915
FXUS66 KSEW 070335
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
835 PM PDT SUN SEP 6 2026
UPDATE
SHOWERS FORMED OVER THE OLYMPICS BEFORE SUNSET. THESE SHOWERS
ARE NOW MOVING OFF THE OLYMPICS TO THE SOUTHEAST INTO MASON AND
THURSTON COUNTY. HAVE DONE A QUICK UPDATE TO ADD SHOWERS TO THE
FORECAST TO THESE AREAS THIS EVENING. THE SHOWERS WILL DISSIPATE
BY MIDNIGHT. REMAINDER OF THE FORECAST UNCHANGED. UPPER LEVEL
LOW MOVING OUT OF THE AREA TONIGHT WITH LOW LEVEL ONSHORE FLOW
INCREASING BRINGING THE MARINE LAYER INTO THE INTERIOR MONDAY
MORNING. UPDATED AVIATION AND MARINE SECTIONS BELOW. FELTON
SYNOPSIS
SOME SHOWERS LINGER THROUGH TONIGHT AS 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/
THE UPPER LOW 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 WITH LOW LEVEL FLOW TURNING
ONSHORE THIS EVENING. VFR CONDITIONS AT ALL AREA TERMINALS THIS
AFTERNOON AND WILL CONTINUE THROUGHOUT THE EVENING, WITH THE
EXCEPTION OF KHQM WHERE MVFR CIGS HAVE ALREADY ARRIVED. MARINE
STRATUS WILL CONTINUE SPREADING OVER THE AREA THROUGH 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).
KSEA...VFR CONDITIONS WITH INCREASINGLY WESTERLY WINDS 5 TO 7 KNOTS.
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
AROUND 4 TO 8 KNOTS.
MAZURKIEWICZ/21
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 UNTIL 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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