077
FXUS66 KSEW 082153
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
153 PM PST SAT MAR 8 2025
SYNOPSIS
A WEAK ATMOSPHERIC RIVER WILL SAG SOUTH OVER THE AREA
ON SUNDAY THEN DISSIPATE ON SUNDAY NIGHT AS COLD FRONT SHIFTS
ONSHORE. A SERIES OF WEATHER SYSTEMS WILL MOVE THROUGH WESTERN
WASHINGTON BEGINNING TUESDAY WITH ADDITIONAL SYSTEMS LATER
WEDNESDAY AND FRIDAY.
SHORT TERM /TONIGHT THROUGH TUESDAY/
PRECIPITATION IS MAINLY
CONCENTRATED OVER THE OLYMPIC PENINSULA EARLY THIS AFTERNOON AS A
WARM FRONT LIFTS NORTH OF THE AREA AND THE TRAILING COLD STALLS
OFFSHORE TONIGHT. THIS WILL KEEP THE SOUTHERN EDGE OF A WEAK
ATMOSPHERIC RIVER AIMED AT THE NORTHWEST CORNER OF THE OLYMPIC
PENINSULA INTO TONIGHT WHILE THE SOUTHERN TWO THIRDS OF THE
INTERIOR REMAIN LARGELY DRY, CLOUDY, AND MILD OVERNIGHT. THE
PRECIP SHIELD AHEAD OF AN APPROACHING COLD FRONT WILL SAG
SOUTHWARD ACROSS THE REGION ON SUNDAY MORNING WITH A SOGGY,
BREEZY SUNDAY AFTERNOON AND EVENING EXPECTED. THE COLD FRONT WILL
SWEEP ONSHORE EARLY SUNDAY EVENING WITH A BRIEF CONVERGENCE ZONE
EXPECTED OVER SNOHOMISH AND NORTH KING COUNTIES. SNOWFALL TOTALS
SUNDAY NIGHT LOOK TO EASILY MEET WINTER WEATHER ADVISORY CRITERIA
AT MOUNT BAKER AND WILL BE MARGINALLY CLOSE AT STEVENS PASS. A
WINTER WEATHER ADVISORY WILL BE IN EFFECT FOR THE NORTH AND CENTRAL
CASCADES ABOVE 3500 FEET SUNDAY NIGHT.
POST-FRONTAL ONSHORE FLOW GRADUALLY WEAKENS THROUGH THE DAY ON
MONDAY. ASIDE FROM A FEW LINGERING SHOWERS IN THE MOUNTAINS,
MONDAY LOOKS TO BE MORE DRY THAN WET. ADDITIONAL PRECIP WILL BEGIN
TO MOVE ONSHORE BY TUESDAY AFTERNOON AS A MORE SIGNIFICANT SYSTEM
TAKES SHAPE OFFSHORE. THERE IS STILL SOME UNCERTAINTY WITH REGARD
TO THE DEPTH AND TRACK, BUT MODELS ARE BEGINNING TO ZERO IN ON A
SURFACE LOW DEEPENING TO AROUND 975 TO 980-ISH MILLIBARS AS IT
TRACKS TOWARD THE NORTH END OF VANCOUVER ISLAND LATE TUESDAY NIGHT
OR EARLY WEDNESDAY.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
THE COLD FRONT
ASSOCIATED WITH THE ABOVE MENTIONED SURFACE LOW IS EXPECTED TO
PUSH ONSHORE WEDNESDAY MORNING FOR MORE LOWLAND RAIN, MOUNTAIN
SNOW, AND WINDY CONDITIONS FOR THE COAST AND NORTH INTERIOR.
SHOWERY, COOL CONDITIONS ARE EXPECTED ON THURSDAY WITH AN UPPER
LEVEL TROUGH AXIS MOVING ONSHORE. ANOTHER SYSTEM IS EXPECTED TO
FOLLOW FRIDAY INTO SATURDAY WITH GENEROUS SNOWFALL FOR THE
MOUNTAINS, BUT LESS IN THE WAY OF WIND. 27
AVIATION
SOUTHWESTERLY FLOW ALOFT AS AN UPPER LEVEL TROUGH
REMAINS OFFSHORE WITH A PLUME OF MOISTURE AIMED AT THE NORTHERN
HALF OF WESTERN WASHINGTON AND COAST. VFR CONDITIONS FOR MOSTLY
ALL AREA TERMINALS THIS AFTERNOON WITH THE EXCEPTION FOR KHQM,
KPWT, AND KBLI WHERE RAIN SHOWERS AND LOW CLOUDS KEEP MVFR/IFR
CONTINUING. RAINFALL WILL START TO INCREASE IN COVERAGE LATE
TONIGHT INTO SUNDAY MORNING WHERE WIDESPREAD MVFR LOOKS TO BE
LIKELY ACROSS MOST AREA TERMINALS, WITH A 15-20% CHANCE OF IFR AT
LOWER PRONE TERMINALS (KOLM, KPWT, KPAE). BREEZY SOUTHERLY WINDS
STARTING THIS AFTERNOON WITH GUSTS UP TO 20 TO 25 KT FOR SITES
SUCH AS KPAE, KSEA, KOLM. KHQM AND KBLI COULD SEE GUSTS AS HIGH AS
30 TO 35 KT. ANOTHER ROUND OF BREEZY WINDS IS LIKELY SUNDAY
MORNING.
KSEA...VFR CONDITIONS THIS AFTERNOON WITH SOME LIGHT SHOWERS NEAR
THE VICINITY OF THE TERMINAL, WHICH HAVE NOT BEEN AFFECTING ANY
CEILING RESTRICTIONS THUS FAR. SOUTHERLY WINDS WILL START TO
INCREASE THIS AFTERNOON 8 TO 12 KNOTS WITH GUSTS UP TO 20 TO 25
KTS. WINDS LOOK TO DIMINISH OVERNIGHT BEFORE ANOTHER ROUND OF
BREEZY SOUTHERLY WINDS (09Z-15Z) AS WIDESPREAD RAIN ARRIVES. MVFR
CEILINGS WILL START TO DEVELOP AND CONTINUE INTO THE AFTERNOON
HOURS.
MAZURKIEWICZ
MARINE
A FRONT OFFSHORE WILL CONTINUE TO BRING ELEVATED WINDS
AND SEAS OVER THE COASTAL WATERS. SMALL CRAFT ADVISORY SOUTHERLIES
LOOK TO CONTINUE OVER THE COASTAL WATER ZONES, THE NORTHERN INLAND
WATERS, THE EAST ENTRANCE OF THE STRAIT, AND ADMIRALTY INLET.
THERE WILL BE A BRIEF LULL IN THE WINDS TONIGHT, BEFORE THE FRONT
MOVES OVER THE WATERS RESULTING IN ANOTHER UPTICK IN SOUTHERLY
WINDS OVER THE AREA WATERS.
LATEST GUIDANCE SHOWS THE POTENTIAL FOR SOME GALE GUSTS IN THE
EAST ENTRANCE OF THE STRAIT AND NORTHERN INLAND WATERS, THEREFORE,
HAVE UPGRADED THE SMALL CRAFT ADVISORY TO GALE STARTING EARLY
SUNDAY MORNING. THESE WINDS WILL START TO DECREASE BY THE
AFTERNOON, LEVELING OUT. ALSO HAVE INCLUDED AN SCA FOR THE PUGET
SOUND AND HOOD CANAL WATERS FOR INCREASING SOUTHERLIES.
COMBINED SEAS THIS MORNING GENERALLY AROUND 10 TO 14 FEET,
REMAINING ABOVE 10 FEET THROUGH SUNDAY BEFORE DECREASING INTO THE
FIRST HALF OF THE WEEK.
ACTIVE WEATHER LOOKS TO RESUME MIDWEEK AS A LOW PRESSURE SYSTEM
LOOKS TO APPROACH OUR AREA WATERS, WHICH COULD BRING ELEVATED WIND
AND SEAS.
MAZURKIEWICZ
HYDROLOGY
RAIN TOTALS ALONG THE NORTH COAST AND IN THE OLYMPICS
IN THE 2.5 TO 4 INCH RANGE THIS WEEKEND. RIVERS FLOWING OFF THE
OLYMPICS ARE RUNNING LOW SO EVEN WITH THIS AMOUNT OF RAIN ONLY
THE SKOKOMISH RIVER IS FORECAST TO GET INTO ACTION STAGE.
NO RIVER FLOODING EXPECTED OVER THE NEXT 7 DAYS FOR THE REMAINDER
OF THE RIVERS.
FELTON/27
SEW WATCHES/WARNINGS/ADVISORIES
WA...WINTER WEATHER ADVISORY FROM 4 PM SUNDAY TO 5 AM PST MONDAY FOR
WEST SLOPES NORTH CASCADES AND PASSES-WEST SLOPES NORTH
CENTRAL CASCADES AND PASSES.
PZ...SMALL CRAFT ADVISORY UNTIL 1 AM PST SUNDAY FOR ADMIRALTY INLET-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA-NORTHERN
INLAND WATERS INCLUDING THE SAN JUAN ISLANDS.
GALE WARNING FROM 1 AM TO 2 PM PST SUNDAY FOR ADMIRALTY INLET-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA-NORTHERN
INLAND WATERS INCLUDING THE SAN JUAN ISLANDS.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 11 AM PST SUNDAY
FOR PUGET SOUND AND HOOD CANAL.
SMALL CRAFT ADVISORY UNTIL 5 PM PST SUNDAY 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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