510
FXUS66 KSEW 172106
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
206 PM PDT SUN MAY 17 2026
SYNOPSIS
HIGH PRESSURE WILL REMAIN SITUATED OFFSHORE THROUGH MUCH OF NEXT
WEEK, MAINTAINING NEAR-NORMAL TEMPERATURES ACROSS WESTERN
WASHINGTON WITH CLOUDY MORNINGS AND SUNSHINE IN THE AFTERNOONS.
A FEW WEAK SYSTEMS WILL MOVE OVER THE TOP OF THE RIDGE TOWARDS
THE MIDDLE OF NEXT WEEK, BRINGING LITTLE MORE THAN A FEW PERIODS
OF SPRINKLES.
SHORT TERM /TODAY THROUGH TUESDAY NIGHT/
A HIGH PRESSURE RIDGE WILL CONTINUE TO BUILD OFFSHORE THROUGHOUT
THE SHORT TERM, BRINGING NORTHWEST FLOW ALOFT AND ONSHORE FLOW
AT THE SURFACE TO WESTERN WASHINGTON. THIS WILL BRING MORE
SPRING-LIKE CONDITIONS TO THE REGION, WITH TEMPERATURES THROUGH
TUESDAY PEAKING NEAR NORMAL GENERALLY IN THE 60S. IN ADDITION,
ONSHORE FLOW WILL ALLOW MARINE STRATUS TO EXPAND INLAND EACH
MORNING, BREAKING UP FOR MOST AREAS BY THE AFTERNOON. A
SPLITTING FRONTAL SYSTEM WILL ATTEMPT TO OVERRUN THE RIDGE ON
TUESDAY, BUT WILL LIKELY BRING LITTLE MORE THAN A FEW SPRINKLES
TO THE AREA.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
WEDNESDAY WILL SEE MORE OF THE SAME, WITH POTENTIAL FOR A CLOUDY
MORNING, MOSTLY SUNNY AFTERNOON, AND MILD TEMPERATURES PEAKING
IN THE 60S TO LOWER 70S.
BY THURSDAY, THE UPPER LEVEL RIDGE OFFSHORE WILL BEGIN TO
FLATTEN AS A LOW PRESSURE SYSTEM SLOWLY STRENGTHENS AND LOWERS
FROM THE GULF OF ALASKA. CONDITIONS ARE FAVORED TO REMAIN DRY
INTO THE FIRST HALF OF THE WEEKEND AS ZONAL FLOW SETS UP ALOFT,
WITH CONTINUED MILD TEMPERATURES.
ENSEMBLES ARE HONING IN ON A POTENTIAL PATTERN CHANGE BY THE END
OF NEXT WEEKEND, WITH INCREASING CHANCES FOR ACCUMULATING
RAINFALL OVER THE NORTH CASCADES ON SATURDAY. HOWEVER, THE
DETAILS REMAIN UNCERTAIN AT THIS TIME.
15
AVIATION
HIGH PRESSURE UNDER A RIDGE WILL BUILD ALONG THE COAST TODAY INTO
MONDAY. THE FLOW ALOFT WILL DECREASE OUT OF THE NORTH TONIGHT AS THE
RIDGE AXIS PASSES OVERHEAD. CLOUD COVERAGE CONTINUES TO DECREASE
THIS AFTERNOON FROM WEST TO EAST. TERMINALS OUTSIDE OF THE CASCADES
HAVE BECOME VFR WITH FEW OR SCATTERED DECK. GIVEN THE CURRENT
SYNOPTIC SETUP INTO MONDAY, A MARINE PUSH OF STRATUS INLAND IS
LIKELY IN THE MORNING. HIGHEST PROBABILITIES FOR MVFR CEILINGS IS
FROM THE KITSAP PENINSULA WESTWARD, WITH CHANCES DECREASING (BUT
REMAINING ELEVATED) FOR THE PUGET SOUND TERMINALS MONDAY MORNING.
ADDITIONALLY, THERE IS SOME POTENTIAL AGAIN FOR FOG/MIST UNDER THE
CLOUDS FOR THE KITSAP/SOUTH INTERIOR TERMINALS (BUT THIS IS LOWER
CONFIDENCE DUE TO THE CLOUD COVERAGE). CEILINGS MONDAY AFTERNOON
WILL RETREAT TOWARDS THE COAST (BUT LIKELY REMAIN ALONG THE
IMMEDIATE COASTLINE). WINDS OUTSIDE OF THE INTERIOR TERMINALS WILL
REMAIN NORTHWEST 5-10 KT (COUPLE GUSTS TO 20 KT NEAR THE STRAIT OF
JUAN DE FUCA). NORTH INTERIOR/PUGET SOUND WINDS BOTH AFTERNOONS WILL
FAVOR THE NORTHWEST 5-10 KT, WITH WINDS RETURNING TO THE SOUTH UNDER
5 KT OVERNIGHT.
KSEA...VFR WITH FEW OR SCATTERED CLOUDS THIS AFTERNOON THROUGH
TONIGHT. STRATUS LIKELY TO REACH INTERIOR MONDAY MORNING. LOWER-END
VFR IS FAVORED, BUT THERE IS A 40% CHANCE THE CEILINGS MAY GET DOWN
INTO MVFR CRITERIA IN THE MORNING, BEFORE CLEARING EARLY MONDAY
AFTERNOON. WINDS TO INCREASE OUT OF THE NORTH THIS AFTERNOON 5-10
KT, RETURNING TO THE SOUTH UNDER 5 KT OVERNIGHT, BEFORE RETURNING TO
THE NORTH AGAIN EARLY MONDAY AFTERNOON.
HPR
MARINE
HIGH PRESSURE WILL CONTINUE TO BUILD OFFSHORE THROUGH MUCH OF
THE NEXT WEEK. THIS WILL GENERATE A SMALL CRAFT WESTERLY PUSH
THROUGH THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA TONIGHT,
AS WELL AS DAILY PUSHES OF WESTERLY WINDS THROUGH THE STRAIT OF
JUAN DE FUCA THROUGH MUCH OF THE COMING WEEK. A SPLITTING
FRONTAL SYSTEM WILL MOVE ACROSS THE AREA WATERS MONDAY INTO
TUESDAY, BEFORE HIGH PRESSURE BUILDS BACK IN ITS WAKE ON
WEDNESDAY. ANOTHER WEAK FRONTAL SYSTEM LOOKS TO MOVE INTO THE
AREA WATERS ON THURSDAY.
SEAS AROUND 6 TO 8 FEET TODAY WILL BUILD TO 8 TO 10 FEET ON
MONDAY, REMAINING NEAR 10 FEET THROUGH WEDNESDAY. SEAS WILL
BUILD TO 10 TO 13 FEET BY LATE THURSDAY AND HOVER AROUND 10 FEET
HEADING INTO NEXT WEEKEND.
15
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...NONE.
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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