834
FXUS66 KSEW 152130
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 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/
SKIES HAVE CLEARED THIS AFTERNOON WITH SUNNY SKIES AND
TEMPERATURES AROUND THE REGION IN THE MID TO UPPER 60S.
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 ON FRIDAY. FLOW ALOFT WILL REMAIN SOUTHWESTERLY THROUGH
THE PERIOD. LATEST SATELLITE IMAGERY SHOWS FOG AND LOW CLOUDS
HAVE LARGELY SCATTERED ACROSS THE AREA THIS AFTERNOON, LEADING
TO MOSTLY SUNNY SKIES ACROSS WESTERN WASHINGTON. CONDITIONS
ACROSS THE AREA TERMINALS HAVE REBOUNDED TO VFR AS A RESULT.
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
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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