278
FXUS66 KSEW 060930
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 AM PDT SUN SEP 6 2026
SYNOPSIS
LOW PRESSURE WILL BRING MOUNTAIN SHOWERS TODAY WITH
DRY AND MILD WEATHER MOVING TOWARD MIDWEEK. THE NEXT
DISTURBANCE WILL BRING A RETURN OF COOLER CONDITIONS AND SHOWER
CHANCES LATE IN THE WEEK.
SHORT TERM /TODAY THROUGH TUESDAY/
AN UPPER LEVEL LOW
CONTINUES TO SPIN OVER THE PAC NW TODAY. UNLIKE THE PAST FEW
DAYS, THOUGH, SHOWERS WILL MAINLY STICK OVER THE MOUNTAINS WITH
HIGHEST POPS OVER MOUNT RAINIER. THUNDERSTORM PROBABILITIES HAVE
DECREASED WITH THE GREATEST THREAT OVER EASTERN OR/WA AND ID.
WITH SUNBREAKS WE SHOULD SEE AFTERNOON TEMPERATURES NEAR AVERAGE
WITH HIGHS IN THE LOWER TO MID 70S. THE COAST WILL BE COOLER
AND IN THE 60S.
THE UPPER LOW DEPARTS TO THE N/NE ON MONDAY WITH WEAK TROUGHING
OVER WESTERN WA. LOW LEVEL ONSHORE FLOW WILL BE STRONGER FOR
MORNING CLOUDS AND POSSIBLE DRIZZLE. EXPECT LATE AFTERNOON
SUNBREAKS WITH TEMPS MOSTLY IN THE 60S.
TUESDAY WILL BE DRY AND MILD WITH WESTERN WA IN BETWEEN WEATHER
SYSTEMS. MORNING LOWS WILL BE A LITTLE COOLER AND IN THE 40S
AROUND THE SOUTH SOUND. EXPECT AFTERNOON HIGHS CLOSE TO AVERAGE.
33
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
THE AIR MASS WILL
BE A LITTLE WARMER WEDNESDAY AND THURSDAY WITH STRONG HIGH
PRESSURE FORMING OVER THE FOUR CORNERS. IN WESTERN WA, EXPECT
HIGHS IN THE 70S TO LOWER 80S. TOWARD THE END OF THE WEEK, THE
RIDGE FLATTENS AND LOW PRESSURE OVER WESTERN CANADA WILL SAG
SOUTH AND INTO WA. THIS WILL BRING COOLER CONDITIONS WITH A
CHANCE OF SHOWERS FRIDAY AND INTO THE WEEKEND. 33
AVIATION
VFR CONDITIONS EARLY THIS MORNING WITH LIGHT
SURFACE WINDS. VFR EXPECTED TO PREVAIL TODAY, WITH THE EXCEPTION
OF HQM. BRIEF LOW CLOUDS MAY DEVELOP THIS MORNING WITH MVFR/IFR
CONDITIONS. BRIEF VIS REDUCTIONS ALSO POSSIBLE IN THE SOUTHERN
INTERIOR THIS MORNING. SURFACE FLOW WILL TRANSITION TO ONSHORE
STARTING THIS AFTERNOON, RESULTING IN THE MARINE LAYER BRINGING
WIDESPREAD MVFR CIGS THIS EVENING ALONG THE COAST AND BY MONDAY
MORNING FOR THE INTERIOR TERMINALS.
KSEA...VFR TODAY. NORTHEASTERLY WINDS THIS MORNING AROUND 5 KT OR
LESS WILL TRANSITION NW THIS AFTERNOON AROUND 7-10 KT. SOUTHWESTERLY
WINDS THIS EVENING. MVFR CEILINGS LIKELY MONDAY MORNING WITH MARINE
STRATUS.
29
MARINE
THE LOW PRESSURE SYSTEM THAT HAS BEEN HOVERING OVER
THE COASTAL WATERS THE PAST DAYS WILL FINALLY PUSH INLAND TODAY.
BEHIND THE LOW PRESSURE SYSTEM, HIGH PRESSURE WILL BUILD OVER
THE WATERS. A STRONG AREA OF BROAD HIGH PRESSURE OVER THE NE
PACIFIC WILL CONTINUE TO STRENGTHEN AND EXPAND INTO AREA WATERS
MONDAY THROUGH THE MIDDLE OF THE WEEK. HIGH PRESSURE WILL WEAKEN
ON THURSDAY AS THE NEXT FRONTAL SYSTEM ARRIVES. ONSHORE FLOW
WILL INCREASE THIS AFTERNOON, BRINGING A PUSH OF WESTERLIES
THROUGH THE STRAIT OF JUAN DE FUCA. GUIDANCE IS IN GOOD
AGREEMENT (70%+) FOR SMALL CRAFT WINDS STARTING AFTERNOON
THROUGH MONDAY MORNING. THEREFORE, A SMALL CRAFT ADVISORY HAS
ISSUED FOR THE CENTRAL AND EAST PORTIONS OF THE STRAIT OF JUAN
DE FUCA. INCREASING NORTHWESTERLY WINDS OVER THE COASTAL WATERS
TUESDAY THROUGH THURSDAY, BUT AT THIS TIME LOOK TO REMAIN BELOW
SMALL CRAFT THRESHOLDS.
SEAS GENERALLY BETWEEN 4-7 FT THROUGH THE MIDDLE OF THE WEEK AND
WILL BUILD TO 7-10 FT LATE IN THE WEEK.
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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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