...LOWER PRES OVER THE OFFSHORE WATERS WITH HIGH PRESSURE E
OF THE CASCADES WILL KEEP THE FLOW EASTERLY THROUGH MIDWEEK.
THE SURFACE HIGH EAST OF THE CASCADES WILL GRADUALLY WEAKEN STARTING
ON TUESDAY. A WEAK WARM FRONT WILL MOVE NORTHEAST THROUGH THE
COASTAL WATERS ON WED. ANOTHER FRONTAL SYSTEM WILL APPROACH THE
COASTAL WATERS LATE THU.

OFFSHORE FLOW THIS MORNING IS GIVING SMALL CRAFT ADVISORY CONDITIONS
TO THE WEST ENTRANCE TO THE STRAIT OF JUAN DE FUCA AND TO THE
COASTAL WATERS ADJACENT TO THE WEST ENTRANCE. THE WINDS WILL EASE
AROUND NOON TODAY...THEN WILL INCREASE TO SMALL CRAFT ADVISORY
LEVELS AGAIN AFTER MIDNIGHT TONIGHT THROUGH MIDDAY TUESDAY.

A 10-11 FT SWELL AT 16 OR 17 SECONDS IS MOVING THROUGH THE COASTAL
WATERS TODAY AND WILL SUBSIDE LATE THIS EVENING. A SMALL CRAFT
ADVISORY FOR HAZARDOUS SEAS IS IN EFFECT FOR THE REMAINING COASTAL
WATERS THROUGH LATE THIS EVENING. A SMALL CRAFT ADVISORY IS ALSO IN
EFFECT FOR ROUGH GRAYS HARBOR BAR CONDITIONS THROUGH THIS EVENING.
ALBRECHT

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST THIS
     EVENING FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES
     ISLAND 10 TO 60 NM-COASTAL WATERS FROM JAMES ISLAND TO
     POINT GRENVILLE 10 TO 60 NM-COASTAL WATERS FROM JAMES
     ISLAND TO POINT GRENVILLE OUT 10 NM-COASTAL WATERS FROM
     POINT GRENVILLE TO CAPE SHOALWATER 10 TO 60 NM-COASTAL
     WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER OUT 10 NM.

     SMALL CRAFT ADVISORY FOR ROUGH BAR UNTIL 10 PM PST THIS EVENING
     FOR GRAYS HARBOR BAR.

     SMALL CRAFT ADVISORY UNTIL 10 AM PST TUESDAY FOR COASTAL WATERS
     FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-WEST ENTRANCE
     U.S. WATERS STRAIT OF JUAN DE FUCA.

&&

$$

WWW.WEATHER.GOV/SEATTLE

AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION CAN BE SEEN AT
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