091
FXUS66 KSEW 091020
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
320 AM PDT TUE JUN 9 2026
SYNOPSIS
FRONT MOVING EAST OF THE CASCADES THIS MORNING. TRAILING UPPER
LEVEL TROUGH MOVING OVER THE AREA LATER TODAY. THE TROUGH WILL
MOVE EAST WEDNESDAY. UPPER LEVEL RIDGE BEGINNING TO BUILD
WEDNESDAY NIGHT. WEAK SYSTEM MOVING BY TO THE NORTH WILL SLOW
THE RIDGE BUILDING THURSDAY. STRONG UPPER LEVEL RIDGE BUILDING
OFFSHORE FRIDAY WITH THE RIDGE MOVING EAST THROUGH THE WEEKEND.
LOW LEVEL FLOW GOING OFFSHORE SATURDAY NIGHT WITH RECORD HIGHS
POSSIBLE SUNDAY AND MONDAY.
SHORT TERM /TODAY THROUGH THURSDAY/
SATELLITE IMAGERY SHOWS FRONT JUST ABOUT THROUGH SEATTLE AT 3
AM/10Z WITH RAIN CONTINUING TO THE EAST AND DRYING ALONG THE
COAST. TEMPERATURES WERE IN THE LOWER TO MID 50S. SEATTLE-TACOMA
AIRPORT RECORDED 0.66 INCHES OF RAIN MONDAY JUST SHORT OF THE
RECORD 0.81 INCHES SET IN 1981. THE 0.66 INCHES IS THE SECOND
WETTEST JUNE 8TH AT THE AIRPORT AND IS 46 PERCENT OF THE MONTHLY
NORMAL RAINFALL FOR JUNE ( 1.45 INCHES ).
FRONT MOVING EAST EARLY THIS MORNING WITH TRAILING UPPER LEVEL
TROUGH MOVING OVER THE AREA LATER IN THE DAY. STRONG WESTERLY
PUSH DOWN THE STRAIT OF JUAN DE FUCA BEHIND THE FRONT WITH A
CONVERGENCE ZONE FORMING OVER SNOHOMISH AND SOUTHERN SKAGIT
COUNTY. BREEZY SOUTHWESTERLY WINDS BEHIND THE FRONT COMING UP
THE PUGET SOUND WILL KEEP THE CONVERGENCE ZONE NORTH OF THE KING
COUNTY LINE. SHOWER COVERAGE INCREASING AND A SLIGHT CHANCE OF
THUNDERSTORMS THIS AFTERNOON WITH THE TROUGH OVERHEAD. IT WILL
BE ANOTHER COOL DAY WITH HIGHS IN THE MID 50S TO LOWER 60S.
UPPER LEVEL TROUGH HANGING OVER THE AREA TONIGHT KEEPING AT
LEAST A CHANCE SHOWERS IN THE FORECAST. SOUTHERLY SURFACE
GRADIENTS WEAKEN OVERNIGHT ALLOWING THE CONVERGENCE ZONE TO
DRIFT SOUTH INTO KING COUNTY AFTER MIDNIGHT. LOWS IN THE MID 40S
TO LOWER 50S.
TROUGH MOVING EAST WEDNESDAY BRINGING AN END TO THE SHOWER
THREAT. CONVERGENCE ZONE DISSIPATING IN THE CENTRAL CASCADES
EARLY. ONSHORE GRADIENTS WEAKENING DURING THE DAY. THIS COMBINED
WITH THE NEAR SOLSTICE SUN WILL DISSIPATE THE MARINE LAYER IN
THE AFTERNOON GIVING THE AREA SOME SUNSHINE. HIGH TEMPERATURES
WILL BE WARMER BUT STILL A LITTLE BELOW NORMAL, IN THE 60S.
UPPER LEVEL RIDGE STARTS TO BUILD WEDNESDAY NIGHT BUT A WEAK
SYSTEM RIDING BY WELL TO THE NORTH THURSDAY PUTS A TEMPORARY
HALT TO THE RIDGE BUILDING. EVEN SO TEMPERATURES ALOFT WARMING
AND LOW LEVEL FLOW REMAINS FLAT. WITH PLENTY OF SUNSHINE HIGHS
THURSDAY GETTING INTO THE MID 60S TO MID 70S. LOWS THURSDAY
MORNING WILL BE A LITTLE COOL, IN THE 40S. FELTON
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
UPPER LEVEL RIDGE BUILDING OFFSHORE THURSDAY NIGHT WITH THE
RIDGE AXIS NEAR 140W THROUGH FRIDAY. RIDGE SHIFTING EAST OVER
THE WEEKEND WITH 500 MB HEIGHTS GOING FROM THE MID 570 DMS TO
THE UPPER 580S AND LOWER 590 DMS BY SUNDAY AFTERNOON. THERMALLY
INDUCED SURFACE TROUGH MOVING UP THE COASTLINE REACHING
WASHINGTON SATURDAY NIGHT WITH THE LOW LEVEL FLOW GOING OFFSHORE
SUNDAY AND MONDAY. TEMPERATURES ALOFT WARMING WITH THE RIDGE
BUILDING. 850 MB TEMPERATURES PEAKING AROUND PLUS 20C MONDAY.
ALL THIS ADDS UP TO A WARMING TREND THROUGH THE PERIOD WITH
POSSIBLE RECORD HIGHS SUNDAY AND MONDAY. HIGHS IN THE 70S
FRIDAY WARMING TO THE UPPER 70S TO MID 80S SATURDAY, 80S SUNDAY
AND 80S TO MID 90S MONDAY. LOWS IN THE MID 40S TO LOWER 50S
THURSDAY NIGHT WARMING TO THE 50S AND LOWER 60S BY SUNDAY NIGHT.
MINOR HEATRISK FRIDAY AND SATURDAY INCREASING TO MODERATE
SUNDAY AND MONDAY. RIGHT NOW MONDAY LOOKS TO BE THE PEAK OF THE
HEAT.
HERE IS A LIST OF SOME RECORD HIGHS FOR SUNDAY AND MONDAY.
SEATTLE SUNDAY 86 DEGREES SET IN 1988 AND MONDAY 88 SET IN 1963.
OLYMPIA 88 DEGREES BOTH DAYS, 1999 FOR SUNDAY AND 1963 FOR
MONDAY. BELLINGHAM 83 IN 1988 SUNDAY AND 82 IN 1961 MONDAY.
HOQUIAM 79 IN 1988 SUNDAY AND 81 IN 1961 MONDAY. QUILLAYUTE 84
IN 1988 SUNDAY AND 80 IN 1969 MONDAY. FELTON
AVIATION
NORTHWESTERLY FLOW ALOFT THIS MORNING PERSISTING INTO
WEDNESDAY. SOME TERMINALS ALREADY SEEING AN INCREASE IN
SOUTHWESTERLY WINDS WITH SPEEDS 10-15 KTS AND GUSTS UP TO 25 KTS
/SEA, HQM/, WHILE MAJORITY OF LOCATIONS STILL SEEING LOWER SPEEDS
GENERALLY RANGING 5-10 KTS. ALL TERMINALS EXPECTED TO CLIMB INTO 10-
15 KTS WITH GUST UP TO 25 KTS BY 12-14Z THIS MORNING AND REMAINING
THERE FOR NEARLY ALL OF THE TAF PERIOD. WINDS DO LOOK TO EASE
SLIGHTLY TO 8-12 KTS LATE TONIGHT.
WIDESPREAD MVFR TO IFR CONDITIONS THROUGHOUT W WA THIS EARLY MORNING
WITH LITTLE CAUSE FOR IMPROVEMENT IN THE REMAINING MORNING HOURS.
THE AFOREMENTIONED WIND SPEEDS COUPLED WITH AFTERNOON MIXING WILL
ALLOW FOR SOME SLOW IMPROVEMENT IN THE AFTERNOON HOURS. WESTERN
TERMINALS /HQM, OLM, CLM/ WILL IMPROVE SOME, BUT NOT ENOUGH TO CLAW
THEIR WAY OUT OF MVFR WHILE REMAINING EASTERN TERMINALS ARE EXPECTED
TO RECOVER TO VFR BY AROUND 22Z TODAY. LINGERING SHOWERS AND
ABUNDANT LOW-LEVEL MOISTURE SHOULD RESULT IN CIGS DIPPING BACK DOWN
INTO AT LEAST MVFR CONDITIONS AREA-WIDE TONIGHT.
KSEA...CIGS CURRENTLY IFR BUT WILL BOUNCE BACK AND FORTH BETWEEN
THERE AND LOW-END MVFR THROUGHOUT THE MORNING HOURS. SHOULD SEE
SOLIDLY MVFR CONDITIONS EMERGE IN THE LATE MORNING /AFTER 18Z/ WITH
LOW-END VFR CONDITIONS EXPECTED IN THE AFTERNOON. CONTINUED
IMPROVEMENT EXPECTED IN THE EARLY EVENING. ALTHOUGH SHOWERS WILL
BEGIN TO TAPER OFF STARTING TONIGHT, PLENTY OF LOW LEVEL MOISTURE
WILL BRING A RETURN TO MVFR CONDITIONS LATE TONIGHT. SW WINDS
ALREADY BLOWING FROM FROPA, 10-15 KTS GUSTING TO 25 KTS, WITH NOT
MUCH IN THE WAY OF VARIATION FROM THESE SPEEDS OR DIRECTION FOR MUCH
OF THE TAF PERIOD. A SLIGHT DECREASE IN SPEED WILL BE POSSIBLE AFTER
06Z TONIGHT AS GUSTS EASE OFF...BUT SPEEDS STILL REMAINING ELEVATED
AT 8-12 KTS.
18
MARINE
NORTHWESTERLY WINDS OVER THE COASTAL WATERS EXPECTED TO
MAINTAIN SCA WINDS AND SEAS THROUGHOUT THE REMAINDER OF THE MORNING
BEFORE EASING BY NOON TODAY AND BECOMING MORE WESTERLY. SOUTHWEST
WINDS ALSO INCREASE FOR INTERIOR WATERS THIS MORNING AND CONTINUING
THROUGH THE AFTERNOON. SMALL CRAFT ADVISORY WINDS AND GUSTS ARE
EXPECTED FOR MOST WATERS WITH THIS STRENGTHENING ONSHORE FLOW. A
STRONG WEST PUSH THROUGH THE STRAIT OF JUAN DE FUCA IS EXPECTED TO
RESULT IN GALE FORCE WIND GUSTS FOR THE CENTRAL AND EASTERN STRAIT
AND INHERITED GALE WARNING LOOKS GOOD. WINDS SLOWLY EASE TONIGHT
INTO WEDNESDAY.
WINDS BECOME LIGHTER WEDNESDAY AS HIGH PRESSURE BUILDS BACK INTO THE
COASTAL WATERS. NORTHWEST WINDS OVER THE COASTAL WATERS INCREASE
THURSDAY INTO LATE WEEK AS HIGH PRESSURE CONTINUES TO BUILD
OFFSHORE. FLOW WILL TRANSITION TO OFFSHORE AT TIMES OVER THE WEEKEND
INTO EARLY NEXT WEEK AS A THERMAL TROUGH EXPANDS NORTHWARDS ALONG
THE COAST.
SEAS WILL RANGE BETWEEN 6 TO 9 FEET TODAY WITH ISOLATED AREAS IN THE
CENTRAL AND SOUTHERN OUTER COASTAL WATERS SEEING 10 OR 11 FOOT SEAS.
NOT EXPECTED TO BE WIDESPREAD BEFORE SEAS BEGIN TO EASE THIS
AFTERNOON, INHERITED 11 AM EXPIRATION FOR THE CURRENT SCA LOOKS TO
COVER THIS ASPECT OF THE FORECAST WELL. SEAS SUBSIDE TO 4 TO 7 FEET
BY WEDNESDAY AND REMAIN IN THIS RANGE INTO LATE WEEK. 18/JD
FIRE WEATHER
NO FIRE WEATHER CONCERNS UNTIL THE WARM TEMPERATURES BEGINNING
THIS WEEKEND. LOW LEVEL OFFSHORE FLOW WILL DRIVE MINIMUM
RELATIVE HUMIDITY VALUES DOWN BELOW 30 PERCENT SUNDAY AND
MONDAY. SOME THE DRIER LOCATIONS LIKE CASCADE VALLEYS AND THE
SOUTHWEST INTERIOR MINIMUM RH VALUES WILL DROP INTO THE TEENS.
FINE FUELS WILL BE APPROACHING CRITICAL THRESHOLDS THIS WEEKEND
AND LARGER FUELS WILL BE DRYING OUT AS WELL. ELEVATED FIRE
WEATHER CONDITIONS BEGINNING SATURDAY AND CONTINUING THROUGH THE
EARLY PART OF NEXT WEEK ACROSS THE AREA. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 AM EARLY THIS MORNING TO 2 PM PDT
THIS AFTERNOON FOR WEST ENTRANCE U.S. WATERS STRAIT OF
JUAN DE FUCA.
GALE WARNING FROM 5 AM EARLY THIS MORNING TO 11 PM PDT THIS
EVENING FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 5 AM EARLY THIS MORNING TO 11 PM PDT
THIS EVENING FOR ADMIRALTY INLET-NORTHERN INLAND WATERS
INCLUDING THE SAN JUAN ISLANDS.
SMALL CRAFT ADVISORY FROM 5 AM EARLY THIS MORNING TO 8 PM PDT
THIS EVENING FOR PUGET SOUND AND HOOD CANAL.
SMALL CRAFT ADVISORY UNTIL 11 AM PDT 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.
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