895
FXUS66 KSEW 191002
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
302 AM PDT SAT SEP 19 2026
SYNOPSIS
WESTERN WASHINGTON ON THE BACKSIDE OF AN UPPER LEVEL RIDGE WITH
LOW LEVEL ONSHORE FLOW THROUGH THE WEEKEND. THE RIDGE MOVES EAST
MONDAY AS A WEAK SYSTEM MOVES BY TO THE NORTH. UPPER LEVEL
TROUGH DEVELOPING OFFSHORE TUESDAY REMAINING THROUGH FRIDAY.
DISSIPATING SYSTEM ARRIVING WEDNESDAY WITH ANOTHER POSSIBLE WEAK
SYSTEM FRIDAY.
SHORT TERM /TODAY THROUGH MONDAY/
SATELLITE IMAGERY SHOWS STRATUS ALONG THE COAST, OVER THE
WESTERN HALF OF THE STRAIT OF JUAN DE FUCA AND THROUGH THE
LOWER CHEHALIS VALLEY. MOSTLY CLEAR SKIES OVER THE REMAINDER OF
THE AREA. TEMPERATURES AT 3 AM/10Z WERE IN THE MID 40S TO MID
50S.
NOT MUCH GOING ON WEATHERWISE THIS WEEKEND. WESTERN WASHINGTON
ON THE BACKSIDE OF AN UPPER LEVEL RIDGE WITH WESTERLY FLOW
ALOFT OVER THE AREA. IN THE LOWER LEVELS LIGHT ONSHORE FLOW.
THIS MORNING THE STRATUS IS NOT MAKING EASTWARD VERY FAST BUT
WITH THE LONGER NIGHTS, LOW LEVEL MOISTURE AND LIGHT ONSHORE
FLOW EXPECT THE STRATUS TO FORM IN PLACE OVER THE PUGET SOUND AT
OR A LITTLE AFTER SUNRISE. WITH THE LIGHT FLOW IN THE LOWER
LEVELS AREAS OF FOG ALSO FORMING AROUND SUNRISE. THE LAYER WILL
BE SHALLOW AND DISSIPATE AROUND MIDDAY LEAVING PLENTY OF
AFTERNOON SUNSHINE FOR THE INTERIOR. STRATUS WILL BE TOUGH TO
GET RID OF ALONG THE COAST WITH JUST SOME LATE DAY SUNSHINE.
HIGHS MID 60S COAST AND MID 60S TO LOWER 70S INLAND.
LITTLE CHANGE IN THE PATTERN TONIGHT AND SUNDAY. ANOTHER ROUND
OF LATE NIGHT AND MORNING LOW CLOUDS WITH PATCHY FOG OVER THE
INTERIOR WHILE THE COAST STAYS MOSTLY CLOUDY. SUNSHINE IN THE
AFTERNOON OVER THE INTERIOR WILL PUT HIGHS IN THE MID 60S TO
MID 70S. HIGHS ALONG THE COAST IN THE MID 60S. IT WILL BE A COOL
MORNING SUNDAY WITH LOWS IN THE MID 40S TO LOWER 50S.
A FEW CHANGES MONDAY BUT THE FORECAST WILL REMAIN THE SAME.
UPPER LEVEL RIDGE MOVES OFF TO THE EAST WHILE A WEAK SYSTEM
MOVES INLAND WELL NORTH OF THE AREA. WEAK LOW LEVEL ONSHORE FLOW
IN THE LOWER LEVELS KEEPING THE MORNING CLOUDS AFTERNOON
SUNSHINE SCENARIO INTACT. HIGHS REMAINING IN THE MID 60S TO MID
70S WITH LOWS IN THE MID 40S TO LOWER 50S. FELTON
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
MODELS IN GOOD AGREEMENT THROUGH THURSDAY WITH AN UPPER LEVEL
TROUGH OFFSHORE. DISSIPATING SYSTEM MOVING INTO THE AREA
WEDNESDAY FOR A SLIGHT CHANCE OF SHOWERS OVER THE NORTHERN
PORTION. GFS BRINGS THE TROUGH INTO THE AREA FRIDAY WHILE THE
ECMWF KEEPS THE TROUGH OFFSHORE. ENSEMBLES HAVE ENOUGH
SOLUTIONS WITH LIGHT PRECIPITATION TO PUT SLIGHT CHANCE POPS IN
THE FORECAST. SLOW COOLING TREND WITH HIGHS IN THE MID 60S TO
LOWER 70S TUESDAY DROPPING TO THE LOWER TO MID 60S BY FRIDAY.
LOWS REMAINING IN THE MID 40S TO LOWER 50S. FELTON
AVIATION
WESTERLY ZONAL FLOW WILL PREVAIL ALOFT TODAY. WITH VERY LIGHT TO
MOSTLY CALM WINDS THIS MORNING, MVFR MARINE STRATUS WILL
STRUGGLE TO PROGRESS INLAND ON ITS OWN THIS MORNING PAST
SHN/CLM. THIS WILL ALLOW FOR ADDITIONAL DEVELOPMENT THROUGH THE
INTERIOR OF WESTERN WASHINGTON TO BE VERY LOW-BASED STRATUS OR
FOG FOR LIFR CONDITIONS. LOW STRATUS AND FOG WILL CONTINUE TO
SLOWLY FILL IN, WITH THE GREATEST EXTENT EXPECTED JUST AFTER
SUNSET, OR AROUND 14-17Z THIS MORNING. CLOUDS SHOULD SLOWLY LIFT
AND SCATTER FROM AROUND 17-21Z FOR MOST, THROUGH THE COAST MAY
STAY MOSTLY CLOUDY THROUGH MUCH OF THE DAY. VFR CONDITIONS WILL
THEN PREVAIL UNTIL LATE TONIGHT/EARLY SUNDAY MORNING WITH
ANOTHER ROUND OF LOW STRATUS AND PATCHY FOG EXPECTED.
WINDS LOOK TO REMAIN LIGHT FOR MOST THOUGH TONIGHT, AS WELL. A
WEAK PUSH THROUGH THE STRAIT OF JUAN DE FUCA THIS EVENING WILL
SWITCH WIND DIRECTIONS THROUGH THE PUGET SOUND FROM SOUTH TO
NORTH.
KSEA...VFR CONDITIONS THROUGH MOST OF THE TAF PERIOD, WITH THE
EXCEPTION OF BETWEEN AROUND 13-17Z THIS MORNING AS FOG AND LOW
STRATUS IS EXPECTED TO DEVELOP AROUND THE TERMINAL. MODELS SHOW
A RELATIVELY SLOW LIFT AND SCATTER BETWEEN AROUND 17-20Z THIS
MORNING BEFORE MOSTLY CLEAR SKIES THEN PREVAIL UNTIL EARLY
SUNDAY MORNING. SOUTH/SOUTHWESTERLY WINDS 5 KT OR LESS WILL
TRANSITION TO WEST/NORTHWEST THIS AFTERNOON AND REMAINING
LIGHT NORTHERLY OVERNIGHT INTO SUNDAY MORNING.
62
MARINE
WEAK ONSHORE FLOW WILL CONTINUE INTO NEXT WEEK AS BROAD HIGH
PRESSURE REMAINS OVER THE OFFSHORE WATERS. WEAKENING FRONTAL
SYSTEMS MOVING BY TO THE NORTH THROUGH NEXT WEEK WILL HELP TO
INCREASE ONSHORE FLOW, ALLOWING FOR INCREASED CHANCES FOR SMALL
CRAFT ADVISORY CONDITIONS EACH EVENING WITH WESTERLY PUSHES
THROUGH THE STRAIT OF JUAN DE FUCA. PUSHES WILL BEGIN TO
INCREASE TONIGHT AND SUNDAY EVENING, BUT WILL MOST LIKELY
REMAIN BELOW THRESHOLDS. CHANCES FOR MEETING SMALL CRAFT
THRESHOLDS RISE TO 50-80% BY MONDAY EVENING, WITH SLIGHTLY LOWER
CHANCES ON TUESDAY EVENING.
SEAS REMAIN 3 TO 5 FT UNTIL MONDAY AS INCOMING SWELL RISES SEAS
TO AROUND 6 TO 8 FT. SEAS REMAIN IN THAT RANGE THROUGH MID-WEEK.
62
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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