688
FXUS66 KSEW 191616
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
916 AM PDT SAT APR 19 2025
UPDATE
A WEAK FRONTAL SYSTEM HAS MOVED OVER WESTERN WASHINGTON
EARLY THIS MORNING AND BROUGHT SOME LIGHT PRECIPITATION TO THE
AREA. THE FRONT HAS NOW MOVED INTO EASTERN WASHINGTON. SATURDAY
WILL REMAIN GENERALLY DRY, ALTHOUGH SOME LIGHT POST-FRONTAL
ISOLATED LIGHT SHOWERS REMAIN POSSIBLE THROUGHOUT THE DAY. SOME
CLEARING BEHIND THE FRONT IS EXPECTED THIS AFTERNOON AS WELL,
RANGING FROM MOSTLY SUNNY TO PARTLY CLOUDY SKIES. OVERALL NO MAJOR
CHANGES TO THE FORECAST, AND THE INHERITED FORECAST REMAINS ON
TRACK. PLEASE REFER TO AN UPDATED AVIATION SECTION BELOW.
SYNOPSIS
A WEAK UPPER LEVEL TROUGH WILL MOVE THROUGH THE REGION
THIS MORNING. A COOLER, STRONGER, TROUGH ARRIVING SUNDAY FOR MORE
WIDESPREAD SHOWER ACTIVITY. POST TROUGH CONVERGENCE ZONE COULD
GIVE STEVENS OR SNOQUALMIE PASS A COUPLE INCHES OF SNOW SUNDAY
EVENING. NORTHWESTERLY FLOW ALOFT MONDAY FOR DRY AND COOLER
WEATHER. DRY WEATHER INTO MIDWEEK WITH HIGH PRESSURE.
SHORT TERM /TODAY THROUGH MONDAY/
A WEAK FRONT PASSED THROUGH
WESTERN WA EARLY THIS MORNING WITH LIGHT RAINFALL OVER THE REGION.
MOST AREAS SAW A TRACE TO A FEW HUNDREDTHS. WE'RE UNDER POST-
FRONTAL ONSHORE FLOW THROUGH THE REMAINDER OF THE DAY LEADING TO
COOLER CONDITIONS AND HIGHS IN THE 50S TO AROUND 60.
ONSHORE FLOW WILL PERSIST INTO SUNDAY AND SHOWERS WILL INCREASE
WITH A PASSING TROUGH AXIS. MOST OF THE SHOWERS WILL BE ALONG THE
COAST AND MOUNTAINS, WITH THE FOCUS SHIFTING TO THE CENTRAL SOUND
AND CASCADES SUNDAY AFTERNOON/EVENING AS A PUGET SOUND
CONVERGENCE ZONE DEVELOPS. SNOW LEVELS WILL START AROUND 4000 FT
AND WILL LOWER TO AROUND 2500 FT OVERNIGHT WITH A FEW INCHES OF
SNOW EXPECTED AT BOTH STEVENS AND SNOQUALMIE PASS.
MONDAY WILL BE DRIER BUT ALSO COOLER UNDER NW FLOW. FORECAST
HIGHS ARE IN THE 50S WITH LOWS MONDAY NIGHT IN THE 30S TO LOWER
40S. AREAS AROUND THE SOUTH SOUND MAY SEE FREEZING TEMPS WITH LOWS
IN THE LOWER 30S POSSIBLE. 33
LONG TERM /TUESDAY THROUGH FRIDAY/
HIGH PRESSURE KEEPS WESTERN
WA DRY AND MILD MOVING FORWARD NEXT WEEK. TEMPERATURES WILL PEAK
ON THURSDAY WITH HIGHS REACHING THE UPPER 60S IN THE INTERIOR.
ONSHORE FLOW WILL KEEP THE COAST A FEW DEGREES COOLER (AROUND 60).
ON FRIDAY, THE RIDGE SHIFTS EAST WHILE A TROUGH DIGS OFFSHORE. THE
TROUGH MAY PULL SOME MOISTURE NORTH FOR A CHANCE OF SHOWERS AND
COOLER CONDITIONS. 33
AVIATION
WESTERLY FLOW ALOFT WILL BECOME MORE NORTHWESTERLY
TODAY AS AN UPPER LEVEL TROUGH GRADUALLY DEEPENS OVER THE REGION
INTO SUNDAY. CONDITIONS ARE A MIXED BAG OF MOSTLY MVFR TO VFR
ACROSS THE AREA IN THE WAKE OF A FRONTAL SYSTEM THAT MOVED THROUGH
EARLIER THIS MORNING, THOUGH A FEW TERMINALS REMAIN IFR. LATEST
HI-RES GUIDANCE DOES STILL SHOW SOME LIGHT SHOWER ACTIVITY POSSIBLE
ACROSS PORTIONS OF THE SOUND THROUGH THE MORNING HOURS AND INTO
THE EARLY AFTERNOON. MORE LIKELY WILL BE LINGERING CLOUD COVER,
THOUGH EXPECT CEILINGS TO LIFT TOWARDS VFR AGAIN THIS AFTERNOON.
A MORE WIDESPREAD DROP DOWN TO MVFR CEILINGS IS EXPECTED HEADED
INTO SUNDAY MORNING. BREEZY SURFACE WINDS TO 20-25 KT REMAIN LIKELY
INTO THIS EVENING FOR TERMINALS ALONG THE PACIFIC COAST AND STRAIT
OF JUAN DE FUCA TODAY. OTHERWISE EXPECT W/NW WINDS 5-10 KT THIS
AFTERNOON, WITH WIND SHIFTING TO THE SW AND EASING TONIGHT INTO
SUNDAY.
KSEA...CEILINGS MVFR, GENERALLY BETWEEN 1000-1500 FT THIS MORNING.
SOME LIGHT SHOWER ACTIVITY MAY LINGER IN THE VICINITY OF THE TERMINAL
INTO THE EARLY AFTERNOON. EXPECT CIGS TO LIFT BACK TOWARDS VFR THIS
AFTERNOON. WINDS REMAINING LIGHT AND VARIABLE THIS MORNING, BUT
DIRECTION IS EXPECTED TO SWITCH TO THE NORTH TODAY AND PERSIST AT 5
TO 10 KT INTO THIS EVENING. A SHIFT BACK TO THE SOUTH IS EXPECTED
TONIGHT, LIKELY BETWEEN 05-08Z. LOWER CEILINGS DOWN TO MVFR ARE
LIKELY AGAIN BY 12Z SUNDAY MORNING.
HPR/14
MARINE
NORTHWESTERLY WINDS WILL REMAIN BREEZY ACROSS THE
COASTAL WATERS THIS MORNING IN THE WAKE OF A FRONTAL SYSTEM THAT
MOVED THROUGH EARLIER TODAY. HIGH PRESSURE WILL BUILD ACROSS THE
NORTHEASTERN PACIFIC THIS WEEKEND, THOUGH ANOTHER DISTURBANCE WILL
MOVE ALONG ITS PERIPHERY AND ACROSS THE AREA WATERS ON SUNDAY.
GUSTY WINDS WILL CONTINUE THIS WEEKEND, WITH ANOTHER ROUND OF
SMALL CRAFT STRENGTH WESTERLIES/NORTHWESTERLIES EXPECTED DOWN THE
ENTIRE STRAIT OF JUAN DE FUCA AND ADMIRALTY INLET THIS AFTERNOON
AND EVENING. ANOTHER ONSHORE PUSH IS EXPECTED ALONG THE STRAIT SUNDAY
NIGHT INTO MONDAY, LIKELY YIELDING ANOTHER ROUND OF SMALL CRAFT
ADVISORIES.
SEAS ACROSS THE COASTAL WATERS REMAIN STEEP AND GENERALLY PERSIST
BETWEEN 8-12 FT AT AROUND 8-10 SECONDS THIS MORNING. SEAS WILL
SUBSIDE TOWARDS 7-9 FT BY TONIGHT, BEFORE FALLING TO 6-8 FT ON
SUNDAY. A BRIEF UPTICK TOWARDS 10 FT IS POSSIBLE AGAIN LATE
SUNDAY INTO MONDAY, BEFORE SEAS SUBSIDE TOWARDS 4-6 FT ON TUESDAY.
14
HYDROLOGY
NO RIVER FLOODING IS EXPECTED THROUGH THE NEXT 7
DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM PDT SUNDAY
FOR ADMIRALTY INLET-CENTRAL U.S. WATERS STRAIT OF JUAN DE
FUCA-EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA-WEST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT SUNDAY FOR COASTAL WATERS
FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 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.
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