966
FXUS66 KSEW 070326
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
826 PM PDT SAT JUN 6 2026
SYNOPSIS
AN UPPER LEVEL TROUGH OVER WESTERN WASHINGTON TODAY
WILL SHIFT EASTWARD TONIGHT. A WEAK UPPER RIDGE WILL PRODUCE A
BRIEF DRYING TREND ON SUNDAY BEFORE A SERIES OF SYSTEMS PRODUCE
COOL AND UNSETTLED CONDITIONS FOR THE FIRST HALF OF THE COMING
WEEK. A PATTERN SHIFT TOWARD DRY AND CONSIDERABLY WARMER
CONDITIONS IS EXPECTED LATE NEXT WEEK AS STRONG HIGH PRESSURE
ALOFT BUILDS INTO THE REGION.
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/
SHOWERS AND
THUNDERSTORM THREAT WINDING DOWN THIS EVENING AS AN UPPER LOW
DEPARTS THE REGION. CURRENT TRENDS LOOK GOOD AND MATCH THE
FORECAST. 33
PREVIOUS FORECAST...DAYTIME HEATING COUPLED WITH AN UPPER
TROUGH AXIS OVER WESTERN WASHINGTON WILL PRODUCE SCATTERED
SHOWERS, ISOLATED THUNDERSTORMS AND UNSEASONABLY COOL
TEMPERATURES INTO THIS EVENING. THE HIGHER TERRAIN OF THE
CASCADES AND OLYMPICS ABOVE 4500 FEET WILL SEE SOME LIGHT
SNOWFALL, BUT IT IS NOT EXPECTED TO PRODUCE ANY TRAVEL IMPACTS
ACROSS THE PASSES. THE TROUGH WILL SHIFT EASTWARD TONIGHT AND A
WEAK SHORTWAVE RIDGE WILL SLIDE ONSHORE ON SUNDAY ALLOWING THE
AREA TO BRIEFLY DRY OUT THOUGH TEMPERATURES WILL REMAIN BELOW
NORMAL. THE NEXT IN A SERIES OF TROUGHS WILL SPREAD ADDITIONAL
CLOUDS AND SHOWERS INTO THE REGION SUNDAY NIGHT INTO MONDAY.
IT'S EASTWARD PROGRESSION WILL, HOWEVER, BE HINDERED AS A WEAK
SURFACE LOW DEVELOPING OFF THE OREGON COAST SPLITS THE SYSTEM
APART AND TAKES THE FOCUS OF THE BULK OF THE PRECIPITATION INTO
OREGON.
LONG TERM /TUESDAY THROUGH SATURDAY/
THE COOL AND UNSETTLED
PATTERN CONTINUES INTO THE MIDDLE OF THE COMING WEEK AS ANOTHER
UPPER TROUGH DIGGING SOUTHWARD ALONG THE BRITISH COLUMBIA COAST
KEEPS SHOWERS AND COOL TEMPERATURES IN THE FORECAST.
THE NARRATIVE TAKES A DECIDED TURN FROM THAT POINT FORWARD.
ENSEMBLES ARE VIRTUALLY UNANIMOUS THAT WE'LL SEE A SUBSTANTIVE
CHANGE IN THE SYNOPTIC PATTERN HEADING INTO LATE NEXT WEEK AND
THE DAYS THAT FOLLOW. A BUILDING UPPER RIDGE WILL PRODUCE A
WARMING TREND THAT WILL RESULT IN TEMPERATURES CLIMBING BACK TO
JUST ABOVE NORMAL LEVELS SWIFTLY ON THURSDAY. THE CLIMB UPWARD
CONTINUES AS WE ROUND OUT THE WEEK AND LIKELY BEYOND. HIGH
TEMPERATURES BY THE BEGINNING OF NEXT WEEKEND COULD RUN 10 TO 15
DEGREES ABOVE SEASONAL AVERAGES AS ANOMALOUSLY STRONG UPPER
RIDGING TAKES UP RESIDENCE JUST TO OUR WEST.
LONGER TERM GUIDANCE STRONGLY SUGGESTS THAT THE UPWARD TREND IN
TEMPERATURES WILL PERSIST BEYOND THE 7 DAY PERIOD. PROBABILISTIC
HEATRISK SUGGESTS A 90-100% CHANCE OF MINOR HEATRISK ACROSS
MUCH OF THE LOWLANDS BY FRIDAY AND SATURDAY AND A 40-70%
PROBABILITY OF MODERATE HEATRISK ON SATURDAY FOR THE INTERIOR
LOWLANDS OF SOUTH PUGET SOUND AND THE SOUTHWEST INTERIOR. THOUGH
IT'S EARLY YET, CURRENT PROBABILISTIC DATA HAS A CONSIDERABLE
PORTION OF THE CWA LIKELY REACHING MODERATE HEATRISK AS WE ENTER
THE JUNE 14TH/15TH PERIOD WITH POTENTIAL DAYTIME TEMPERATURES
IN THE MID 80S TO MID 90S FOR INTERIOR AREAS FROM SEATTLE
SOUTHWARD. STAY TUNED.
27
AVIATION
AN UPPER TROUGH AXIS OVER THE INTERIOR THIS AFTERNOON WILL SHIFT
EAST OF THE CASCADES TONIGHT. WESTERLY FLOW ALOFT WILL BECOME
NORTH TO NORTHWESTERLY TONIGHT. LOW LEVEL CONVERGENCE WILL
ENHANCE SOME ADDITIONAL SHOWERS THIS EVENING ACROSS CENTRAL
PUGET SOUND, WITH MOST SHOWER COVERAGE DIMINISHING TONIGHT.
MVFR CEILINGS CAN BE EXPECTED AROUND HEAVIER SHOWERS. REMNANT
LOW LEVEL MOISTURE AND LIGHT SURFACE WINDS WILL LEAD TO GREATER
COVERAGE OF MVFR CEILINGS ACROSS THE REGION ON SUNDAY MORNING.
THIS WILL GRADUALLY LIFT TO VFR SUNDAY AFTERNOON.
KSEA...VFR CONDITIONS AT THE TERMINAL THIS EVENING AS MOST OF
THE THUNDERSTORM ACTIVITY HAS DIMINISHED NEAR THE TERMINAL.
MORE PREDOMINANT MVFR CEILINGS ARE EXPECTED SUNDAY AM AS REMNANT
LOW LEVEL MOISTURE REMAINS IN THE AREA. THESE WILL LIFT TO VFR
SUNDAY AFTERNOON. SURFACE WINDS SOUTH TO SOUTHWESTERLY 9 TO 13
KNOTS INTO THE THROUGHOUT THE EVENING.
27/MAZURKIEWICZ
MARINE
A WEAK TROUGH OVER THE COASTAL WATERS WILL SHIFT INLAND TONIGHT
AS WEAK HIGH PRESSURE BUILDS JUST OFFSHORE. ANOTHER TROUGH AND
ASSOCIATED FRONTAL SYSTEM WILL APPROACH THE OUTER COASTAL WATERS
SUNDAY EVENING THEN SLOW AND DISSIPATE IN RESPONSE TO A WEAK
SURFACE LOW MOVING TOWARD THE OREGON COAST. ONSHORE FLOW WILL
INCREASE TUESDAY AND WEDNESDAY AS BROAD HIGH PRESSURE GRADUALLY
EXPANDS INTO THE COASTAL AND OFFSHORE WATERS. ONSHORE FLOW WEAKENS
LATE NEXT WEEK AS THERMALLY INDUCED LOW PRESSURE BEGINS TO
EXPAND NORTHWARD ACROSS WESTERN OREGON.
COASTAL SEAS ARE EXPECTED TO REMAIN BELOW 10 FEET THROUGH THE
PERIOD.
27
FIRE WEATHER
AS UPPER LEVEL RIDGING BUILDS INTO THE AREA
STARTING THURSDAY, CONDITIONS, INCLUDING FUELS, WILL NEED TO BE
MONITORED AS TEMPERATURES ARE EXPECTED TO CLIMB TO ABOVE NORMAL
VALUES ENTERING INTO THE WEEK 2 TIME PERIOD.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT SUNDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
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