031
FXUS66 KSEW 180311
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
811 PM PDT FRI JUL 17 2026
SYNOPSIS
DRIER CONDITIONS WITH SEASONABLE TEMPERATURES
THROUGH THE WEEKEND. HIGH PRESSURE BUILDS OVER WESTERN
WASHINGTON NEXT WEEK BRINGING CONTINUED DRY WEATHER AND WELL-
ABOVE AVERAGE TEMPERATURES THROUGH AT LEAST MIDWEEK.
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
NO PLANNED UPDATES
TONIGHT AND THE CURRENT FORECAST REMAINS ON TRACK. 33
PREVIOUS DISCUSSION...CLOUDS CONTINUE TO CLEAR FOR MOST AREAS
THIS AFTERNOON WITH TEMPERATURES IN THE 60S AND 70S. THE UPPER
LOW REMAINS POSITIONED OFFSHORE OF CAPE FLATTERY AND WILL SLOWLY
PROGRESS NORTHEASTWARD INTO BRITISH COLUMBIA THROUGH SATURDAY.
THIS WILL RESULT IN ANOTHER ROUND OF MORNING STRATUS ACROSS
WESTERN WASHINGTON SATURDAY AM. TEMPERATURES WILL REMAIN
SEASONABLE AGAIN ON SATURDAY WITH HIGHS IN THE 60S ALONG THE
COAST, AND 70S FOR THE INTERIOR. HIGH PRESSURE SLOWLY BEGINS TO
BUILD OVER THE PACIFIC NORTHWEST SUNDAY, RESULTING IN LESS
MORNING CLOUD COVER, AND TEMPERATURES WARMING INTO THE 80S FOR
SOME LOCATIONS BY THE AFTERNOON.
LONG TERM /MONDAY THROUGH FRIDAY/
UPPER LEVEL RIDGING
FURTHER BUILDS INTO WESTERN WASHINGTON MONDAY THROUGH MIDWEEK.
THIS WILL RESULT IN A MORE SIGNIFICANT WARMING TREND, WITH
TEMPERATURES RISING INTO THE 80S AND LOW 90S DURING THIS
PERIOD. WIDESPREAD MODERATE HEATRISK IS EXPECTED FOR INTERIOR
LOCATIONS, WITH A 20 TO 50% PROBABILITY OF MAJOR HEATRISK FOR
CASCADE VALLEYS AND PORTIONS OF CENTRAL PUGET SOUND TUESDAY AND
WEDNESDAY. UNCERTAINTY BEGINS TO INCREASE IN ENSEMBLES IN
REGARDS TO POTENTIAL WEAK TROUGHING OFFSHORE OF THE WEST COAST
BY LATE WEDNESDAY/THURSDAY. AT THIS TIME, A SLIGHT COOLING TREND
MAY BEGIN ON THURSDAY AND CONTINUE INTO FRIDAY. ANOTHER ASPECT
OF THE FORECAST THAT WILL BE FURTHER MONITORED IS THE EXISTENCE
OF ANY MONSOONAL MOISTURE AROUND THE THURSDAY PERIOD WHICH COULD
RESULT IN POP CHANCES, AT LEAST FOR THE CASCADES AND OLYMPICS.
NBM POPS AT THIS TIME REMAIN LOW (AROUND 10 TO 20%), BUT WILL BE
DEPENDENT ON THE VICINITY TO TROUGHING OFFSHORE. JD
AVIATION
VFR CONDITIONS ACROSS ALL WESTERN WASHINGTON
TERMINALS THIS EVENING, WITH ANOTHER ONSHORE MARINE PUSH
EXPECTED TO BRING INCREASED LOW END VFR TO MVFR CEILINGS INLAND
TONIGHT. ISOLATED AREAS OF IFR/LIFR IN LOW STRATUS ARE FAVORED
OVERNIGHT ALONG THE PACIFIC COAST AND THROUGH THE STRAIT OF JUAN
DE FUCA. DETERIORATED CONDITIONS IN LOW CLOUDS WILL LIKELY
PERSIST THROUGH MUCH OF THE MORNING SATURDAY BEFORE THE CLOUDS
BEGIN TO BREAK UP. A RETURN TO VFR IS EXPECTED FOR MOST AREAS
SATURDAY AFTERNOON, WITH POTENTIAL FOR MVFR CEILINGS TO CONTINUE
ALONG THE COAST AND THROUGH THE STRAIT. WEST TO SOUTHWEST WINDS
THIS EVENING GENERALLY 8 KT OR LESS WILL SHIFT WEST/NORTHWEST
THIS EVENING AND TURN BACK TO SOUTHERLY SATURDAY MORNING WITH
LIGHT WINDS 10 KT OR LESS.
KSEA...VFR THIS EVENING WITH LIGHT SOUTHERLY WINDS SHIFTING
NORTHERLY BRIEFLY OVERNIGHT. WINDS WILL FLIP BACK TO THE SOUTHWEST
SATURDAY MORNING. CEILINGS ARE FAVORED TO REMAIN VFR TONIGHT, WITH A
LOW CHANCE (15% TO 20%) OF MVFR STRATUS DEVELOPING OVER THE
TERMINAL. CEILINGS MAY ONCE AGAIN BOUNCE BETWEEN VFR AND MVFR
OVERNIGHT, WITH A RETURN TO VFR BY 16Z SATURDAY.
15
MARINE
A LOW/TROUGH OFFSHORE WILL CONTINUE TO MOVE INLAND
TODAY WITH HIGH PRESSURE REBUILDING OFFSHORE. THERE WILL ALSO BE
A THERMAL TROUGH BUILDING UNDER A RIDGE GOING INTO NEXT WEEK.
WHILE FLOW DOES NOT APPEAR TO GO OFFSHORE COMPLETELY, THERE WILL
BE VARYING DEGREES OF ONSHORE PUSHES THROUGH THE STRAIT OF JUAN
DE FUCA, AS WELL AS SOME NORTH/NORTHWEST WINDS IN THE COASTAL
WATERS EARLY NEXT WEEK. THE NEXT POTENTIAL FOR WINDS OVER 20 KT
IS A 40-60% CHANCE OF GUSTS OVER THIS THRESHOLD IN THE STRAIT OF
JUAN DE FUCA SATURDAY EVENING. POTENTIAL FOR THESE WINDS NEXT
WEEK REMAINS LOW AT THIS TIME.
SEAS OF 3-6 FT WILL INCREASE TO 6-9 FT EARLY NEXT WEEK, WITH SEAS
POTENTIALLY BECOMING CHOPPY AS PERIODS DECREASE TO AROUND 8 SECONDS
SUNDAY INTO MONDAY. SEAS DECREASE BACK DOWN TO 4-6 FT THE REMAINDER
OF NEXT WEEK.
HPR
FIRE WEATHER
FIRE WEATHER CONCERNS WILL LINGER THROUGHOUT
THE FORECAST PERIOD AS A HOTTER AND DRIER PATTERN RETURNS
QUICKLY OVER WESTERN WASHINGTON, ESPECIALLY MONDAY THROUGH MUCH
OF NEXT WEEK. THIS HAS THE POTENTIAL FOR INCREASING FIRE
ACTIVITY FROM ANY NEW LIGHTNING STARTS FROM THURSDAY'S
CONVECTION.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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