519
FXUS66 KSEW 172138
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
238 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/
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 /SUNDAY NIGHT 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
AN UPPER LEVEL LOW WILL CONTINUE TO MOVE
NORTHEASTWARD TODAY WITH SOUTH TO SOUTHWEST FLOW ALOFT AS THE
TROUGH TRANSITS INLAND. SATELLITE THIS AFTERNOON CONTINUES TO
SHOW SCATTERING AND LIFTING OF CEILINGS, WITH MOST TERMINALS
REPORTING VFR WITH BROKEN OR SCATTERED DECKS BETWEEN 3,000 AND
5,000 FT. A FEW MVFR AREAS REMAIN ALONG THE NORTH OLYMPICS.
MODELS STILL HAVE THE MARINE PUSH BRINGING STRATUS IN SATURDAY
MORNING, BUT HAVE DECREASED PROBABILITIES FOR NON-VFR CEILINGS
FOR THE MAJORITY OF THE MAIN PUGET SOUND TERMINALS (KSEA AND
KBFI DROPPED TO 20-40% CHANCE OF MVFR SATURDAY MORNING). THE
HIGHER LIKELIHOODS OF MVFR (AND ALSO IFR/LIFR) IS FROM KPAE WEST
THROUGH THE STRAIT OF JUAN DE FUCA, AND FROM KOLM WESTWARD
WHERE THE PACIFIC COAST/STRAIT OF JUAN DE FUCA COASTS HAVE
40-60% CHANCE OF CEILINGS DOWN TO LIFR OVERNIGHT. WINDS WILL
REMAIN OUT OF THE SOUTHWEST AROUND 5-10 KT, WITH SOME NORTH
WINDS AT TIMES IN THE AFTERNOONS FROM KPAE DOWN THROUGH PUGET
SOUND TO KSEA/KBFI.
KSEA...SCATTERING/VFR CEILINGS THIS AFTERNOON, WITH A 20-40% CHANCE
OF MVFR CEILINGS DEVELOPING BETWEEN 11Z-17Z SATURDAY. WINDS 5-10 KT
OUT OF THE SOUTHWEST - DIMINISHING TO 6 KT OR LESS AFTER 03Z WITH
WINDS SWITCHING BRIEFLY TO THE NORTHWEST/NORTH THROUGH 10Z. WINDS
FLIP BACK TO THE SOUTHWEST BETWEEN 10Z-21Z BEFORE SWITCHING TO THE
NORTHWEST AGAIN.
HPR
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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