720
FXUS66 KSEW 072121
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
221 PM PDT THU AUG 7 2025
SYNOPSIS
LINGERING SHOWERS WILL CONTINUE TO DIMINISH THIS
AFTERNOON, WITH COOLER TEMPERATURES AND CLOUDS HANGING AROUND. THE
PATTERN CHANGES FRIDAY INTO EARLY NEXT WEEK AN UPPER LEVEL RIDGE
BUILDS ACROSS THE REGION. TEMPERATURES WILL INCREASE AND
CONDITIONS WILL DRY OUT AS A RESULT. CONDITIONS WILL COOL GOING
INTO THE MIDDLE OF THE WEEK AS THE RIDGE DEPARTS THE REGION, WITH
A TROUGH PATTERN MOVING IN.
SHORT TERM /TONIGHT THROUGH SUNDAY/
RADAR IS MUCH QUIETER THIS
AFTERNOON WITH JUST A COUPLE OF SHOWERS LINGERING IN REMNANTS OF
THIS MORNING'S CONVERGENCE ZONE IN NORTH PUGET SOUND. SATELLITE
SHOWS QUITE A BIT OF CLOUD COVERAGE BEGINNING TO SCATTER AS THE
TROUGH RESPONSIBLE FOR THE SHOWER ACTIVITY DIGS SOUTHEASTWARD AND
OUT OF THE REGION. TEMPERATURES WILL REMAIN COOL TODAY WITH HIGHS
LIKELY ONLY REACHING THE UPPER 60S TO LOW 70S IN THE INTERIOR
(MANY AREAS WERE STILL IN THE 60S AS OF 1 PM THIS AFTERNOON).
ON FRIDAY, AN UPPER LEVEL HIGH OFFSHORE WILL INCH CLOSER TO THE
SHORE. FLOW WILL BECOME MERIDIONAL AS A THE DEPARTING TROUGH DIGS
SOUTHWARD OVER THE NORTHERN GREAT PLAINS (AND AS THE HIGH
AMPLIFIES AND BUILDS A RIDGE OVER THE HIGH UP TO ALASKA).
CONDITIONS WON'T WARM UP TOO MUCH ON FRIDAY (GIVEN SOME MARINE AIR
WILL BRING SOME CLOUDS IN THE MORNING), BUT SKIES WILL CLEAR OUT
OVER MUCH OF THE REGION IN THE AFTERNOON. WINDS WILL GENERALLY BE
LIGHT OUT OF THE NORTHWEST DURING THE DAY. HIGHS IN THE INTERIOR
WILL CLIMB INTO THE MID AND UPPER 70S (POTENTIAL FOR AN 80 IN THE
SOUTH INTERIOR), BUT REMAIN IN THE 60S ALONG THE COAST. SATURDAY
WILL LIKELY BE A REPEAT OF FRIDAY, WITH MORE WIDESPREAD CLEARING
TAKING PLACE IN THE AFTERNOON/OVERNIGHT PERIOD AS THE RIDGE AXIS
TILTS OVER THE REGION. MID 70S TO LOW 80S ARE EXPECTED IN THE
INTERIOR, WITH MINOR (YELLOW) HEATRISK.
WITH THE RIDGE AXIS COMING OVER A LITTLE SOONER, TEMPERATURES ON
SUNDAY INCREASED QUITE A BIT WITH SKIES REMAINING CLEAR OVERNIGHT
(AND SKIES REMAINING CLEAR DURING THE DAY). SOME MODELS ALSO SHOW
A BRIEF THERMAL TROUGH ALONG THE COAST (TYPICALLY A GOOD SOURCE
FOR SOME INSTABILITY IN THE AIR AND AIDING IN WARMER
TEMPERATURES - FORECAST SOUNDINGS SHOW A CONDITIONALLY UNSTABLE
AIRMASS OVER THE REGION). TEMPERATURES NOW APPEAR TO PEAK SUNDAY
AFTERNOON, WITH HIGHS IN THE INTERIOR IN THE 80S (AND SOME LOW 90S
IN THE SOUTH INTERIOR). AN INCREASED AREA OF MODERATE (ORANGE)
HEATRISK NOW SPANS ACROSS THE SOUTH INTERIOR (AND SOME
CASCADE/OLYMPIC VALLEY AREAS). LOWS WILL ALSO CREEP UP INTO THE
UPPER 50S TO LOW 60S SUNDAY INTO MONDAY.
LONG TERM /MONDAY THROUGH THURSDAY/
THE SUNDAY PATTERN IS
EXPECTED TO CONTINUE INTO MONDAY WITH HIGH TEMPERATURES LIKELY
REMAINING WARM IN THE 80S AND LOW 90S IN THE INTERIOR (WARMEST
TOWARDS THE SOUTH). THE TEMPERATURE SPREAD FOR TUESDAY REMAINS
LARGE AS THE ENSEMBLES STILL HAVE QUITE A BIT OF A TIMING ISSUE
WITH THE BREAKDOWN OF THE RIDGE. A COUPLE SOLUTIONS ALSO HAVE A
TROUGH POTENTIALLY DIGGING SOUTHWARD OVER THE REGION (THOUGH SOME
MODELS KEEP THIS UP INTO CANADA). NEVERTHELESS, HEATRISK WILL DROP
TO MINOR TUESDAY THROUGH MIDWEEK, TEMPERATURES WILL COOL DOWN
GRADUALLY WITH INCREASING ONSHORE FLOW, AND AT THIS TIME
CONDITIONS ARE EXPECTED TO REMAIN DRY.
HPR
AVIATION
NORTHWESTERLY WINDS WILL CONTINUE ACROSS THE AREA IN
THE WAKE OF AN UPPER LEVEL LOW.
CLOUD COVER IS SLOWLY BEGINNING TO BREAK UP, AND CEILINGS HAVE
LIFTED TO VFR AREA-WIDE. CLOUDS SHOULD SLOWLY CONTINUE TO SCATTER
OUT AND CLEAR THROUGH THIS AFTERNOON AND EVENING. MARINE STRATUS IS
EXPECTED TO REDEVELOP LATE TONIGHT INTO EARLY TOMORROW MORNING.
THERE IS A BIT OF UNCERTAINTY AS TO HOW FAR INLAND THE STRATUS MAKE
IT. PROBABILITIES HAVE GONE DOWN ACROSS THE INTERIOR TERMINALS
COMPARED TO THIS MORNING BUT REMAIN IN THE 25-40% RANGE. CEILINGS
WILL LOWER TO THE MVFR TO IFR RANGE, WITH THE LOWEST CEILINGS
EXPECTED ALONG THE COAST. WESTERLY WINDS ACROSS THE AREA WILL BECOME
LARGELY NORTHWESTERLY TONIGHT THEN BECOMING LIGHT AND VARIABLE
OVERNIGHT. WINDS WILL BE WEST TO NORTHWEST AGAIN TOMORROW, BUT A BIT
WEAKER.
KSEA...VFR CONDITIONS THROUGH THE REST OF TODAY AND THROUGH EARLY
MONDAY. MARINE STRATUS IS EXPECTED TO PUSH TOWARDS THE TERMINAL,
ALLOWING FOR A FEW HOURS OF MVFR (POTENTIALLY IFR) CONDITIONS.
MOSTLY CLEAR SKIES ARE EXPECTED FOR MUCH OF FRIDAY. WINDS
NORTHWESTERLY THIS AFTERNOON, BECOMING LIGHT NORTHEASTERLY
OVERNIGHT. WINDS TOMORROW WILL BE NORTHWESTERLY.
62
MARINE
A WEAK FRONTAL SYSTEM WELL OFFSHORE WILL DISSIPATE NEAR
THE AREA WATERS ON FRIDAY, THEN, HIGH PRESSURE WILL SLOWLY REBUILD
OVER THE NORTHEAST PACIFIC THIS WEEKEND INTO NEXT WEEK. A DIURNALLY
DRIVEN WESTERLY PUSH DOWN THE STRAIT OF JUAN DE FUCA WILL BRING LOW-
END SMALL CRAFT ADVISORY WINDS TONIGHT, WITH ONE MORE WEAKER PUSH
FRIDAY EVENING THAT WILL REMAIN BELOW THRESHOLDS.
AS HIGH PRESSURE BUILDS OVER THE WATERS, WITH A WEAK THERMAL TROUGH
ALONG THE COASTLINE, NORTHWESTERLY WINDS WILL BUILD ALONG THE COAST
STARTING SUNDAY INTO NEXT WEEK.
SEAS 4 TO 6 FT WILL EASE A BIT TOMORROW, BEFORE RISING UP TO 6 TO 8
FT BY SUNDAY. DEPENDING ON THE STRENGTH OF THE NORTHWEST WINDS,
WAVES MAY GET UP TO 10-12 FT THROUGH THE OUTER COASTAL WATERS EARLY
NEXT WEEK.
62
FIRE WEATHER
COOLER AND CLOUDIER CONDITIONS WILL CONTINUE TODAY,
HELPING TO MODERATE TEMPERATURES WITH GOOD OVERNIGHT RH RECOVERIES.
THE NEXT ELEVATED FIRE WEATHER CONCERN IS THE HOT AND DRY PATTERN
EXPECTED LATE THIS WEEKEND INTO EARLY NEXT WEEK AS RIDGING BUILDS
IN OVER THE AREA FROM THE PACIFIC. WARMING TEMPERATURES, WITH
HIGHS IN THE 80S TO LOW 90S AND MINIMUM RELATIVE HUMIDITIES DIPPING
DOWN INTO THE 20S AND 30S BY EARLY NEXT WEEK WILL ELEVATE FIRE
WEATHER CONCERNS ACROSS PORTIONS OF THE INTERIOR. ENSEMBLES THEN
SUGGEST TROUGHING REDEVELOPING ACROSS THE REGION AGAIN BY MIDWEEK,
WHICH WOULD HELP MODERATE TEMPERATURES AND INCREASE ONSHORE FLOW.
14/MAZURKIEWICZ
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT FRIDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
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