Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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883
FXUS66 KSEW 081121
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
321 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...SATELLITE IMAGERY SHOWS CLEAR SKIES MOST OF OVER
WESTERN WASHINGTON THIS MORNING WITH AN UPPER LEVEL RIDGE BUILDING
OVER THE AREA. SOME LINGERING SC OVER THE SAN JUANS AND WHATCOM
COUNTY PREVENTING THE SKIES FROM BEING TOTALLY CLEAR OVER THE AREA
THIS HOUR. WITH THE RIDGE BUILDING...TEMPERATURES ALOFT ARE
WARMING UP. THE SANDPOINT PROFILER REPORTED PLUS 8C AT 1000 METERS
AT 00Z MONDAY AND PLUS 14C AT 10Z. AT THE LOWER LEVEL OFFSHORE
FLOW HAS TAKEN OVER WITH THE KUIL-KBLI GRADIENT -4 MB AND THE
CROSS CASCADE GRADIENT -5 TO -6 MB AT 10Z. TEMPERATURE AT 3 AM ARE
IN THE 30S TO LOWER 40S EXCEPT AT BELLINGHAM AND FRIDAY HARBOR
WHERE TEMPERATURES ARE IN THE MID 40S.

LITTLE CHANGE TO THE FORECAST TODAY WITH THE UPPER LEVEL RIDGE
OVER THE AREA AND THE LOW LEVEL OFFSHORE FLOW PATTERN REMAINING
INTACT. TEMPERATURES ALOFT CONTINUING TO WARM AND BY 00Z MODEL
850 MB TEMPERATURES ARE IN THE PLUS 12 TO 15C RANGE. HIGHS WILL BE
WELL ABOVE NORMAL WITH 50S AND LOWER 60S COMMON OVER THE INTERIOR
AND LOWER TO MID 60S ALONG THE COAST. RIGHT NOW THE ONLY RECORD
HIGH IN JEOPARDY LOOKS TO BE AT KUIL (61/1970).

UPPER LEVEL RIDGE STARTS TO DRIFT EAST TONIGHT AND WILL CONTINUE
TO MOVE EAST ON TUESDAY. TEMPERATURES ALOFT COOL SLIGHTLY WITH
THERIDGE SHIFTING EAST BUT THE LOW LEVEL OFFSHORE WILL CONTINUE.
THIS WILL LIMIT THE FOG IN THE MORNING ON TUESDAY AND KEEP HIGHS
TUESDAY SIMILAR TO MONDAYS READINGS...50S TO LOWER 60S. LOWS
TUESDAY MORNING IN THE MID 30S TO MID 40S.

RIDGE CONTINUES TO SLOWLY MOVE EAST AND WEAKEN TUESDAY NIGHT WITH
SOUTHWESTERLY FLOW ALOFT INCREASING OFF THE COAST. WEATHER SYSTEM
MOVING INTO THE BACK SIDE OF THE RIDGE TRYING TO GET INTO WESTERN
WASHINGTON ON WEDNESDAY. THE 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. FOR NOW WILL
COMPROMISE THE SOLUTIONS AND KEEP THE RAIN CHANCES ALONG THE COAST
FOR WEDNESDAY. WITH THE INCREASING CLOUD COVER OVERNIGHT LOWS WILL
BE A LITTLE WARMER TUESDAY NIGHT/WEDNESDAY MORNING...UPPER 30S TO
MID 40S WHILE DAYTIME HIGHS ON WEDNESDAY WILL BE COOLER...LOWER TO
MID 50S.

.LONG TERM...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

&&

.AVIATION...AN UPPER LEVEL RIDGE IS EXPECTED TO REMAIN OVER THE
REGION THROUGH LATE TUESDAY/EARLY WEDNESDAY. UPPER LEVEL FLOW WILL
REMAIN WESTERLY TODAY...SHIFTING TO A MORE SOUTH TO SOUTHWEST
DIRECTION EARLY TUESDAY MORNING. LOW LEVEL FLOW IS EXPECTED TO
REMAIN OFFSHORE. CIGS GENERALLY REMAINING VFR TONIGHT. WHILE THERE
WAS THE EXPECTATION FOR SOME FOG TO DEVELOP...THAT SO FAR HAS NOT
BEEN THE CASE...ALTHOUGH THERE IS ONE OB IN TACOMA SUGGESTING THAT
THERE IS AT LEAST SOME FOG OUT THERE. WILL REMOVE ANY FG/BR FROM 12Z
TAFS...ALTHOUGH WILL KEEP FOG IN OLM JUST IN CASE. OTHERWISE...VFR
CONDITIONS EXPECTED TO PERSIST THROUGH THE DAY TODAY. SMR

KSEA...WINDS GENERALLY NORTHERLY...ALTHOUGH A NE COMPONENT MIGHT BE
OBSERVED FROM TIME TO TIME. SPEEDS AROUND 5 TO 7 KTS. CIGS REMAINING
VFR WITH EITHER CLEAR SKIES OR HIGH CIRRUS THROUGH THE MAJORITY OF
THE DAY TODAY. SMR

&&

.MARINE...LOWER PRES OVER THE OFFSHORE WATERS WITH HIGH PRESSURE E
OF THE CASCADES WILL KEEP THE FLOW EASTERLY THROUGH
MIDWEEK...ALTHOUGH THE SURFACE HIGH WILL WEAKEN WITH TIME. A WEAK
WARM FRONT MAY CLIP THE AREA ON WED.

COASTAL WATERS WILL SEE SWELLS EXCEED 10 FT THIS MORNING AND REMAIN
THAT WAY BEFORE SUBSIDING TONIGHT. THAT SAID...A SMALL CRAFT
ADVISORY FOR HAZARDOUS SEAS HAS BEEN POSTED. THIS WILL CREATE ROUGH
BAR CONDITIONS FOR GRAYS HARBOR BY THIS AFTERNOON...RESULTING IN A
SMALL CRAFT ADVISORY FOR ROUGH BAR. SMR

&&

.HYDROLOGY...NO RIVER FLOODING IS EXPECTED IN THE NEXT 7 DAYS.
WILL BE KEEPING AN EYE ON THE SOLUTIONS FOR NEXT SUNDAY AND
MONDAY WITH A POSSIBLE ATMOSPHERIC RIVER SCENARIO SETTING UP.
FELTON

&&

.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 POINT
     GRENVILLE TO CAPE SHOALWATER 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH BAR FROM 10 AM THIS MORNING TO 10
     PM PST THIS EVENING FOR GRAYS HARBOR BAR.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 10 AM THIS MORNING
     TO 10 PM PST THIS EVENING FOR COASTAL WATERS FROM CAPE
     FLATTERY TO JAMES ISLAND OUT 10 NM-COASTAL WATERS FROM
     JAMES ISLAND TO POINT GRENVILLE OUT 10 NM-COASTAL WATERS
     FROM POINT GRENVILLE TO CAPE SHOALWATER OUT 10 NM.

     SMALL CRAFT ADVISORY UNTIL 6 AM PST EARLY THIS MORNING FOR
     COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-
     WEST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.

&&

$$

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