846
FXUS66 KSEW 181148
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
348 AM PST WED DEC 18 2024
SYNOPSIS
A FRONTAL SYSTEM WILL CONTINUE TO MOVE ACROSS WESTERN
WASHINGTON EARLY THIS MORNING. BRIEF, DRY CONDITIONS EXPECTED THIS
AFTERNOON THROUGH TONIGHT. A SYSTEM WILL BRING LIGHTER
PRECIPITATION THURSDAY INTO THURSDAY NIGHT. ADDITIONAL WEAKER
FRONTS WILL BRING PRECIPITATION CHANCES LATE IN THE WEEK. A MORE
ACTIVE PATTERN DEVELOPS LATER IN THE WEEKEND THROUGH NEXT WEEK.
SHORT TERM /TODAY THROUGH FRIDAY/
WIDESPREAD STRATIFORM
PRECIPITATION CONTINUES ACROSS WESTERN WASHINGTON EARLY THIS
MORNING WITH A COLD FRONT DRAPED OVER OLYMPIC PENINSULA. WINDS
WILL PEAK FOR MOST AREAS THROUGH APPROXIMATELY 500 AM AS THE FRONT
SLIDES EASTWARD ACROSS PUGET SOUND AND INTO THE CASCADES.
LOCALIZED POWER OUTAGES AND TREE DAMAGE REMAIN POSSIBLE INTO THE
EARLY MORNING PERIOD.
IN ADDITION, POST-FRONTAL WESTERLY WINDS WILL INCREASE THROUGH
THE STRAIT OF JUAN DE FUCA OVER THE NEXT FEW HOURS, REACHING
WHIDBEY ISLAND FOR ANOTHER PERIOD OF GUSTY WEST WINDS THROUGH
MID-MORNING. THIS WILL ALSO BRING ENHANCED CONVERGENCE ALONG THE
COLD FRONT ACROSS PORTIONS OF ADMIRALTY INLET INTO SNOHOMISH AND
SKAGIT COUNTIES. HI-RES GUIDANCE HIGHLIGHT A THIN, BUT IMPRESSIVE
BAND OF PRECIP MOVING EASTWARD GENERALLY BETWEEN 500 TO 700 AM
ACROSS THESE AFOREMENTIONED AREAS. THIS MAY BE ACCOMPANIED BY
HEAVIER RAIN RATES, AS WELL AS BRIEF GUSTY WINDS. PRECIPITATION
BY LATE MORNING WILL BE CONFINED TO THE CASCADES, WITH A COUPLE OF
INCHES OF SNOW POSSIBLE AT STEVENS PASS. PRECIPITATION WILL TAPER
THIS AFTERNOON FOR THE CASCADES, ALLOWING FOR DRIER WEATHER INTO
TONIGHT.
A WARM FRONT WILL MOVE NORTHWARD THURSDAY INTO EARLY FRIDAY FOR
ANOTHER ROUND OF LIGHTER LOWLAND RAIN. TEMPERATURES WILL REMAIN
ABOVE NORMAL THROUGH FRIDAY, WITH HIGHS IN THE LOW TO MID 50S,
WITH NEAR 60 DEGREES POSSIBLE FOR QUILLAYUTE ON FRIDAY.
LONG TERM /SATURDAY THROUGH TUESDAY/
ANOTHER FRONTAL SYSTEM
WILL MOVE ACROSS WESTERN WASHINGTON LATER SATURDAY FOR LOWLAND
RAIN AND MOUNTAIN SNOWFALL. A STRONGER SYSTEM IS EXPECTED TO
APPROACH THE AREA ON SUNDAY FOR ADDITIONAL PRECIPITATION.
ENSEMBLES SUGGEST THIS ACTIVE PATTERN CONTINUES THROUGH AT LEAST
THE MIDDLE OF NEXT WEEK, WITH SYSTEMS ACCOMPANIED BY LOWLAND RAIN,
MOUNTAIN SNOWFALL, AND BREEZY WINDS. THIS IS HIGHLIGHTED WELL BY
THE CPC WEEK 2 HAZARDS OUTLOOK. TEMPERATURES WILL BE SLIGHTLY
COOLER SATURDAY INTO NEXT WEEK. JD
AVIATION
A SURFACE WARM FRONT CONTINUES TO PASS THROUGH
THE REGION EARLY THIS MORNING (POSITIONED OVER PUGET SOUND AS OF
WRITING). WIDESPREAD SHOWER ACTIVITY CONTINUES THIS MORNING WITH
THIS FRONT, AND A TRAILING COLD FRONT ABOUT 60-80 SM OFF THE
WASHINGTON COAST. VARIABLE CEILINGS AND VISIBILITIES ARE EXPECTED
WITH THE SHOWER ACTIVITY AS IT PROGRESSES THROUGH THE REGION THIS
MORNING. THE HEAVIEST OF THE RAIN HAS BROUGHT VISIBILITIES DOWN TO
JUST UNDER 2 SM, WITH CIGS REMAINING EITHER VFR OR MVFR (ONLY
EXCEPTION IS BEHIND THE RAIN WHERE IFR VIS AND/OR CIGS WILL MOVE IN
ALONG THE COAST THIS MORNING, AND DEVELOP IN THE CASCADES WITH
ISOLATED POCKETS OF LIFR POSSIBLE). ONCE THE TRAILING COLD FRONT
MOVES THROUGH LATER TODAY, CIGS WILL IMPROVE TO VFR WITH A MIX OF
BROKEN TO OVERCAST DECKS AT OR ABOVE 3,000 FT FOR MOST AREAS.
WINDS CONTINUE TO REMAIN GUSTY THIS MORNING, ESPECIALLY IN PARTS OF
THE SOUTH INTERIOR AND EAST STRAIT OF JUAN DE FUCA UP TO BELLINGHAM.
GUSTS HAVE REACHED 45 TO 50 KT OUT OF THE SOUTH THIS MORNING IN SOME
OF THE PREVIOUSLY MENTIONED AREAS (COUPLE HIGHER GUSTS WERE OBSERVED
AT KHQM). REMAINING AREAS WILL SEE GUSTY WINDS THIS MORNING AS WINDS
CONTINUE TO MIX DOWN (WITH A CONTINUING WIND SHEAR THREAT THROUGH
THE EARLY MORNING HOURS. THE GUSTY WINDS WILL CEASE BETWEEN 20Z-00Z
THURSDAY, AND REMAIN BELOW 12 KT AFTER THAT TIME OUT OF THE SOUTH.
THE FLOW ALOFT WILL SHIFT TO NORTHWESTERLY ONCE THE UPPER LEVEL
TROUGH PASSES THROUGH.
KSEA...LIGHT TO MODERATE RAIN CONTINUES OVER THE TERMINAL THIS
MORNING. CIGS IMPROVED TO VFR WITH THE LATEST ROUND OF SHOWERS, BUT
WILL LIKELY FALL BACK TO MVFR ONCE THE SHOWER ACTIVITY BEGINS TO
TAPER BACK AFTER 10-12Z THIS MORNING. THE HEAVIER RAIN SHOWERS MAY
DROP VISIBILITIES DOWN TO 2-3 MI. RETURN TO VFR IS EXPECTED AFTER
AROUND 20Z WITH CIGS RISING TO AT OR ABOVE 4,500 FT. WIND GUSTS OUT
OF THE SOUTHWEST OF 25-30 KT WILL CONTINUE THROUGH AROUND 18Z, AND
BEGIN TO DECREASE AFTER THAT TIME TO BELOW 12 KT.
HPR
MARINE
A COMBINATION WARM/COLD FRONT SURFACE SYSTEM WILL CONTINUE
TO TRACK OVER THE WATERS THIS MORNING. WIDESPREAD RAIN SHOWERS MAY
REDUCE VISIBILITIES AT TIMES TO MARINERS OUT IN THE WATERS (DOWN TO
2 SM). THE PRECIPITATION WITH THIS SYSTEM WILL WRAP UP LATE THIS
MORNING INTO THE AFTERNOON FROM WEST TO EAST. WINDY CONDITIONS
CONTINUE THIS MORNING, WITH THE WINDIEST AREAS (PRODUCING HIGHER-END
GALE GUSTS) INCLUDING THE INNER COASTAL WATERS, AND ADMIRALTY
INLET/EAST STRAIT OF JUAN DE FUCA AREAS. WHILE THE SOUTH WINDS WILL
BEGIN TO DIMINISH EARLY THIS MORNING, ANOTHER WEST PUSH THROUGH THE
STRAIT OF JUAN DE FUCA WILL PRODUCE GALE GUSTS THROUGH LATER THIS
MORNING.
THERE WILL BE A BREAK IN ACTIVITY BEHIND THIS FRONTAL SYSTEM REST OF
WEDNESDAY AFTERNOON (ALTHOUGH SEAS WILL REMAIN AROUND 8 TO 14 FT
OVER THE COASTAL WATERS, WITH HIGHER SEAS FURTHER OUT). THE NEXT
SYSTEM WILL ARRIVE THURSDAY INTO FRIDAY WITH GUSTY SOUTH WINDS
EXPECTED. THERE IS INCREASING CHANCES FOR GALES IN THE COASTAL
WATERS WITH THIS SYSTEM. ADDITIONAL WEATHER SYSTEMS WILL CONTINUE TO
BRING ADDITIONAL CHANCES OF GUSTY WINDS THIS WEEKEND INTO NEXT WEEK
(INCLUDING GALES). SEAS WILL REMAIN ABOVE 10 FT UNTIL FOR THE
FORESEEABLE FUTURE (APPROACHING AT OR ABOVE 20 FT THIS WEEKEND INTO
NEXT WEEK).
HPR
HYDROLOGY
STEADIER RAIN CONTINUES ACROSS WESTERN WASHINGTON
EARLY THIS MORNING AS A FRONTAL SYSTEM MOVES ACROSS THE AREA.
SIGNIFICANT RISES ON RIVER LEVELS HAVE OCCURRED OVER THE LAST 12
HOURS ACROSS THE OLYMPIC PENINSULA DUE TO 4 TO 7 INCHES OF
RAINFALL RECORDED OVER THE OLYMPICS. THE SKOKOMISH RIVER IS
CURRENTLY IN MODERATE FLOOD STAGE EARLY THIS MORNING AND EXPECTED
TO CREST TODAY. IN ADDITION, THE BOGACHIEL AND SATSOP RIVERS
CONTINUE TO RISE RAPIDLY. THESE RIVERS WILL NEED TO BE MONITORED
FOR POTENTIAL RIVER FLOODING THIS MORNING. THE CHEHALIS RIVER WILL
ALSO RISE THROUGH THURSDAY, WITH THE CHEHALIS AT PORTER AND THE
CHEHALIS NEAR GRAND MOUND RISING INTO ACTION STAGE. RIVERS
ELSEWHERE WILL RISE INTO TODAY, BUT EXPECTED TO REMAIN BELOW FLOOD
STAGE.
ADDITIONAL INCOMING PRECIPITATION FROM WET SYSTEMS LATER IN THE
WEEK AND INTO NEXT WEEK WILL MAINTAIN THE THREAT OF RIVER FLOODING
ACROSS WESTERN WASHINGTON, BUT MODELS CONTINUE TO SHOW LARGE
DISCREPANCIES AND THE FORECAST REMAINS UNCERTAIN AT THIS TIME. JD
SEW WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY UNTIL 4 AM PST EARLY THIS MORNING FOR SAN JUAN
COUNTY-WESTERN SKAGIT COUNTY-WESTERN WHATCOM COUNTY.
COASTAL FLOOD ADVISORY UNTIL NOON PST TODAY FOR SAN JUAN COUNTY-
WESTERN SKAGIT COUNTY-WESTERN WHATCOM COUNTY.
WIND ADVISORY UNTIL 7 AM PST THIS MORNING FOR BELLEVUE AND
VICINITY-BREMERTON AND VICINITY-EAST PUGET SOUND LOWLANDS-
EVERETT AND VICINITY-HOOD CANAL AREA-LOWER CHEHALIS VALLEY
AREA-SEATTLE AND VICINITY-SOUTHWEST INTERIOR-TACOMA AREA.
WIND ADVISORY UNTIL 10 AM PST THIS MORNING FOR ADMIRALTY INLET
AREA.
HIGH WIND WARNING UNTIL 4 AM PST EARLY THIS MORNING FOR CENTRAL
COAST-NORTH COAST.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR WEST
SLOPES NORTH CENTRAL CASCADES AND PASSES.
PZ...SMALL CRAFT ADVISORY UNTIL 10 AM PST THIS MORNING FOR GRAYS
HARBOR BAR.
GALE WARNING UNTIL 10 AM PST THIS MORNING FOR ADMIRALTY INLET-
CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-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-EAST ENTRANCE U.S. WATERS STRAIT OF
JUAN DE FUCA-WEST ENTRANCE U.S. WATERS STRAIT OF JUAN DE
FUCA.
SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 4 AM PST
THURSDAY 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.
GALE WARNING UNTIL 7 AM PST THIS MORNING FOR NORTHERN INLAND
WATERS INCLUDING THE SAN JUAN ISLANDS-PUGET SOUND AND HOOD
CANAL.
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