706
FXUS66 KSEW 211610
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
910 AM PDT THU MAY 21 2026
UPDATE
SATELLITE IMAGERY SHOWS A LITTLE FOG LEFT ALONG THE CHEHALIS
RIVER GOING INTO GRAYS HARBOR OTHERWISE MOSTLY CLEAR SKIES OVER
WESTERN WASHINGTON THIS MORNING. TEMPERATURES WITH THE SUNNY
SKIES ARE ALREADY IN THE 50S WITH A FEW LOCATIONS NEAR 60 AT 9
AM/16Z. FORECAST ON TRACK WITH A PAIR OF SUNNY AND WARM DAYS IN
STORE TODAY AND FRIDAY. HIGHS IN THE MID TO UPPER 60S ALONG THE
COAST AND UPPER 60S TO UPPER 70S INLAND. TRANSITION TO ONSHORE
FLOW OVER THE WEEKEND WILL COOL THINGS DOWN WITH THE NEXT SYSTEM
DUE INTO WESTERN WASHINGTON MEMORIAL DAY. NO UPDATE THIS
MORNING. PREVIOUS DISCUSSION FOLLOWS WITH UPDATED AVIATION AND
MARINE SECTIONS. FELTON
SHORT TERM /TODAY THROUGH SATURDAY/
BROAD UPPER-LEVEL TROUGHING RESIDES OVER WESTERN CONUS WHILE AN
UPPER-RIDGE IS NOSING INTO BC AND W WA. MOSTLY CLEAR SKIES
ACROSS THE CWA THIS MORNING ASIDE FROM MARINE STRATUS ALONG
SECTIONS OF THE COAST AND SOUTHWEST INTERIOR. THIS ACTIVITY
ALONG WITH PATCHY RIVER VALLEY FOG WILL CONTINUE BEFORE BURNING
OFF AS THE MORNING PROGRESS. MOSTLY SUNNY SKIES TODAY AS LARGE-
SCALE SUBSIDENCE ENSUES. HIGH TEMPERATURES ARE FORECAST TO BE
ABOVE AVERAGE - IN THE 70S ACROSS THE INTERIOR WITH NEAR 80 F
THROUGHOUT THE CHEHALIS RIVER VALLEY. COASTAL AREAS TO REMAIN IN
THE 60S. OVERNIGHT LOWS WILL FALL INTO THE 40S AND LOWER 50S.
UPPER-RIDGING WILL FLATTEN ON FRIDAY AS ZONAL FLOW SWITCHES INTO
GEAR ON SATURDAY. TEMPERATURES WILL WARM INTO INTO THE 70S AGAIN
FOR BOTH FRIDAY AND SATURDAY BUT LOW-LEVEL ONSHORE FLOW WILL
ALSO BEGIN TO STRENGTHEN. COASTAL AREAS WILL SEE AFTERNOON HIGHS
IN THE 60S WITH LOWS IN THE 40S AND LOWER 50S AREA-WIDE.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
DETERMINISTIC GUIDANCE CONTINUE TO HOLD OFF RAIN OVER THE
INTERIOR UNTIL LATE MONDAY. HOWEVER, ENSEMBLES ARE MORE
PROGRESSIVE WITH AN EARLIER ARRIVAL OF THE FRONT LATE SUNDAY.
THIS IS IN THE CURRENT FORECAST WITH A CHANCE OF RAIN SUNDAY
NIGHT AND RAIN SPREADING OVER THE AREA ON MEMORIAL DAY. UPPER-
TROUGHING ON MONDAY/TUESDAY BEFORE ANOTHER RIDGE NOSES INTO THE
REGION TOWARDS MIDWEEK.
41
AVIATION
HIGH PRESSURE WILL BRING DRY AND STABLE CONDITIONS TO WESTERN
WA TODAY. THE FLOW ALOFT IS NORTHERLY. FOG/STRATUS IS DISSIPATING
AT HQM THIS MORNING SHOULD LIFT BEFORE 18Z THIS MORNING. VFR
CONDITIONS SHOULD PREVAIL FOR MOST THROUGH THE REST OF THE TAF
PERIOD. ANOTHER ROUND OF STRATUS ALONG THE COAST WILL LIKELY
BRING IFR CONDITIONS TO THE COAST AND MAY PUSH A BIT FARTHER
INLAND, BUT IT SHOULD STAY WEST OF THE PUGET SOUND INTERIOR
TERMINALS. HIGHER LIKELIHOOD OF OCCURRENCE AT TERMINALS SUCH AS
OLM, PWT, AND CLM (30- 50% PROBABILITIES). WINDS REMAIN N/NW
5-10 KT TODAY, BECOMING LIGHT NE OVERNIGHT.
KSEA...VFR CONDITIONS PREVAIL THROUGH THE TAF PERIOD. WINDS N/NW 5-
10 KT TODAY, BECOMING LIGHT (<5 KT) NE OVERNIGHT.
62
MARINE
ONSHORE FLOW WILL PREVAIL THIS WEEK WITH HIGH PRESSURE OFFSHORE
AND LOWER PRESSURE INLAND. EXPECT DIURNAL WESTERLY PUSHES
THROUGH THE STRAIT OF JUAN DE FUCA WITH HIGHEST WIND AND WAVES
DURING THE LATE AFTERNOON AND EVENING HOURS. STRONGER ONSHORE
FLOW SATURDAY EVENING DOES HAVE THE POTENTIAL TO PRODUCE GALES
THROUGH THE STRAIT. A LOW PRESSURE SYSTEM MONDAY WILL LIKELY
PRODUCE WIDESPREAD SMALL CRAFT CONDITIONS THROUGH THE AREA
WATERS.
33/62
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 FROM 5 PM THIS AFTERNOON TO 5 AM PDT
FRIDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 11 AM PDT
FRIDAY 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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