099
FXUS66 KSEW 112151
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
251 PM PDT SAT JUL 11 2026
SYNOPSIS
WEAK SYSTEM MOVING BY TO THE NORTH WILL ENHANCE THE LOW LEVEL
ONSHORE FLOW OVERNIGHT. LOW LEVEL FLOW TURNING NORTHERLY SUNDAY
AFTERNOON AND REMAINING NORTHERLY INTO TUESDAY LEADING TO LESS
MORNING CLOUDS AND WARMER DAYS. WEAK UPPER LEVEL TROUGH MOVING
OVER THE AREA WEDNESDAY AFTERNOON THROUGH THURSDAY. UPPER LEVEL
RIDGE BUILDING OVER WESTERN WASHINGTON BEGINNING FRIDAY.
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/
SATELLITE IMAGERY SHOWS PLENTY OF FAIR WEATHER CUMULUS OVER
WESTERN WASHINGTON WITH A WEAK UPPER LEVEL SHORTWAVE JUST
OFFSHORE THIS AFTERNOON. TEMPERATURES A LITTLE BELOW NORMAL,
MID 60S TO LOWER 70S OVER THE INTERIOR AND MID 60S ALONG THE
COAST.
WEAK UPPER LEVEL SHORTWAVE MOVING BY TO THE NORTH TONIGHT.
INCREASING LOW LEVEL ONSHORE FLOW WITH AND BEHIND THE SHORTWAVE
WITH THE MARINE LAYER MAKING ITS WAY BACK INLAND EARLY SUNDAY
MORNING. LOWS TONIGHT IN THE UPPER 40S TO MID 50S.
MOSTLY CLOUDY SUNDAY MORNING. LOW LEVEL FLOW TURNING NORTHERLY
SUNDAY AFTERNOON. THIS WILL GET RID OF THE MARINE LAYER OVER THE
INTERIOR RESULTING IN SOME AFTERNOON SUNSHINE. HIGHS IN THE MID
60S TO MID 70S.
LOW LEVEL NORTHERLY FLOW CONTINUING THROUGH MONDAY NIGHT WHICH
WILL KEEP THE MARINE LAYER AT BAY. TEMPERATURES ALOFT WARMING
SLIGHTLY WITH 500 MB HEIGHTS NEAR 580 DMS MONDAY AFTERNOON.
HIGHS WARMING INTO THE 70S AND LOWER 80S. LOWS MONDAY MORNING IN
THE UPPER 40S TO MID 50S. FELTON
LONG TERM /TUESDAY THROUGH SATURDAY/
UPPER LEVEL TROUGH DIGGING OFFSHORE TUESDAY PUSHING 500 MB
HEIGHTS INTO THE LOWER TO MID 580 DMS OVER WESTERN WASHINGTON.
HIGHS WARMING INTO THE MID 70S TO MID 80S OVER THE INTERIOR AND
NEAR 70 ALONG THE COAST.
UPPER LEVEL TROUGH AXIS REACHING THE COAST WEDNESDAY AFTERNOON
WITH THE TROUGH SLOWLY MOVING OVER THE REMAINDER OF THE AREA
WEDNESDAY NIGHT INTO THURSDAY. SLIGHT CHANCE OF SHOWERS IN THE
MOUNTAINS AS THE TROUGH MOVES OVERHEAD. FOR THE LOWLANDS SLOW
COOLING TREND WITH HIGH WEDNESDAY IN THE LOWER 70S TO LOWER 80S
AND JUST 70S FOR THURSDAY.
UPPER LEVEL TROUGH MOVING EAST THURSDAY NIGHT. UPPER LEVEL RIDGE
BUILDING FRIDAY AND SATURDAY WITH 500 MB HEIGHTS RISING INTO THE
MID 580 DMS. THIS COULD BE THE START OF A SUSTAINED WARM SPELL
OVER THE AREA. HIGHS WARMING INTO THE MID 70S TO MID 80S BY
SATURDAY INLAND WITH HIGHS ON THE COAST REMAINING NEAR 70.
FELTON
AVIATION
VFR OBSERVED AREA WIDE THIS AFTERNOON AS PREVIOUS MARINE STRATUS HAS
SCATTERED WITH DIURNAL HEATING. HOWEVER, ANOTHER ROUND OF STRONG LOW-
LEVEL ONSHORE FLOW THIS EVENING WILL REINTRODUCE MARINE STRATUS INTO
WESTERN WASHINGTON TONIGHT INTO SUNDAY MORNING. MVFR CEILINGS LIKELY
TO FORM ALONG THE COAST (KHQM) BETWEEN 02-04Z - GRADUALLY SPREADING
INLAND TOWARDS PUGET SOUND TERMINALS AROUND 10-12Z SUNDAY. STRATUS
IS FORECAST TO BURN OFF TO VFR BY 18-21Z. BREEZY WEST TO
SOUTHWESTERLY WINDS FOR PUGET SOUND TERMINALS AND COASTAL TERMINALS
THIS EVENING WITH GUSTS NEAR 20-25 KT. SURFACE WINDS SHOULD SUBSIDE
ON SUNDAY MORNING.
KSEA...VFR CONDITIONS WILL PREVAIL THIS EVENING THROUGH TONIGHT. THE
NBM HAS A 20-25% CHANCE OF CEILINGS BELOW 3,000 FT DEVELOPING OVER
THE TERMINAL AFTER 09Z BUT IF MANIFEST, VFR SHOULD RETURN BY 18Z.
SOUTHWEST WINDS GUSTS UP TO 20-25 KT 03Z ONWARD BUT SHOULD SUBSIDE
INTO SUNDAY MORNING.
MARINE
A WEAK SURFACE TROUGH WILL REMAIN OVER THE OFFSHORE WATERS TONIGHT
BEFORE HIGH PRESSURE BROADLY REBUILDS INTO THE COASTAL AND OFFSHORE
WATERS SUNDAY AND MONDAY AND REMAINING INTO MIDWEEK. THIS WILL
PROMOTE A FAIRLY TYPICAL SUMMER PATTERN WITH VARYING DEGREES OF
ONSHORE FLOW PROMOTING A DIURNALLY DRIVEN INCREASE IN WESTERLIES
THROUGH THE STRAIT OF JUAN DE FUCA NEAR DAILY. NORTHWEST WINDS OVER
THE COASTAL WATERS ARE LIKELY TO INCREASE LATER MONDAY INTO TUESDAY
AS THERMALLY INDUCED SURFACE LOW PRESSURE EXPANDING OVER THE
INTERIOR OF WESTERN WASHINGTON TIGHTENS THE ONSHORE GRADIENT.
FIRE WEATHER
THE LACK OF OFFSHORE FLOW THROUGH THE MIDDLE OF NEXT WEEK WILL
KEEP FIRE WEATHER CONCERNS AT A MINIMUM. WARMING TEMPERATURES
LATE NEXT WEEK WILL BEGIN TO INCREASE THE FIRE WEATHER RISKS
GOING INTO THE WEEKEND. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 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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