829
FXUS66 KSEW 262140
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
240 PM PDT SAT SEP 26 2026
SYNOPSIS
ZONAL FLOW ALOFT IS CONTRIBUTING TO CALMER CONDITIONS THROUGH
THIS WEEKEND. ANOTHER SYSTEM WILL ARRIVE ON TUESDAY FOR MORE
RAIN AND BREEZY WINDS. ANOTHER WEAK FRONT WILL ARRIVE ON
THURSDAY. FOR THE LATE WEEK PERIOD INTO EARLY NEXT WEEK, HIGH
PRESSURE LOOKS FAVORED WITH THERMALLY INDUCED TROUGHING ALONG
THE OREGON COAST.
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/
THIS AFTERNOON'S SATELLITE IMAGERY SHOWS MOSTLY CLEAR CONDITIONS
ACROSS WESTERN WASHINGTON WITH ONLY MID AND UPPER LEVEL CLOUDS
STREAMING THROUGH. HIGHS IN THE LOW 60S FOR BOTH TODAY AND
TOMORROW. GIVEN THE CLEAR SKIES AND LIGHT SURFACE WINDS, SOME
PATCHY FOG DEVELOPMENT IS POSSIBLE OVERNIGHT INTO SUNDAY
MORNING. WHATEVER DEVELOPS WILL GENERALLY DISSIPATE BY
MIDMORNING. SUNDAY MORNING LOWS WILL BE IN THE LOW 40S TO UPPER
30S IN THE CASCADES AND ADJACENT FOOTHILLS. DESPITE THE ZONAL
FLOW, DRIER AFTERNOON RELATIVE HUMIDITY IS IN THE FORECAST FOR
TOMORROW PRIMARILY IN THE MOUNTAINS. AFTERNOON RH MINIMUMS IN
THE UPPER 30 PERCENT RANGE IS LIKELY.
MONDAY NOW LOOKS GENERALLY CLEAR AND A COUPLE DEGREES COOLER,
WITH THE NEXT SYSTEM ARRIVING MONDAY NIGHT INTO TUESDAY FROM THE
NORTHWEST.
LONG TERM /TUESDAY THROUGH SATURDAY/
INTO TUESDAY, AREAS FAVORED FOR MORE PRECIPITATION
WILL BE THE NORTH CASCADES, OLYMPICS AND AREAS FROM KING COUNTY
NORTH. BREEZY WINDS ARE FORECAST FOR THE COAST AND NORTHERN
INLAND WATERS. THE RAIN WILL TAPER OFF LATE TUESDAY, FOR A DRIER
WEDNESDAY AND THURSDAY. A DECAYING FRONTAL SYSTEM MAY INCREASE
SOME CLOUDS OVER THE AREA ON THURSDAY, WITH LITTLE IN THE WAY OF
MEANINGFUL PRECIPITATION FOR THAT TIME FRAME.
HIGH PRESSURE SEEMS FAVORED TO RETURN LATE IN THE WEEK AND OVER
NEXT WEEKEND. THE HIGH WILL CAUSE THERMALLY INDUCED TROUGHING
OVER THE OR/WA BORDER AND INCREASE THE HIGH TEMPERATURES BACK
INTO THE UPPER 60S AND POSSIBLY LOW 70S.
21
AVIATION
WEAK HIGH PRESSURE AND OFFSHORE FLOW WILL LEAD TO
DRY AND STABLE CONDITIONS ACROSS WESTERN WA TONIGHT. POCKETS OF
LOW CLOUDS AND FOG ARE LIKELY AROUND THE SOUTH SOUND OVERNIGHT.
ANY FOG AND/OR LOW CLOUDS WILL BE SHALLOW AND DISSIPATE BY 18Z
SUN. OTHERWISE, EXPECT VFR CONDITIONS ON SUNDAY WITH MAINLY HIGH
CLOUDS ALOFT. 33
KSEA...VFR CONDITIONS EXPECTED TONIGHT INTO SUNDAY WITH A N WIND
AROUND 10 KT. 33
MARINE
WEAK HIGH PRESSURE AND OFFSHORE FLOW TONIGHT. A WEAK
FRONT WILL DISSIPATE OVER THE OFFSHORE WATERS ON SUNDAY.
SOUTHERLY FLOW WILL INCREASE MONDAY NIGHT AND TUESDAY WITH A
STRONGER FRONTAL SYSTEM. WEAK HIGH PRESSURE AND OFFSHORE FLOW
WILL FOLLOW ON WEDNESDAY. 33
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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