307
FXUS66 KSEW 202213
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
313 PM PDT SAT JUN 20 2026
SYNOPSIS
HIGH PRESSURE WILL BUILD INTO THE NORTHWEST TOMORROW THROUGH
EARLY NEXT WEEK FOR ANOTHER ROUND OF HOT TEMPERATURES AND DRY
CONDITIONS. DRY CONDITIONS WILL ELEVATE FIRE WEATHER CONCERNS
WEST OF THE CREST THROUGH WEDNESDAY. HIGH PRESSURE BEGINS TO
WEAKEN IN THE SECOND HALF OF NEXT WEEK, WITH THE NEXT CHANCE FOR
PRECIPITATION OCCURRING LATE NEXT WEEK INTO THE WEEKEND.
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/
ALL AREAS, WITH THE EXCEPTION OF THE COAST, HAVE CLEARED UP THIS
AFTERNOON FOR MOSTLY SUNNY SKIES. HIGH PRESSURE WILL BUILD MORE
BEGINNING TOMORROW AND LASTING THROUGH THE MIDDLE OF THE WEEK.
TOMORROW, EXPECT ANOTHER ROUND OF MARINE STRATUS CLOUDS
IMPACTING PARTS OF THE PUGET SOUND REGION, BREAKING OUT IN THE
LATE MORNING TO EARLY AFTERNOON. HIGHS WILL GENERALLY BE IN THE
UPPER 70S TO LOW 80S WITH 60S ALONG THE COAST. THERMAL TROUGHING
DEVELOPING JUST EAST OF THE IMMEDIATE COAST WILL HELP BRING
ABOUT A SHARPER INCREASE IN THE TEMPERATURES COME MONDAY DUE TO
A PERIOD OF OFFSHORE FLOW, WITH HIGHS EXPECTED TO GET INTO THE
UPPER 80S TO 90S IN WARMER LOCATIONS. HEAT ADVISORIES HAVE BEEN
POSTED FOR MUCH OF WESTERN WASHINGTON, BEGINNING LATE MONDAY
MORNING. THIS LEVEL OF HEAT CORRESPONDS TO MODERATE HEAT RISK.
GIVEN THE LOCATION OF THE THERMAL TROUGH AND TEMPERATURE
EXPECTATIONS ALONG THE IMMEDIATE COAST, THIS AREA WAS LEFT OUT
OF THE HEAT ADVISORY.
LONG TERM /TUESDAY THROUGH SATURDAY/
OFFSHORE FLOW CONTINUES INTO TUESDAY MORNING, TRANSITIONING TO A
MORE NORTHERLY FLOW DURING THE REST OF THE DAY. TEMPERATURES
JUMP TO THEIR PEAK FOR THIS HEAT EVENT, WITH LOW 90S EXPECTED
THROUGHOUT MUCH OF THE PUGET SOUND REGION SOUTH OF EVERETT, AND
CLIMB INTO THE MID 90S FOR AREAS SOUTH OF OLYMPIA. WIDESPREAD
MODERATE HEAT RISK CONTINUES, WITH A 20 TO 40% CHANCE OF MAJOR
HEAT RISK OCCURRING IN THE URBAN HEAT ISLANDS.
WARM CONDITIONS PREVAIL INTO WEDNESDAY, THOUGH SEVERAL DEGREES
COOLER THAN TUESDAY IN THE UPPER 80S. MORE APPRECIABLE COOLING
SETS IN FROM THURSDAY INTO THE REST OF THE WEEK AS THE RIDGE
WEAKENS AND POTENTIAL FOR RAIN ENTERS THE FORECAST BY LATE NEXT
WEEK AND WEEKEND. IF TUESDAY WAS MUCH TOO WARM, CONSIDER THAT
THE FORECAST FOR FRIDAY IS BACK INTO THE UPPER 60S WITH CHANCES
FOR RAIN. RAIN WOULD BE WELCOME TO AT LEAST TEMPORARILY QUELL
SOME FIRE DANGER.
21
AVIATION
VFR CIGS HAVE RETURNED FOR MOST TERMINALS OUTSIDE OF THE
IMMEDIATE COAST. SOUTHWESTERLY WINDS GUSTING TO 15-20 KTS WILL
CONTINUE AT LEAST UNTIL 00Z BEFORE EASING. GUIDANCE IS
SUGGESTIVE OF ANOTHER MARINE PUSH TOMORROW MORNING INTRUDING
INTO MUCH OF PUGET SOUND, WHICH HAS BEEN INDICATED IN THE TAFS
FOR THE AFFECTED TERMINALS. A WIND SHIFT TO A NORTHERLY WIND IS
EXPECTED TOMORROW AFTERNOON FOR PUGET SOUND TERMINALS AFTER 18Z.
KSEA...VFR AT THE TERMINAL PRESENTLY WITH SOUTHWESTERLY WINDS 8
TO 10 KTS. OCCASIONAL GUSTS TO 15 KTS WILL CONTINUE THROUGH 00Z.
ANOTHER ROUND OF MARINE STRATUS IS LIKELY TO OCCUR AT THE
TERMINAL AROUND 12Z TOMORROW MORNING. PROBABILITIES FOR CIGS OF
2000 FEET OR LESS BY 12Z ARE AROUND 30 TO 40%, WITH GENERALLY
CLEARING SKIES BY 18Z.
21
MARINE
HIGH PRESSURE WILL BUILD OVER THE REGIONAL WATERS, LENDING
TOWARD PERIODS OF STRONGER NORTHWESTERLY FLOW OVER THE OUTER
COASTAL WATERS AND DIURNAL WESTERLY PUSHES THROUGH THE STRAIT
OF JUAN DE FUCA. LATEST GUIDANCE SUGGESTS THAT THE BEST CHANCES
FOR FOR SMALL CRAFT WINDS WILL BE WEDNESDAY AND THURSDAY. ON
WEDNESDAY THERE IS A 65-85% CHANCE FOR SMALL CRAFT WINDS AND A
SLIGHT CHANCE (25-35%) OF GALES. THE PUSH ON THURSDAY WILL BE
SLIGHTLY WEAKER, BUT THERE IS MODERATE TO HIGH CONFIDENCE
FOR SMALL CRAFT WINDS. SEAS BUILD TO 10-12 FEET OVER THE OUTER
COASTAL WATERS ON WEDNESDAY, BUT THE RIDGE BEGINS TO WEAKEN LATE
IN THE WEEK AND ALLOW FOR A WEATHER SYSTEM TO MOVE THROUGH INTO
THE WEEKEND.
21
FIRE WEATHER
HOT AND DRY WEATHER RETURNS IN EARNEST FOR THE FIRST HALF OF
NEXT WEEK, WITH MINIMUM RELATIVE HUMIDITY VALUES DROPPING INTO
THE 20 PERCENT RANGE OR LESS THROUGH TUESDAY IN THE SOUTH
INTERIOR AND CASCADE VALLEYS. A THERMAL TROUGH DEVELOPING
SLIGHTLY INLAND FROM THE IMMEDIATE COAST ON MONDAY AND TUESDAY
LENDS ITSELF TO A CONDITIONALLY UNSTABLE ATMOSPHERE EARLY IN THE
WEEK. AREA FUELS ARE GETTING MUCH CLOSER TO CRITICAL LEVELS AS
ADDITIONAL WAVES OF HOT AND DRY WEATHER CONTINUES. GRASSES ARE
CURING EXPEDITIOUSLY AND HAVE ALREADY CONTRIBUTED TO A NUMBER OF
ROADSIDE BRUSH FIRES IN RECENT DAYS. PLEASE CONTINUE TO EXERCISE
CAUTION WITH IGNITION SOURCES.
21
SEW WATCHES/WARNINGS/ADVISORIES
WA...HEAT ADVISORY FROM 11 AM MONDAY TO 11 PM PDT TUESDAY FOR
EASTERN STRAIT OF JUAN DE FUCA-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-LOWER CHEHALIS RIVER
VALLEY-LOWLANDS OF LEWIS AND SOUTHERN THURSTON 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-
SOUTHERN HOOD CANAL-WILLAPA AND BLACK HILLS.
HEAT ADVISORY FROM 11 AM MONDAY TO 11 PM PDT WEDNESDAY FOR
CITY OF SEATTLE-DOWNTOWN EVERETT / MARYSVILLE AREA-
EASTERN KITSAP COUNTY-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-LOWLANDS OF PIERCE AND
SOUTHERN KING COUNTIES-SHORELINE / LYNNWOOD / SOUTH
EVERETT AREA.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING 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