554
FXUS66 KSEW 072111
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
211 PM PDT SUN JUN 7 2026
SYNOPSIS
COOL AND UNSETTLED CONDITIONS WILL CONTINUE ACROSS WESTERN
WASHINGTON FOR THE FIRST HALF OF THE WEEK AS A PAIR OF SYSTEMS
MOVE THROUGH THE REGION. A PATTERN SHIFT TOWARD DRY AND
CONSIDERABLY WARMER CONDITIONS IS EXPECTED LATE IN WEEK AS
STRONG HIGH PRESSURE ALOFT BUILDS INTO THE REGION.
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/
WE'VE GOTTEN A BRIEF REPRIEVE FROM PRECIPITATION THIS AFTERNOON
ACROSS THE AREA AS WEAK SHORTWAVE RIDGING SLIDES ONSHORE AHEAD
OF THE NEXT APPROACHING SYSTEM. AS MENTIONED IN THE UPDATE THIS
MORNING, MODEL SOLUTIONS ARE TRENDING FURTHER NORTHWARD WITH THE
SURFACE LOW WHICH IMPLIES THAT MUCH OF THE FORECAST AREA WILL
SEE A SOGGY STRETCH OF WEATHER MONDAY AFTERNOON INTO MUCH OF
TUESDAY. UNLIKE THIS PAST SATURDAY, WE'RE LOOKING FOR
STRATIFORM PRECIP TO SPREAD ONSHORE DURING THE DAY MONDAY.
BETWEEN MONDAY AFTERNOON AND TUESDAY MORNING, LOWLAND AREAS FROM
AROUND SEATTLE SOUTHWARD COULD SEE 0.50" TO 0.75" OF RAIN WITH
HIGHER AMOUNTS IN THE CASCADES. SNOW LEVELS WILL BE HIGHER THIS
ROUND KEEPING ANY ACCUMULATING SNOW ONLY IN THE HIGHEST OF
ELEVATIONS. ONSHORE FLOW RAMPS UP ON TUESDAY AS THE TRAILING
UPPER TROUGH MOVES ONSHORE. THIS IS EXPECTED TO GENERATE A
FAIRLY POTENT CONVERGENCE ZONE. AS A WHOLE, CONVECTIVE INDICES
ARE PRETTY MINUSCULE ACROSS THE CWA ON TUESDAY, BUT IT WOULDN'T
BE SURPRISING TO GET THE WELL-KNOWN ONE CLAP WONDER IN THE
PSCZ. TEMPERATURES THROUGHOUT THE SHORT TERM FORECAST WILL
REMAIN ON THE COOL SIDE. AS FOR THE COOL TEMPERATURES: TO QUOTE
A SONG TITLE BY THE SUNDAYS, "HERE'S WHERE THE STORY ENDS".
LONG TERM /WEDNESDAY THROUGH SUNDAY/
AN UPPER LEVEL TROUGH EXITS THE AREA ON WEDNESDAY MAKING IT
SOMETHING OF A TRANSITIONAL DAY. CLOUDS AND A FEW, MAINLY
MOUNTAIN, SHOWERS WILL BE PRESENT EARLY IN THE DAY. THE TREND
TOWARD CLEARING AND MODEST WARMING WILL BE UNDERWAY BY
WEDNESDAY AFTERNOON. AN UPPER LEVEL RIDGE CENTERED OFFSHORE
BEGINS TO BUILD INTO THE REGION ON THURSDAY. SOME RESIDUAL
UPPER TROUGHING OVER THE WESTERN CANADIAN PROVINCES WILL TEMPER
IT'S STRENGTH INITIALLY, BUT ONLY LOOKS TO TEMPORARILY SLOW
WHAT NOW LOOKS LIKE AN INEVITABLE CLIMB IN TEMPERATURES TO WELL
ABOVE SEASONAL NORMALS.
BY THE WEEKEND, A HIGH AMPLITUDE RIDGE IS EXPECTED TO BE CENTERED
JUST OFFSHORE WITH 500 MILLIBAR HEIGHTS OVER WESTERN WASHINGTON IN
THE MID TO UPPER 580S DECAMETERS. NEAR THE SURFACE, THERMALLY
INDUCED LOW PRESSURE WILL EXPAND INTO THE REGION AND THE LOW
LEVEL FLOW IS EXPECTED TO TURN OFFSHORE SATURDAY NIGHT INTO
SUNDAY AS THE THERMAL TROUGH SHIFTS TOWARD THE COAST. BROADLY
SPEAKING, A LARGE PORTION OF THE FORECAST AREA WILL BE LOOKING
AT POTENTIAL HIGH TEMPERATURES IN THE MID 80S TO MID 90S BY THE
EARLY PORTION OF NEXT WEEK. PROBABILISTIC GUIDANCE IS POINTING
TOWARDS LIKELY MODERATE HEATRISK FOR A SUBSTANTIAL PORTION OF
THE LOWLANDS (COAST INCLUDED) BY SUNDAY. RECORD HIGHS FOR SEA-
TAC FOR SUNDAY AND MONDAY ARE WELL WITHIN REACH AT 86 AND 88,
RESPECTIVELY. THE RECORD HIGH ON MONDAY HAS STOOD FOR 63 YEARS.
27
AVIATION
NORTHWEST FLOW ALOFT OVER WESTERN WASHINGTON WILL BACK TO
SOUTHWESTERLY AGAIN TONIGHT AS THE NEXT IN A SERIES OF UPPER TROUGHS
AND ASSOCIATED FRONTAL SYSTEMS APPROACHES THE AREA. HIGH AND
MID LEVEL MOISTURE AHEAD OF THE NEXT SYSTEM WILL SPREAD ONSHORE
THIS AFTERNOON AND TONIGHT. VFR CEILINGS ARE EXPECTED TO PREVAIL
AREAWIDE INTO THIS EVENING. CEILINGS WILL DETERIORATE BACK TO
MVFR IN INCREASING RAIN ALONG THE COAST MID TO LATE MONDAY
MORNING WITH SAID CONDITIONS GRADUALLY SPREADING TO MOST
INTERIOR TERMINALS 21Z MONDAY ONWARD.
KSEA...VFR CEILINGS EXPECTED INTO THIS EVENING WITH CEILINGS
GRADUALLY COMING DOWN OVERNIGHT. MVFR CEILINGS IN RAIN ARE
EXPECTED TO DEVELOP AROUND 21Z MONDAY. SURFACE WINDS S/SW 7 TO
10 KNOTS GRADUALLY EASE THIS AFTERNOON AND VEER LIGHT W/NW FOR A
PERIOD THIS EVENING. WINDS ARE EXPECTED TO BECOME LIGHT E/SE
LATE TONIGHT BEFORE BACKING NORTHERLY 9 TO 14 KNOTS LATE MONDAY
AFTERNOON.
27
MARINE
A SLOW MOVING FRONT AND ASSOCIATED SUB-1000 MILLIBAR SURFACE
LOW WILL MOVE INTO THE COASTAL WATERS LATE TONIGHT AND EARLY
MONDAY THEN GRADUALLY DRAG ONSHORE AND WEAKEN LATE MONDAY
AFTERNOON AND EVENING. ONSHORE FLOW WILL INCREASE BEHIND THIS
SYSTEM ON TUESDAY AND CONTINUE INTO WEDNESDAY AS A SURFACE
RIDGE REBUILDS INTO OFFSHORE AND COASTAL WATERS. ONSHORE FLOW
WEAKENS AND TURNS MORE NORTHERLY LATE IN THE WEEK AS THERMALLY
INDUCED LOW PRESSURE EXPANDS NORTHWARD INTO WESTERN OREGON.
SMALL CRAFT ADVISORY WINDS ARE EXPECTED OVER THE COASTAL WATERS
LATE TONIGHT AND ON MONDAY WITH THE INCOMING FRONT AND SURFACE
LOW. THE ONSHORE FLOW ON TUESDAY LOOKS SUFFICIENT TO GENERATE
SMALL CRAFT ADVISORY WINDS FOR NEARLY ALL OF THE INTERIOR WATERS
AND POSSIBLE GALES IN THE CENTRAL AND EAST STRAIT. ONSHORE FLOW
RELAXES ENOUGH ON WEDNESDAY TO KEEP SMALL CRAFT ADVISORY
WESTERLIES ISOLATED TO THE STRAIT BEFORE QUIETER CONDITIONS TAKE
HOLD ACROSS ALL WATERS AT THE END OF THE WEEK. COASTAL SEAS
ARE EXPECTED TO REMAIN BELOW 10 FEET.
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
BY THE END OF THE EXTENDED FORECAST PERIOD. GIVEN THE STEEP
CLIMB IN TEMPERATURES, EXTRA CAUTION WOULD BE ADVISED IN ANY
PLANNING DURING THIS TIME. CURRENT NBM MINIMUM RELATIVELY
HUMIDITY VALUES ARE RUNNING IN THE 25-35 PERCENT RANGE BY DAY 7
ACROSS PORTIONS OF THE AREA. THESE ARE LIKELY A TAD HIGHER THAN
WHAT WILL TRANSPIRE. IF THE CROSS CASCADE GRADIENT GOES
NEGATIVE BY SUNDAY AS ADVERTISED IN A NUMBER OF MODELS, HUMIDITY
VALUES DROPPING INTO THE TEENS IN THE CASCADES VALLEYS AND
PORTIONS OF THE SOUTHWEST INTERIOR BECOME A DISTINCT
POSSIBILITY.
27
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 AM TO 1 PM PDT MONDAY FOR COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-
COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE OUT
10 NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE
SHOALWATER OUT 10 NM.
SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 1 PM PDT
MONDAY FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES
ISLAND 10 TO 60 NM-COASTAL WATERS FROM JAMES ISLAND TO
POINT GRENVILLE 10 TO 60 NM-COASTAL WATERS FROM POINT
GRENVILLE TO CAPE SHOALWATER 10 TO 60 NM.
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