999
FXUS66 KSEW 101005
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
305 AM PDT SUN AUG 10 2025
SYNOPSIS
HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION
THROUGH EARLY NEXT WEEK, BRINGING A WARMING AND DRYING TREND.
WIDESPREAD MODERATE (ORANGE) HEATRISK WILL CONTINUE ACROSS THE
LOWLANDS THROUGH TUESDAY, AND A HEAT ADVISORY REMAINS IN EFFECT
ACROSS THE LOWLANDS. AN UPPER TROUGH WILL MOVE INTO THE AREA
TOWARDS THE SECOND HALF OF NEXT WEEK, BRINGING IN COOLER AND
CLOUDIER CONDITIONS WITH INCREASING CHANCES FOR RAIN.
SHORT TERM /TODAY THROUGH TUESDAY/
A RIDGE OF HIGH PRESSURE
CENTERED OVER THE PACIFIC WILL CONTINUE TO AMPLIFY THROUGH THE
SHORT-TERM, RESULTING IN WARM AND DRY CONDITIONS ACROSS WESTERN
WASHINGTON. FOG AND LOW STRATUS HAS SET UP ALONG THE PACIFIC COAST
AND THROUGH THE STRAIT OF JUAN DE FUCA EARLY THIS MORNING, BUT
WILL BURN OFF BY THE AFTERNOON WITH CLEAR SKIES AND WARMING
RESUMING ACROSS THE REGION. TEMPERATURES TODAY WILL REACH THE MID
TO UPPER 80S ACROSS MUCH OF THE LOWLANDS, WITH POCKETS OF 90
DEGREES ACROSS THE CHEHALIS RIVER BASIN SOUTHWEST OF OLYMPIA. THIS
WILL RESULT IN WIDESPREAD MODERATE (ORANGE) HEATRISK ACROSS THE
LOWLANDS, AND ELEVATED OVERNIGHT LOW TEMPERATURES IN THE UPPER 50S
TO LOW 60S WILL PROVIDE LITTLE RELIEF TO THE DAYTIME HEAT. A HEAT
ADVISORY REMAINS IN EFFECT ACROSS MOST LOWLAND AREAS FOR SUNDAY
AFTERNOON, AND THE ADVISORY CONTINUES THROUGH TUESDAY EVENING AS
TEMPERATURES WILL REMAIN ELEVATED.
WARMING WILL CONTINUE ON MONDAY AS HIGH PRESSURE CONTINUES TO
BUILD INTO WESTERN WASHINGTON. AS A THERMAL TROUGH FORMS ALONG
THE COAST, MONDAY WILL BE THE WARMEST DAY FOR COASTAL AREAS.
TEMPERATURES WILL INCREASE INTO THE UPPER 80S AND LOW 90S ACROSS
THE REGION, WITH THE WARMEST TEMPERATURES SOUTHWEST OF THE PUGET
SOUND AND SOUTHWARD ALONG THE I-5 CORRIDOR. CLEAR SKIES AND LIGHT
WINDS WILL PREVAIL ONCE AGAIN, WITH EVEN WARMER OVERNIGHT LOWS IN
THE MID 60S FOR MUCH OF THE LOWLANDS.
THE THERMAL TROUGH WILL SHIFT INLAND ON TUESDAY, RESULTING IN
EVEN WARMER TEMPERATURES ACROSS THE INTERIOR LOWLANDS AND SUBTLE
COOLING ALONG THE COAST. WHILE SOME UNCERTAINTY REMAINS OVER
TEMPERATURES ON TUESDAY, ENSEMBLES MAINTAIN HIGH CHANCES OF 90
DEGREES OR HIGHER ACROSS THE METRO AREAS EAST AND SOUTH OF THE
PUGET SOUND. ENSEMBLES SHOW A MODERATE (60% TO 70%) CHANCE OF
REACHING 90 DEGREES ON TUESDAY IN SEATTLE, AND A HIGHER (70% TO
80%) CHANCE OF 90 DEGREES OR HIGHER IN OLYMPIA. THE WARMEST
TEMPERATURES ARE ON TRACK TO OCCUR SOUTH OF THE PUGET SOUND AND
ALONG THE CASCADE FOOTHILLS, WITH CONTINUED WIDESPREAD MODERATE
HEATRISK ACROSS THE LOWLANDS.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
WHILE FORECAST MODELS
CONTINUE TO STRUGGLE TO PREDICT THE BREAKDOWN OF THE UPPER RIDGE,
MOST ENSEMBLE MEMBERS SHOW A PATTERN CHANGE BY WEDNESDAY WITH A
TROUGH MOVING OVER THE PACIFIC NORTHWEST. THIS WILL BRING
TEMPERATURES BACK TO NEAR-NORMAL, PEAKING IN THE UPPER 70S ACROSS
THE LOWLANDS AND IN THE MID TO UPPER 60S ALONG THE COAST.
INCREASED ONSHORE FLOW WILL PROMOTE CONTINUED COOLER TEMPERATURES
AND PERIODS OF CLOUDY SKIES THROUGH THE REMAINDER OF THE WEEK AS A
SERIES OF TROUGHS IS SET TO PASS OVER THE REGION. CHANCES FOR
RAINFALL INCREASE THURSDAY THROUGH SATURDAY, PRIMARILY OVER HIGHER
TERRAIN, BUT THE EXACT PLACEMENT AND INTENSITY REMAINS UNCERTAIN
AT THIS TIME.
15
AVIATION
UPPER LEVEL RIDGE WITH NORTHWESTERLY FLOW ALOFT INTO
MONDAY. NORTHWESTERLY SURFACE GRADIENTS TODAY GOING LIGHT TONIGHT
INTO MONDAY AS THERMALLY INDUCED SURFACE TROUGH MOVES UP THE
COASTLINE THEN INLAND MONDAY.
IFR/LIFR STRATUS ALONG THE COAST AND DOWN THE STRAIT OF JUAN DE
FUCA TO NEAR WHIDBEY ISLAND WILL RETREAT BACK OFF THE COAST BY MID
TO LATE MORNING. IFR STRATUS RETURNING TO THE COAST AFTER 03Z
TONIGHT.
KSEA...MOSTLY CLEAR SKIES. NORTHEAST WIND 6 TO 10 KNOTS BECOMING
NORTH NORTHWEST 8 TO 12 KNOTS AROUND 19Z. WINDS EASING TO
NORTHEAST 4 TO 8 KNOTS AFTER 04Z TONIGHT.
FELTON
MARINE
HIGH PRESSURE WILL REMAIN OVER THE COASTAL WATERS THROUGH
WEDNESDAY. A THERMALLY INDUCED SURFACE TROUGH WILL MOVE UP THE
COASTLINE TONIGHT THEN SHIFT INLAND MONDAY AND TUESDAY. HIGH
PRESSURE WILL WEAKEN WEDNESDAY WITH A WEAK TROUGH MOVING INTO THE
COASTAL WATERS THURSDAY.
SMALL CRAFT ADVISORY OUTER COASTAL WATERS TODAY FOR CHOPPY SEAS 7
OR 8 FEET WITH 8 OR 9 SECOND PERIOD, TONIGHT FOR A COMBINATION OF
15 TO 25 KNOTS WINDS AND BUILDING SEAS TO 10 FEET AND FOR MONDAY
SEAS 10 OR 11 FEET WITH A 10 OR 11 SECOND PERIOD. STRONG
POSSIBILITY SMALL CRAFT ADVISORY CONDITIONS WILL CONTINUE OVER THE
OUTER COASTAL WATERS UNTIL AT LEAST TUESDAY NIGHT.
SMALL CRAFT ADVISORY WESTERLIES FOR THE CENTRAL AND EASTERN STRAIT
OF JUAN DE FUCA TUESDAY NIGHT.
FELTON
FIRE WEATHER
A WARMING AND DRYING TREND WILL CONTINUE TODAY
THROUGH TUESDAY 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 TODAY THROUGH TUESDAY TO DIP AS
LOW AS 25-35%, WITH THE LOWEST RH 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 INCREASED ATMOSPHERIC
INSTABILITY, POTENTIALLY RESULTING IN MORE ACTIVITY ON OUR ONGOING
FIRES. MORE PERSISTENT TROUGHING IS EXPECTED TO DEVELOP 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 THIS AFTERNOON 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 UNTIL 6 PM 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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