532  
FXUS66 KSEW 062200  
AFDSEW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SEATTLE WA  
300 PM PDT MON APR 6 2020  
   
SYNOPSIS
 
UPPER LEVEL RIDGING ACROSS THE NORTHEASTERN PACIFIC  
WILL REMAIN THE DOMINANT INFLUENCE ACROSS THE REGION OVER THE NEXT  
SEVERAL DAYS, KEEPING WESTERN WASHINGTON DRY. TEMPERATURES WILL  
WARM THROUGH THURSDAY AND CHANCES OF RAIN WILL INCREASE LATE IN  
THE WEEK AND INTO THE WEEKEND AS A WEAK SYSTEM BRUSHES THROUGH  
THE REGION.  
 

 
   
SHORT TERM /TONIGHT THROUGH THURSDAY/
 
CURRENT SATELLITE IMAGERY  
SHOWS SOME SCATTERED CUMULUS PRESENT ACROSS THE MOUNTAINS THIS  
AFTERNOON. HIGH LEVEL CLOUDS HAVE ALSO STARTED TO INCREASE ACROSS  
THE REGION THIS AFTERNOON ASSOCIATED WITH A FRONTAL SYSTEM MOVING  
INTO BRITISH COLUMBIA. EXPECT THE REGION TO REMAIN DRY, WITH  
HIGHS CURRENTLY IN THE MID TO UPPER 50S, WITH A FEW SPOTS HITTING  
THE LOW 60S ACROSS THE SOUTHERN INTERIOR.  
 
WITH UPPER LEVEL RIDGING REMAINING THE DOMINANT INFLUENCE ACROSS  
THE REGION THIS WEEK, WESTERN WASHINGTON WILL REMAIN DRY AND  
TEMPERATURES WILL GRADUALLY WARM. AS ONSHORE FLOW INCREASES ACROSS  
THE REGION TONIGHT, COULD SEE STRATUS MAKE ITS WAY INTO PORTIONS  
OF THE SOUND OVERNIGHT TONIGHT. STRATUS THAT DOES MAKE ITS WAY  
INLAND WILL RETREAT AND DISSIPATE BY THE AFTERNOON HOURS FOR A  
DOSE OF AFTERNOON SUN ON TUESDAY. HIGHS WILL BE IN THE MID TO  
UPPER 50S ACROSS MUCH OF THE LOWLANDS.  
 
TEMPERATURES WILL CONTINUE TO WARM A FEW DEGREES ON WEDNESDAY AND  
THURSDAY, WITH THURSDAY STILL LOOKING TO BE THE WARMEST DAY OF  
THE WEEK WITH HIGHS CLIMBING INTO THE LOW TO MID 60S ACROSS  
ACROSS THE SOUTHERN AND CENTRAL SOUND.  
   
LONG TERM /FRIDAY THROUGH MONDAY/
 
RAIN CHANCES INCREASE AGAIN  
LATE THIS WEEK AND INTO THE WEEKEND AS A WEAK SYSTEM RIDES THE  
PERIPHERY OF THE RIDGE AND QUICKLY TRAVERSES THE REGION. RECENT  
RUNS OF THE DETERMINISTIC GFS AND ECMWF HAVE STARTED TO ALIGN A  
BIT BETTER, MOSTLY HOLDING OFF ON THE BEST CHANCES OF PRECIPITATION  
UNTIL SATURDAY. HOWEVER, THE GFS DOES STILL BRINGS SOME MOISTURE  
INTO THE REGION ON FRIDAY, SO HAVE KEPT A CHANCE OF POPS IN THE  
FORECAST, MOSTLY CONFINED TO HIGHER TERRAIN. OVERALL, ENSEMBLES  
STILL HINT AT UPPER LEVEL RIDGING REMAINING THE DOMINANT WEATHER  
FEATURE IN THE EXTENDED TIME FRAME-HINTING THAT CONDITIONS COULD  
REMAIN DRIER. 14  
 

 
   
AVIATION
 
NORTHWEST FLOW ALOFT CONTINUES AS UPPER RIDGING  
GRADUALLY BUILDS INTO THE REGION. LOW LEVEL ONSHORE HAS DEVELOPED  
TODAY AND WILL INCREASE SOMEWHAT THROUGH THIS EVENING. VFR EXPECTED  
ACROSS THE REGION THROUGH THIS EVENING. SOME STRATUS IS POSSIBLE  
NEAR THE COAST LATE TONIGHT AND MAY PUSH LOCALLY INLAND FOR AREAS OF  
MVFR POSSIBLE TUESDAY A.M. ANY STRATUS SHOULD BURN OFF BY 19Z-21Z  
TUESDAY AFTERNOON.  
 
KSEA...VFR CONDITIONS THROUGH LATE TONIGHT. SOME STRATUS MAY REACH  
THE TERMINAL BRIEFLY TUESDAY AM, BUT CONFIDENCE IN THIS OCCURRING IS  
NOT HIGH. LIGHT WIND BECOME S-SW 5 TO 10 KNOTS FROM THIS EVENING  
THROUGH THE OVERNIGHT HOURS. 27  
 

 
   
MARINE
 
ONSHORE FLOW TODAY AS HIGH PRESSURE BUILDS OVER THE  
AREA WITH SOLID ADVISORY LEVEL WESTERLIES EXPECTED IN THE CENTRAL  
AND EASTERN STRAIT THIS EVENING. SURFACE RIDGING BUILDING OVER THE  
INTERIOR OF BRITISH COLUMBIA WILL TURN THE FLOW OFFSHORE BY MIDWEEK,  
BUT ONLY WEAKLY SO. ONSHORE FLOW RETURNS LATE IN THE WEEK, BUT DOES  
NOT APPEAR TO BE ENOUGH FOR ADVISORY LEVEL WINDS AT THIS TIME. ALL  
IN ALL, LOOKS LIKE A FAIRLY QUIET WEEK AHEAD ON AREA WATERS. 27  
 

 
   
HYDROLOGY
 
NO RIVER FLOODING EXPECTED OVER THE NEXT 7 DAYS.  
 

 
   
SEW WATCHES/WARNINGS/ADVISORIES
 
 
WA...NONE.  
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 5 AM PDT  
TUESDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST  
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.  
 

 
 

 
 
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