877
FXUS66 KSEW 141022
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
322 AM PDT FRI AUG 14 2026
SYNOPSIS
UPPER LEVEL TROUGH OVER THE AREA TODAY WILL DISSIPATE TONIGHT.
WEAK UPPER LEVEL RIDGE BUILDING IN FROM THE SOUTHEAST OVER THE
WEEKEND. ANOTHER UPPER LEVEL TROUGH WILL ARRIVE MONDAY AND
REMAIN OVER WESTERN WASHINGTON FOR MOST OF NEXT WEEK.
SHORT TERM /TODAY THROUGH SUNDAY/
SATELLITE IMAGERY SHOWS STRATUS COVERING MOST OF THE LOWLANDS
WEST OF PUGET SOUND. STRATUS JUST TO THE WEST OF SEATTLE-TACOMA
AIRPORT AND HAS ALREADY REACHED WHIDBEY ISLAND AT 3 AM/10Z.
SMOKEY SKIES OVER THE REMAINDER OF THE AREA. TEMPERATURES WERE
MOSTLY IN THE MID 50S TO MID 60S.
WEAK UPPER LEVEL TROUGH REMAINING OVER THE AREA TODAY WITH LIGHT
LOW LEVEL ONSHORE FLOW. MARINE LAYER WILL RETREAT BACK TO THE
COAST IN THE AFTERNOON. LIKE THE PREVIOUS TWO DAYS AIR MASS
BECOMING UNSTABLE OVER THE HIGHER TERRAIN IN THE AFTERNOON
CREATING A CHANCE FOR CONVECTION OVER THE OLYMPICS AND CASCADES.
THERE IS A GOOD CHANCE THAT THESE STORMS WILL NOT PRODUCE
WETTING RAINS. GIVEN THE CURRENT VERY DRY CONDITIONS HAVE
UPGRADED THE FIRE WEATHER WATCH TO A RED FLAG WARNING THIS
AFTERNOON INTO THE EVENING HOURS FOR THE OLYMPICS AND CASCADES.
ANY STORM THAT DOES DEVELOP COULD PRODUCE GUSTY AND ERRATIC
OUTFLOW WINDS IN ADDITION TO THE LIGHTNING OUTPUT. HIGHS IN THE
70S AND LOWER 80S INLAND AND MID TO UPPER 60S COAST.
UPPER LEVEL TROUGH DISSIPATING TONIGHT. CONVECTION THREAT OVER
THE MOUNTAINS COMING TO AN END QUICKLY THIS EVENING. LOW LEVEL
FLOW REMAINING LIGHT ONSHORE WITH THE MARINE LAYER MOVING INLAND
AGAIN LATE TONIGHT INTO THE EARLY MORNING HOURS. THE LAYER WILL
MOST LIKELY NOT GET TO THE PUGET SOUND BY 12Z. LOWS IN THE 50S.
WEAK UPPER LEVEL RIDGE BUILDING IN FROM THE SOUTHEAST SATURDAY
WITH THE FLOW ALOFT BECOMING SOUTH SOUTHWESTERLY. THIS WILL
BEGIN TO PUSH THE SMOKE OUT OF THE AREA. IN THE LOWER LEVELS
LIGHT ONSHORE FLOW CONTINUING WITH THE MARINE LAYER GETTING EAST
OF PUGET SOUND AROUND SUNRISE. THE MARINE LAYER WILL DISSIPATE
OVER THE INTERIOR BY MIDDAY LEAVING STRATUS JUST ALONG THE
COASTLINE. AIR MASS BECOMING SLIGHTLY UNSTABLE OVER THE HIGHER
TERRAIN IN THE AFTERNOON. WITH THE SOUTH SOUTHWESTERLY FLOW
ALOFT BEST CHANCE FOR A THUNDERSTORM WILL BE NEAR THE CASCADE
CREST. THUNDERSTORM CHANCES WILL BE LESS THAN TODAY. HIGHS IN
THE 70S AND LOWER 80S FOR THE INTERIOR AND MID TO UPPER 60S
COAST.
LITTLE CHANGE IN THE PATTERN SATURDAY NIGHT AND SUNDAY WITH THE
WEAK, 500 MB HEIGHTS IN THE LOWER 580 DMS, UPPER LEVEL RIDGE
OVER THE AREA AND SOUTH SOUTHWESTERLY FLOW ALOFT. GOOD CHANCE
UPPER LEVEL SMOKE GETTING OUT OF THE AREA BY SUNDAY. LOW LEVEL
ONSHORE FLOW WILL PUSH THE MARINE LAYER INLAND FROM THE COAST
AGAIN EARLY SUNDAY MORNING. STRATUS DISSIPATING BACK TO THE
COAST BY MIDDAY. SOME HIGH CLOUDS EMBEDDED IN THE FLOW ALOFT
MOVING THROUGH DURING THE DAY SUNDAY WILL HAVE LITTLE EFFECT ON
THE TEMPERATURES. HIGHS, YOU GUESSED IT, IN THE 70S AND LOWER
80S INLAND, MID TO UPPER 60S COAST. LOWS IN THE 50S.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
UPPER LEVEL RIDGE FLATTENING OUT SUNDAY NIGHT WITH ANOTHER WEAK UPPER
LEVEL TROUGH DIGGING DOWN FROM THE NORTH ARRIVING MONDAY.
TROUGH REMAINING OVER THE AREA TUESDAY. VERY LITTLE MOISTURE
WITH THE TROUGH. THE FLOW ALOFT WILL TURN NORTHERLY BRINGING
UPPER LEVEL SMOKE BACK INTO THE AREA. IN THE LOWER LEVELS
ONSHORE FLOW CONTINUING BRINGING STRATUS INLAND EACH LATE NIGHT
AND EARLY MORNING. HIGHS IN THE 70S INLAND AND MID 60S COAST.
LOWS IN THE 50S.
DIFFERENCES IN THE MODELS SHOW UP WEDNESDAY AND THURSDAY. SOME
OF THE SOLUTIONS PRODUCE THE SAME SCENARIO AS THIS WEEKEND WITH
A WEAK UPPER LEVEL RIDGE BUILDING BACK INTO THE AREA FROM THE
SOUTHEAST. THE OTHER GROUPING OF SOLUTIONS KEEPS THE UPPER
LEVEL TROUGH OVER THE AREA. IN EITHER SOLUTION THE LOW LEVEL
FLOW REMAINS ONSHORE. WILL GO WITH A CLIMATOLOGY FORECAST FOR
THE MIDDLE OF NEXT WEEK, MORNING CLOUDS AFTERNOON SUN FOR THE
INTERIOR WITH HIGHS STAYING IN THE 70S. CLOUDS HANGING TOUGH
MOST OF THE DAY ON THE COAST WITH HIGHS ONLY IN THE MID 60S.
LOWS BOTH DAYS IN THE 50S. FELTON
AVIATION
A NEARLY-STATIONARY TROUGH OVER SOUTHWESTERN B.C. WILL MAINTAIN
SOUTHWESTERLY FLOW ALOFT. THIS WILL CONTINUE TO PROMOTE CHANCES
FOR SHOWERS AND THUNDERSTORMS OVER THE CASCADES AND OLYMPICS
ONCE AGAIN THIS AFTERNOON. STRATUS WILL CONTINUE TO BUILD
EASTWARD ACROSS WESTERN WASHINGTON AND IS EXPECTED TO REACH MOST
ALL AREA TERMINALS BY SUNRISE THIS MORNING. THE STRATUS IS LOW
TO THE GROUND ONCE AGAIN, WITH LIFR CEILINGS AND IMPACTS TO
VISIBILITY DUE TO FOG. WITH SLIGHTLY STRONGER ONSHORE FLOW
FORECAST FOR TODAY, STRATUS WILL LIKELY BE A BIT SLOWER TO
RETREAT LATE THIS MORNING, AND LIKELY NOT CLEAR OUT ALONG THE
COAST. THIS WILL ALSO PROMOTE A SLIGHTLY EARLIER RETURN OF THE
STRATUS LATE TONIGHT INTO SATURDAY MORNING.
WEST TO SOUTHWESTERLY WINDS WILL CONTINUE THROUGH THE MORNING,
THOUGH WILL BEGIN TO SWITCH TO NORTHWESTERLY THROUGH THE CENTRAL
PUGET SOUND FROM AROUND 23Z FRI - 03Z TUE AND EASE LATE TONIGHT.
KSEA...VFR CONDITIONS EARLY THIS MORNING. LIFR STRATUS IS STILL
ON TRACK TO REACH THE TERMINAL AROUND 12Z THIS MORNING, LIFTING
SLIGHTLY BEFORE SCATTERING AROUND 17-18Z. VFR CONDITIONS REMAIN
THROUGH THE REMAINDER OF THE DAY. STRATUS WILL LIKELY RETURN
AFTER AROUND 12Z SATURDAY. LIGHT SW WINDS WILL PREVAIL THROUGH
MUCH OF THE DAY, BUT WILL BEGIN TO TURN W/NWLY AFTER AROUND
01-03Z SATURDAY. 62
MARINE
HIGH PRESSURE WILL REMAIN WELL TO THE SOUTH AND WEST, OFF THE
COAST OF CALIFORNIA, ALLOWING WINDS OVER THE COASTAL WATERS TO
REMAIN LIGHT THROUGH SATURDAY. HIGH PRESSURE LOOKS TO REBUILD
OFFSHORE OF CANADA AND MOVE SOUTHWARD ON SUNDAY AND INTO NEXT
WEEK, BRINGING BACK NORTHWESTERLY WINDS OVER THE COASTAL WATERS.
DIURNALLY DRIVEN WESTERLY PUSHES DOWN THE STRAIT OF JUAN DE FUCA
REMAINS THE ONLY AREA OF CONCERN THIS WEEKEND INTO NEXT WEEK,
WITH WINDS LIKELY REACHING SMALL CRAFT ADVISORY THRESHOLDS EACH
EVENING.
SEAS REMAIN 3 TO 6 FT THROUGH THE NEXT SEVEN DAYS. 62
FIRE WEATHER
FIRE WEATHER WATCH HAS BEEN UPGRADED TO A RED FLAG WARNING FOR
THE OLYMPICS AND CASCADES THIS AFTERNOON AND EVENING FOR THE
POTENTIAL OF ANOTHER ROUND OF CONVECTION. PRETTY MUCH THE SAME
SCENARIO AS THURSDAY WITH MOST OF THE STORMS NOT PRODUCING
WETTING RAINS. GIVEN THE DRY CONDITIONS ANY STORMS THAT DO
DEVELOP COULD HAVE GUSTY AND ERRATIC OUTFLOW WINDS WHICH
COMBINED WITH THE LIGHTNING AND DRY CONDITIONS PRESENT COULD
PRODUCE NEW FIRE STARTS. THERE IS A SMALL CHANCE THE STORMS
COULD REMAIN STATIONARY OVER A BURN SCAR. IF THAT IS THE CASE
FLASH FLOODING CAN NOT TOTALLY BE RULED OUT.
CHANCES FOR CONVECTION OVER THE MOUNTAINS DECREASING THIS WEEKEND
WITH THE UPPER LEVEL RIDGE BUILDING INTO THE AREA. YET ANOTHER
UPPER LEVEL TROUGH ARRIVING MONDAY INCREASING FIRE WEATHER
CONCERNS FOR NEXT WEEK. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...RED FLAG WARNING FROM NOON TODAY TO 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 FROM 2 PM THIS AFTERNOON TO 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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