978
FXUS66 KSEW 162222
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
322 PM PDT THU JUL 16 2026
SYNOPSIS
CONDITIONS ARE FAVORED TO TREND DRIER OVER THE WEEKEND WITH
NEAR-SEASONAL TEMPERATURES. HIGH PRESSURE THEN BUILDS OVER THE
AREA NEXT WEEK, BRINGING CONTINUED DRY WEATHER AND WELL-ABOVE
AVERAGE TEMPERATURES ALONG WITH MODERATE HEATRISK.
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
SHOWERS AND THUNDERSTORMS ARE PERSISTING BUT MAINLY ALONG THE
WESTERN HALF OF THE CWA (OLYMPIC PENINSULA AND ISLAND COUNTY).
THIS ACTIVITY WILL PERSIST BEFORE DECREASING IN COVERAGE INTO
THE EVENING. FOR TONIGHT, DRIER WEATHER IS EXPECTED AS THE
UPPER- LOW RESPONSIBLE FOR THUNDERSTORMS LIFTS NORTH INTO BC.
MINIMUM TEMPERATURES WILL FALL INTO THE LOWER TO MID 50S.
BAGGY TROUGHING IN THE 500 MB LEVELS FRIDAY AND SATURDAY AS THE
AFOREMENTIONED UPPER-LOW CONTINUES TO TRACK WELL INTO BC AND
ALBERTA. CAN'T RULE OUT LINGERING SHOWERS (15-30% POPS),
PRIMARILY OVER THE OLYMPICS AND NORTH CASCADES ON FRIDAY BUT
CONDITIONS ARE FAVORED TO TREND DRIER, ESPECIALLY INTO SATURDAY.
HIGH TEMPERATURES WILL BE RIGHT AROUND SEASONAL AVERAGES WITH
HIGHS IN THE LOWER 70S TO NEAR 80 F AND OVERNIGHT LOWS IN THE
50S. DAYTIME HIGHS ALONG THE COAST WILL BE ABOUT 10 DEGREES
COOLER - IN THE 60S.
LONG TERM /SUNDAY THROUGH THURSDAY/
GUIDANCE HAS THE UPPER-LEVEL PATTERN INTO EARLY NEXT WEEK
FEATURING THE RETURN OF HIGH PRESSURE ACROSS THE REGION. A
SHARP WARM-UP IN TEMPERATURE IS EXPECTED AS HIGHS TOP OUT 7-10
DEGREES ABOVE AVERAGE FOR MONDAY AND TUESDAY. WIDESPREAD
MODERATE HEATRISK IS FAVORED DURING THIS TIME. THERE'S
DISAGREEMENT IN GUIDANCE REGARDING THE EVOLUTION OF THE PATTERN
MIDWEEK ONWARD. GFS AND CANADIAN ENSEMBLES ARE HINTING AT
UPPER-LEVEL RIDGING PERSISTING ACROSS THE PNW WITH UPPER-
TROUGHING OFFSHORE. THE ECMWF RESEMBLES ARE SIMILAR IN RIDGING
OVER THE PNW BUT ALSO OVER THE OFFSHORE WATERS OF THE NE PAC,
DISSIMILAR THAN ITS GFS AND CANADIAN COUNTERPARTS. NONETHELESS,
WELL-ABOVE AVERAGE TEMPERATURES ARE FAVORED IN THE LONG-TERM
FORECAST WITH NO MAJOR SIGNAL FOR PRECIPITATION.
AVIATION
THE CUTOFF LOW REMAINS ALONG THE COAST AND WILL NORTH INTO B.C.
TONIGHT/FRIDAY MORNING WITH SOUTH FLOW ALOFT. THE CONVECTION THREAT
THIS AFTERNOON HAS SHIFTED TO THE COAST AND OLYMPICS REGION THIS
AFTERNOON, WHERE THERE ARE CONTINUING THUNDERSTORMS IN THESE AREAS
MOVING TO THE NORTH-NORTHWEST AT AROUND 30-35 MPH. THUNDERSTORM TOPS
HAVE PEAKED AT 30,000-35,000 FT, BUT THE MAIN THREATS CONTINUE TO
REMAIN LIGHTNING, WITH REDUCED CEILINGS/VISIBILITIES IN THE RAIN
SHAFTS, AND A LESSER THREAT OF SMALL HAIL AND GUSTY WINDS. A FEW
ENSEMBLE MEMBERS HAVE CONVECTION FLARING UP AGAIN IN THE SOUTH SOUND
MOVING INTO THE SEATTLE METRO FROM 23-02Z THIS AFTERNOON, WHICH WILL
KEEP THE PROB30'S FOR THUNDER THROUGH EARLY THIS EVENING BEFORE
ACTIVITY WINDS DOWN. LAMP GUIDANCE IS FAVORING MVFR CONDITIONS
CONTINUING FOR MOST TERMINALS THROUGH TONIGHT INTO FRIDAY (WITH
LIMITED VFR). A FEW TERMINALS (PARTICULARLY ALONG THE COAST, KITSAP
AND AROUND KPAE) HAVE 20-30% CHANCES OF IFR/LIFR CONDITIONS AROUND
12Z. SOUTHWEST WINDS WILL CONTINUE THROUGH THE TAF PERIOD FOR MOST
AREAS AT 5-10 KT, WITH A FEW GUSTS TO 20 KT THIS AFTERNOON/EVENING
IN THE INTERIOR, AND IN THE STRAIT OF JUAN DE FUCA.
KSEA...CEILINGS LIKELY TO REMAIN PREDOMINATELY MVFR THROUGH FRIDAY
MORNING. THERE IS A BRIEF 20% CHANCE OF IFR AROUND 15Z AS CEILINGS
LOWER IN THE MORNING BEFORE CONVECTION. THIS MORNING'S CONVECTION
HAS WRAPPED UP, THOUGH THERE REMAINS A 20-30% CHANCE OF ANOTHER
ROUND OF CONVECTION FROM 23-02Z IF CONVECTION FORMS IN THE SOUTH
SOUND AND MOVES NORTHEAST. SOUTHWEST WINDS THROUGH THE TAF, WITH
GUSTS DIMINISHING TO 5-10 KT TONIGHT/FRIDAY.
HPR
MARINE
A LOW/TROUGH REMAINS OVER THE WATERS, AND WILL MOVE NORTH INTO B.C.
TONIGHT. THUNDERSTORMS WILL CONTINUE OVER THE COASTAL WATERS AND
PORTIONS OF THE INTERIOR WATERS THIS AFTERNOON AND EVENING BEFORE
SUBSIDING. A PUSH OF WINDS THROUGH THE STRAIT OF JUAN DE FUCA WILL
FOLLOW TONIGHT INTO FRIDAY, WHERE A SMALL CRAFT ADVISORY IS IN
EFFECT. HIGH PRESSURE WILL REBUILD OFF THE COAST THIS WEEKEND, WITH
REGULAR ONSHORE PUSHES CONTINUING. SATURDAY AFTERNOON AND EVENING
LOOKS LIKE THE NEXT BEST CHANCE OF WINDS EXCEEDING 20 KT IN THE
STRAIT. A FEW PORTIONS OF THE COASTAL WATERS MAY GET SLIGHTLY WINDY
NEXT WEEK, BUT CONFIDENCE IS LOW AT THIS TIME FOR ANY HEADLINE
WORTHY WINDS.
SEAS TO DROP TO 4-6 FT TONIGHT, WITH THEM BUILDING TO 6-8 FT NEXT
WEEK AND POTENTIALLY 9 FT IN A FEW AREAS WITH PERIODS AT 8-9 SECONDS.
HPR
FIRE WEATHER
SHOWERS AND THUNDERSTORMS ARE MAINLY ALONG THE OLYMPIC PENINSULA
AS CONDITIONS HAVE TRENDED DRIER FOR THE CASCADES SO FAR THIS
AFTERNOON. AS A RESULT, A RFW REMAINS FOR THE OLYMPIC MOUNTAINS
UNTIL TONIGHT BUT THE CASCADES RFW HAS BEEN CANCELED DUE TO THE
LACK OF THUNDERSTORM COVERAGE. FIRE WEATHER CONCERNS WILL
LINGER THROUGH THE REMAINDER OF THE FORECAST PERIOD AS A HOTTER
AND DRIER PATTERN RETURNS QUICKLY OVER WESTERN WASHINGTON,
ESPECIALLY INTO EARLY NEXT WEEK. THIS HAS THE POTENTIAL FOR
INCREASING FIRE ACTIVITY FROM ANY NEW LIGHTNING STARTS FROM
TODAY'S CONVECTION.
SEW WATCHES/WARNINGS/ADVISORIES
WA...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR EAST PORTION
OF THE OLYMPIC MOUNTAINS-WEST PORTION OF THE OLYMPIC
MOUNTAINS-WEST SLOPES OF THE CENTRAL CASCADES GENERALLY
ABOVE 1500 FEET-WEST SLOPES OF THE NORTH CASCADES
GENERALLY ABOVE 1500 FEET.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR CENTRAL
U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S.
WATERS STRAIT OF JUAN DE FUCA.
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