191
FXUS66 KSEW 010440
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
840 PM PST SUN NOV 30 2025
SYNOPSIS
THE OVERALL PATTERN FOR THE WEEK LOOKS TO REMAIN ON THE COOL
SIDE WITH A FEW PERIODS OF PRECIPITATION. SHOWERY PRECIPITATION
WILL BRUSH THE AREA MONDAY INTO TUESDAY AND NOT AGAIN UNTIL
MORE WIDESPREAD PRECIPITATION THREATENS THE REGION THURSDAY INTO
FRIDAY. TEMPERATURES LATE IN THE WEEK SHOULD ALSO TREND A BIT
WARMER.
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/
COOL, BUT SUNNY AND DRY CONDITIONS WILL CLOSE THE WEEKEND OUT
THIS AFTERNOON. ALREADY SEEING SOME HIGH LEVEL CLOUDS STREAM
INTO WESTERN WASHINGTON FROM THE NORTHWEST, THIS WILL CONTINUE
OVERNIGHT AS AN UPPER LEVEL SYSTEM RIDES OVER THE RIDGE INTO
BRITISH COLUMBIA. ANOTHER CHILLY AND FOGGY START LOOKS TO BE ON
TAP FOR PARTS OF WESTERN WASHINGTON LATE TONIGHT INTO MONDAY
MORNING, ESPECIALLY ACROSS THE SOUTHERN SOUND AND CHEHALIS
VALLEY. ONE WILDCARD HERE MAY BE THE HIGH CLOUDS OVERNIGHT -
ESPECIALLY TO OVER THE NORTHERN HALF OF THE AREA - WHICH MAY
HELP LIMIT SOME OF THE RADIATIONAL COOLING. HREF AND REFS
CONTINUE TO SHOW A SERIES OF WEAK UPPER LEVEL DISTURBANCES WAVES
RIDING OVER THE UPSTREAM RIDGE MONDAY INTO TUESDAY. SOME
MEMBERS SHOW THE FIRST OF THESE WAVES EARLIER MONDAY MORNING,
WITH POTENTIALLY A SECOND SOMETIME MONDAY NIGHT INTO EARLY
TUESDAY. THIS WILL BRING PERIODS OF SHOWERS MONDAY INTO TUESDAY
MORNING. FOR THE MOST PART THIS WILL BE LIGHT RAIN TO THE
LOWLANDS - HOWEVER OVERNIGHT LOWS ESPECIALLY IN THE OUTLYING
AREAS AWAY FROM THE WATER WILL DIP TO NEAR FREEZING, SO THAT ANY
EARLY MORNING SHOWERS THAT DO PAN OUT ESPECIALLY MONDAY
MORNING, COULD CONTAIN A RAIN/SNOW MIX. FOR THE MOUNTAINS LIGHT
SNOW WITH ACCUMULATIONS LESS THAN 2 INCHES IS EXPECTED - MOSTLY
STEVENS PASS NORTHWARD. TEMPERATURES MONDAY AND TUESDAY WILL
TREND A LITTLE COOLER THAN NORMAL - ESPECIALLY THE OVERNIGHT
LOWS.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
THE UPPER LEVEL RIDGE WILL CONTINUE TO DRIVE THE DOWNSTREAM
WEATHER THROUGH WEDNESDAY NIGHT. ENSEMBLES ARE CONSISTENTLY
MAINTAINING THE EASTERN PACIFIC RIDGE WELL INTO THURSDAY, WITH
SOME VARIABILITY SHOWING UP IN THE FORM OF A SYSTEM RIDING OVER
THE RIDGE INTO BRITISH COLUMBIA THURSDAY. LREF ENSEMBLES DO
HINT AT A SCENARIO BEHIND THIS WITH A SECOND, MORE ORGANIZED
PACIFIC SYSTEM MOVING INTO THE GULF OF ALASKA FRIDAY. THIS WOULD
RESULT IN A REGIONALLY WETTER PATTERN FOR MUCH OF BRITISH
COLUMBIA, WASHINGTON AND OREGON. 35% OF THE LREF MEMBERS ARE
SHOWING A STRONGER VARIATION OF THIS PATTERN, WHICH WOULD FOCUS
MOST OF THE HEAVIER PRECIPITATION ON THE NORTHERN BRITISH
COLUMBIA COAST AND LESSER AMOUNTS THROUGH MUCH OF WESTERN
WASHINGTON THROUGH FRIDAY INTO AT LEAST THE START OF THE
WEEKEND. THIS PATTERN WILL LIKELY RESULT IN WARMER CONDITIONS
GOING INTO FRIDAY WITH BOTH LOW AND HIGH TEMPERATURES TRENDING
ABOVE NORMAL FRIDAY INTO THE WEEKEND.
AVIATION
MAJORITY OF TERMINALS VFR THIS EVENING, BUT ALREADY STARTING TO
SEE FOG DEVELOP AROUND OLM. INCREASING MID AND HIGH LEVEL CLOUDS
MONDAY MORNING WILL RESULT IN OVERALL VFR CEILINGS RANGING
BETWEEN 3,500 AND 10,000 FT. THERE REMAINS A GOOD CHANCE FOR
ANOTHER ROUND OF RADIATIONAL FOG OR LOW CEILINGS, ESPECIALLY IN
THE RIVER VALLEYS FROM KING COUNTY SOUTHWARD - SIMILAR TO SUNDAY
MORNING. CALM WINDS OR VERY LIGHT WINDS 3-6 KT OUT OF
EAST/NORTHEAST EXPECTED ACROSS MOST TERMINALS. MVFR CEILINGS
RETURN MONDAY AFTERNOON/EVENING AFTER 22Z-00Z. GUIDANCE IS ALSO
HINTING AT ANOTHER ROUND OF IFR/LIFR FOG FOR THE SOUTHERN
INTERIOR.
KSEA...
VFR CONDITIONS WITH A FEW HIGH CLOUDS THIS EVENING. SHALLOW FOG
EXPECTED TO DEVELOP AGAIN OVERNIGHT TO THE EAST OF THE TERMINAL
ALONG THE GREEN RIVER, BUT IS NOT EXPECTED TO AFFECT THE
TERMINAL. THERE IS LOWER CONFIDENCE IN FOG FORMING MONDAY
MORNING WITH MOST GUIDANCE KEEPING THE ODDS BELOW 40%. LIGHT
NORTHEASTERLY WINDS AROUND 3-5 KT, BECOMING VARIABLE AT TIMES
OVERNIGHT. MVFR CEILINGS RETURN MONDAY EVENING AFTER 02Z AND
WINDS WILL BECOME SOUTHERLY.
MARINE
HIGH PRESSURE WILL CONTINUE TO BUILD OVER AREA WATERS
THROUGHOUT THE NEXT WEEK, WITH A SERIES OF SYSTEMS CROSSING THE
WATERS. WHILE CONDITIONS REMAIN BENIGN TODAY, A WEAK FRONT WILL PASS
OVER THE PACIFIC NORTHWEST LATER ON MONDAY, BRINGING IN ELEVATED
NORTHWEST WINDS OVER THE OUTER COASTAL WATERS LIKELY REACHING SCA
CRITERIA ALONGSIDE ELEVATED SEAS. CONDITIONS WILL CALM MID-WEEK
BEFORE AN ADDITIONAL WEATHER SYSTEM TOWARDS THE END OF NEXT WEEK
BRINGS IN ELEVATED WESTERLY WINDS WITH POTENTIAL FOR GALE FORCE
WESTERLIES THROUGH THE STRAIT OF JUAN DE FUCA ON FRIDAY AND NEXT
SATURDAY. HOWEVER, FORECAST MODELS CONTINUE TO SHOW SOME UNCERTAINTY
OVER WIND STRENGTH TOWARDS THE END OF NEXT WEEK.
SEAS AROUND 6 TO 8 FEET TODAY WILL BUILD TO 9 TO 12 FEET ON TUESDAY
AFTERNOON, EASING BACK DOWN TO 5 TO 7 FEET BY LATE WEDNESDAY. SEAS
ARE EXPECTED TO BUILD AS HIGH AS 10 TO 15 FEET FEET TOWARDS NEXT
WEEKEND WITH THE NEXT INCOMING SYSTEM.
15
HYDROLOGY
RIVER FLOODING IS NOT EXPECTED OVER THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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