627
FXUS66 KSEW 160251
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
751 PM PDT THU OCT 15 2026
SYNOPSIS
A RIDGE WILL BRING DRY AND WARM CONDITIONS INTO FRIDAY WITH
HIGHS IN THE MID 70S. THE PATTERN FLIPS BACK TO TROUGH DOMINANT
OVER THE WEEKEND WITH A WEAK SYSTEM BRINGING LIGHT RAIN ON
SATURDAY. ADDITIONAL RAINFALL IS EXPECTED EARLY NEXT WEEK.
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
WINDS WILL BECOME BREEZY OVERNIGHT FROM THE EAST. THE WINDS
WILL BE MOST ELEVATED IN THE CASCADES AND ADJACENT FOOTHILLS,
EASING BY FRIDAY MORNING. GUSTS IN THESE LOCATIONS WILL LIKELY
BE BETWEEN 25-30 MPH. GIVEN THE OFFSHORE FLOW, FOG POTENTIAL
WILL BE LIMITED TOMORROW MORNING. ISOLATED PATCHY FOG IN THE
SOUTH SOUND AND FOG PRONE VALLEY LOCATIONS MAY STILL OCCUR.
FRIDAY WILL BE SLIGHTLY WARMER, WITH ANTICIPATED HIGHS IN THE
MID TO UPPER 70S. RESIDUAL INFLUENCE OF THE OFFSHORE FLOW WILL
ALSO DRY THINGS OUT WITH AFTERNOON RELATIVE HUMIDITY VALUES
DIPPING INTO THE UPPER 30 TO LOW 40 PERCENT RANGES ACROSS
WESTERN WASHINGTON.
ONSHORE FLOW RESUMES FRIDAY AFTERNOON AND BY SATURDAY, THE NEXT
WEAK FRONTAL SYSTEM WILL TRAVERSE THE AREA. THIS WILL BRING A
FEW HUNDREDTHS OF AN INCH TO MOST LOWLAND LOCATIONS AND AROUND A
QUARTER OF AN INCH TO THE CASCADES. AREAS OF CENTRAL PUGET SOUND
MAY END UP MORE RAINSHADOWED GIVEN THE WEAK MOISTURE PROFILE AND
SOUTHWESTERLY FLOW. ELEVATED WESTERLY WINDS WILL MOVE THROUGH
THE STRAIT OF JUAN DE FUCA AND ADMIRALTY INLET SATURDAY
AFTERNOON AND EVENING BEHIND THE FRONT.
LONG TERM /SUNDAY THROUGH THURSDAY/
SUNDAY WILL BE COOL AND MOSTLY DRY AS THE TROUGH OFFSHORE
LINGERS. HIGHS WILL BE IN THE UPPER 50S AND LOW 60S. MOST MODEL
GUIDANCE REGARDING THE LOW PRESSURE SYSTEM ON MONDAY ACTUALLY
TAKE THE FEATURE TO THE SOUTH OF THE CWA. WITH THAT PROGNOSIS,
THE AREA GENERALLY STAYS DRY, BUT COOL INTO MONDAY. THAT TROUGH
WILL CONTINUE MOVING SOUTH, BUT GULF OF ALASKA TROUGHING BUILDS
BACK IN THROUGH THE MIDDLE OF THE WEEK. A WEAK FRONT MOVING OFF
THAT LOW MAY ARRIVE WEDNESDAY INTO THURSDAY BUT DOES NOT LOOK
PARTICULARLY STRONG AND MAY PRODUCE ISOLATED SHOWERS THROUGH
THURSDAY.
21
AVIATION
HIGH PRESSURE ALOFT OVER THE REGION THIS AFTERNOON WILL SHIFT INLAND
FRIDAY. FLOW ALOFT WILL REMAIN SOUTHWESTERLY THROUGH THE PERIOD.
SURFACE WINDS GENERALLY NORTHERLY HOWEVER MANY TERMINALS HAVE
ALREADY GONE LIGHT AND VARIABLE, WITH THE REMAINING TERMINALS
EXPECTED TO GO IN THIS DIRECTION OVERNIGHT TONIGHT AND INTO FRIDAY
MORNING. A SHIFT TO SOUTHERLY WINDS EXPECTED BY NOON WITH SPEEDS
INCREASING SLIGHTLY TO 4-8 KTS.
CLEAR SKIES OVER W WA THIS EVENING VIA SATELLITE WITH WIDESPREAD VFR
IN PLACE. A SYSTEM APPROACHING THE REGION OFFSHORE WILL BRING
INCREASING HIGH CLOUD COVER TO THE AREA TONIGHT INTO FRIDAY. HIGH
CLOUD COVER AND CONTINUED OFFSHORE FLOW IN THE LOW LEVELS TONIGHT
WILL LIKELY LIMIT WIDESPREAD FOG DEVELOPMENT ON FRIDAY MORNING, WITH
HI-RES GUIDANCE SHOWING MINIMAL DEVELOPMENT EXPECTED FOR THE AREA
TERMINALS. HOWEVER, A SHALLOW LAYER OF MOISTURE REMAINS PRESENT AND
COULD LEAD TO SOME FOG DEVELOPMENT AT MORE FOG-PRONE TERMINALS.
EAST/NORTHEASTERLY WINDS WILL PERSIST AT 5-10 KT THROUGH THE
EVENING HOURS, BEFORE EASING TONIGHT. WINDS WILL THEN TRANSITION
TO THE SOUTHEAST OVERNIGHT INTO EARLY FRIDAY AND THEN BECOME
MORE SOUTHERLY THROUGH THE MORNING HOURS.
KSEA...VFR CONDITIONS. NORTHERLY WINDS PERSISTING BETWEEN 5-10
KT WILL EASE LATER TONIGHT AND BECOME 5 KT OR LESS. WINDS WILL
THEN GRADUALLY SHIFT TO THE SOUTHEAST OVERNIGHT AND THEN BECOME
MORE SOUTHERLY THROUGH THE MORNING HOURS ON FRIDAY. FOG DEVELOPMENT
WILL LIKELY BE MORE LIMITED OVERNIGHT DUE TO OFFSHORE FLOW AND
HIGH CLOUD COVER STREAMING IN OVERHEAD, HOWEVER AREAS OF PATCHY
FOG MAY DEVELOP WITHIN THE VICINITY OF THE TERMINAL.
14/18
MARINE
HIGH PRESSURE OVER THE OFFSHORE WATERS WITH A THERMAL TROUGH
ALONG THE COAST WILL PROMOTE OFFSHORE FLOW ACROSS THE AREA
WATERS INTO FRIDAY MORNING. THE TROUGH WILL PUSH INLAND ON
FRIDAY AHEAD OF AN APPROACHING FRONTAL SYSTEM, ALLOWING FOR
WINDS TO SWITCH BACK TO ONSHORE. WINDS WILL INCREASE FRIDAY
NIGHT INTO SATURDAY, WITH THE STRONGEST WINDS EXPECTED ALONG
THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA, WHERE LATEST HI-
RES GUIDANCE CONTINUES TO SHOW ROUGHLY A 35-50% LIKELIHOOD OF
GUSTS EXCEEDING GALE FORCE. WINDS WILL BECOME BREEZY AS THE
FRONTAL SYSTEM APPROACHES, WITH OTHER LOCATIONS SUCH AS THE
OUTER COASTAL WATERS AND WATERS OF PUGET SOUND AND HOOD CANAL
LIKELY SEEING WIND GUSTS EXCEED SMALL CRAFT CRITERIA. WINDS WILL
DECREASE AS THE SYSTEM EXITS THE AREA SATURDAY EVENING AND WILL
REMAIN RELATIVELY LIGHT ON SUNDAY. A LOW PRESSURE SYSTEM WILL
TRACK SOUTHWARD OFFSHORE ON MONDAY, JUST SKIRTING THE COASTAL
WATERS. THIS SYSTEM WILL THEN LIKELY BRING ANOTHER ROUND OF
OFFSHORE FLOW TO THE AREA WATERS MONDAY NIGHT INTO TUESDAY.
SEAS WILL PERSIST BETWEEN 3-6 FT INTO FRIDAY, BEFORE BUILDING TO
8-10 FT OVER THE WEEKEND. SEAS COULD EVEN BUILD FURTHER EARLY
NEXT WEEK, BUT WILL BE DEPENDENT ON THE TRACK OF THE SYSTEM
OFFSHORE. THE MOST LIKELY SCENARIO SHOWS SEAS BUILDING TO 9-12
FT ON MONDAY, HOWEVER THE GEFS DOES CONTINUE TO HIGHLIGHT A
40-50% OF SEAS EXCEEDING 12 FT.
14
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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