221
FXUS66 KSEW 130343
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
843 PM PDT FRI JUN 12 2026
SYNOPSIS
A STRONG UPPER LEVEL RIDGE WILL MOVE ONSHORE THIS WEEKEND INTO EARLY
NEXT WEEK. A HEAT ADVISORY CONTINUES FOR MUCH OF WESTERN WASHINGTON
FOR WIDESPREAD MODERATE HEATRISK AS HIGHS CLIMB INTO THE 80S AND 90S
ON SUNDAY AND MONDAY. FIRE DANGER WILL ALSO BECOME ELEVATED AS
RELATIVE HUMIDITIES DIP WITH OFFSHORE FLOW. THE HIGH WILL WEAKEN
MIDWEEK FOR INCREASING ONSHORE FLOW AND COOLER TEMPERATURES.
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
STRONG UPPER LEVEL RIDGING CONTINUES TO BUILD INTO THE REGION THIS
EVENING. THERMALLY INDUCED LOW PRESSURE OVER WESTERN OREGON TONIGHT
WILL CONTINUE TO EXPAND NORTH AND WESTWARD ON SATURDAY WITH THE LOW
LEVEL FLOW FLIPPING WEAKLY OFFSHORE. NBM HIGH TEMPERATURES IN THE
SHORT TERM, PARTICULARLY AROUND CENTRAL PUGET SOUND, LOOKED A BIT ON
THE LOW SIDE. SO, HIGH TEMPERATURES WERE GIVEN A MODEST BOOST. THIS
PUTS SEATTLE METRO IN THE MID 80S TOMORROW AND A DEGREE OR TWO
EITHER SIDE OF 90 FOR SUNDAY/MONDAY WITH REGIONAL HIGH TEMPERATURE
RECORDS IN JEOPARDY. THE REST OF THE FORECAST IS UNCHANGED AT THIS
TIME. PREVIOUS DISCUSSION FOLLOWS WITH UPDATES TO MARINE/AVIATION
PORTIONS. 27
IT'S A DRY AND MOSTLY SUNNY DAY ACROSS MUCH OF WESTERN
WASHINGTON THIS AFTERNOON. SATELLITE HAS A FEW AREAS OF CLOUDS
OVER THE CASCADES, AND OLYMPICS, AND SOME LOW STRATUS AROUND
NEAH BAY. QUITE A FEW PLACES IN THE LOWLANDS HAVE CLIMBED INTO
THE 70S THIS AFTERNOON. A FEW LOCATIONS WEST OF OLYMPIA/CHEHALIS
VALLEY MAY TRACK TOWARDS 80 THIS AFTERNOON. OTHERWISE, ONLY
MINOR HEATRISK TODAY WITH THE TEMPERATURES, WITH WINDS OUT OF
THE NORTH AROUND 5-10 MPH. LOWS TONIGHT DROP DOWN TO AROUND 50
TO 55.
THE MAIN STORY REMAINS WARM, AND DRY AIR GOING INTO THE WEEKEND,
AND INTO MONDAY ACROSS WESTERN WASHINGTON. AN UPPER LEVEL RIDGE
BUILDING OFFSHORE WILL BEGIN TO MOVE INLAND THIS WEEKEND, WITH
THE AXIS OVERHEAD BY SUNDAY EVENING. A THERMAL TROUGH IS ALSO
EXPECTED TO BUILD ALONG THE COAST, WHICH WILL IN TURN MAKE THE
FLOW MORE OFFSHORE IN THE OVERNIGHT PERIODS. WINDS WILL TURN
MORE OUT OF THE EAST, BUT MOST PLACES WILL SEE LIGHT WINDS
OVERNIGHT (WITH THE EXCEPTION OF THE WEST CASCADES AND OLYMPIC
SLOPES WHERE A FEW GUSTS UP TO 20 MPH MAY OCCUR). DURING THE
DAYS, THE WINDS WILL TURN TO THE NORTH/NORTHWEST 5 TO 10 MPH,
WITH SATURDAY BEING BREEZY IN MUCH OF PUGET SOUND AS WINDS PICK
UP TO 15-20 MPH IN THE AFTERNOON.
NOW FOR THE HEAT: SATURDAY WILL BE THE COOLER OF THE TWO WEEKEND
DAYS, BUT WILL STILL BE QUITE A BIT WARMER TO FRIDAY, AS HIGHS
APPROACH THE MID 70S INTO THE UPPER 80S (WITH A COUPLE LOW 90S
IN AREAS WEST OF OLYMPIA). HEATRISK INCREASES TO MODERATE FOR A
LARGE SWATH OF THE SOUTH/SOUTHWEST INTERIOR, BUT REMAINS MINOR
FOR THE REMAINDER OF THE LOWLANDS. LOWS WILL DROP INTO THE MID
AND UPPER 50S SATURDAY NIGHT INTO SUNDAY. SUNDAY WILL BE THE
WARMEST DAY OF THE WEEKEND, WITH HIGHS AROUND 80 TO NEAR 100 IN
THE SOUTHWEST INTERIOR. ALL OF THE LOWLANDS WILL SEE MODERATE
HEATRISK IMPACTS, WITH A FEW ISOLATED INSTANCES OF MAJOR
HEATRISK (BUT THIS HAS DECREASED SLIGHTLY TO 20-40% WITH THE
LATEST FORECAST UPDATE DUE TO LOW TEMPERATURES DROPPING A COUPLE
DEGREES TO AROUND 60). NEVERTHELESS, THE HEAT ADVISORY WILL
CONTINUE FOR THE EMPHASIS OF THOSE SPENDING TIME OUTSIDE (WHO
ARE SENSITIVE TO EXTREME HEAT) TO TAKE BREAKS IN THE AIR
CONDITIONING/SHADE, AND STAYING HYDRATED.
HPR
LONG TERM /MONDAY THROUGH FRIDAY/
SURFACE THERMAL TROUGH DEEPENS INLAND WITH HIGHEST SURFACE
TEMPERATURES ON MONDAY. WIDESPREAD MODERATE HEATRISK REMAINS LIKELY
ON MONDAY, WITH MORE HIGHS LIKELY TO BREAK 90 IN THE INTERIOR.
MONDAY EVENING, THIS THERMAL TROUGH WILL BEGIN TO WEAKEN AND
DISORGANIZE. OVERNIGHT TEMPERATURES HAVE COOLED A COUPLE DEGREES,
BUT WILL STILL LIKELY RANGE FROM THE UPPER 50S TO LOW 60S. TUESDAY
WILL BE MUCH COOLER DUE TO THIS WEAKENING OF THE THERMAL TROUGH,
BRINGING WINDS WITH A NORTHWESTERLY COMPONENT. A FEW GUSTY WINDS
WILL BE POSSIBLE ON TUESDAY. THE UPPER LEVEL RIDGE THAT HAD BUILT
OVER WESTERN WASHINGTON SHIFTS INLAND ON TUESDAY, CAUSING TEMPORARY
ZONAL/ONSHORE FLOW UNTIL A UPPER LEVEL TROUGH PUSHES IN ON THURSDAY,
KEEPING TEMPERATURES COOL THROUGH THE END OF THE WEEK.
HPR/NW
AVIATION
UPPER LEVEL RIDGING CENTERED JUST OFFSHORE WILL CONTINUE TO AMPLIFY
INTO SATURDAY WITH NORTHWEST FLOW ALOFT OVER WESTERN WASHINGTON. THE
LOW LEVEL FLOW WILL BE NORTHERLY OR WEAKLY OFFSHORE INTO SATURDAY
AFTERNOON. THE AIR MASS IS DRY AND STABLE WITH CLEAR SKIES AND VFR
CONDITIONS IN PLACE.
KSEA...CLEAR SKIES. SURFACE WINDS NORTHERLY 7 TO 10 KNOTS WILL
BECOME NORTHEASTERLY 5 TO 7 KNOTS OVERNIGHT THEN RISE AGAIN TO
NORTHERLY 8 TO 12 KNOTS SATURDAY AFTERNOON.
27
MARINE
BROAD SURFACE HIGH PRESSURE WILL REMAIN CENTERED OVER THE OFFSHORE
WATERS INTO EARLY NEXT WEEK. THERMALLY INDUCED LOW PRESSURE OVER
WESTERN OREGON WILL EXPAND NORTH AND WESTWARD ON SATURDAY FOR
PERIODS OF LIGHT OFFSHORE FLOW SATURDAY INTO SUNDAY. THE THERMAL
TROUGH WILL SHIFT INTO THE INTERIOR OF WESTERN WASHINGTON SUNDAY
NIGHT WITH ONSHORE FLOW INCREASING ACROSS THE COASTAL WATERS. A
TYPICAL SUMMERTIME PATTERN OF VARYING DEGREES OF ONSHORE FLOW WILL
BE IN PLACE EARLY NEXT WEEK WITH HIGH PRESSURE OFFSHORE AND LOWER
PRESSURE ACROSS THE INTERIOR OF THE PACIFIC NORTHWEST. WEAK SYSTEMS
PASSING WELL NORTH OF THE REGION WILL INDUCE ENOUGH ONSHORE FLOW FOR
POSSIBLE GALES IN THE CENTRAL AND EAST STRAIT MONDAY EVENING AND
AGAIN ON TUESDAY.
COASTAL SEAS WILL REMAIN WELL UNDER 10 FEET THROUGH THE WEEKEND
BEFORE BUILDING TO AROUND 9 OR 10 FEET ON TUESDAY.
27
FIRE WEATHER
DRYING TREND OVER THE AREA THE NEXT FEW DAYS WITH ELEVATED FIRE
WEATHER CONCERNS BEGINNING SATURDAY AND LASTING INTO TUESDAY.
UPPER LEVEL RIDGE BUILDING THIS WEEKEND WITH THE LOW LEVEL FLOW
TURNING OFFSHORE SATURDAY NIGHT. HIGHS WARMING INTO THE 80S
SATURDAY, 80S TO LOWER 90S SUNDAY AND FOR THE INTERIOR 80S TO
MID 90S MONDAY. RELATIVE HUMIDITY VALUES LOWERING IN THE DRIER
LOCATIONS, LIKE THE SOUTHWEST INTERIOR, INTO THE TEENS BOTH
SUNDAY AND MONDAY AFTERNOON. EVEN THOUGH FINE FUELS HAVE NOT
REACHED CRITICAL THRESHOLDS, THIS RAPID DRYING WILL CREATE
ELEVATED FIRE CONCERNS ESPECIALLY FOR DRY GRASSY/SHRUBBY AREAS,
AS WELL AS PILES OF DEAD FUELS. OFFSHORE FLOW SUNDAY INTO MONDAY
WILL PREVENT GOOD RELATIVE HUMIDITY RECOVERIES OVERNIGHT.
RELATIVE HUMIDITIES WILL IMPROVE WITH THE RETURN OF ONSHORE FLOW
TUESDAY. WINDS WILL BECOME PARTICULARLY GUSTY, WITH PORTIONS OF
THE COAST/MOUNTAINS/SOUTH INTERIOR SEEING WEST TO NORTHWEST
WIND GUSTS UP TO 20 TO 30 MPH. LOW LEVEL ONSHORE FLOW AND
COOLER TEMPERATURES WEDNESDAY AND THURSDAY WILL EASE FIRE
WEATHER CONCERNS THE MIDDLE OF NEXT WEEK. FELTON/HPR
SEW WATCHES/WARNINGS/ADVISORIES
WA...HEAT ADVISORY FROM 11 AM SUNDAY TO 5 AM PDT TUESDAY FOR CITY
OF SEATTLE-DOWNTOWN EVERETT / MARYSVILLE AREA-EASTERN
KITSAP COUNTY-EASTERN STRAIT OF JUAN DE FUCA-EASTSIDE-
FOOTHILLS AND VALLEYS OF CENTRAL KING COUNTY-FOOTHILLS
AND VALLEYS OF PIERCE AND SOUTHERN KING COUNTIES-
FOOTHILLS AND VALLEYS OF SNOHOMISH AND NORTHERN KING
COUNTIES-FOOTHILLS AND VALLEYS OF THURSTON AND LEWIS
COUNTIES-FOOTHILLS AND VALLEYS OF THE NORTH CASCADES-
FOOTHILLS OF THE WESTERN AND SOUTHERN OLYMPIC PENINSULA-
ISLAND COUNTY-LAKE CRESCENT AREA INCLUDING US 101-LOWER
CHEHALIS RIVER VALLEY-LOWLANDS OF LEWIS AND SOUTHERN
THURSTON COUNTIES-LOWLANDS OF PIERCE AND SOUTHERN KING
COUNTIES-LOWLANDS OF WESTERN SKAGIT AND NORTHWESTERN
SNOHOMISH COUNTIES-LOWLANDS OF WESTERN WHATCOM COUNTY-
MIDDLE CHEHALIS RIVER VALLEY-NORTHERN HOOD CANAL-OLYMPIA
AND SOUTHERN PUGET SOUND-PORT TOWNSEND AREA-SAN JUAN
COUNTY-SHORELINE / LYNNWOOD / SOUTH EVERETT AREA-SOUTHERN
HOOD CANAL-WILLAPA AND BLACK HILLS.
PZ...NONE.
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