315
FXUS66 KSEW 052316
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
416 PM PDT SAT SEP 5 2026
SYNOPSIS
LOW PRESSURE WILL BRING SHOWERS AND THUNDERSTORMS TO
WESTERN WASHINGTON THIS WEEKEND, WITH WARMER AND DRIER
CONDITIONS RETURNING EARLY NEXT WEEK. OFFSHORE FLOW WILL LEAD
TO SLIGHTLY WARMER WEATHER MIDWEEK. THE NEXT DISTURBANCE WILL
BRING A RETURN OF COOLER CONDITIONS AND SHOWER CHANCES LATER
NEXT WEEK.
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/
AN UPPER LOW REMAINING OVER THE REGION WILL CONTINUE TO GENERATE
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. THE PRIMARY THREATS
WILL CONTINUE TO BE BRIEF DOWNPOURS AND LIGHTNING, THOUGH SMALL
HAIL AND GUSTY OUTFLOW WINDS ARE ALSO POSSIBLE WITH THE
STRONGEST STORMS THAT DEVELOP. EXPECT STORMS AND SHOWERS TO
REMAIN ACTIVE THROUGH EARLY THIS EVENING, WITH A GRADUAL
WEAKENING AS THE SUN GOES DOWN WITH THE LOSS OF DAYTIME HEATING.
THE UPPER LOW CONTINUES TO MOVE OVER THE REGION BUT BEGINS TO
FINALLY SLIDE AWAY ON SUNDAY. WITH GENERALLY LIGHT FLOW ALOFT,
THIS SHOULD KEEP SHOWERS MORE CONFINED TO THE MOUNTAINS. THE
CHANCES WILL REMAIN HIGHEST OVER THE CASCADES SOUTH OF I-90, AND
THERE COULD BE LOCALLY HIGHER RAINFALL AMOUNTS WITH THE SLOWER
MOVING STORMS.
EXPECT SHOWERS TO BE MOSTLY LIMITED AND GENERALLY DRY CONDITIONS
MONDAY FOR MUCH OF THE AREA WITH THE UPPER LOW FINALLY PUSHING
WELL INLAND AND AWAY FROM THE REGION. ONSHORE FLOW INCREASES AT
THE LOW-LEVEL, BRINGING A STEADY PUSH OF MARINE CLOUDS FOR THE
MORNING BEFORE SOME CLEARING IN THE LATE AFTERNOON.
LONG TERM /TUESDAY THROUGH SATURDAY/
EXPECT A SHIFT TO WARMER AND DRIER CONDITIONS TOWARD MIDWEEK
WITH THE REGION REMAINING IN BETWEEN ANY SIGNIFICANT WEATHER
DISTURBANCES. LIGHT OFFSHORE FLOW IN THE LOWER LEVELS WILL
BRING A SLIGHT WARMING BACK INTO THE MID TO UPPER 70S FOR MID-
WEEK, CORRESPONDING TO MINOR (YELLOW) HEATRISK VALUES. ANOTHER
DISTURBANCE ARRIVES LATER IN THE WITH A RETURN OF COOLER
TEMPERATURES AND RAIN CHANCES.
AVIATION
VARIABLE FLOW WILL CONTINUE AS AN UPPER LEVEL LOW
CONTINUES TO WOBBLE OVER WESTERN WASHINGTON THIS AFTERNOON. VFR
CONDITIONS AT ALL TERMINALS THIS AFTERNOON WITH GENERALLY LIGHT
AND VARIABLE WINDS ACROSS TERMINALS. SHOWER AND THUNDERSTORM
CHANCES WILL EXIST ONCE AGAIN, BUT SHOULD BE CONFINED TO THE
CASCADES, WITH LARGELY NO IMPACTS TO ANY TERMINALS THIS
EVENING. WINDS WILL START TAKING A MORE N/NE DIRECTION THIS
EVENING, BUT WILL CONTINUE TO REMAIN LIGHT. VFR CONDITIONS WILL
CONTINUE TO REMAIN OVERNIGHT, THE EXCEPTION BEING HQM, WHERE
BRIEF LOW CLOUDS MAY DEVELOP SUNDAY MORNING (09Z-14Z) WITH
MVFR/IFR CONDITIONS. ELSEWHERE, VFR CONTINUING INTO SUNDAY.
KSEA...VFR AT THE TERMINAL THIS AFTERNOON CONTINUING THROUGH THE
TAF PERIOD. LIGHT AND VARIABLE WINDS TAKING A MORE N/NE
DIRECTION AFTER 00Z, REMAINING LIGHT. LIGHT RAIN SHOWERS MAY
IMPACT THE TERMINAL THIS EVENING, BUT LATEST GUIDANCE SHOWS MOST
OF THESE SHOWERS WILL BE RATHER WEAK AND WILL KEEP CONDITIONS
AT VFR. VFR WILL CONTINUE INTO SUNDAY WITH NE WINDS BY THE
AFTERNOON 3 TO 6 KNOTS.
MAZURKIEWICZ
MARINE
BROAD LOW PRESSURE REMAINS OVER THE AREA WITH SHOWERS AND A FEW
THUNDERSTORMS POSSIBLE OVER THE COASTAL WATERS THIS AFTERNOON.
OTHERWISE, MARINE SEAS AND WINDS ARE BENIGN AND REMAINING UNDER
ANY ADVISORY CRITERIA. NORTHERLY WINDS WILL CONTINUE OVER MOST
OF THE AREA WATERS THROUGH THE REST OF THIS WEEKEND AND INTO
EARLY NEXT WEEK. ONSHORE FLOW LOOKS TO INCREASE LATE SUNDAY INTO
MONDAY, WHICH COULD BRING A PUSH OF WESTERLIES DOWN THE STRAIT
OF JUAN DE FUCA FOR POTENTIAL HEADLINES.
COASTAL SEAS REMAINING GENERALLY AROUND 3 TO 6 FEET THROUGH THE
REST OF THE WEEKEND, WITH SOME LOCATIONS IN THE OUTER COASTAL
WATERS INCREASING TO 6 TO 7 FEET ON MONDAY. SEAS WILL LEVEL BACK
DOWN TO 3 TO 5 FEET THROUGH MIDWEEK.
MAZURKIEWICZ
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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