725
FXUS66 KSEW 171519
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
819 AM PDT SUN MAY 17 2026
UPDATE
AREAS OF FOG HAVE DEVELOPED EARLIER THIS MORNING OVER SEVERAL
TRAVEL CORRIDORS SOUTH AND SOUTHWEST OF THE PUGET SOUND,
INCLUDING I-5 THROUGH CHEHALIS, ALONG US-101 ALONG THE KITSAP
PENINSULA, AND US-12 THROUGH MONTESANO. A DENSE FOG ADVISORY HAS
BEEN ISSUED THROUGH NOON TODAY FOR THESE AREAS. CONDITIONS ARE
EXPECTED TO IMPROVE THROUGHOUT THE MORNING AS THE FOG SLOWLY
BURNS OFF, WITH THE REMAINDER OF THE FORECAST THIS MORNING ON
TRACK AS BENIGN CONDITIONS SETTLE OVER THE AREA.
SYNOPSIS
UPPER LEVEL RIDGE CENTERED OFFSHORE BUILDING TODAY AND TONIGHT.
THE RIDGE WILL REMAIN IN PLACE THROUGH MOST OF THE WEEK. WEAK
SYSTEMS MOVING OVER THE TOP OF THE RIDGE AT TIMES. RIDGE WEAKENS
SATURDAY WITH AN UPPER LEVEL TROUGH APPROACHING THE COAST.
SHORT TERM /TODAY THROUGH TUESDAY/
WESTERN WASHINGTON GETTING OFF THE WEATHER ROLLER COASTER THIS
WEEK. UPPER LEVEL RIDGE BUILDING OFFSHORE TODAY WITH THE RIDGE
REMAINING IN PLACE THROUGH TUESDAY. FOR TODAY AND MONDAY WEAK
ONSHORE FLOW WITH AREAS OF MORNING CLOUDS AND SUNNY AFTERNOONS.
PATCHY FOG THIS MORNING SOUTH SOUND. WEAK SYSTEM RIDING BY TO
THE NORTH TUESDAY WILL INCREASE THE LOW LEVEL ONSHORE FLOW FOR
MORE CLOUD COVER. HIGHS WARMING INTO THE LOWER TO MID 60S TODAY
AND 60S ALL AREAS MONDAY. A LITTLE COOLER WITH MORE CLOUD COVER
TUESDAY, UPPER 50S TO MID 60S. THE SYSTEM ON TUESDAY COULD
PRODUCE A SHOWER IN THE NORTH CASCADES IN THE AFTERNOON.
FELTON
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
LITTLE CHANGE IN THE PATTERN WITH FLAT UPPER LEVEL RIDGE
CENTERED OFFSHORE AND WEAK SYSTEMS MOVING BY TO THE NORTH AT
TIMES THROUGH FRIDAY. WEAK UPPER LEVEL TROUGH APPROACHING THE
COAST SATURDAY WILL STILL BE FAR ENOUGH OFFSHORE TO HAVE A DRY
FORECAST. HIGHS IN THE 60S AND LOWER 70S WEDNESDAY AND THURSDAY,
MID 60S TO MID 70S FRIDAY AND SATURDAY. LOWS MOSTLY IN THE 40S.
AVIATION
NORTHERLY FLOW ALOFT WILL PERSIST TODAY AS AN UPPER LEVEL TROUGH
EXITS THE REGION TO THE SOUTHEAST AND AN UPPER LEVEL RIDGE STARTS TO
BUILD BACK INTO THE AREA FROM THE NE PACIFIC. THERE IS A MIX OF MVFR
CEILINGS IN THE EASTERN TERMINALS, AND A FEW LOWER CEILINGS/PATCHES
OF MIST/FOG IN THE CENTRAL AND SOUTH INTERIOR. THESE WILL CONTINUE
TO SCATTER/LIFT THROUGH THE MORNING AND EARLY AFTERNOON FOR VFR
CONDITIONS REGIONWIDE. EXPECT WINDS TO INCREASE OUT OF THE
NORTH/NORTHWEST TODAY. THEY WILL PERSIST AT 5-10 KT INTO THE EVENING
HOURS BEFORE EASING TONIGHT. EAST TERMINALS WILL SEE THE DIRECTION
OF THE WIND FLIP TO THE SOUTH OVERNIGHT. A WEAKER ONSHORE PUSH
MONDAY MORNING WILL BRING STRATUS INLAND. HIGHEST LIKELIHOOD FOR
MVFR IS FROM THE KITSAP PENINSULA SOUTH AND WESTWARD. THERE IS ALSO
A MEDIUM CHANCE FOR PATCHES OF FOG IN THE KITSAP/CHEHALIS VALLEY
MONDAY MORNING.
KSEA...THERE REMAINS A CHANCE OF CEILINGS DIPPING DOWN TO MVFR THIS
MORNING THROUGH 18Z (A FEW LOWER CLOUDS REMAIN TO THE WEST OF THE
TERMINAL BUT AT THIS POINT WILL LIKELY STAY OVER THE KITSAP
PENINSULA). CALM WINDS WILL PICK UP FROM THE NORTH AT AROUND 18Z,
HOLDING AT 5-8 KT THIS AFTERNOON AND EVENING BEFORE EASING TONIGHT
AND SWITCHING BACK TO THE SOUTH. PROBABILITIES FOR CEILINGS MONDAY
FAVOR LOWER-END VFR AT THIS TIME.
14/HPR
MARINE
HIGH PRESSURE WILL BUILD BACK OVER THE WATERS TODAY. ANOTHER
PUSH OF SMALL-CRAFT WESTERLY WINDS IS EXPECTED ALONG THE CENTRAL
AND EASTERN STRAIT THIS AFTERNOON AND EVENING. SEAS ACROSS THE
COASTAL WATERS HAVE ALSO SUBSIDED AND WILL PRIMARILY RANGE
BETWEEN 6-8 FT THROUGHOUT THE DAY.
A WEAK, DISSIPATING FRONTAL SYSTEM WILL MOVE ACROSS THE AREA
WATERS MONDAY INTO TUESDAY, BEFORE HIGH PRESSURE BUILDS BACK IN
ITS WAKE ON WEDNESDAY. ONSHORE FLOW WILL PERSIST THROUGH THE
FIRST HALF OF THE WEEK AND WILL RESULT IN DAILY PUSHES OF WESTERLY
WINDS THROUGH THE STRAIT OF JUAN DE FUCA. ANOTHER WEAK FRONTAL
SYSTEM LOOKS TO MOVE INTO THE AREA WATERS ON THURSDAY. SEAS
WILL GENERALLY HOVER BETWEEN 6-8 FT THROUGH THE FIRST HALF OF
THE WEEK, BEFORE SLIGHTLY INCREASING TOWARDS 8-10 FT BY LATE WEEK.
14
HYDROLOGY
THE DAILY HYDROLOGY DISCUSSION HAS ENDED UNTIL THE START OF THE
NEXT RAINY SEASON; IT WILL ONLY BE UPDATED DURING THIS TIME AS
NEEDED.
SEW WATCHES/WARNINGS/ADVISORIES
WA...DENSE FOG ADVISORY UNTIL NOON PDT TODAY FOR LOWER CHEHALIS
RIVER VALLEY-LOWLANDS OF LEWIS AND SOUTHERN THURSTON
COUNTIES-MIDDLE CHEHALIS RIVER VALLEY-OLYMPIA AND
SOUTHERN PUGET SOUND.
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 5 AM PDT
MONDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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