984
FXUS66 KSEW 150323
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
823 PM PDT FRI AUG 14 2026
SYNOPSIS
AN UPPER LEVEL TROUGH OVER THE AREA TODAY WILL BRING CHANCES OF
THUNDERSTORMS ACROSS THE MOUNTAINS AND CRITICAL FIRE WEATHER
CONDITIONS. THUNDERSTORM POTENTIAL WILL CONTINUE ALONG THE CASCADES
ON SATURDAY, BUT WILL WANE THROUGHOUT THE WEEKEND AS AN UPPER
LEVEL RIDGE STARTS TO BUILDS INTO THE AREA FROM THE SOUTHEAST.
ANOTHER UPPER LEVEL TROUGH WILL MOVE INTO THE REGION EARLY NEXT
WEEK. UNCERTAINTY THEN INCREASES IN THE FORECAST HEADING INTO
MIDWEEK AS GUIDANCE REMAINS SPLIT BETWEEN A WARMER, DRIER PATTERN
AND A COOLER, WETTER ONE.
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
THE THUNDERSTORM AND FIRE THREAT HAVE ENDED THIS EVENING AS
ACTIVITY DIMINISHES ACROSS BOTH THE CASCADES AND OLYMPICS.
REMAINDER OF THE SHORT TERM SECTION IS ON TRACK FOR TONIGHT/THIS
WEEKEND. UPDATES WERE ALSO MADE TO THE FIRE AND AVIATION
SECTIONS THIS EVENING. -HPR
AN UPPER LEVEL TROUGH WILL WEAKEN ACROSS THE AREA TONIGHT,
ALLOWING FOR A RIDGE TO BUILD INTO THE AREA FROM THE SOUTHEAST
OVER THE WEEKEND. SOUTHWESTERLY FLOW WILL DEVELOP ALOFT AND WILL
HELP TO PUSH SMOKE OUT OF THE AREA THIS WEEKEND. LOW LEVEL FLOW
WILL REMAIN ONSHORE, ALLOWING FOR MARINE STRATUS TO PUSH INLAND
DURING THE OVERNIGHT PERIODS BOTH SATURDAY AND SUNDAY. WHILE
OVERALL THUNDERSTORM CHANCES WILL PRIMARILY WANE THROUGHOUT THE
WEEKEND, ANOTHER ROUND OF THUNDERSTORMS WILL BE POSSIBLE ACROSS
THE CASCADES ON SATURDAY AFTERNOON AND EVENING AS THE AIR MASS
BECOMES UNSTABLE DURING THE AFTERNOON HOURS AND SOME MONSOONAL
MOISTURE WORKS ITS WAY UP INTO THE REGION. BY SUNDAY, ANY
THUNDERSTORMS THAT DO DEVELOP WILL MOSTLY BE CONFINED TO THE
CASCADE CREST AND AREAS EAST OF THE CREST. AFTERNOON HIGHS OVER
THE WEEKEND WILL BE IN THE UPPER 70S TO LOW 80S ACROSS THE
INTERIOR AND IN THE MID TO UPPER 60S ALONG THE COAST, WHILE
OVERNIGHT LOWS WILL BE IN THE 50S.
14
LONG TERM /MONDAY THROUGH FRIDAY/
THE FIRST PART OF NEXT WEEK REMAINS TO FOLLOW A RATHER TYPICAL
PATTERN OF ONSHORE LOW-LEVEL FLOW MAINTAINING MORNING CLOUDS, WITH
SOME CLEARING IN THE AFTERNOON. A PASSING TROUGH AROUND TUESDAY
COULD PROVIDE A REINFORCING PUSH OF CLOUDS AND KNOCK TEMPERATURES A
FEW DEGREES COOLER THAN NORMAL. OTHERWISE, ENSEMBLE GUIDANCE BEGINS
TO SPREAD A BIT LARGER TOWARD THE MIDDLE OF NEXT WEEK WITH A FAIRLY
EVEN SPLIT BETWEEN A COOLER TROUGH PATTERN AND A WARMER (NEAR
NORMAL) PATTERN UNDER ZONAL FLOW OR A WEAK RIDGE. IN ANY EVENT,
THERE'S NOT A SIGNIFICANT SIGNAL FOR ANY PRECIPITATION OF NOTE.
AVIATION
VFR CIGS AT THE MAJORITY OF TERMINALS THIS EVENING AND MVFR
ALONG THE COAST. ANOTHER SURGE OF STRATUS IS LIKELY LATER
TONIGHT THROUGH SATURDAY MORNING FOR MOST OF THE AREA, WITH IFR
CEILINGS AND VISIBILITY EXPECTED FOR MOST TERMINALS. IMPROVEMENT
TO VFR IN THE AFTERNOON. THE COAST MAY SEE SOME BRIEF
IMPROVEMENT, BUT CONDITIONS WILL LIKELY QUICKLY DETERIORATE BY
THE EVENING. THUNDERSTORM ACTIVITY CONTINUES THIS EVENING AND
WILL REMAIN CONFINED TO THE MOUNTAINS. ANOTHER ROUND OF
THUNDERSTORMS POSSIBLE FOR THE CASCADES TOMORROW.
KSEA...VFR FOR THE REMAINDER OF TODAY. SOME THUNDERSTORMS WILL
DEVELOP WELL EAST OF THE TERMINAL AREA AND CONTINUE INTO THE
EVENING, BUT IS NOT EXPECTED AT KSEA ITSELF. WINDS PREDOMINANTLY
FROM THE SOUTHWEST, BECOMING WEST/NORTHWEST (BUT 5 KT OR LESS) THIS
EVENING THROUGH 06Z. A RETURN TO LIGHT SOUTHWEST WINDS THEN FOLLOWS
OVERNIGHT, ALONG WITH THE RETURN OF LOW STRATUS AROUND 12Z WITH
IFR/LIFR CONDITIONS. CEILINGS EXPECTED TO IMPROVE IN THE AFTERNOON
TO VFR.
29
MARINE
HIGH PRESSURE REMAINING OFF THE COAST OF CALIFORNIA WILL KEEP
WINDS OVER THE COASTAL WATERS LIGHT THROUGH SATURDAY. HIGH
PRESSURE WILL THEN REBUILD OFFSHORE BRITISH COLUMBIA AND MOVE
SOUTHWARD ON SUNDAY AND REMAIN SITUATED OFF THE PACIFIC NORTHWEST
INTO NEXT WEEK. THIS WILL BRING THE RETURN OF NORTHWESTERLY WINDS
TO THE COASTAL WATERS. DIURNALLY DRIVEN WESTERLY WINDS DOWN THE
STRAIT OF JUAN DE FUCA WILL OCCUR EACH AFTERNOON AND EVENING
OVER THE NEXT SEVERAL DAYS, WITH WINDS APPROACHING SMALL CRAFT
ADVISORY STRENGTH AT TIMES.
SEAS WILL PRIMARILY REMAIN BETWEEN 3 TO 6 FT THROUGH THE
WEEKEND AND THROUGH MUCH WEEK.
14
FIRE WEATHER
THE RED FLAG WARNING WILL BE ALLOWED TO EXPIRE AT 9 PM THIS
EVENING FOR THE WEST CASCADES AND OLYMPICS. THE THUNDERSTORM
THREAT IN THESE AREAS HAS DIMINISHED THIS EVENING.
ELEVATED FIRE WEATHER CONDITIONS WILL CONTINUE ACROSS THE CASCADES
INTO SATURDAY WITH CHANCES OF THUNDERSTORMS POSSIBLE AGAIN ALONG
THE CASCADE CREST ON SATURDAY AFTERNOON AND EVENING. OVERALL
CHANCES FOR CONVECTION WILL DECREASE THROUGH THE WEEKEND, HOWEVER,
AS AN UPPER LEVEL RIDGE STARTS TO BUILD INTO THE AREA FROM THE
SOUTHEAST. BY SUNDAY, EXPECT CONVECTION TO MAINLY BE CONFINED TO
THE CASCADE CREST AND AREAS EAST OF THE CREST. ANOTHER UPPER
LEVEL TROUGH WILL MOVE INTO THE AREA NEXT WEEK AND COULD BRING
SOME ADDITIONAL ELEVATED FIRE WEATHER CONCERNS TO WESTERN
WASHINGTON AT TIMES.
14/HPR
SEW WATCHES/WARNINGS/ADVISORIES
WA...RED FLAG WARNING UNTIL 9 PM PDT THIS EVENING FOR EAST PORTION
OF THE OLYMPIC MOUNTAINS-WEST PORTION OF THE OLYMPIC
MOUNTAINS-WEST SLOPES OF THE CENTRAL CASCADES GENERALLY
ABOVE 1500 FEET-WEST SLOPES OF THE NORTH CASCADES
GENERALLY ABOVE 1500 FEET.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT SATURDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
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