732
FXUS66 KSEW 241552
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
852 AM PDT THU APR 24 2025
SYNOPSIS
HIGH PRESSURE WILL MAINTAIN WARM AND DRY CONDITIONS
THROUGH THURSDAY. SPLIT FLOW ALOFT WILL KEEP CONDITIONS MOSTLY
DRY AND MILD THROUGH SATURDAY. CHANCES FOR PRECIPITATION INCREASE
BY THE END OF THE WEEKEND AS A SYSTEM MOVES OVER THE PACIFIC
NORTHWEST, WITH DRY AND WARMER CONDITIONS RETURNING BY MID-WEEK.
SHORT TERM /TODAY THROUGH SATURDAY/
A HIGH PRESSURE RIDGE WILL
CONTINUE TO AMPLIFY AND SHIFT INLAND TODAY, ALLOWING FOR CONTINUED
DRY CONDITIONS AND HIGH TEMPERATURES IN THE 70S ACROSS MUCH OF
WESTERN WASHINGTON. A WEAK TROUGH APPROACHING THE NORTHERN
CALIFORNIA COAST WILL ADVECT SOME MOISTURE INTO THE REGION,
RESULTING IN LITTLE MORE THAN SOME PASSING HIGH CLOUDS TODAY.
FORECAST MODELS REMAIN IN GOOD AGREEMENT OVER THE TROUGH MOVING
INLAND OVER CALIFORNIA ON FRIDAY, KEEPING ANY PRECIPITATION
CHANCES TO OUR SOUTH. CONDITIONS FRIDAY WILL BE SIMILAR TO TODAY,
WITH PARTLY CLOUDY SKIES AND HIGHS IN THE 70S ONCE AGAIN FOR MUCH
OF THE LOWLANDS.
SPLIT FLOW ALOFT WILL BE IN PLACE BY SATURDAY, ALLOWING FOR
CONTINUED DRY CONDITIONS AND MOSTLY SUNNY SKIES. TEMPERATURES WILL
COOL A FEW DEGREES BUT WILL STAY MILD IN THE MID TO UPPER 60S
ACROSS MOST WESTERN WASHINGTON LOWLANDS. THE EXCEPTION WILL BE
ALONG THE PACIFIC COAST, WHERE HIGH TEMPERATURES WILL BE LIMITED
TO THE 50S DUE TO THE DEVELOPMENT OF MARINE STRATUS.
LONG TERM /SUNDAY THROUGH WEDNESDAY/
SPLIT FLOW ALOFT WILL
SHIFT EASTWARD ON SUNDAY AS A HIGH PRESSURE RIDGE MOVES TOWARDS
THE PACIFIC COAST. ENSEMBLES HAVE CONTINUED TO DECREASE CHANCES
FOR SHOWERS ON SUNDAY, WITH A SLIGHT CHANCE ALONG THE CASCADE
FOOTHILLS AND OVER THE CHEHALIS BASIN. MUCH OF THE REGION WILL SEE
LITTLE MORE THAN CLOUDY SKIES, WITH MILD TEMPERATURES ONCE AGAIN
ON SUNDAY.
MOISTURE AHEAD OF AN APPROACHING WEAK TROUGH WILL SPREAD TOWARDS
WESTERN WASHINGTON ON MONDAY, THOUGH FORECAST MODELS CONTINUE TO
SHOW UNCERTAINTY OVER THE TIMING AND AMOUNT OF RAINFALL THAT WILL
MOVE INTO THE REGION WITH THIS APPROACHING SYSTEM. CHANCES FOR
SHOWERS WILL INCREASE INTO TUESDAY BEFORE A COLD FRONT CROSSES
THE REGION AND A DRIER AIR MASS FILLS IN BEHIND. MODELS HAVE COME
INTO BETTER AGREEMENT OVER HIGH PRESSURE REBOUNDING BY MID-WEEK,
WITH DRY AND WARMER CONDITIONS ON TRACK TO RETURN BY WEDNESDAY.
15
AVIATION
AN UPPER RIDGE OVER THE AREA EARLY THIS MORNING WILL
SLOWLY SHIFT EAST TODAY AS AN UPPER TROUGH DIGS OFFSHORE. A CLOSED
LOW WILL DEVELOP OFFSHORE OF CALIFORNIA TONIGHT INTO FRIDAY. LIGHT
FLOW ALOFT WILL INCREASE SOUTHERLY TODAY. CLEAR SKIES TODAY, WITH A
FEW HIGH CLOUDS INCREASING LATER THIS AFTERNOON INTO THIS EVENING.
LIFR STRATUS MAY BE POSSIBLE ALONG THE SOUTH COAST, APPROACHING KHQM
FRIDAY MORNING. GENERALLY LIGHT N/NW SURFACE WINDS.
KSEA...CLEAR SKIES, A FEW HIGH CLOUDS INCREASING LATER THIS
AFTERNOON. NORTHWEST WIND 5 TO 8 KTS INCREASING TO 8 TO 12 KTS EARLY
THIS AFTERNOON. WINDS WILL BECOME NE AT 4 TO 8 KTS TONIGHT. JD
MARINE
A SURFACE RIDGE CENTERED OFFSHORE WILL WEAKEN TODAY. A
BROAD AREA OF WEAK SURFACE LOW PRESSURE WILL DEVELOP TONIGHT AND
FRIDAY OVER THE PACIFIC NORTHWEST WHILE HIGH PRESSURE REMAINS
CENTERED WELL OFFSHORE. THIS WILL LEAD TO AN OVERALL INCREASE IN
ONSHORE FLOW INTO THE WEEKEND. HIGH PRESSURE WILL BUILD OVER THE
WATERS LATER SUNDAY INTO THE FIRST PART OF NEXT WEEK.
SMALL CRAFT ADVISORY WINDS DEVELOPING OVER THE OUTER COASTAL
WATERS TONIGHT WILL CONTINUE INTO AT LEAST SATURDAY AND POSSIBLY
SATURDAY NIGHT FOR THE NORTHERN OUTER WATERS. SMALL CRAFT ADVISORY
WESTERLIES IN THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA
FRIDAY NIGHT WITH THE INCREASING ONSHORE FLOW.
SEAS BUILDING TONIGHT INTO FRIDAY PEAKING IN THE 8 TO 11 FOOT
RANGE FRIDAY NIGHT INTO SATURDAY NIGHT. SEAS SUBSIDING SUNDAY AND
BE IN THE 3 TO 6 FOOT RANGE BY EARLY NEXT WEEK. FELTON
HYDROLOGY
NO RIVER FLOODING IS EXPECTED OVER THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 8 PM FRIDAY TO 5 AM PDT SATURDAY FOR
CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 8 PM FRIDAY TO 6 PM PDT SATURDAY 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.
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