506
FXUS66 KSEW 192025
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
125 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 AFTERNOON WITH SOME SCATTERED CLOUDS OVER THE
TERRAIN. 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 HAS BEEN ISSUED 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 HAS NOW RETREATED TO THE IMMEDIATE COASTLINE, AND WILL
REMAIN LIKE SO THROUGH THE REMAINDER OF THE DAY FOR VFR
CONDITIONS TODAY. 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
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.
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