056  
FXUS66 KSEW 092201  
AFDSEW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SEATTLE WA  
301 PM PDT THU OCT 9 2025  
   
SYNOPSIS
 
AN APPROACHING, OFFSHORE UPPER LEVEL LOW WILL SET  
THE STAGE FOR A PATTERN SHIFT TO COOLER AND WETTER WEATHER  
THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. IN ADDITION TO  
WIDESPREAD RAIN THERE WILL BE PERIODS OF BREEZY CONDITIONS, AND  
LOWERING SNOW LEVELS SATURDAY NIGHT INTO EARLY NEXT WEEK THAT  
WILL RESULT IN THE FIRST NOTABLE HIGH ELEVATION SNOW OF THE  
SEASON.  
 

 
   
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
 
THE OFFSHORE  
UPPER LEVEL LOW LINGERING ALONG 130W WILL BEGIN TO SHIFT ONSHORE  
FRIDAY AFTERNOON AND EVENING. LIGHT PRECIPITATION ASSOCIATED  
WITH THIS SYSTEM MAY BEGIN TO TRICKLE INTO INTO SOUTHWESTERN  
WASHINGTON THIS EVENING, AND MORE EARNESTLY FRIDAY MORNING WITH  
WIDESPREAD STRATIFORM RAIN SETTING UP OVER MOST OF THE REGION BY  
FRIDAY AFTERNOON AND LINGERING THROUGH SATURDAY. AS THE UPPER  
LEVEL LOW BEGINS TO SHIFT ONSHORE INTO OREGON FRIDAY EVENING  
THERE MAY BE ENOUGH MARGINAL SUPPORT FOR ISOLATED THUNDERSTORMS  
MAINLY ALONG THE COAST AND POSSIBLY OVER THE HIGHER TERRAIN.  
GUSTY SOUTHERLY WINDS PARTICULARLY EARLY SATURDAY MORNING NEAR  
WHIDBEY ISLAND TO WESTERN WHATCOM COUNTY ARE POSSIBLE.  
TEMPERATURES WILL REMAIN NEAR NORMAL FRIDAY, TRENDING COOLER  
WITH HIGHS OVER THE LOWLANDS IN THE MID TO UPPER 50S SATURDAY.  
 

 
   
LONG TERM /SUNDAY THROUGH THURSDAY/
 
ANOTHER SURGE OF  
WIDESPREAD PRECIPITATION IS EXPECTED EARLY SUNDAY MORNING AS AN  
UPPER LEVEL TROUGH SLIDES SOUTHWARD THROUGH BRITISH COLUMBIA.  
IN ADDITION TO PRECIPITATION, THIS WILL BRING A SURGE OF COOLER  
AIR AND MUCH LOWER SNOW LEVELS, NOW EXPECTED DIP TO AROUND 3000  
FEET IN THE NORTHERN CASCADES TO 4000 FT IN THE SOUTHERN  
CASCADES BY MONDAY MORNING. THIS WILL OPENING THE DOOR THE FIRST  
NOTABLE HIGH ELEVATION SNOWFALL FOR THE HIGHER ELEVATIONS. BEST  
BETS FOR ACCUMULATIONS ARE ABOVE 5000 FEET, WITH AN 80% CHANCE  
OF 2 OR MORE INCHES AT RAINY PASS, AND A 45% CHANCE AT STEVENS  
PASS. ACCUMULATIONS ARE NOT EXPECTED AT SNOQUALMIE PASS, HOWEVER  
THERE IS A GOOD CHANCE FOR PERIODS OF MIXED RAIN AND SNOW  
PARTICULARLY IN THE EARLY MORNING HOURS SUNDAY AND AGAIN MONDAY  
MORNING. FOR THOSE THAT PLAN TO HEAD TO THE HIGHER MOUNTAIN  
ELEVATIONS THIS WEEKEND SHOULD BE PREPARED TO ENCOUNTER SNOW AND  
COLD CONDITIONS AND CLOSELY MONITOR THE WEATHER FORECAST IN THE  
NEXT FEW DAYS.  
 
ENSEMBLE GUIDANCE INTO THE MEDIUM RANGE CONTINUES TO FAVOR THE  
UPPER LOW DIGGING SOUTH INTO CALIFORNIA EARLY NEXT WEEK, PULLING  
PRECIPITATION WITH IT RESULTING IN A DRIER TREND. IT WILL ALSO  
HELP SUPPORT THE POTENTIAL FOR COOL, CLEAR NIGHTS AND THE  
POTENTIAL FOR FROST IN THE MORNINGS AS LOW TEMPERATURES TREND  
CLOSER TO THE 30S FOR SOME LOCATIONS IN THE INTERIOR AWAY FROM  
THE WATER.  
 

 
   
AVIATION
 
SOUTHERLY FLOW ALOFT WITH AN UPPER LEVEL LOW OFFSHORE  
TODAY, SHIFTING SOUTHEASTERLY FRIDAY MORNING. SURFACE WINDS  
REMAINING LIGHT AND VARIABLE A LITTLE LATER THAN EXPECTED FOR MOST  
TERMINALS, BUT STILL EXPECTED TO BECOME NORTHERLY 4-8 KTS BY 00Z  
LATE THIS AFTERNOON AND CONTINUE THIS EVENING. LIGHT AND VARIABLE  
WINDS WILL RETURN OVERNIGHT TONIGHT.  
 
VFR CONDITIONS REMAIN IN PLACE OVER THE BULK OF W WA THIS AFTERNOON  
WITH MOST TERMINALS SEEING ONLY MID TO HIGH LEVEL CLOUDS AT THE TIME  
OF THIS WRITING /22Z/. CLM IS THE ONLY EXCEPTION, WHERE LINGERING  
STRATUS IS RESULTING IN CONTINUED MVFR CONDITIONS THERE. MODEL  
GUIDANCE CONTINUES TO SUGGEST THEY SHOULD BREAK OUT AND BECOME VFR  
BY 00Z...BUT WITH HOW LONG THESE STRATUS HAS LINGERED, CONFIDENCE IN  
THIS SOLUTION IS SHAKEN. MAY OPT TO KEEP THE LOWER CIGS IN FOR THE  
00Z UPDATE. AS THE UPPER LEVEL LOW SHIFTS EASTWARD TONIGHT, WILL SEE  
BETTER CHANCES FOR SHOWERS OVERNIGHT WITH CIGS LOWERING DOWN INTO  
MORE UNIFORM MVFR CONDITIONS THROUGHOUT THE AREA CARRYING OVER INTO  
THE REMAINDER OF THE TAF PERIOD.  
 
KSEA...VFR CONDITIONS THROUGH TONIGHT AND A MAJORITY OF THE  
OVERNIGHT PERIOD. AS SHOWERS BECOME MORE CONSISTENT BY VERY EARLY  
FRIDAY MORNING, WILL SEE CIGS FALL TO MVFR /AROUND 2000 FT/ BETWEEN  
09-12Z REMAINING THERE FOR THE REST OF THE TAF PERIOD. SURFACE WIND  
DISCUSSION FROM ABOVE APPLIES, WITH SEA EXPECTED TO BE ON THE HIGHER  
END OF THE RANGE OF WIND SPEEDS AFTER 00Z. ADDITIONALLY, WINDS  
OVERNIGHT WILL BE MORE SOUTHERLY WITH SPEEDS AROUND 5 KTS.  
 
18  
 

 
   
MARINE
 
THE OFFSHORE LOW PRESSURE SYSTEM WILL TO LINGER OVER  
THE OFFSHORE WATERS OF OREGON INTO FRIDAY THEN MOVE INLAND  
FRIDAY INTO SATURDAY. WINDS AND SEAS WILL INCREASE ON SATURDAY  
AS STRENGTHENING HIGH PRESSURE ACROSS THE NE PACIFIC PUSHES IN  
QUICKLY BEHIND THE LOW. WINDS LOOK TO REACH HIGH-END SCA  
CRITERIA ACROSS THE COASTAL WATERS WITH 40-70% CHANCES FOR GALE  
FORCE GUSTS THROUGH SUNDAY MORNING. SEAS ABOVE 10 FEET WILL ALSO  
BEGIN TO MOVE INTO THE OUTER COASTAL WATERS WITH STEEP SEAS  
POSSIBLE. WINDS AREA ALSO EXPECTED TO INCREASE THROUGH THE  
STRAIT OF JUAN DE FUCA AS WELL. ANOTHER LOW PRESSURE SYSTEM  
LOOKS TO MOVE INTO THE COASTAL WATERS SUNDAY NIGHT INTO MONDAY.  
THIS WILL ALLOW WINDS TO BECOME OFFSHORE, WITH WINDS REQUIRING  
ADDITIONAL HEADLINES POSSIBLE THROUGH THE STRAIT, WITH A 70%  
CHANCE OF GUSTS AT OR ABOVE 34 KTS ON MONDAY IN THE CENTRAL  
STRAIT.  
 
SEAS 4 TO 6 FT TONIGHT WILL LINGER INTO FRIDAY THEN BUILD  
SATURDAY TO 12 TO 16 FT OVER THE WEEKEND. SEAS THEN LOOK TO EASE  
SUNDAY, BECOMING 6 TO 8 FT FOR THE FIRST PART OF NEXT WEEK.  
 

 
   
SEW WATCHES/WARNINGS/ADVISORIES
 
 
WA...NONE.  
PZ...NONE.  
 

 
 

 
 
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