890
FXUS66 KSEW 200404
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
904 PM PDT SUN JUL 19 2026
SYNOPSIS
UPPER LEVEL RIDGING BUILDING INTO THE REGION WILL
LEND ITSELF TO MUCH ABOVE NORMAL TEMPERATURES THROUGHOUT THE
FIRST HALF OF THE WEEK. DRY CONDITIONS ARE EXPECTED TO ACCOMPANY
THE HEAT FOR ELEVATED FIRE WEATHER CONCERNS. THE RIDGE WILL
WEAKEN IN THE SECOND HALF OF THE WEEK AS LOW PRESSURE MOVES UP
FROM THE SOUTH AND MAY REINTRODUCE CHANCES FOR THUNDERSTORMS IN
THE FORECAST FOR LATER THIS WEEK.
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/
MOSTLY CLEAR THIS
EVENING WITH STRATUS ALONG THE IMMEDIATE COASTLINE. INCREASING
HAZE ALOFT ALSO NOTICEABLE ACROSS NORTHWEST WASHINGTON. THE
WARMUP WILL BEGIN IN EARNEST THROUGH THE MIDDLE OF THE WEEK AS
TEMPERATURES CLIMB INTO THE UPPER 80S AND LOW 90S THROUGHOUT
MUCH OF THE LOWLAND LOCATIONS. AS SUCH, A HEAT ADVISORY IS IN
EFFECT BEGINNING ON TUESDAY AND LASTING INTO LATE WEDNESDAY
NIGHT. EXPECT WIDESPREAD MODERATE HEATRISK LEVELS ON MONDAY,
INCREASING TO MAJOR FOR THE URBAN HEAT ISLANDS AND AREAS OF THE
SOUTH PUGET SOUND ON TUESDAY. WARMING OVERNIGHT LOWS ON TUESDAY
AND WEDNESDAY MORNING CONTRIBUTED TO THE BUMP IN HEATRISK
LEVELS. OVERNIGHT LOWS ARE EXPECTED TO BE AS WARM AS 60 TO 65
DEGREES FOR MANY LOCATIONS, MEANING THAT ADEQUATE RELIEF FROM
THE HEAT OF THE DAY MAY NOT BE FULLY REALIZED, ESPECIALLY FOR
THOSE WHO ARE SENSITIVE TO THE HEAT OR LACK COOLING.
TEMPERATURES IN FAR NORTHWESTERN WASHINGTON, INCLUDING THE
BELLINGHAM AND SAN JUAN COUNTY AREA, MAY BE SUBJECT TO BEING A
FEW DEGREES COOLER DUE TO SMOKE COMING IN TOMORROW FROM ACTIVE
FIRES IN BRITISH COLUMBIA. AS THE FLOW GOES NORTHERLY, SMOKE
GETS INTO THE FRASER RIVER VALLEY AND EXITS IN AND AROUND THE
BELLINGHAM AREA. A MORE NOTICEABLE HAZE MAY BE PRESENT IN THESE
AREAS TOMORROW. PLEASE REFER TO YOUR LOCAL CLEAN AIR AGENCY FOR
INFORMATION ON THE AIR QUALITY READINGS AND FORECAST.
AS THE RIDGE CONTINUES TO AMPLIFY, TEMPERATURES REACH THE UPPER
80S TO LOW 90S ON TUESDAY, WHILST CONTINUING TO BE VERY DRY.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
THE AFOREMENTIONED HEAT
ADVISORY WILL REMAIN IN EFFECT THROUGH LATE WEDNESDAY NIGHT AS
TEMPERATURES REMAIN IN THE LOW 90S. WHILE TEMPERATURES WILL BE
DECREASING THROUGH THE END OF THE WEEK, THERE IS STILL
CONSIDERABLE UNCERTAINTY AS TO THE FATE OF THE REMNANT TROPICAL
MOISTURE FROM ELIDA OR POSSIBLE MONSOONAL MOISTURE RE-ENTERING
THE NORTHWEST.
SPECIFICS AREN'T IN FOCUS YET, THOUGH THE ENSEMBLE CLUSTER
ANALYSIS SHOWS SIGNALS FOR A TROUGH COMING UP THE WEST COAST,
BUT IN VARIOUS POSITIONS WHICH DOES HAVE A BEARING ON WHAT TO
EXPECT WEST OF THE CASCADE CREST. SOME MODEL SOLUTIONS SHOW THE
LOW SPINNING UP SOME SHOWERS IN THE AREA COME THURSDAY MORNING.
THUNDERSTORM CHANCES ARE LOW AT THIS TIME, BUT CANNOT BE FULLY
RULED OUT FOR THURSDAY AND FRIDAY. WITH THE SOLUTION POSSIBLY
BEING A LOW PRESSURE SYSTEM TRAVERSING THE REGION LATE IN THE
WEEK, THE RESUMPTION OF ONSHORE FLOW CAN BE EXPECTED, COOLING
THINGS OFF BY UP TO 10 DEGREES FROM THE PEAK HEAT OF THE WEEK.
TEMPERATURES AS OF NOW FOR THE WEEKEND ARE FORECAST TO BE IN THE
MID 70S.
AVIATION
STRATUS ALONG THE IMMEDIATE COASTLINE WITH FOR VFR
CONDITIONS SO FAR THIS EVENING. STRATUS LOOKS TO REDEVELOP
TONIGHT ALONG THE COAST, BUT REMAIN WEST OF THE INLAND
TERMINALS. VFR CONDITIONS LOOK TO OTHERWISE CONTINUE TOMORROW
WITH HIGH CLOUDS OVERHEAD. INCREASING SMOKE ACROSS NORTHWEST WA
ON MONDAY MAY BEGIN TO LIMIT BOTH HORIZONTAL AND SLANT-RANGE
VISIBILITY BY MONDAY AFTERNOON. N/NW WINDS 5 TO 10 KT BECOME 5
KT OR LESS OVERNIGHT AND REMAIN LIGHT INTO MONDAY.
KSEA...VFR CONDITIONS PREVAIL THROUGH THE TAF PERIOD. NW WINDS 5
TO 10 KT BECOMING NE 5 KT OR LESS OVERNIGHT. N WINDS CONTINUE
TOMORROW.
62/41
MARINE
HIGH PRESSURE WILL REMAIN CENTERED OFFSHORE WITH LOWER
PRESSURE INLAND THROUGH THE WEEK. BREEZY NORTHWEST WINDS WILL
CONTINUE OVER THE COASTAL WATERS TODAY AND TONIGHT, MAKING FOR
STEEP 6 TO 8 FT SEAS. WINDS AND SEAS ARE ON TRACK TO EASE EARLY
MONDAY MORNING. ONSHORE GRADIENTS WILL EASE THROUGH THE EARLY
PART OF THE WEEK AS THERMALLY-INDUCED LOW PRESSURE DEVELOPS
ACROSS WESTERN WASHINGTON AND OREGON. STRONGER ONSHORE FLOW AND
PUSHES DOWN THE STRAIT LOOK TO RESUME IN THE LATTER HALF OF THE
WEEK AS THE THERMAL TROUGH SHIFTS EASTWARD. THERE IS MORE
UNCERTAINTY IN THE PATTERN IN THE LONG TERM, WITH THE POTENTIAL
FOR DISTURBANCES TO MOVE ACROSS THE AREA LATE WEEK INTO NEXT
WEEKEND. 62
FIRE WEATHER
THE BUILDING RIDGE WILL COME WITH VERY DRY
CONDITIONS. MINIMUM RELATIVE HUMIDITY VALUES ARE EXPECTED TO BE
IN THE 20 TO 30 PERCENT RANGE, WITH DRIER LOCATIONS IN THE SOUTH
SOUND CAPABLE OF GETTING INTO THE UPPER TEENS. ELEVATED FIRE
WEATHER CONDITIONS ARE GOING TO BE IN PLACE THROUGH THE MIDDLE
OF THE WEEK. WHILE THERE IS STILL A LOT OF UNCERTAINTY REGARDING
THE LOW PRESSURE SYSTEM OFF THE COAST FROM WHAT WAS ONCE
TROPICAL STORM ELIDA, CHANCES FOR THUNDERSTORMS LATE IN THE WEEK
ARE LOW AT THIS POINT, BUT CANNOT BE FULLY RULED OUT. ANY
THUNDERSTORMS THAT DEVELOP AFTER ANOTHER ROUND OF HOT AND VERY
DRY CONDITIONS POSE A RISK OF ADDITIONAL IGNITIONS FROM
LIGHTNING.
21
SEW WATCHES/WARNINGS/ADVISORIES
WA...HEAT ADVISORY FROM 10 AM TUESDAY TO 11 PM PDT WEDNESDAY 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-
LAKE CRESCENT AREA INCLUDING US 101-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-
SHORELINE / LYNNWOOD / SOUTH EVERETT AREA-SOUTHERN HOOD
CANAL.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT MONDAY FOR COASTAL WATERS
FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL
WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO 60 NM-
COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER 10
TO 60 NM.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page