261
FXUS66 KSEW 111010
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
310 AM PDT SUN OCT 11 2026
SYNOPSIS
UPPER LEVEL LOW OVER EASTERN OREGON COMBINED WITH UPPER LEVEL
RIDGE OVER CENTRAL BRITISH COLUMBIA GIVING WESTERN WASHINGTON
DRY NORTHEASTERLY FLOW ALOFT THROUGH MONDAY. THE RIDGE WILL MOVE
OVER WESTERN WASHINGTON TUESDAY. ATMOSPHERIC RIVER MOVING
INLAND NORTH OF THE AREA TUESDAY NIGHT AND WEDNESDAY. UPPER
LEVEL RIDGE BUILDING THURSDAY WILL MOVE EAST FRIDAY. LOW LEVEL
OFFSHORE FLOW THURSDAY AND FRIDAY PRODUCING ABOVE NORMAL
HIGH TEMPERATURES. NEXT SYSTEM POSSIBILITY MOVING INTO THE AREA
FRIDAY NIGHT INTO SATURDAY.
SHORT TERM /TODAY THROUGH TUESDAY/
SATELLITE IMAGERY SHOWS MOSTLY CLEAR SKIES WITH A PATCH OF
STRATUS FROM ABOUT RENTON TO EVERETT. FOLKS OVER NORTHERN
WASHINGTON GOT A GOOD VIEW OF THE AURORA BETWEEN MIDNIGHT AND 2
AM. TEMPERATURES AT 3 AM/10Z WERE IN THE MID 30S TO NEAR 50.
LIGHT FLOW IN THE LOWER LEVELS THIS MORNING WITH PATCHY FOG
DEVELOPING BEFORE SUNRISE. THE STRATUS AND PATCHY FOG WILL
DISSIPATE BY MID MORNING LEAVING SUNNY SKIES OVER THE AREA. HIGH
TEMPERATURES NEAR NORMAL, UPPER 50S TO MID 60S.
LITTLE CHANGE IN THE PATTERN TONIGHT INTO MONDAY WITH DRY
NORTHEASTERLY FLOW ALOFT AND LIGHT FLOW IN THE LOWER LEVELS.
MONDAY MORNING WILL BE THE COLDEST MORNING SINCE MAY WITH LOWS
IN THE 30S AND LOWER 40S. A FROST ADVISORY HAS ALREADY BEEN
ISSUED FOR MOST OF THE AREA SOUTH OF SEATTLE PLUS THE HOOD CANAL
AND NORTH COAST. PLENTY OF SUNSHINE MONDAY WITH HIGHS AGAIN IN
THE UPPER 50S TO MID 60S.
UPPER LEVEL RIDGE TO THE NORTH MOVING OVER WESTERN WASHINGTON
MONDAY NIGHT INTO TUESDAY. SLIGHT INCREASE IN ONSHORE FLOW
OVERNIGHT PLUS SOME HIGH CLOUDS KEEPING LOWS IN THE MID 30S TO
MID 40S. HIGH CLOUDS REMAINING OVER THE AREA DURING THE DAY
TUESDAY WITH HIGHS IN THE MID 50S TO MID 60S. COOLER HIGH
TEMPERATURES TO THE NORTH WITH THICKER HIGH CLOUD COVER. FELTON
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
ATMOSPHERIC RIVER AIMED AT VANCOUVER ISLAND AND CENTRAL BRITISH
COLUMBIA TUESDAY NIGHT INTO WEDNESDAY. SLIGHT CHANCE OF RAIN
ALONG THE COAST AND NEAR THE CANADIAN BORDER. LOWS IN THE 40S
AND HIGHS IN THE 60S.
MODELS IN GOOD AGREEMENT WITH A STRONG UPPER LEVEL RIDGE
BUILDING WEDNESDAY NIGHT AND THURSDAY. 500 MB HEIGHTS IN THE MID
TO UPPER 580 DMS BY THURSDAY NIGHT. LOW LEVEL FLOW TURNING
OFFSHORE WARMING HIGHS INTO THE 60S AND LOWER 70S. LOWS
REMAINING IN THE 40S.
UPPER LEVEL RIDGE MOVING OFF TO THE EAST FRIDAY WITH LOW LEVEL
OFFSHORE FLOW CONTINUING. FRIDAY LOOKS TO BE THE WARMEST DAY
WITH HIGHS IN THE MID 60S TO MID 70S. NO RECORDS EXPECTED FRIDAY
WITH OCTOBER 16TH IN 2022 BEING ONE OF THE WARMEST OCTOBER DAYS
ON RECORD ( SEATTLE HIGH THAT DAY WAS 88, THE SECOND WARMEST
OCTOBER DAY ). LOWS IN THE 40S AND LOWER 50S.
UPPER LEVEL RIDGE WELL TO THE EAST BY FRIDAY NIGHT. THIS OPENS
THE DOOR FOR A WEAKENING WARM FRONT TO POSSIBLY REACH THE AREA
FRIDAY NIGHT INTO SATURDAY. FOR NOW JUST CHANCE OR SLIGHT CHANCE
POPS. HIGHS MUCH COOLER, IN THE LOWER TO MID 60S. FELTON
AVIATION
NORTHEAST FLOW ALOFT CONTINUES OVER WESTERN WASHINGTON TODAY AS THE
REGION REMAINS BETWEEN AN UPPER TROUGH EAST OF THE CASCADES AND AN
UPPER RIDGE CENTERED WELL OFFSHORE. LOW LEVEL MOISTURE AND LIGHT
SURFACE WINDS HAVE LED TO AREAS OF LIFR CONDITIONS IN FOG AND LOW
CLOUDS AROUND LAKE WASHINGTON AS WELL AS OUTLYING RIVER VALLEYS. LOW
CLOUDS WILL LIFT AND SCATTER BY AROUND 18Z. VFR IS EXPECTED AREAWIDE
THIS AFTERNOON WITH VALLEY FOG AND LOW CLOUDS REFORMING AGAIN
TONIGHT.
KSEA...VALLEY FOG IS FORMING EAST OF THE TERMINAL THIS MORNING. THE
GENERAL EXPECTATION IS THAT IT WILL NOT IMPACT THE TERMINAL
DIRECTLY, BUT IT WILL BE IN THE VICINITY THROUGH 18Z OR SO.
OTHERWISE, VFR IS EXPECTED THROUGH THE DAY AHEAD. SURFACE WINDS
LIGHT E/NE THIS MORNING WILL BECOME NORTHERLY AND RISE TO 7 TO 11
KNOTS THIS AFTERNOON.
27
MARINE
HIGH PRESSURE OVER THE INTERIOR OF BRITISH COLUMBIA WILL LEAD TO
NORTHERLY OR WEAK OFFSHORE FLOW TODAY. THE RIDGE OVER INTERIOR
BRITISH COLUMBIA WILL WEAKEN TONIGHT FOR LIGHT WINDS ACROSS AREA
WATERS. A WEAK FRONTAL SYSTEM WILL MOVE ACROSS THE WATERS LATE
TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE REBUILDS ACROSS THE AREA
ON THURSDAY WITH OFFSHORE FLOW DEVELOPING. SEAS ARE EXPECTED TO
REMAIN BELOW 10 FEET ACROSS THE COASTAL WATERS THROUGH THE PERIOD.
27
SEW WATCHES/WARNINGS/ADVISORIES
WA...FROST ADVISORY UNTIL 8 AM PDT THIS MORNING FOR FOOTHILLS AND
VALLEYS OF PIERCE AND SOUTHERN KING COUNTIES-FOOTHILLS
AND VALLEYS OF THURSTON AND LEWIS COUNTIES-MIDDLE
CHEHALIS RIVER VALLEY.
FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM PDT MONDAY FOR
EASTERN KITSAP COUNTY-FOOTHILLS AND VALLEYS OF PIERCE AND
SOUTHERN KING COUNTIES-FOOTHILLS AND VALLEYS OF THURSTON
AND LEWIS COUNTIES-FOOTHILLS OF THE WESTERN AND SOUTHERN
OLYMPIC PENINSULA-LAKE CRESCENT AREA INCLUDING US 101-
LOWLANDS OF LEWIS AND SOUTHERN THURSTON COUNTIES-LOWLANDS
OF PIERCE AND SOUTHERN KING COUNTIES-MIDDLE CHEHALIS
RIVER VALLEY-NORTHERN HOOD CANAL-NORTHERN WASHINGTON
COAST-OLYMPIA AND SOUTHERN PUGET SOUND-SOUTHERN HOOD
CANAL-WILLAPA AND BLACK HILLS.
PZ...NONE.
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