836
FXUS66 KSEW 151204
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
404 AM PST SUN DEC 15 2024
SYNOPSIS
SHOWERS CONTINUE THIS MORNING, WITH A BRIEF BREAK IN
THE PRECIPITATION THIS AFTERNOON. ANOTHER FRONTAL SYSTEM WILL LIFT
NORTHWARD TONIGHT INTO MONDAY FOR WIDESPREAD PRECIPITATION. THE
ACTIVE PATTERN CONTINUES TUESDAY INTO WEDNESDAY ANOTHER SYSTEM
BRINGS LOWLAND RAIN, WARMING TEMPERATURES, AND BREEZY WINDS.
TEMPERATURES WILL BE ABOVE NORMAL LATE WEEK INTO NEXT WEEKEND.
SHORT TERM /TODAY THROUGH TUESDAY/
SHOWERS CONTINUE EARLY THIS
MORNING ACROSS WESTERN WASHINGTON WITH CONTINUED MOUNTAIN SNOW AT
TIMES. THE WINTER WEATHER ADVISORY HAS BEEN EXTENDED UNTIL 1000 AM
FOR THE CENTRAL CASCADES DUE TO ADDITIONAL SNOW AMOUNTS OF 1 TO 4
INCHES FOR THE PASSES, PARTICULARLY STEVENS PASS. OTHERWISE,
SHOWERS WILL SLOWLY TAPER OFF INTO THIS AFTERNOON FOR MOST OF THE
AREA. IN ADDITION, A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR
PORTIONS OF PUGET SOUND THIS MORNING, WITH INUNDATION OF AROUND 2
FEET ABOVE GROUND LEVEL POSSIBLE ALONG SHORELINES AND LOW-LYING
COASTAL AREAS.
THE BREAK IN PRECIPITATION WILL BE BRIEF AS ANOTHER FRONTAL
SYSTEM WILL SPREAD PRECIPITATION NORTHWARD TONIGHT INTO MONDAY FOR
ADDITIONAL LOWLAND RAIN AND MOUNTAIN SNOWFALL. WINDS WILL BE
LIGHTER WITH THIS FRONT COMPARED TO THE SATURDAY WEATHER SYSTEM,
WITH BREEZIER WINDS MAINLY CONFINED TO THE COAST. THE ACTIVE
PATTERN WILL CONTINUE TUESDAY INTO MIDWEEK AS ANOTHER SYSTEM
OFFSHORE LOOKS TO TRACK TOWARDS VANCOUVER ISLAND. A WARM FRONT
WILL LIKELY LIFT NORTHWARD TUESDAY INTO TUESDAY NIGHT FOR
ADDITIONAL PRECIPITATION, AS WELL AS INCREASING SNOW LEVELS. HIGH
TEMPERATURES THROUGH TUESDAY EXPECTED TO BE IN THE MID TO UPPER
40S.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
THE AFOREMENTIONED
SYSTEM WILL CONTINUE TO IMPACT WESTERN WASHINGTON INTO WEDNESDAY.
UNCERTAINTY REMAINS IN ENSEMBLES IN THE EXACT TRACK OF THE SYSTEM.
HOWEVER, ECMWF EFI HIGHLIGHTS BOTH WINDS AND QPF AS ANOMALOUS
FROM CLIMO FROM 00Z WED TO 00Z THURS. THIS WILL BE ANOTHER PERIOD
TO MONITOR FOR PERHAPS MORE IMPACTFUL WEATHER. RIDGING THEN
BUILDS ACROSS THE INTERIOR WESTERN US THURSDAY INTO THE WEEKEND.
HOWEVER, THERE REMAINS CONTINUED UNCERTAINTY AS TO THE EXTENT THE
RIDGING INFLUENCES WESTERN WASHINGTON WITH SOME TROUGHING WELL
OFFSHORE. KEPT THE FORECAST NBM PRECIPITATION POTENTIAL IN THE
FORECAST DURING THIS PERIOD LATER THURSDAY INTO SATURDAY, BUT
ECMWF ENSEMBLES REMAIN THE DRIER SOLUTION OUT OF THE CLUSTERS.
TEMPERATURES WILL WARM ABOVE NORMAL LATER IN THE WEEK. JD
AVIATION
CEILINGS ARE EXPECTED TO TREND BETWEEN VFR AND MVFR
ACROSS THE TERMINALS THROUGH THE EARLY MORNING HOURS OF SUNDAY.
LIGHT ISOLATED SHOWERS ARE POSSIBLE AT THE TERMINALS AND SHOULD
DISSIPATE SUNDAY MORNING. WITH SHOWERS DISSIPATING, IMPROVEMENT IS
EXPECTED INTO VFR LATE INTO SUNDAY MORNING AND EXPECTED TO STAY VFR
THROUGH SUNDAY AFTERNOON. HOWEVER, CEILINGS ARE EXPECTED TO TREND
TOWARD MVFR AS RAIN SHOWERS ARE EXPECTED TO BECOME MORE WIDESPREAD
ACROSS WESTERN WASHINGTON STARTING SUNDAY NIGHT AND CONTINUING
THROUGHOUT MONDAY. SOUTH/SOUTHWESTERLY FLOW IS EXPECTED TO SHIFT
MORE EASTERLY AROUND SUNDAY EVENING.
KSEA...ISOLATED LIGHT SHOWERS ARE STILL POSSIBLE INTO EARLY
SUNDAY MORNING, HOWEVER SHOWERS SHOULD TAPER OFF BY SUNDAY
AFTERNOON. CEILINGS HAVE BEEN TRENDING MVFR, HOWEVER IT'S POSSIBLE
THAT CEILINGS MAY BOUNCE AROUND TO VFR AT TIMES. STILL EXPECTING
CEILINGS TO TREND MOSTLY MVFR. CEILINGS SHOULD BOUNCE BACK TO HIGH
END VFR BY SUNDAY AFTERNOON. CEILINGS ARE EXPECTED TO LOWER INTO
MVFR ONCE AGAIN ON EARLY MONDAY MORNING AS RAIN BEGINS TO BECOME
MORE WIDESPREAD THROUGHOUT THE DAY.
WINDS ARE CURRENTLY FROM THE SOUTHWEST WITH POSSIBLE WINDS GUST OF
20-23 KTS. THIS MAY LAST TO AROUND 15Z SUNDAY. WINDS EXPECTED TO
SHIFT EAST AFTER 0Z ON MONDAY AND THEN BECOMING MORE SOUTHEASTERLY.
WINDS WILL SHOULD BE LIGHT AROUND 4-6 KTS.
MGF
MARINE
HIGH PRESSURE WILL BUILD OVER THE COASTAL WATERS SUNDAY
MORNING BRINGING CALMER WINDS TO THE WATERS TEMPORARILY. HOWEVER,
ANOTHER WEATHER SYSTEM IS EXPECTED TO BEGIN IMPACTING THE COASTAL
WATERS ON SUNDAY EVENING. WINDS ON THE COASTAL WATERS ARE EXPECTED
TO REACH SMALL CRAFT CRITERIA BY SUNDAY EVENING AND INCREASE TO GALE
FORCE BY THE EARLY MORNING HOURS ON MONDAY. THE WESTERN PART OF THE
STRAIT IS ALSO EXPECTED TO SEE GALE FORCE WINDS. SMALL CRAFT WINDS
ARE ALSO EXPECTED ALONG THE CENTER AND EASTERN STRAIT, THE NORTHERN
INLAND WATERS, AND GRAYS HARBOR. WINDS SHOULD SUBSIDE BELOW SMALL
CRAFT CRITERIA ON MONDAY AFTERNOON. FOLLOWING THIS EVENT, A SERIES
OF WEATHER SYSTEMS WILL KEEP THE WATER CONDITIONS ACTIVE BRINGING
THE CHANCE FOR MORE SMALL CRAFT CRITERIA WINDS THROUGHOUT THE WEEK.
WAVES ON THE COASTAL WATERS WILL REMAIN BELOW 10 FT UNTIL THE NEXT
STORM SYSTEM BEGINS TO IMPACT THE WATERS ON SUNDAY EVENING. WAVES
ARE EXPECTED TO BUILD TO 13-15 FT IN THE OUTER COASTAL WATERS AND 7-
11 FT IN THE INNER COASTAL WATERS. WITH SEVERAL UPCOMING WEATHER
SYSTEMS INCOMING INTO THE WATERS NEXT WEEK, WAVES ARE EXPECTED TO
REMAIN ABOVE 10 FT FOR MOST OF NEXT WEEK.
MGF
HYDROLOGY
AREA RIVERS WILL RISE WITH ADDITIONAL PRECIPITATION
OVER THE NEXT WEEK, AND INCREASING SNOW LEVELS TUESDAY INTO LATER
IN THE WEEK. ADDITIONAL ROUNDS OF PRECIPITATION WILL KEEP AT LEAST
THE SKOKOMISH RIVER ELEVATED THROUGH THE WEEK. JD
SEW WATCHES/WARNINGS/ADVISORIES
WA...COASTAL FLOOD ADVISORY UNTIL 9 AM PST THIS MORNING FOR BREMERTON
AND VICINITY-EVERETT AND VICINITY-HOOD CANAL AREA-SAN JUAN
COUNTY-SEATTLE AND VICINITY-SOUTHWEST INTERIOR-TACOMA AREA-
WESTERN SKAGIT COUNTY-WESTERN WHATCOM COUNTY.
COASTAL FLOOD ADVISORY FROM 9 AM THIS MORNING TO 3 PM PST THIS
AFTERNOON FOR CENTRAL COAST.
WINTER STORM WARNING UNTIL 4 AM PST EARLY THIS MORNING FOR WEST
SLOPES NORTH CASCADES AND PASSES.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR WEST
SLOPES NORTH CENTRAL CASCADES AND PASSES.
WINTER WEATHER ADVISORY UNTIL 4 AM PST EARLY THIS MORNING FOR
WEST SLOPES SOUTH CENTRAL CASCADES AND PASSES.
PZ...SMALL CRAFT ADVISORY UNTIL 7 AM PST THIS MORNING FOR GRAYS
HARBOR BAR.
GALE WARNING FROM 4 PM THIS AFTERNOON TO 4 AM PST MONDAY 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-WEST ENTRANCE U.S.
WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM PST
MONDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA-NORTHERN INLAND
WATERS INCLUDING THE SAN JUAN ISLANDS.
SMALL CRAFT ADVISORY UNTIL 4 PM PST THIS AFTERNOON 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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