396
FXUS66 KSEW 090915
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
215 AM PDT SUN AUG 9 2026
SYNOPSIS
ZONAL FLOW ALOFT AND INCREASING ONSHORE FLOW WILL LEAD TO DAYTIME
HIGH TEMPERATURES NEAR SEASONAL NORMALS. THIS PATTERN WILL PERSIST
THROUGH THE FIRST HALF OF THIS WEEK. A HIGH DEGREE OF UNCERTAINTY
CONTINUES FOR THE SECOND HALF OF THE WEEK, ALTHOUGH CONDITIONS ARE
EXPECTED TO REMAIN GENERALLY DRY.
SHORT TERM /TODAY THROUGH TUESDAY/
LATEST SATELLITE IMAGERY IS MORE AKIN TO THIS TIME FRIDAY MORNING
THAN 24 HOURS AGO, WITH MARINE STRATUS PUSHING INLAND ALONG BOTH THE
NORTH AND SOUTH COAST. THE EXTENT OF THE NORTHERN PORTION IS STILL
FAIRLY LIMITED...ALTHOUGH THERE IS A LITTLE SEEPAGE DOWN THE STRAIT.
THE SOUTHERN PORTION HOWEVER IS VERY SIMILAR TO YESTERDAY MORNING,
ALREADY REACHING INTO SHELTON. EASTWARD PROGRESS SEEMS TO HAVE
STALLED, BUT WILL CONTINUE TO MONITOR. VARIATIONS ON THIS THEME ARE
EXPECTED AGAIN DURING THE OVERNIGHT PERIOD TONIGHT/EARLY MONDAY
MORNING AND MONDAY NIGHT/EARLY TUESDAY MORNING.
WHEN IT COMES TO THE FORECAST, THE SONG REMAINS THE SAME AS THE
COMBINATION OF ZONAL FLOW ALOFT AND LOW-LEVEL ONSHORE FLOW WILL
ALLOW FOR ANOTHER DEGREE OR TWO OF COOLING WHEN COMPARED TO HIGH
TEMPS YESTERDAY. AT THIS POINT, DAYTIME HIGHS WILL LEVEL OUT, WITH
SIMILAR TEMPS EXPECTED FOR MONDAY AND TUESDAY. THIS PATTERN WILL
KEEP HEATRISK LIMITED TO MINOR/YELLOW.
18
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
MODELS ARE TRYING TO COME TO A CONSENSUS WITH REGARDS TO THE SECOND
HALF OF THE WEEK, BUT AS THIS IS SEEMINGLY THE FIRST TIME THIS
SOLUTION HAS ARISEN, ONE WOULD BE WISE TO TAKE IT WITH A GRAIN OF
SALT UNTIL THIS SOLUTION BECOMES CONSISTENT OVER FUTURE RUNS. THAT
BEING SAID, AN UPPER LEVEL TROUGH DIPPING DOWN THROUGH BC IS
EXPECTED TO START IMPACTING W WA AS EARLY AS TUESDAY NIGHT OR
HOLDING OFF UNTIL WEDNESDAY MORNING. LARGELY, THIS FEATURE WILL BE
DRY FOR MUCH OF THE CWA WITH ANY POTENTIAL PRECIP BEING CONFINED TO
RIGHT ALONG THE INTERNATIONAL BORDER ON THE GENEROUS SIDE OF THE
SOLUTIONS OR JUST TO THE FAR NE CORNER OF THE NORTH CASCADES ON THE
STINGIER SIDE. THERE ARE HINTS THAT ISOLATED THUNDERSTORMS MAY BE
POSSIBLE WITH THIS FEATURE, AGAIN, CONFINED TO THE LOCATIONS WHERE
CHANCE FOR PRECIP EXIST, MAINLY LATE WEDNESDAY AFTERNOON INTO
WEDNESDAY EVENING. THIS TROUGHY PATTERN CONTINUES FOR THE REMAINDER
OF THE WEEK AND INTO THE WEEKEND, WITH SOME SLIGHT HINTS AT THE
POSSIBILITY OF A MORE ACTIVE PATTERN FOR THE UPCOMING WEEKEND.
IN SPITE OF THIS POTENTIALLY TROUGHY PATTERN, EXTENDED GUIDANCE
CONTINUES TO SUGGEST A WARMING TREND THURSDAY THROUGH SATURDAY. HIGH
TEMPS THURSDAY ARE EXPECTED TO CLIMB BACK INTO THE UPPER 70S TO
LOWER 80S. DAYTIME HIGHS REACH THEIR PEAK FRIDAY WITH MID 80S TO
NEAR 90 FORECAST FOR THE INTERIOR LOWLANDS BEFORE SLIPPING A LITTLE
BIT FOR SATURDAY, RANGING IN THE LOWER TO MID 80S.
18
AVIATION
ZONAL FLOW PERSISTS TODAY AND AGAIN MONDAY AS LOW LEVEL FLOW REMAINS
ONSHORE. THIS PATTERN WILL ALLOW FOR SOME TERMINALS TO HAVE WINDS GO
LIGHT AND VARIABLE DURING THE OVERNIGHT AND EARLY MORNING HOURS WITH
DIRECTION BEING VARIATIONS ON A WESTERLY THEME, THOUGH THERE SEEMS
TO BE A GENERAL CONSENSUS THAT MOST TERMINALS WILL FAVOR
SOUTHWESTERLY WINDS THIS AFTERNOON, BECOMING MORE NORTHWESTERLY THIS
EVENING AND TONIGHT. SPEEDS DURING THIS TIME FRAME WILL TYPICALLY
RANGE 4-8 KTS ALTHOUGH CLM AND HQM MAY SEE SLIGHTLY HIGHER SPEEDS
RANGING 8-12 KTS WITH OCCASIONAL GUSTS.
CIGS DEPEND GREATLY ON HOW FAR EASTWARD MARINE STRATUS HAS PUSHED
INLAND. COASTAL SITES REMAIN MVFR TO IFR AND IFR CONDITIONS STRETCH
AS FAR INLAND AS SHN...ALTHOUGH NOT QUITE GETTING TO CLM AT THE TIME
OF THIS WRITING. MODELS SEEM CONTENT TO LEAVE THESE CIGS CONFINED
WITH LITTLE ADDITIONAL EASTWARD PROGRESS EXPECTED, BUT WILL CONTINUE
TO MONITOR. REMAINDER OF TERMINALS VFR AND EXPECTED TO REMAIN THAT
WAY FOR THE BULK OF THE DAY.
KSEA...VFR CONDITIONS EXPECTED TO PERSIST FOR THE TAF PERIOD. AS
MENTIONED ABOVE, MARINE STRATUS HAVING A TOUGH TIME GETTING EAST OF
SHN BUT SOME SCT AT OR AROUND 1000 FT SEEMS LIKE A GOOD POSSIBILITY.
LIGHT NW WINDS IN THE EARLY MORNING EXPECTED TO SWITCH TO SW BY 18Z
FOR SURE, BUT COULD DO SO EARLIER. RETURNING TO NW IS EXPECTED LATE
THIS AFTERNOON/EARLY THIS EVENING BEFORE BECOMING LIGHT AND VARIABLE
OVERNIGHT. SPEEDS GENERALLY 4-8 KTS.
18
MARINE
BROAD SURFACE HIGH PRESSURE WILL REMAIN CENTERED OVER THE OFFSHORE
WATERS WITH LOWER PRESSURE EAST OF THE CASCADES INTO NEXT WEEK. THIS
WILL MAINTAIN ONSHORE FLOW OVER THE NEXT SEVERAL DAYS AND BRING
DIURNALLY DRIVEN SMALL CRAFT ADVISORY STRENGTH WESTERLIES TO THE
CENTRAL AND EAST STRAIT OF JUAN DE FUCA DAILY. A SERIES OF WEAK
SYSTEMS PASSING TO THE NORTH OF THE AREA THIS UPCOMING WEEK MAY
STRENGTHEN ONSHORE FLOW AT TIMES FOR ADDITIONAL RISKS OF GALES ALONG
THE CENTRAL AND EASTERN STRAIT.
SEAS ACROSS THE COASTAL WATERS WILL PRIMARILY PERSIST AT 4-6 FT INTO
EARLY NEXT WEEK AND MAY BECOME STEEP AT TIMES THIS WEEKEND UNDER
LOCALLY DRIVEN WINDS. SEAS WILL THEN SUBSIDE TO 2-4 FT BY TUESDAY,
BEFORE INCREASING BACK TO 4-6 FT BY MIDWEEK.
27/18
FIRE WEATHER
ONSHORE FLOW REMAINS IN PLACE SO ALTHOUGH CONDITIONS REMAIN DRY,
MORE SEASONABLE TEMPERATURES AND PERSISTENT GOOD TO EXCELLENT
OVERNIGHT RH RECOVERIES WILL PREVENT ANY WIDESPREAD FIRE WEATHER
CONCERNS AT LEAST UNTIL WEDNESDAY. MODELS ARE STARTING TO GEL AROUND
A CONSENSUS SHOWING AN UPPER LEVEL LOW TRACKING JUST NORTH OF THE
AREA LATE TUESDAY/EARLY WEDNESDAY. ANY IMPACTS TO W WA WILL BE
MINIMAL, HOWEVER THERE IS A SUGGESTION FOR POSSIBLE THUNDERSTORMS
WEDNESDAY AFTERNOON AND EVENING FOR THE FAR NORTHERN CASCADES. THE
EXTEND OF THIS POSSIBILITY IS EXTREMELY LIMITED IN MODEL SOLUTIONS
RIGHT NOW, BUT IT WILL BE SOMETHING TO KEEP AN EYE ON. WARMING
TEMPERATURES OVER THE SECOND HALF OF THE WEEK COULD RESULT IN
INCREASED POTENTIAL FOR ELEVATED FIRE WEATHER CONCERNS, BUT TOO
EARLY TO SPECULATE ON THAT JUST YET AS A HIGH DEGREE OF UNCERTAINTY
CONTINUES TO SURROUND THE LONG TERM FORECAST.
18
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...GALE WARNING UNTIL 3 AM PDT EARLY THIS MORNING FOR CENTRAL
U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S.
WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 5 AM PDT
MONDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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