673
FXUS66 KSEW 100336
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
836 PM PDT SAT AUG 9 2025
SYNOPSIS
HIGH PRESSURE CONTINUES TO BUILD OVER WESTERN
WASHINGTON INTO EARLY NEXT WEEK, BRINGING WARM AND DRY
CONDITIONS OVER THE REGION. MODERATE HEATRISK IS EXPECTED FOR
THE LOWLANDS SUNDAY AND MONDAY, WITH HIGH TEMPERATURES REACHING
THE 90S INLAND. HEAT CONCERNS LINGER INTO TUESDAY. AN UPPER
TROUGH MOVES INTO THE AREA AROUND MIDWEEK, SPREADING COOLER AND
CLOUDIER CONDITIONS AND A RETURN OF RAIN CHANCES.
SHORT TERM /TONIGHT THROUGH TUESDAY/
HIGH PRESSURE OVER THE
PACIFIC WILL CONTINUE TO BUILD OVER THE PACIFIC NORTHWEST
BRINGING WARMER AND DRIER CONDITIONS. HEADING INTO SUNDAY, AREAS
ALONG THE COAST MAY SEE MARINE STRATUS THROUGHOUT THE MORNING
BRIEFLY, BUT WILL BURN BACK RATHER QUICKLY FOR ANOTHER DAY OF
CLEAR SKIES AND WARMING TEMPERATURES.
WE WILL SEE TEMPERATURES WARM ON SUNDAY INTO THE UPPER 80S AND
EVEN LOWER 90S FOR MOST AREAS, WITH AREAS LIKE THE SOUTHWEST
INTERIOR AND THE CASCADE FOOTHILLS BEING THE WARMEST LOCATIONS.
THESE OVERALL TEMPERATURES WILL RESULT IN MODERATE (ORANGE)
HEATRISK FOR ACROSS MUCH OF THE INTERIOR OF WESTERN WASHINGTON.
THEREFORE, A HEAT ADVISORY HAS BEEN ISSUED FOR MOST OF THE
INTERIOR ZONES AND MOUNTAIN VALLEYS STARTING SUNDAY EVENING.
OVERNIGHT TEMPERATURES INTO MONDAY WILL BE ELEVATED, IN THE LOW TO
MID 60S FOR MUCH OF THE LOWLANDS, WHICH CAN PROVIDE LITTLE RELIEF
TO THE WARM DAYTIME TEMPERATURES.
WARM AND DRY WILL CONTINUE INTO MONDAY AS THE HIGH PRESSURE
AMPLIFIES, WARMING UP TEMPERATURES ACROSS THE AREA. AFTERNOON
TEMPERATURES IN THE UPPER 80S AND LOWER TO MID 90S ACROSS MUCH OF
THE INTERIOR CAN BE EXPECTED, WITH AREAS ALONG THE SOUTHWEST
INTERIOR (CHEHALIS RIVER BASIN) AND THE CASCADE FOOTHILLS SEEING
THE WARMEST TEMPERATURES. MOST OF THE INTERIOR WILL CONTINUE TO
BE IN MODERATE (ORANGE) HEATRISK, WITH THOSE AFOREMENTIONED WARMER
LOCATIONS POTENTIALLY SEEING POCKETS OF MAJOR (RED) HEATRISK.
AGAIN, OVERNIGHT TEMPERATURES MONDAY NIGHT WILL BE IN THE LOW TO
MID 60S ACROSS MOST OF THE REGION, WHICH WILL PROVIDE LITTLE
TO NO RELIEF TO THE WARM DAYTIME TEMPERATURES, ESPECIALLY THOSE
WITHOUT EFFECTIVE COOLING.
LATEST ENSEMBLE GUIDANCE CONTINUES TO SHOW DIFFERENCES IN WHEN THE
UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN. THE LATEST FORECAST
RUNS HAVE BEEN SUGGESTING THAT TUESDAYS TEMPERATURES WILL STILL
BE WARM, IN THE UPPER TO LOWER 90S ACROSS THE AREA, THEREFORE, THE
HEAT ADVISORY IS CONTINUED THROUGH TUESDAY EVENING TO ACCOUNT FOR
THIS.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
A SERIES OF UPPER LEVEL
TROUGHS LOOK TO PASS OVER WESTERN WASHINGTON STARTING ON WEDNESDAY,
BRINGING A COOL DOWN FOR THE REGION. TEMPERATURES LOOK TO FALL
BELOW NORMAL STARTING ON WEDNESDAY, IN THE UPPER 60S TO LOWER 70S
WITH ONSHORE FLOW PROMOTING CLOUDIER CONDITIONS ACROSS THE AREA
AND PROVIDING RELIEF TO THE EARLIER WEEKS HEAT. ENSEMBLES ARE
SUGGESTING POSSIBLE RAIN CHANCES THURSDAY AND FRIDAY, BUT
CONFIDENCE IN COVERAGE AND TIMING OF THE INCOMING PRECIPITATION IS
LOW AT THIS TIME.
MAZURKIEWICZ
AVIATION
VFR CONDITIONS CONTINUE UNDER GENERALLY CLEAR SKIES
FOR MUCH OF THE INTERIOR THROUGH THE PERIOD, THOUGH SOME SHALLOW
LOW CLOUDS ARE POSSIBLE. MEANWHILE, LOW STRATUS WILL REMAIN
ALONG THE IMMEDIATE COAST AND ALONG THE STRAIT OF JUAN DE FUCA
OVERNIGHT, WITH IMPROVEMENT BY MID-MORNING SUNDAY. GENERALLY
NORTHWESTERLY WINDS THIS EVENING BECOMING NORTHEASTERLY
OVERNIGHT.
KSEA...VFR CONDITIONS WILL PREVAIL THROUGH SUNDAY UNDER
GENERALLY CLEAR SKIES. NORTHERLY SURFACE WINDS AROUND 10 KT EASE
THIS EVENING AND BECOME INCREASINGLY NORTHEASTERLY AS THEY EASE.
EXPECT INCREASING NORTHWEST WINDS AROUND 10-15 KT SUNDAY
AFTERNOON.
MARINE
SURFACE HIGH PRESSURE WILL PERSIST OVER THE COASTAL
WATERS INTO EARLY NEXT WEEK. A WEAK THERMALLY INDUCED SURFACE
TROUGH WILL MOVE UP THE COASTLINE SUNDAY NIGHT AND MOVE INLAND
ON MONDAY.
A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE OUTER COASTAL WATERS
FOR STEEP SEAS. COMBINED SEAS WILL BUILD EARLY SUNDAY MORNING TO 7-9
FT WITH A DOMINANT PERIOD OF AROUND 7-8 SECONDS. COMBINED SEAS WILL
CONTINUE BUILDING SUNDAY NIGHT INTO TUESDAY TO 10-12 FT. NORTHWESTERLY
WINDS WILL ALSO INCREASE TO 20-25 KT. ERGO, THE SMALL CRAFT
ADVISORY IS LIKELY TO BE EXTENDED.
WESTERLY PUSHES MEETING SMALL CRAFT CRITERIA ARE POSSIBLE EACH
EVENING IN THE CENTRAL AND EASTERN STRAIT STARTING TUESDAY.
29
FIRE WEATHER
THE WARM AND DRYING TREND WILL CONTINUE ON
SUNDAY AND MONDAY AS AN UPPER LEVEL RIDGE BUILDS OVER THE AREA
AND A WEAK RESULTANT THERMAL TROUGH DEVELOPS ALONG THE COAST.
THIS WILL ALLOW FOR MINIMUM RH VALUES SUNDAY AND MONDAY TO REACH
AS LOW AS 25-35%, WITH THE LOWEST VALUES FROM THE SOUTH PUGET
SOUND, THE SOUTHWEST INTERIOR, AND THE SOUTHERN WASHINGTON
CASCADES. A SHORTWAVE TROUGH LOOKS TO MOVE THROUGH LATE SUNDAY
INTO MONDAY, AND ALONG WITH THE THERMAL TROUGH, WILL RESULT IN
POORER RH RECOVERIES AND MAY SLIGHTLY INCREASE ATMOSPHERIC
INSTABILITY, POTENTIALLY RESULTING IN MORE ACTIVITY ON OUR
ONGOING FIRES. MORE PERSISTENT TROUGHING IS EXPECTED TO DEVELOP
TUESDAY INTO WEDNESDAY, ALLOWING FOR COOLER AND MORE MOIST AIR
TO RETURN TO THE REGION WITH A SLIGHT CHANCE FOR LIGHT SHOWERS
FOR PORTIONS OF THE NORTH CASCADES AND THE PACIFIC COAST
BEGINNING THURSDAY.
62
SEW WATCHES/WARNINGS/ADVISORIES
WA...HEAT ADVISORY FROM 2 PM SUNDAY TO 10 PM 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-
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-SHORELINE / LYNNWOOD / SOUTH EVERETT AREA-SOUTHERN
HOOD CANAL-WILLAPA AND BLACK HILLS.
PZ...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 8 PM PDT SUNDAY
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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