410
FXUS66 KSEW 191533
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
833 AM PDT SUN JUL 19 2026
SYNOPSIS
UPPER LEVEL RIDGE BUILDING OVER THE AREA BEGINNING TONIGHT WITH
THE RIDGE REMAINING IN PLACE THROUGH WEDNESDAY. RIDGE WEAKENS
WEDNESDAY NIGHT WITH THE REMNANTS OF WHAT IS NOW TROPICAL STORM
ELIDA APPROACHING THE AREA THURSDAY AND FRIDAY. ELIDA REMNANTS
WEAKENING INTO AN UPPER LEVEL TROUGH OFFSHORE SATURDAY.
SHORT TERM /TODAY THROUGH TUESDAY/
NO MAJOR CHANGES HAVE BEEN MADE THIS MORNING. THE REST OF THE
PREVIOUS DISCUSSION FOLLOWS, WITH AN UPDATE TO THE AVIATION AND
MARINE SEGMENTS.
UPPER LEVEL TROUGH MOVING OFF TO THE NORTHEAST TODAY. WEAK
ONSHORE FLOW THIS MORNING BECOMING LIGHT THIS AFTERNOON. LIKE
SATURDAY MORNING THE MARINE LAYER IS SHALLOW, AROUND 1000 FEET
THICK. THE COMBINATION OF THE TROUGH MOVING OUT, LOW LEVEL FLOW
TURNING LIGHT AND JULY SUNSHINE WILL DISSIPATE THE MARINE LAYER
LATE MORNING/EARLY AFTERNOON LEAVING SUNNY SKIES ACROSS THE
AREA. HIGHS A LITTLE WARMER THAN SATURDAY, MID 60S TO LOWER 70S
COAST AND 70S TO LOWER 80S INLAND.
UPPER LEVEL RIDGE, CENTERED WELL TO THE SOUTHEAST, WILL BEGIN
BUILDING OVER WESTERN WASHINGTON TONIGHT. LIGHT FLOW IN THE
LOWER LEVELS WILL KEEP THE SHALLOW MARINE LAYER ALONG THE COAST.
LOWS IN THE 50S.
UPPER LEVEL RIDGE REMAINING OVER WESTERN WASHINGTON MONDAY AND
TUESDAY. 500 MB HEIGHTS IN THE MID TO UPPER 580 DMS. FLOW ALOFT
SOUTHWESTERLY WHICH WILL SEND SOME HIGH LEVEL CLOUDS ACROSS THE
AREA AT TIMES. IN THE LOWER LEVELS, FLOW GOING NORTHERLY.
UNFORTUNATELY THIS CHANGE IN THE LOW LEVEL FLOW WILL PULL SMOKE
FROM THE WILDFIRES IN CANADA DOWN OVER AT LEAST THE NORTHERN
PORTION OF WESTERN WASHINGTON BEGINNING MONDAY AFTERNOON. SMOKE
REMAINING OVER THE AREA THROUGH TUESDAY. RIGHT NOW THE SMOKE
LOOKS TO BE THICK ENOUGH OVER THE NORTHWEST INTERIOR TO KNOCK A
FEW DEGREES OFF THE HIGH TEMPERATURES ESPECIALLY TUESDAY. HIGHS
MONDAY IN THE 70S ALONG THE COAST AND MID 70S TO NEAR 90 OVER
THE INTERIOR. HIGHS A COUPLE OF DEGREES WARMER OVER THE INTERIOR
TUESDAY WITH 80S TO MID 90S WHILE THE COAST STAYS IN THE 70S.
LOWS IN THE MID 50S TO MID 60S.
MINOR TO MODERATE HEATRISK FOR THE INTERIOR MONDAY. MODERATE
HEATRISK TUESDAY WITH A POCKET OF MAJOR HEATRISK FROM SOUTHERN
SNOHOMISH COUNTY AWAY FROM THE PUGET SOUND OVER TO GOLD BAR
DOWN TO AROUND MOUNT RAINIER AND BACK UP TO NEAR TACOMA. A HEAT
ADVISORY MAY BE NEEDED FOR THIS AREA TUESDAY. FELTON
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
LITTLE CHANGE TUESDAY NIGHT INTO WEDNESDAY WITH THE UPPER LEVEL
RIDGE OVER THE AREA, SOUTHWESTERLY FLOW ALOFT AND LIGHT
NORTHERLY FLOW IN THE LOWER LEVELS. ONE MORE VERY WARM DAY
WEDNESDAY WITH HIGHS SIMILAR TO TUESDAY. SMOKE MOST LIKELY
CONTINUING OVER AT LEAST THE NORTHERN PORTION OF THE AREA.
AS SHOULD BE EXPECTED THE MODELS ARE HAVING TROUBLE WITH THE
REMNANTS OF TROPICAL STORM ELIDA. THE 00Z RUN IS MUCH FASTER
WITH THE NORTHWARD MOVEMENT OF THE REMNANTS PUTTING A WEAK LOW
OFF THE COAST WEDNESDAY NIGHT INTO THURSDAY. MORE THAN ENOUGH OF
THE ENSEMBLE SOLUTIONS HAVE A FEATURE SPINNING OUT OF THE LOW
THAT PRODUCES AT LEAST A SLIGHT CHANCE OF SHOWERS FOR MOST OF
THE LOWLANDS AS WELL AS THE OLYMPICS THURSDAY MORNING. LOW
SITTING OFF THE COAST THURSDAY NIGHT INTO FRIDAY BEFORE
WEAKENING INTO A TROUGH SATURDAY. ANOTHER SLIGHT CHANCE OF
SHOWERS FOR SOME LOCATIONS SATURDAY MORNING. LOW LEVEL FLOW
TURNING ONSHORE WEDNESDAY NIGHT WITH A MARINE PUSH THURSDAY
LOWERING TEMPERATURES BY AT LEAST 5 TO 10 DEGREES VERSUS THE
HIGHS WEDNESDAY. IF WE DO END UP GETTING SOME CONVECTION IN THE
MORNING HIGHS WILL BE EVEN COOLER. WITH THE LACK OF CONSISTENCY
IN THE SOLUTIONS FRIDAY AND SATURDAY HAVE ONCE AGAIN TILTED THE
FORECAST TOWARDS CLIMATOLOGY WITH HIGHS BACK DOWN INTO THE 70S
FOR THE INTERIOR AND MID 60S FOR THE COAST.
THERE IS A CHANCE FOR ANOTHER POCKET OF MAJOR HEATRISK OVER THE
CENTRAL SOUND WEDNESDAY. HEATRISK EASING THURSDAY INTO THE
WEEKEND. FELTON
AVIATION
WESTERLY FLOW ALOFT CONTINUES TODAY. IFR STRATUS IS
BEGINNING TO SHOW SIGNS OF BURNING OFF ACROSS THE SOUTHWEST INTERIOR
THIS MORNING AND WILL CONTINUE TO DO SO AREA-WIDE THROUGH THE NEXT
FEW HOURS. VFR CONDITIONS WILL PREVAIL THROUGH THE REMAINDER OF THE
DAY AND TONIGHT. IFR/LIFR STRATUS WILL RETURN TO THE COAST AGAIN
EARLY MONDAY MORNING WITH VFR CONTINUING FOR INTERIOR AREAS.
KSEA...VFR PREVAILING THROUGH THE TAF PERIOD. SURFACE WINDS
NORTHERLY 8 TO 12 KNOTS, BECOMING AROUND 5 KT LATE TONIGHT.
27/62
MARINE
HIGH PRESSURE WILL REMAIN CENTERED OFFSHORE WITH LOWER
PRESSURE INLAND INTO MIDWEEK FOR VARYING DEGREES OF ONSHORE FLOW.
BREEZY NORTHWEST WINDS WILL CONTINUE OVER THE COASTAL WATERS TODAY
AND TONIGHT, MAKING FOR STEEP 6 TO 8 FT SEAS. ONSHORE GRADIENTS WILL
EASE THROUGH THE EARLY PART OF THE WEEK AS THERMALLY-INDUCED LOW
PRESSURE DEVELOPS ACROSS WESTERN WASHINGTON AND OREGON. STRONGER
ONSHORE FLOW AND PUSHES DOWN THE STRAIT LOOK TO RESUME IN THE LATTER
HALF OF THE WEEK AS THE THERMAL TROUGH SHIFTS EASTWARD.
27/62
FIRE WEATHER
ANOTHER PERIOD OF HOT AND DRY WEATHER WILL INCREASE FIRE
WEATHER CONCERNS BEGINNING MONDAY. TEMPERATURES CLIMBING BACK
INTO THE 80S AND LOW 90S WITH MINIMUM RELATIVE HUMIDITY VALUES
DROPPING BELOW 30 PERCENT IN THE AFTERNOONS MONDAY THROUGH
WEDNESDAY. BRIEF SPELLS OF LOW LEVEL OFFSHORE FLOW ARE POSSIBLE IN
THIS WINDOW WHICH WOULD HELP TO DRY OUT THE ENVIRONMENT AND
MAKE FUELS MORE RECEPTIVE. BEYOND WEDNESDAY, THE PATTERN WILL
NEED TO BE MONITORED AS THERE IS A SUGGESTION OF ANOTHER INFLUX
OF MONSOONAL MOISTURE THAT COULD LEAD TO ANOTHER ROUND OF
CONVECTION THURSDAY INTO THE WEEKEND. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM 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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