610
FXUS66 KSEW 190247
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
747 PM PDT MON MAY 18 2026
SYNOPSIS
THE WEATHER PATTERN REMAINS FAIRLY STEADY WITH HIGH PRESSURE
SITUATED OFFSHORE THROUGH THE WEEK WITH MORNING CLOUDS AND
AFTERNOON SUN. TEMPERATURES WILL RISE A BIT EACH DAY THROUGH
THE END OF THE WEEK BEFORE BEGINNING TO COOL OFF THIS WEEKEND
INTO EARLY NEXT WEEK.
SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/
NORTH/NORTHWESTERLY FLOW PREVAILS ACROSS WESTERN WASHINGTON
THROUGH THE NEXT SEVERAL DAYS, AND WITH SURFACE HIGH PRESSURE
DOMINATING OFFSHORE, THE PATTERN REMAINS PRETTY STEADY. PLENTY
OF SUNSHINE FOR MOST THIS AFTERNOON WITH SOME MOUNTAIN CUMULUS
AND A DISSIPATING FRONT APPROACHING THE COAST. HIGH TEMPERATURES
THIS AFTERNOON ON TRACK TO REACH THE MID TO UPPER 60S. THIS
FRONT WILL, HOWEVER, BE ENOUGH TO BRING A STRONGER ONSHORE PUSH
TONIGHT WHICH WILL BRING MORE WIDESPREAD LOW STRATUS AND SOME
DRIZZLY CONDITIONS ACROSS THE AREA FOR TUESDAY MORNING. LOWS IN
THE LOW TO MID 40S. CLOUDS SHOULD SLOWLY LIFT THROUGH THE DAY
BUT EXPECT MOST OF THE DAY TO BE CLOUDY. HIGHS A LITTLE COOLER,
IN THE LOW TO MID 60S.
THE UPPER LEVEL RIDGE OFFSHORE WILL BEGIN TO AMPLIFY AND TILT
ONSHORE TOWARDS WA AND BC, WHICH WILL ALLOW FOR A WARMING AND
SUNNIER TREND TO BEGIN. WITH CLOUDS EXPECTED TO CLEAR OUT EARLY
WEDNESDAY MORNING, EXPECT TEMPERATURES TO BE WARMER, WITH HIGHS
REACHING THE UPPER 60S TO LOW 70S.
LONG TERM /THURSDAY THROUGH MONDAY/
THE WARMING TREND WILL CONTINUE THROUGH THE END OF THE WEEK,
WITH THE WARMEST TEMPERATURES ACROSS THE REGION EXPECTED
THURSDAY AND FRIDAY AS THE RIDGE TRAVERSES THE AREA AND MORE
ROBUST ONSHORE FLOW BEGINS TO MOVE IN FRIDAY INTO THE WEEKEND.
TEMPERATURES WILL TOP OUT THURSDAY AND FRIDAY INTO THE LOW TO
MID 70S, WITH UPPER 70S TO NEAR 80 POSSIBLE IN THE SOUTHWEST
INTERIOR AND CASCADE VALLEYS.
THE RIDGE DEAMPLIFIES AS IT MOVES EASTWARD AND SHORTWAVES BEGIN
TO MOVE THROUGH IT. THIS SHOULD HELP TO NOT JUST START TO COOL
TEMPERATURES, BUT ALSO BRING IN CLOUDS AND CHANCES FOR SHOWERS.
CURRENTLY THE BEST CHANCES FOR SHOWERS WILL BE SUNDAY NIGHT INTO
MONDAY, BUT THERE IS STILL CONSIDERABLE UNCERTAINTY GIVEN THE
TROUGH'S EVOLUTION/PLACEMENT, OR IF THE RIDGE WILL WIN OUT AND
PUSH THE TROUGH ELSEWHERE.
62
AVIATION
NORTH TO NORTHWESTERLY FLOW ALOFT AS UPPER LEVEL RIDGING REMAINS
OVER THE REGION WITH ONSHORE FLOW IN THE LOW LEVELS CONTINUING.
PUGET SOUND TERMINALS /PWT, SEA, BFI/ GENERALLY SEEING LIGHT AND
VARIABLE WINDS WHILE REMAINING TERMINALS SEEING SPEEDS RANGING 8-12
KTS THIS EVENING. THESE TERMINALS SHOULD SEE SPEEDS DECREASE LATE
THIS EVENING TO THE 4-8 KTS RANGE.
WIDESPREAD VFR CONDITIONS OVER THE MAJORITY OF W WA THIS EVENING
ALTHOUGH STARTING TO SEE MARINE STRATUS TAKE ROOT OVER THE COASTLINE
WHERE MVFR CONDITIONS HAVE SET UP. THE COMBINATION OF THE
AFOREMENTIONED ONSHORE FLOW WITH AN EMBEDDED SHORTWAVE ALOFT WILL
ALLOW FOR THE LOW CLOUDS ALONG THE COAST TO PUSH INLAND. THIS WILL
GIVE RISE TO WIDESPREAD MVFR CONDITIONS OVER THE AREA TUESDAY
MORNING. UPPER LEVEL RIDGING ALOFT WILL ALLOW FOR CIGS TO IMPROVE
BACK INTO VFR CONDITIONS WITH SKIES CLEARING BY LATE TUESDAY
AFTERNOON/EARLY TUESDAY EVENING.
KSEA...VFR CONDITIONS THIS EVENING WITH VARIABLE WINDS GENERALLY AT
OR LESS THAN 5 KTS. SPEEDS WILL INCREASE SLIGHTLY TONIGHT, GENERALLY
REMAINING AROUND TO 5 TO 10 KNOTS AND TURNING S/SW AFTER 06Z
TONIGHT. CIGS TO LOWER OVERNIGHT,REACHING MVFR (50 TO 60% CHANCE) BY
18Z LATE TUESDAY MORNING. CONDITIONS WILL REBOUND TO VFR LATER
TUESDAY AFTERNOON.
18/MAZURKIEWICZ
MARINE
SURFACE HIGH PRESSURE WILL REMAIN OVER THE NORTHEASTERN PACIFIC
THROUGHOUT MUCH OF THE WEEK, BRINGING NORTH TO NORTHWESTERLY
WINDS OVER THE COASTAL WATERS. A SPLITTING WEAK SYSTEM WILL
CROSS OVER THE WATERS TONIGHT INTO TUESDAY, BRINGING AN
INCREASED PERIOD OF ONSHORE FLOW THROUGHOUT THE STRAIT OF JUAN
DE FUCA. A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH TUESDAY
MORNING FOR INCREASED WESTERLIES.
HIGH PRESSURE WILL REBUILD MIDWEEK AND CONTINUE THROUGHOUT THE
REST OF THE WEEK, WHICH WILL PROVIDE CONTINUOUS PERIODS OF
ONSHORE FLOW. CAN EXPECT IN DAILY PUSHES DOWN THE STRAIT OF JUAN
DE FUCA THROUGH THE REST OF THE WEEK, WHICH WOULD LIKELY
GENERATE SMALL CRAFT ADVISORY WINDS. A WEAK SYSTEM LOOKS TO
ENTER THE AREA WATERS THURSDAY INTO FRIDAY.
COASTAL SEAS GENERALLY INCREASING TO 6 TO 8 FEET THROUGH THE
FIRST HALF OF THIS WEEK, WITH SEAS INCREASING MORE TO 8 TO 10
FEET LATE THURSDAY AND INTO FRIDAY.
MAZURKIEWICZ
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 5 AM PDT TUESDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
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