792
FXUS66 KSEW 021723
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
923 AM PST TUE DEC 2 2025
SYNOPSIS
UPPER LEVEL RIDGE OFFSHORE THROUGH THURSDAY. WEAK
SYSTEM MOVING SOUTH OUT OF THE AREA LATER THIS MORNING INTO THE
AFTERNOON. WEAK WARM FRONT WILL BRUSH THE NORTHWEST CORNER
WEDNESDAY. ANOTHER SYSTEM MOVING OVER THE TOP OF THE RIDGE
MOVING THROUGH THURSDAY. RIDGE OFFSHORE WEAKENING THURSDAY NIGHT
INTO FRIDAY. A SERIES OF STRONGER AND WETTER SYSTEMS WILL TAKE
AIM AT WESTERN WASHINGTON BEGINNING FRIDAY AND CONTINUING
THROUGH THE MIDDLE OF NEXT WEEK.
SHORT TERM /TODAY THROUGH THURSDAY/
THE CURRENT FORECAST
REMAINS ON TRACK. 33
PREVIOUS DISCUSSION...WEAK SYSTEM MOVING SOUTH THROUGH WESTERN
WASHINGTON THIS MORNING WITH RAIN CHANCES COMING TO AN END FROM
NORTH TO SOUTH THIS AFTERNOON. EVEN WITH THE SYSTEM OUT OF THE
AREA LIGHT FLOW IN THE LOWER LEVELS COMBINED WITH PLENTY OF LOW
LEVEL MOISTURE WILL KEEP SKIES CLOUDY OVER MOST OF THE AREA.
SOME CLEARING POSSIBLE ALONG THE NORTH COAST. LITTLE IN THE WAY
OF DAYTIME "HEATING" WITH THE CLOUD COVER AS WELL. HIGHS IN THE
MID 40S TO LOWER 50S.
WESTERN WASHINGTON IN-BETWEEN SYSTEMS TONIGHT. LIKE THE
AFTERNOON HOURS, LIGHT FLOW IN THE LOWER LEVELS WITH LOW LEVEL
MOISTURE WILL KEEP SKIES AT LEAST MOSTLY CLOUDY. COULD SEE SOME
FOG FORM OVERNIGHT ESPECIALLY IN THE FOG PRONE LOCATIONS LIKE
THE SOUTHWEST INTERIOR. LOWS MID 30S TO LOWER 40S.
WEAK WARM FRONT MOVING OVER THE TOP OF THE OFFSHORE RIDGE
BRUSHING THE NORTHWEST PORTIONS WEDNESDAY FOR A CHANCE OF RAIN.
FOR THE REMAINDER OF THE AREA, EVEN IF THE LOWER CLOUD DECK
BREAKS UP A LITTLE THE MIDDLE LEVEL CLOUDS ASSOCIATED WITH THE
WARM FRONT WILL KEEP SKIES MOSTLY CLOUDY. HIGHS IN THE MID TO
UPPER 40S.
YET ANOTHER SYSTEM RIDING OVER THE UPPER LEVEL RIDGE OFFSHORE
REACHING WESTERN WASHINGTON THURSDAY. LEADING EDGE OF THE RAIN
COULD REACH THE NORTHERN HALF OF THE AREA AFTER MIDNIGHT EARLY
THURSDAY MORNING. RAIN SPREADING OVER THE ENTIRE AREA THURSDAY
MORNING WITH RAIN CONTINUING INTO THE AFTERNOON HOURS. HIGHS IN
THE MID 40S TO LOWER 50S. FELTON
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
EXTENDED MODELS
CONTINUE TO SHOW GOOD AGREEMENT WITH THE OFFSHORE RIDGE
WEAKENING THURSDAY NIGHT INTO FRIDAY. ANOTHER SYSTEM MOVING OVER
THE TOP OF THE FLATTING RIDGE REACHING WESTERN WASHINGTON
FRIDAY. THIS SYSTEM HAS A WEAK SUB TROPICAL MOISTURE TAP
ASSOCIATED WITH IT BUT THE SYSTEM IS ALSO PROGRESSIVE. FRIDAY
NIGHT THE SYSTEM WILL MOVE SOUTHEAST OF THE AREA. ANOTHER WEAK
IMPULSE EMBEDDED IN THE NOW WESTERLY FLOW ALOFT ARRIVING
SATURDAY KEEPING RAIN IN THE FORECAST. ELONGATED SYSTEM
STRETCHING ALONG THE BRITISH COLUMBIA COAST DOWN INTO WESTERN
WASHINGTON SUNDAY FOR MORE RAIN. WINDY CONDITIONS ALONG THE
COAST AND OVER THE NORTHWEST INTERIOR POSSIBLE WITH THIS
FEATURE. THERE COULD BE A SHORT BREAK SUNDAY NIGHT OR MONDAY AS
AN UPPER LEVEL RIDGE TRIES TO BUILD OVER THE AREA. ENSEMBLES
SOLUTIONS INDICATING THE RIDGE BEING STRONG ENOUGH TO PUSH YET
ANOTHER SYSTEM TO THE NORTH RUNNING AROUND A THIRD OF THE
SOLUTIONS. THIS NEXT SYSTEM IS THE JUICIEST ONE OF THE SERIES
WITH A CONSOLIDATED TAP INTO SUBTROPICAL MOISTURE. RIGHT NOW
EVEN IF THE RIDGE BUILDS ENOUGH TO DEFLECT THE SYSTEM NORTH IT
WILL ONLY BE A ONE DAY REPRIEVE WITH THE RIDGE WEAKENING TUESDAY
AND NUMEROUS ENSEMBLE SOLUTIONS INDICATING SIGNIFICANT
PRECIPITATION.
IN ADDITION TO THE RAIN, HIGH TIDE CYCLE COMBINED WITH THESE
SYSTEMS WILL BRING UP THE POSSIBILITY OF COASTAL FLOODING DUE
TO TIDAL OVERFLOW ALONG THE COAST, STRAIT OF JUAN DE FUCA AND
OVER THE NORTHERN INLAND WATERS BEGINNING WITH THE HIGH TIDES
FRIDAY AND CONTINUING INTO THE EARLY PART OF NEXT WEEK. FELTON
AVIATION
AN UPPER LEVEL RIDGE WILL INCREASE NORTHERLY FLOW
ALOFT TODAY. SHOWERS THIS MORNING ARE PRIMARILY CONCENTRATED
ALONG AND EAST OF I-5. THE ACTIVITY WILL CONSOLIDATE DOWN TO A
CONVERGENCE ZONE BETWEEN SNOHOMISH/KING COUNTIES THROUGHOUT THE
MORNING. SOME MIST MAY ACCOMPANY THE LOW CEILINGS AT TIMES. DUE
TO THE ABUNDANT LOW LEVEL MOISTURE/LIGHT FLOW, MOST TERMINALS
WILL ONLY IMPROVE TO MVFR (ONLY THE COAST WILL HAVE THE BEST
CHANCE OF CEILINGS ABOVE 2,000 FT THIS EVENING) BEFORE CEILINGS
LOWER AGAIN TO IFR-MVFR (POCKETS OF LIFR). SOUTH WINDS 4-8 KT
WILL SWITCH TO THE NORTH BEHIND THE FRONT 3-6 KT THROUGH THE
MORNING (5-10 KT ALONG THE COAST). THE SPEEDS WILL DECREASE
TONIGHT TO LESS THAN 5 KT AND SWITCH TO THE SOUTH.
KSEA...RAIN SHOWERS FROM A NEARBY CONVERGENCE ZONE WILL CONTINUE IN
AND NEAR THE TERMINAL THROUGH THIS MORNING WITH IFR CONDITIONS.
MVFR IMPROVEMENT UP TO 2,000 FT IS EXPECTED LATER THIS
AFTERNOON AND EVENING WITH ANOTHER ELEVATED CHANCE OF IFR
CEILINGS WEDNESDAY MORNING. SOUTH WINDS 4-8 KT WILL SWITCH TO
THE NORTH AROUND 16Z-18Z BUT ARE EXPECTED TO DECREASE TO 3- 6 KT
THROUGH THE DAY, THEN BECOME CALM OR VERY LIGHT SOUTHEAST WIND
AFTER 09Z.
HPR/MAZURKIEWICZ
MARINE
A COLD FRONT HAS PUSHED THROUGH THE COASTAL WATERS
THIS MORNING AND WILL CONTINUE TO TRACK THROUGH THE INTERIOR
WATERS. GUSTY WINDS UP TO 25 KT REMAIN LIKELY IN THE OUTER
COASTAL WATERS THROUGH THIS AFTERNOON, AS WILL SEAS OF 9-12 FT
THROUGH LATE TONIGHT. THE SMALL CRAFT ADVISORY WAS EXTENDED TO
06Z WEDNESDAY FOR THE SLOWER DROP IN SEAS. BENIGN CONDITIONS ARE
EXPECTED WITH LIGHT WINDS, AND SEAS RETURNING TO 4-6 FT
WEDNESDAY THROUGH FRIDAY. A STRONGER SYSTEM WILL APPROACH THE
WATERS FRIDAY THROUGH THE WEEKEND INTO NEXT WEEK WITH GUSTY
WINDS AT TIMES FOR MOST OF THE WATERS. THE BEST CHANCE OF GALE
FORCE WINDS WILL BE IN THE STRAIT OF JUAN DE FUCA MONDAY NIGHT
INTO TUESDAY. SEAS INCREASE BACK TO 9-12 FT SATURDAY, AND
POTENTIALLY INCREASE TO 10-14 FT EARLY NEXT WEEK.
HPR
HYDROLOGY
THE SERIES OF WEATHER SYSTEMS FORECAST TO REACH
THE AREA WILL EVENTUALLY INCREASE THE THREAT OF RIVER FLOODING
IN THE COMING DAYS. WEST NORTHWESTERLY FLOW ALOFT WITH THE
SYSTEM FRIDAY PUTS THE AREA OF GREATEST PRECIPITATION IN THE
NORTH CENTRAL WASHINGTON CASCADES. SNOW LEVELS RISING OVER 6000
FEET. CURRENT FORECAST 18 HOUR PRECIPITATION AMOUNTS BETWEEN 06Z
FRIDAY AND 00Z SATURDAY HAVE AN AREA OF 2 INCH BULLSEYES
BETWEEN SNOQUALMIE PASS AND GLACIER PEAK. THIS WILL PUT PRESSURE
ON THE RIVERS FLOWING OUT OF THIS AREA INCLUDING BUT NOT
LIMITED TO THE SNOQUALMIE, SKYKOMISH, SNOHOMISH AND TOLT RIVERS.
AS THE FLOW ALOFT BECOMES MORE WEST SOUTHWESTERLY THE FLOOD
THREAT WILL SHIFT TO THE FLOOD PRONE SKOKOMISH RIVER LATER IN
THE WEEKEND.
PLENTY OF UNCERTAINTY ON HOW THE PATTERN WILL SET UP EARLY NEXT
WEEK BUT THERE IS A CHANCE FOR A WIDESPREAD RIVER FLOODING
EVENT.
THE LANDSLIDE THREAT IS MINIMAL THE NEXT FEW DAYS. THE SERIES
OF SYSTEMS WILL EVENTUALLY TAKE ITS TOLL WITH THE LANDSLIDE
THREAT INCREASING THIS WEEKEND INTO EARLY NEXT WEEK. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 10 PM PST THIS EVENING 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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