508
FXUS66 KSEW 131539
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
839 AM PDT THU MAR 13 2025
SYNOPSIS
SHOWERS WILL CONTINUE THROUGHOUT THE DAY WITH A CHANCE
FOR ISOLATED THUNDERSTORMS IN THE AFTERNOON. UPPER LEVEL TROUGHING
WILL CONTINUE TO BRING ADDITIONAL SYSTEMS THROUGH FRIDAY AND INTO
THE WEEKEND WHICH HAVE THE POTENTIAL TO BRING MORE ROUNDS OF
HEAVIER RAINFALL, MORE MOUNTAIN SNOW, AND BREEZY CONDITIONS.
UPDATE
ISOLATED TO SCATTERED SHOWERS ARE SPREAD ACROSS THE
REGION THIS MORNING. A WEAK AND NARROW CONVERGENCE BAND WAS
MOVING NORTH ACROSS ISLAND AND SNOHOMISH COUNTIES AT THE TIME OF
WRITING, AND POPCORN SHOWERS WERE MOVING ENE ONSHORE ACROSS THE
COAST AND OLYMPIC PENINSULA. THESE SHOWERS ARE ASSOCIATED WITH A
TROUGH AXIS THAT WILL MOVE ACROSS THE AREA TODAY. BY MID-DAY, SOME
MINOR DAYTIME HEATING WILL RESULT IN 100-250 J/KG SBCAPE AND
ALLOW FOR SOME WEAK THUNDERSTORM ACTIVITY. THE MAIN THREATS WITH
ANY STORMS WILL BE BRIEF HEAVY DOWNPOURS, SMALL HAIL, AND
LIGHTNING. WEAK CONVECTION COULD CONTINUE OVERNIGHT BEFORE
TAPERING OFF FRIDAY. THE CURRENT FORECAST IS ON TRACK BUT WILL BE
MONITORING FOR ANY NEEDED CHANGES.
-WOLCOTT-
SHORT TERM /TODAY THROUGH SATURDAY/
RADAR IMAGERY THIS MORNING
SHOWS SCATTERED SHOWERS ACROSS THE INTERIOR, WITH SNOW IN THE
MOUNTAINS. SNOW LEVELS THIS MORNING GENERALLY IN THE 1000 TO 1500
FEET, WITH THE CASCADES AND PASSES RECEIVING ACCUMULATING SNOW
(POSSIBLY HEAVY AT TIMES) EARLY THIS MORNING AS A BATCH OF HEAVIER
MOISTURE PERSISTS OVER THE MOUNTAINS. A WINTER WEATHER ADVISORY
CONTINUES UNTIL NOON. SCATTERED SHOWERS WILL CONTINUE THROUGHOUT
THE DAY OVER THE INTERIOR AS AN UPPER TROUGH AXIS SHIFTS
OVERHEAD. THE AIR MASS WILL BE UNSTABLE THIS AFTERNOON WHICH MAY
LEAD TO THE CHANCE OF AN ISOLATED THUNDERSTORM OR TWO, ESPECIALLY
THIS EVENING. THE GREATEST AREAS OF INSTABILITY VALUES LOOK TO BE
OVER SW WASHINGTON, BUT REGARDLESS, A FEW ISOLATED LIGHTNING
STRIKES CAN BE POSSIBLE OVER THE INTERIOR THIS AFTERNOON.
COOLER AND WETTER WEATHER IS ON TRACK FOR FRIDAY AS ANOTHER
SHORTWAVE SYSTEM PUSHES THROUGH THE REGION, WITH MOST OF THE
ENERGY ASSOCIATED WITH THIS LOCATED MORE SOUTHWARD. ANOTHER DAY
OF RAIN SHOWERS IS TO BE EXPECTED, WITH SNOWFALL IN THE MOUNTAINS.
SNOW LEVELS LOOK TO RAISE SLIGHTLY TO AROUND 2000 TO 2500 FEET BY
LATE FRIDAY NIGHT.
THE ACTIVE WEATHER PATTERN CONTINUES, WITH A STEADIER STREAM OF
MOISTURE AIMED AT WESTERN WA STARTING FRIDAY NIGHT INTO SATURDAY,
WITH ANOTHER ROUND OF LOWLAND RAIN AND WITH WESTERLY OROGRAPHIC
FLOW, COULD SUPPORT MORE SIGNIFICANT SNOWFALL IN THE MOUNTAINS AS
WELL. COULD ALSO SEE SOME BREEZY WINDS ACROSS THE AREA WITH THE
A SURFACE LOW LOOMING OFFSHORE, MAINLY FOR AREAS NEAR THE
COASTLINE.
LONG TERM /SUNDAY THROUGH WEDNESDAY/
ADDITIONAL SYSTEMS LOOK TO
IMPACT THE AREA CONTINUING THROUGH THE WEEKEND, WITH MORE LOWLAND
RAIN, MOUNTAIN SNOW, AND BREEZY CONDITIONS. SNOW WILL CONTINUE
THROUGH THE WEEKEND WITH SOME LOCATIONS IN THE CASCADES RECEIVING
POTENTIALLY 2 FEET OF FRESH SNOW, WITH SNOW LEVELS GENERALLY
HOVERING AROUND 2000-2500 FEET. HEAVIER PRECIPITATION IN THE
OLYMPICS MAY DRIVE THE SKOKOMISH RIVER IN MASON COUNTY INTO FLOOD
STAGE. CONDITIONS LOOK TO LIGHTEN UP THROUGH MIDWEEK, WITH
ADDITIONAL SHOWERS LIKELY EACH DAY BEFORE A RIDGE ATTEMPT TO SET
UP AT THE END OF THE LONG TERM PERIOD.
MAZURKIEWICZ
AVIATION
MOSTLY VFR WITH MVFR CEILINGS AT THE PUGET SOUND
TERMINALS. POST-FRONTAL SHOWERS WILL INCREASE IN COVERAGE THROUGHOUT
THE DAY FROM WEST TO EAST, WITH BREEZY 20-25 KT SOUTHERLIES PEAKING
THIS AFTERNOON. THIS SHOULD YIELD PRIMARILY VFR CEILINGS THIS
AFTERNOON, BUT POCKETS OF LOWER CEILINGS/VISIBILITY IN HEAVIER
SHOWERS. A FEW ISOLATED THUNDERSTORMS CAN'T BE RULED OUT, ESPECIALLY
INTO THE AFTERNOON, BUT CONFIDENCE ISN'T HIGH ENOUGH FOR INCLUSION
IN ANY TAFS AT THIS TIME.
KSEA...MVFR TO LOW VFR CEILINGS EXPECTED IN RAIN SHOWERS THIS
MORNING WITH SOUTHERLY FLOW. EXPECT A LULL IN SHOWER ACTIVITY
TOWARDS THE LATE MORNING, THOUGH CONFIDENCE IN CEILINGS ISN'T
TERRIBLY HIGH FOR THE MORNING PUSH WITH MVFR MOST LIKELY, BUT SOME
INDICATIONS OF SHORT IMPROVEMENT TOWARD 3000-3500 FT. OTHERWISE,
SOUTHERLY WINDS THROUGH THE REMAINDER OF THE DAY WITH GUSTS TO 20-25
KT THIS AFTERNOON 18Z ONWARD BEFORE EASING AFTER 03Z THIS EVENING.
SHOWERS INCREASE AGAIN TOWARD 21Z INTO THE AFTERNOON, WITH THE
STRONGEST OF THESE PERHAPS BRINGING THE POTENTIAL OF A THUNDERSTORM
OR TWO (10-15% CHANCE). OTHERWISE, DECREASING SHOWERS AND LIKELY VFR
CEILINGS THURSDAY EVENING.
MARINE
SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE COASTAL
WATERS THIS MORNING AS SEAS ARE HOLDING IN THE 9 TO 11 FT RANGE, AND
THE SCA HAS BEEN EXTENDED INTO THE EVENING HOURS AS WAVES HOLD ON.
OTHERWISE, ANOTHER ROUND OF GUSTY SOUTHERLY WINDS AGAIN TONIGHT
INTO EARLY FRIDAY. AS ADDITIONAL DISTURBANCES CONTINUE TO PUSH
THROUGH THE REGION (ONE FRIDAY, ANOTHER AROUND SUNDAY), EXPECT TO
SEE BOTH WINDS AND SEAS INCREASE AND ADDITIONAL ADVISORIES WILL BE
NEEDED. THE LIKELIHOOD OF GALE GUSTS INTO THE WEEKEND THROUGH EARLY
NEXT WEEK PEAK AROUND AROUND 40% OVER THE COASTAL WATERS FRIDAY AND
EARLY SUNDAY, BUT CONFIDENCE ISN'T HIGH ENOUGH OVER THE LOCAL WATERS
TO ISSUE A GALE WATCH AT THIS TIME. HOWEVER, SEAS AROUND 15 FT ARE
EXPECTED OVER THE COASTAL WATERS AT TIMES FRIDAY AND INTO THE
WEEKEND, AND LIKELY REMAIN ABOVE 10 FT THROUGH THE EARLY PART OF
NEXT WEEK.
CULLEN/15
HYDROLOGY
HEAVY PRECIPITATION IN THE SOUTHERN OLYMPICS THIS
WEEKEND WILL FORCE SHARP RISES ON THE SKOKOMISH RIVER WITH
FLOODING POSSIBLE. A HYDROLOGIC OUTLOOK HAS BEEN ISSUED. RIVER
FLOODING IS NOT EXPECTED ELSEWHERE OVER THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...WINTER WEATHER ADVISORY UNTIL NOON PDT TODAY FOR WEST SLOPES
NORTH CASCADES AND PASSES-WEST SLOPES NORTH CENTRAL
CASCADES AND PASSES-WEST SLOPES SOUTH CENTRAL CASCADES AND
PASSES.
PZ...SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR GRAYS
HARBOR BAR.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT THIS MORNING FOR WEST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-
COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-
COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO
60 NM-COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE
OUT 10 NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE
SHOALWATER 10 TO 60 NM-COASTAL WATERS FROM POINT GRENVILLE
TO CAPE SHOALWATER OUT 10 NM.
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