857
FXUS66 KSEW 300251
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
749 PM PDT FRI MAY 29 2026
SYNOPSIS
ONSHORE FLOW WILL CONTINUE BRINGING CONTINUED COOLER TEMPERATURES
THIS WEEKEND. A WARM AND DRY PATTERN MOVES IN MONDAY THROUGH
WEDNESDAY, WITH TEMPERATURES PEAKING ON TUESDAY AS A FEW LOCATIONS
SEE TEMPERATURES APPROACH 90. THE LATTER PART OF NEXT WEEK APPEARS
COOLER, WITH A TROUGH MOVING IN AND THE CHANCE OF A FEW SHOWERS.
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
ONSHORE FLOW CONTINUES BEHIND A COLD FRONT THAT PASSED THROUGH
WESTERN WA LAST NIGHT/THIS MORNING. IT HAS SLOWED AND IS
CURRENTLY EAST OF THE CASCADE CREST. OVERHEAD THERE IS A TROUGH
REMAINING THROUGH SUNDAY AS THE LOW CUTS OFF AND BEGINS TO
PIVOT EAST. THE REMAINING SHOWERS ARE MOVING EAST OF I-5 THIS
AFTERNOON, AND WILL CONTINUE TO TRICKLE EASTWARD THROUGH THE
EVENING. CLOUDS ARE CLEARING WEST OF I-5 ON SATELLITE THIS
AFTERNOON, ALTHOUGH MUCH WILL STILL SEE CLOUD COVERAGE GOING
INTO THE EVENING (ESPECIALLY WITH ANY REMNANTS OF A CONVERGENCE
ZONE THAT ARE ABLE TO PERSIST). WINDS WILL ALSO REMAIN BREEZY
THROUGH TONIGHT FOR AREAS IN THE SOUTHWEST INTERIOR/PACIFIC
COAST/STRAIT OF JUAN DE FUCA COAST AS THE ONSHORE GRADIENT
DECREASES TONIGHT. WESTERN WA WILL REMAIN ONSHORE THROUGH THE
WEEKEND, WITH CLOUD COVERAGE FILLING BACK IN SATURDAY MORNING,
AND SLOWLY SCATTERING IN THE AFTERNOON. SUNDAY IS THE SUNNIER OF
THE TWO WEEKEND DAYS WITH THE TROUGH SPLITTING OFF.
TEMPERATURES THIS WEEKEND REMAIN COOL, WITH HIGHS SATURDAY IN
THE LOW TO MID 60S, AND LOWS IN THE LOW TO MID 40S. SUNDAY WILL
A SEE A SLIGHT INCREASE OF TEMPERATURES, WITH HIGHS IN THE MID
60S TO AROUND 70.
LONG TERM /MONDAY THROUGH FRIDAY/
THE ENSEMBLES REMAIN IN AGREEMENT THAT A RIDGE WILL BUILD IN
BEHIND THE DEPARTING TROUGH MONDAY, AND REMAIN OVERHEAD THROUGH
EARLY WEDNESDAY. THE RIDGE WILL AMPLIFY AS IT GETS SQUISHED IN
BETWEEN THE LOW TO THE EAST, AND THE TROUGH OVER THE GULF OF
ALASKA. THE FLOW WILL TURN MORE OFFSHORE WITH WINDS BECOMING
LIGHT NORTH/NORTHEAST AT 5 TO 15 MPH. A THERMAL TROUGH IS ALSO
EXPECTED TO BUILD ALONG THE COAST UNDER THE RIDGE. THE
COMBINATION OF THE RIDGE, OFFSHORE PATTERN, AND THERMAL TROUGH
WILL LEAD TO A WARM FEW DAYS NEXT WEEK, WITH TUESDAY BEING THE
WARMEST OF THE FORECAST PERIOD. THERE REMAINS A MEDIUM CHANCE
THAT A FEW AREAS IN THE SOUTH SOUND/INTERIOR WILL SEE THEIR
FIRST 90 OF THE YEAR WITH THIS PATTERN. A FEW METRO SEATTLE
AREAS (PARTICULARLY THOSE AWAY FROM THE WATER), AND AREAS SOUTH
OF THE CITY WILL SEE HEATRISK INCREASE TO MODERATE FOR THE DAY
TUESDAY (IT WILL BE MINOR BEFORE AND AFTER). IT'S ALSO IMPORTANT
TO NOTE THAT A LOT OF AREA LAKES AND RIVERS ARE STILL VERY
COLD, WITH TEMPERATURES IN THE 50S TO LOW 60S (FOR THOSE
RECREATING NEAR THE WATERS). LASTLY, THE DRY AND OFFSHORE
PATTERN WILL RESULT IN DRY RELATIVE HUMIDITY (RH) VALUES. SEE
FIRE DISCUSSION BELOW FOR FURTHER DETAILS. THE REMAINDER OF THE
WEEK RETURNS TO ONSHORE AND COOL AS THE LOW IN THE GULF OF
ALASKA DRIFTS SOUTH. THERE WILL ALSO BE A COUPLE CHANCES OF
SHOWERS LATER IN THE WEEK.
HPR
AVIATION
SOUTHWEST FLOW ALOFT WILL CONTINUE TONIGHT AS A BROAD UPPER
LEVEL TROUGH REMAINS SITUATED OVER THE GULF OF ALASKA. ONSHORE
FLOW CONTINUES IN THE LOW LEVELS. SOME LIGHT CONVERGENCE SHOWERS
PRESENT OVER SOUTHERN SNOHOMISH/NORTHERN KING COUNTIES AS PER LATEST
RADAR AND THESE WILL LIKELY PERSIST INTO TONIGHT BEFORE TAPERING OFF
OVERNIGHT. CIGS CONTINUE TO IMPROVE WITH WIDESPREAD VFR CONDITIONS
IN PLACE...ALTHOUGH ISOLATED SPOTS OF MVFR ARE PRESENT. THAT SAID,
THIS IMPROVEMENT WILL EITHER HALT OR REGRESS A BIT OVERNIGHT WITH
LOW-LEVEL MOISTURE STILL PRESENT OVER W WA. LOW-END VFR EXPECTED
OVERNIGHT, WITH OCCASIONAL DIPS INTO HIGH-END MVFR POSSIBLE.
TERMINALS MORE PRONE TO LOWER CIGS, ESPECIALLY PWT, WILL BE MORE
LIKELY FOR LONGER PERIODS OF HIGH-END MVFR CONDITIONS BY EARLY
SATURDAY MORNING. ALL TERMINALS EXPECTED TO REBOUND INTO SOLIDLY VFR
CONDITIONS BY NOON SATURDAY.
KSEA...VFR CEILINGS THIS EVENING WITH PSCZ SHOWERS WELL NORTH OF THE
TERMINAL. CONDITIONS DO NOT LOOK FAVORABLE FOR THESE TO MAKE THEIR
WAY FAR ENOUGH SOUTH TO IMPACT LATEST TAF. CURRENT /AS OF 03Z/ CIGS
OF AT OR AROUND 5000 FT WILL SEE SOME REGRESSION OVERNIGHT,
LEVELING OFF AT AROUND 3000 FT BY 12Z SATURDAY MORNING. OCCASIONAL
DIPS DOWN INTO 2500-3000 FT RANGE ARE POSSIBLE /20-25 PCT CHANCE/,
BUT NOT EXPECTED TO BE LONG-LIVED ENOUGH FOR TAF INCLUSION. CIGS
IMPROVING AGAIN BY NOON SATURDAY WITH VFR CONDITIONS EXPECTED FOR
THE REMAINDER OF THE TAF PERIOD. SURFACE WINDS NE AT 6-10 KT THIS
EVENING SHIFTING SE BY 12Z. W TO NW WINDS RETURNING BY NOON SATURDAY
WITH RANGE OF SPEEDS REMAINING UNALTERED.
14/18
MARINE
STRONG ONSHORE FLOW WILL CONTINUE TONIGHT WITH LOW PRESSURE OVER
THE INTERIOR OF BRITISH COLUMBIA AND HIGH PRESSURE BUILDING OFFSHORE.
GALES WILL CONTINUE ACROSS THE CENTRAL AND EASTERN STRAIT OF JUAN
DE FUCA THROUGH TONIGHT, WITH WINDS EXPECTED TO EASE LATE TONIGHT
INTO EARLY SATURDAY. WINDS PERSISTING AT 15-25 KT ACROSS THE COASTAL
WATERS WILL ALSO EASE BY SATURDAY AS HIGH PRESSURE STARTS TO BUILD
BACK INTO THE AREA WATERS. SEAS HOVERING BETWEEN 10-12 FT ACROSS
THE COASTAL WATERS WILL SUBSIDE TOWARDS 7-9 FT TONIGHT. SEAS OF
8-10 FT ALONG THE CENTRAL STRAIT WILL ALSO SUBSIDE BACK TO 4-6
FT BY TONIGHT. ANOTHER PUSH OF WESTERLY WINDS IS LIKELY ALONG
THE CENTRAL AND EASTERN STRAIT SATURDAY AFTERNOON AND EVENING,
WITH LATEST HREF PROBABILITIES INDICATING ROUGHLY A 70-100
PERCENT CHANCE OF WIND GUSTS EXCEEDING 21 KT.
HIGH PRESSURE OVER THE WATERS WILL ALLOW FOR ONSHORE FLOW TO
CONTINUE TO EASE OVER THE WEEKEND. SEAS ACROSS THE COASTAL
WATERS MAY BECOME CONFUSED AND STEEP AT TIMES BETWEEN 6-8 FEET
AT 6-8 SECONDS UNDER PERSISTENT NORTHWESTERLY WINDS. WEAK
OFFSHORE FLOW WILL THEN DEVELOP EARLY NEXT WEEK AS A THERMAL
TROUGH DEVELOPS NEAR THE COAST. OFFSHORE FLOW WILL BE SHORT-
LIVED, HOWEVER, AS ADDITIONAL SYSTEMS LOOK TO MOVE INTO THE AREA
WATERS BY MIDWEEK AND BRING THE RETURN OF ONSHORE FLOW.
14
FIRE WEATHER
AN UPPER LEVEL RIDGE WILL SETUP A DRIER, OFFSHORE PATTERN ON
MONDAY AND TUESDAY, WITH MAXIMUM TEMPERATURES REACHING INTO THE
80S, AND UP TO 90 IN A FEW SOUTH SOUND/SOUTH INTERIOR LOCATIONS.
WINDS WILL GENERALLY REMAIN LIGHT OUT OF THE NORTHEAST AROUND
5-10 MPH, BUT A FEW LOCATIONS IN THE CASCADES MAY SEE GUSTS UP
TO 20 MPH FROM THE EAST. THE MAIN CONCERN WILL BE A COUPLE DAYS
OF DRIER RELATIVE HUMIDITY (RH) VALUES, WITH VALUES DURING THE
DAY DIPPING TO AS LOW AS 25 TO 30 PERCENT IN THE MENTIONED
AREAS. WHILE FUELS ARE NOT READY YET FOR RED FLAG CONDITIONS, A
FEW DRY AND SHRUBBY GRASSY AREAS, OR DRY PILES OF DEAD FUELS
MAY BE SUSCEPTIBLE TO FIRE STARTS, AND/OR RAPID FIRE SPREAD.
HPR
HYDROLOGY
THE DAILY HYDROLOGY DISCUSSION HAS ENDED UNTIL THE START OF THE
NEXT RAINY SEASON; IT WILL ONLY BE UPDATED DURING THIS TIME AS
NEEDED.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR
ADMIRALTY INLET-GRAYS HARBOR BAR-NORTHERN INLAND WATERS
INCLUDING THE SAN JUAN ISLANDS.
SMALL CRAFT ADVISORY UNTIL 3 AM PDT SATURDAY FOR WEST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA.
GALE WARNING UNTIL 11 PM PDT THIS EVENING FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 8 AM PDT
SATURDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT SATURDAY FOR COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-
COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10
NM-COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10
TO 60 NM-COASTAL WATERS FROM JAMES ISLAND TO POINT
GRENVILLE OUT 10 NM-COASTAL WATERS FROM POINT GRENVILLE
TO CAPE SHOALWATER 10 TO 60 NM-COASTAL WATERS FROM POINT
GRENVILLE TO CAPE SHOALWATER OUT 10 NM.
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