922
FXUS66 KSEW 062057
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
157 PM PDT SUN SEP 6 2026
SYNOPSIS
SOME SHOWERS LINGER THROUGH TONIGHT, ESPECIALLY IN THE CASCADES,
AND AN UPPER LOW REMAINS SOUTH OF THE REGION. THIS SYSTEM MOVES
AWAY INTO MONDAY, WITH THE START OF A WARMER AND DRIER TREND
THAT CONTINUES INTO MIDWEEK. ONSHORE FLOW INCREASES THROUGH
MONDAY, WITH A PUSH OF MORNING LOW CLOUDS. LIGHT OFFSHORE FLOW
HELPS TEMPERATURES TO PEAK AROUND MIDWEEK, FOLLOWED BY THE NEXT
DISTURBANCE BRINGING A RETURN OF COOLER TEMPERATURES AND RAIN
CHANCES LATER IN THE WEEK.
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/
QUITE THE DIFFERENCE IN TERMS OF RAIN SHOWERS, THUNDERSTORMS,
AND EVEN CLOUD COVER ACROSS WESTERN WASHINGTON AS COMPARED TO
THIS TIME YESTERDAY. WITH THE UPPER LOW CENTERED A BIT SOUTH AND
EAST TODAY, THE MOST SIGNIFICANT RAIN CHANCES REMAIN ALONG THE
CASCADES SOUTH OF AROUND I-90. WITH PLENTY OF SUNSHINE ACROSS
THE INTERIOR, TEMPERATURES WILL TOP OUT AROUND THE LOWER 70S FOR
MOST AND IN THE 60S CLOSER TO THE COAST. THE UPPER LOW FURTHER
DEPARTS THE REGION INTO MONDAY, WITH STRONGER ONSHORE LOW-LEVEL
FLOW BRINGING A BLANKET OF MARINE STRATUS TO START THE DAY. WEAK
LINGERING LIFT COULD BRING SOME LIGHT RAIN, BUT ON THE WHOLE
IT'LL BE A DRY DAY AND EXPECT TO SEE AREAS OF SUN DEVELOP INTO
THE AFTERNOON HOURS. THIS BEGINS A DRYING AND WARMING TREND THAT
WILL CONTINUE INTO MIDWEEK, WITH TEMPERATURES A BIT WARMER
TUESDAY IN BETWEEN WEATHER SYSTEMS. CULLEN
LONG TERM /WEDNESDAY THROUGH SUNDAY/
ENSEMBLE GUIDANCE REMAINS IN GOOD AGREEMENT THAT A STRONG HIGH
WILL CONTINUE BUILDING ACROSS THE SOUTHWESTERN U.S. TOWARD
MIDWEEK, WITH THE PACIFIC NORTHWEST REMAINING IN A WEAK
NORTHWESTERLY FLOW PATTERN IN BETWEEN THE STRONGER WEATHER
SYSTEMS. THIS WILL BRING HIGH TEMPERATURES INTO THE LOWER 80S IN
MANY SPOTS WEDNESDAY AND THURSDAY. THE LOW-LEVEL FLOW MAY TURN
WEAKLY OFFSHORE AROUND MIDWEEK, TO BRING LOWER HUMIDITIES ACROSS
THE REGION. EVEN WITH THIS WARM UP, THERE'S NOT MUCH SIGN OF
HEATRISK MOVING ABOVE THE MINOR (YELLOW) CATEGORY; PROBABILISTIC
GUIDANCE SUGGESTS LESS THAN A 10% CHANCE FOR NEARLY ALL OF THE
AREA.
THERE'S A BIT LARGER SPREAD IN ENSEMBLE GUIDANCE LATER IN THE
WEEK, BUT THE RETURN OF A WEAK TROUGH STILL APPEARS THE MOST
LIKELY SCENARIO AROUND FRIDAY, USHERING COOLER TEMPERATURES AND
RAIN CHANCES BACK INTO THE REGION. THAT SAID, THE ENSEMBLES ARE
NOT PARTICULARLY WELL CLUSTERED AND SIGNIFICANT RANGES IN THE
STRENGTH AND TIMING OF THIS SHIFT REMAIN. AS SUCH, THE FORECAST
CARRIES SOME LOW RAIN CHANCES THROUGH THE LATE WEEK AND INTO
NEXT WEEKEND, AND EXPECT THE TEMPERATURES AND RAIN CHANCES TO
FLUCTUATE A BIT AS THIS EVOLUTION IDEALLY COMES INTO CLEARER
FOCUS IN THE DAYS AHEAD. CULLEN
AVIATION
NORTHWESTERLY FLOW ALOFT THIS AFTERNOON WITH LOW
LEVEL FLOW TURNING ONSHORE THIS EVENING. VFR CONDITIONS AT ALL
AREA TERMINALS THIS AFTERNOON AND WILL CONTINUE THROUGHOUT THE
EVENING. MARINE STRATUS WILL START TO SPREAD OVER THE AREA
STARTING ALONG THE COAST AROUND 04Z-07Z, LOWERING CONDITIONS
DOWN TO MVFR/IFR. STRATUS WILL START TO IMPACT INTERIOR
TERMINALS BY EARLY MONDAY MORNING, AROUND 09Z-12Z. EXPECTING A
MIX OF MVFR/IFR CONDITIONS AT MOST TERMINALS THROUGHOUT MONDAY
MORNING, BEFORE MARINE STRATUS DISSIPATES, WITH A RETURN TO VFR
BY THE AFTERNOON (19Z-21Z). NORTHERLY WINDS 8 TO 12 KNOTS THIS
AFTERNOON WITH BRIEF GUSTS UP TO 15 TO 20 KTS. WINDS WILL TURN
S/SW TONIGHT AND GENERALLY BE ARND 4 TO 8 KNOTS, REMAINING INTO
MONDAY.
KSEA...VFR CONDITIONS THIS AFTERNOON WITH NORTHERLY WINDS 8 TO
12 KNOTS, WITH BRIEF GUSTS UP TO 15 KTS. VFR CONTINUING THROUGH
THE EVENING BEFORE MARINE STRATUS MOVES OVER THE AREA OVERNIGHT.
LATEST GUIDANCE SHOWS A 30-35% CHANCE OF MVFR CONDITIONS
STARTING AROUND 10Z-12Z, LASTING THROUGH 17Z-19Z. STRATUS WILL
ERODE BY THE AFTERNOON, WITH VFR CONDITIONS RETURNING BY 20Z.
WINDS WILL TURN SOUTHERLY OVERNIGHT AND INTO MONDAY, STAYING
ARND 4 TO 8 KNOTS.
MAZURKIEWICZ
MARINE
A LOW PRESSURE SYSTEM WILL MOVE INLAND TONIGHT. BEHIND THAT, BROAD
HIGH PRESSURE WILL SLOWLY BUILD IN MONDAY AND THROUGH THE WEEK.
NORTHWESTERLY WINDS WILL BEGIN TO PICK UP OVER THE COASTAL WATERS ON
TUESDAY, AND MAY INCREASE TO NEAR 20 KT THROUGH THE OUTER COASTAL
WATERS WEDNESDAY NIGHT INTO THURSDAY. A WEAK FRONTAL SYSTEM LOOKS TO
MOVE THROUGH THE REGION LATE IN THE WEEK.
AN ONSHORE PUSH TONIGHT, FOLLOWING THE DEPARTING LOW PRESSURE
SYSTEM, WILL INCREASE WINDS THROUGH THE STRAIT OF JUAN DE FUCA.
GUIDANCE REMAINS IN GOOD AGREEMENT FOR SMALL CRAFT ADVISORY GUSTS
THROUGH PORTIONS OF THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA,
AND WILL MAINTAIN THE ADVISORY. SOME MODELS EASE THE WINDS MORE
GRADUALLY AND GUSTS COULD HOLD ON A BIT LATER INTO MONDAY MORNING.
SEAS REMAIN AROUND 3-6 FT THROUGH WEDNESDAY, INCREASING TO AROUND 7-
10 FT LATE IN THE WEEK AND MAY BECOME STEEP AS WAVES ARE DRIVEN BY
THE INCREASING NORTHWEST WINDS.
62
FIRE WEATHER
NO SIGNIFICANT FIRE WEATHER CONCERNS DEVELOP THROUGH THE START
OF THIS WEEK. WITH WARMER AND DRIER CONDITIONS, EXPECT TO SEE
CONDITIONS TO TREND BACK TO SEASONAL LEVELS OF CONCERN AFTER THE
PREVIOUSLY COOL AND WET PATTERN. THERE'S SOME INDICATION THAT
LIGHT OFFSHORE FLOW DEVELOPS MIDWEEK AND MAY BRING MINIMUM
HUMIDITY VALUES CLOSE TO CRITICAL THRESHOLDS AND AROUND
WEDNESDAY, BUT THE OFFSHORE WINDS DO NOT APPEAR SIGNIFICANTLY
STRONG OR LONG-LIVED TO BRING HIGHER LEVELS OF CONCERN AT THIS
TIME.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 5 AM PDT
MONDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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