444  
FXUS66 KSEW 130959  
AFDSEW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SEATTLE WA  
259 AM PDT TUE APR 13 2021  
   
SYNOPSIS
 
UPPER LEVEL RIDGING WILL CONTINUE TO BUILD INTO  
BRITISH COLOMBIA TODAY AND WEDNESDAY, WHILE AN UPPER LEVEL LOW  
SINKS SOUTHWARD OVER THE GREAT BASIN. HIGH PRESSURE ALOFT WILL  
INFLUENCE THE REGION THROUGH THE REMAINDER OF THE WEEK, FOR  
CONTINUED DRY WEATHER AND A GRADUAL WARMING TREND.  
 

 
   
SHORT TERM /TODAY THROUGH THURSDAY/
 
SATELLITE SHOWING CLEAR  
SKIES ACROSS THE REGION THIS MORNING WHILE TEMPERATURES ARE  
TRENDING 5-12 DEGREES WARMER THAN 24 HOURS AGO. MORNING LOWS WILL  
BE A COUPLE DEGREES WARMER THAN THE LAST FEW DAYS-AND MAINLY IN  
THE MID 30S TO LOW 40S ACROSS THE REGION.  
 
AN UPPER LEVEL RIDGE WILL CONTINUE TO NUDGE INTO BRITISH COLUMBIA  
TODAY AND WEDNESDAY AS AN UPPER LEVEL LOW, CURRENTLY SITUATED  
ACROSS EASTERN WASHINGTON AND NORTHERN IDAHO, DROPS SOUTHWARD  
TOWARDS THE GREAT BASIN. AT THE SURFACE, A THERMAL TROUGH ALONG  
THE PACIFIC COAST WILL CONTINUE TO PROMOTE OFFSHORE FLOW IN THE  
LOW LEVELS. THIS PATTERN WILL KEEP WESTERN WASHINGTON DRY AND  
SUNNY. TEMPERATURES WILL CONTINUE TO WARM A FEW DEGREES EACH DAY,  
WITH MANY LOWLAND LOCATIONS PUSHING THE MID 60S BY WEDNESDAY.  
 
THE UPPER LEVEL LOW ACROSS THE GREAT BASIN WILL THEN START TO  
PROGRESS EASTWARD TOWARDS THE ROCKIES ON THURSDAY, ALLOWING FOR  
THE UPPER LEVEL HIGH TO STRENGTHEN ITS HOLD ACROSS WESTERN  
WASHINGTON. AS A RESULT, UPPER LEVEL HEIGHTS WILL RISE AND  
TEMPERATURES WILL CONTINUE TO WARM. THURSDAY COULD BE OUR FIRST  
70 DEGREE DAY OF THE STRETCH FOR AREAS SEATTLE SOUTHWARD.  
   
LONG TERM /FRIDAY THROUGH MONDAY/
 
WITH HIGH PRESSURE ALOFT,  
WARM AND SUNNY WEATHER WILL CONTINUE INTO THE EXTENDED PERIOD.  
TEMPERATURES WILL CONTINUE TO CLIMB, PEAKING OVER THE WEEKEND.  
SATURDAY CURRENTLY LOOKS LIKE THE WARMEST DAY IN THE EXTENDED,  
THOUGH SUNDAY COULD TRACK CLOSE. CURRENT FORECAST STILL CALLING  
FOR MID 70S FOR SEATTLE, HOWEVER SOME GUIDANCE DOES STILL HINT  
THAT TEMPERATURES COULD CLIMB A FEW DEGREES HIGHER. WILL NEED TO  
KEEP AN EYE ON THE TREND AND SEE HOW THIS DEVELOPS THROUGHOUT THE  
WEEK. ENSEMBLE AND DETERMINISTIC GUIDANCE THEN HINT AT A COOL DOWN  
AND A POSSIBLE RETURN TO WETTER WEATHER EARLY NEXT WEEK AS HIGH  
PRESSURE ALOFT WEAKENS ACROSS THE REGION AND OPENS THE DOOR FOR  
WEAK SYSTEMS TO MOVE IN. 14  
 

 
   
AVIATION
 
VFR CONDITIONS WITH CLEAR SKIES THROUGH THE PERIOD.  
WINDS OUT OF THE N EARLY THIS MORNING 5-10KTS WILL PICK UP MID-LATE  
MORNING, BECOMING BREEZY; SUSTAINED AT GENERALLY 10-15KTS WITH GUSTS  
AROUND 25 KTS. GUSTS WILL DIMINISH AFTER SUNSET.  
 
KSEA...CLEAR SKIES. N WIND 5-10KTS THROUGH SUNRISE, THEN PICKING UP  
TO AROUND 15KTS LATE MORNING WITH GUSTS NEAR 25KTS THROUGH SUNSET.  
 
KOVACIK  
 

 
   
MARINE
 
OFFSHORE FLOW PATTERN CONTINUES EARLY THIS MORNING AS HIGH  
PRESSURE REMAIN OVER THE INTERIOR OF THE PACIFIC NORTHWEST AND  
WESTERN CANADA AND A TROUGH OF LOW PRESSURE RESIDES ALONG THE  
WASHINGTON AND OREGON COASTS. WINDS HAVE RELAXED OVER THE WATERS  
AFTER A BREEZY DAY YESTERDAY, AND THIS BREAK IS EXPECTED TO BE  
RATHER SHORT-LIVED. SHORTLY AFTER SUNRISE THIS MORNING, SHOULD SEE  
WINDS PICK BACK UP OUT OF THE NORTH, ESPECIALLY OVER THE NORTHERN  
INLAND WATERS AND PUGET SOUND WHERE A SMALL CRAFT ADVISORY WILL GO  
INTO EFFECT AT NOON. EVENTUALLY SMALL CRAFT ADVISORY LEVEL WINDS  
WILL MAKE IT OVER THE COASTAL WATERS THIS AFTERNOON. ELSEWHERE,  
WINDS WILL BE BREEZY OVER THE WATERS BUT SHOULD REMAIN 20KTS OR  
BELOW.  
 
WINDS WILL EASE AGAIN LATER THIS EVENING AND THROUGH THE OVERNIGHT  
PERIOD INTO EARLY WEDNESDAY, BUT AGAIN EXPECT WINDS TO PICK UP OUT  
OF THE N/NE AS OFFSHORE FLOW CONTINUES. A SMALL CRAFT ADVISORY WILL  
LIKELY BE NEEDED FOR THE INNER COAST WATERS, WITH ALL OTHER WATERS  
POTENTIALLY REMAINING JUST BELOW CRITERIA. ALTHOUGH  
NORTHERLY/OFFSHORE FLOW WILL CONTINUE THURSDAY AND FRIDAY, WINDS  
CURRENTLY LOOK LIGHT OVER ALL WATERS. THESE CONDITIONS APPEAR TO  
CARRY THROUGH MUCH, IF NOT ALL, OF THE WEEKEND.  
 
SWELLS WILL REMAIN BELOW 10 FT OVER THE NEXT 7 DAYS.  
 
KOVACIK  
 

 
   
HYDROLOGY
 
RIVER FLOODING NOT EXPECTED OVER THE NEXT 7 DAYS.  
 

 
   
SEW WATCHES/WARNINGS/ADVISORIES
 
 
WA...NONE.  
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PDT EARLY THIS MORNING FOR  
COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60  
NM-COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10  
NM-COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10  
TO 60 NM-COASTAL WATERS FROM JAMES ISLAND TO POINT  
GRENVILLE OUT 10 NM-COASTAL WATERS FROM POINT GRENVILLE TO  
CAPE SHOALWATER 10 TO 60 NM-COASTAL WATERS FROM POINT  
GRENVILLE TO CAPE SHOALWATER OUT 10 NM.  
 
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS  
EVENING FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES  
ISLAND 10 TO 60 NM-COASTAL WATERS FROM CAPE FLATTERY TO  
JAMES ISLAND OUT 10 NM-COASTAL WATERS FROM JAMES ISLAND TO  
POINT GRENVILLE 10 TO 60 NM-COASTAL WATERS FROM JAMES  
ISLAND TO POINT GRENVILLE OUT 10 NM-COASTAL WATERS FROM  
POINT GRENVILLE TO CAPE SHOALWATER 10 TO 60 NM-COASTAL  
WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER OUT 10 NM.  
 
SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM PDT THIS EVENING  
FOR NORTHERN INLAND WATERS INCLUDING THE SAN JUAN ISLANDS-  
PUGET SOUND AND HOOD CANAL.  
 

 
 

 
 
WWW.WEATHER.GOV/SEATTLE  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WA Page Main Text Page