477
FXUS66 KSEW 131555
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
855 AM PDT MON APR 13 2026
SYNOPSIS
ONSHORE FLOW TODAY WITH SHOWERS MAINLY IN THE
INTERIOR AND CASCADES. COOL, WET AND WINDY CONDITIONS TUESDAY
INTO WEDNESDAY WITH HEAVY SNOW POSSIBLE IN THE CASCADES. DRIER
WEATHER IS IN STORE THURSDAY INTO THE WEEKEND WITH HIGH
PRESSURE.
SHORT TERM /TODAY THROUGH WEDNESDAY/
ONSHORE FLOW CONTINUES
TODAY WITH SHOWERS MAINLY IN THE INTERIOR AND CASCADES, ESPECIALLY
KING AND SNOHOMISH COUNTIES DUE TO LOW LEVEL CONVERGENCE. UP IN
THE MOUNTAINS, SNOW LEVELS WILL HOVER AROUND 5000 FT THEN LOWER
TO AROUND 4000 FT THIS AFTERNOON.
COOL, WET AND WINDY CONDITIONS ARE FAVORED TUESDAY AND WEDNESDAY
AS A DEEP UPPER LOW SPINS DOWN B.C. AND INTO WA. SNOW LEVELS
WILL START AROUND 3500 ON TUESDAY BUT FALL TO AROUND 1500 ON
WEDNESDAY WITH SNOW IN THE CASCADES AND ALL PASSES. PERIODS OF
HEAVY SNOW IS POSSIBLE - A WINTER STORM WATCH IS IN EFFECT.
EXPECT WINDY CONDITIONS ON TUESDAY WITH S/SW WINDS GUSTING TO
20-30 MPH (PEAKING TUESDAY EVENING). TEMPERATURES WILL TRACK
BELOW AVERAGE BOTH DAYS WITH LOWS IN THE 30S AND HIGHS IN THE
40S TO AROUND 50. THE AIR MASS IS SLIGHTLY UNSTABLE ON WEDNESDAY
WITH THE COOL LOW OVERHEAD AND THERE IS ALSO A SLIGHT CHANCE OF
THUNDERSTORMS. PRECIPITATION TAPERS OFF WEDNESDAY NIGHT AS THE
LOW EXITS EAST. 33
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
WESTERN WA IS
UNDER DRY NORTHERLY FLOW THURSDAY AND FRIDAY AS HIGH PRESSURE
FORMS OFFSHORE. LOW TEMPERATURES WILL REMAIN COOL AND IN THE 30S
WITH FREEZING TEMPERATURES (FROST) POSSIBLE AROUND THE SOUTH
SOUND BOTH MORNINGS. HIGHS WILL REACH THE MID 50S. THE RIDGE
SLIDES INLAND OVER THE WEEKEND FOR WARMER CONDITIONS AND HIGHS
IN THE INTERIOR IN THE LOWER 60S. AN UPPER LOW SLOWLY TRACKS
SOUTH THROUGH THE OFFSHORE WATERS ON SUNDAY WITH A CHANCE OF
SHOWERS OVER WESTERN WA. 33
AVIATION
NORTH TO NORTHWESTERLY FLOW ALOFT AS WEAK TROUGHINESS REMAINS OVER
WESTERN WASHINGTON. MIXED CONDITIONS WITH VFR TO LOCALIZED LIFR
(KPAE) BEING OBSERVED SO FAR THIS MORNING. AREAS OF LOW CEILINGS
CONDITIONS WILL LIKELY CONTINUE THROUGHOUT THE MORNING AND THE FIRST
HALF OF THE AFTERNOON. COULD SEE CONDITIONS POP BACK AND FORTH FROM
MVFR/VFR THROUGHOUT THE LATE AFTERNOON. LATEST GUIDANCE HAS
CONDITIONS FALLING BACK DOWN TO MVFR LATER IN THE EVENING (30-40%)
FOR MOST TERMINALS IN THE INTERIOR. S/SW WINDS 8 TO 12 KNOTS THIS
MORNING WITH A FEW GUSTS UP TO 20 KTS POSSIBLE AT TIMES THIS
AFTERNOON AS ONSHORE FLOW CONTINUES.
KSEA...VFR/MVFR CONDITIONS AT THE TERMINAL SO FAR THIS MORNING.
THESE CONDITIONS ARE SLATED TO REMAIN THROUGHOUT MUCH OF THE MORNING
AND AFTERNOON, WITH SOME GUIDANCE SUGGESTING A 30% CHANCE OF VFR
LATER IN THE AFTERNOON. CONDITIONS WILL THEN LOWER TO MVFR ONCE
AGAIN IN THE EVENING AND IN THE OVERNIGHT HOURS. SOUTHWESTERLY WINDS
8 TO 12 KNOTS WITH THE POTENTIAL FOR SOME GUSTS UP TO 20 KTS THIS
MORNING. WINDS LOOK TO REMAIN ABOVE 10 KNOTS THROUGHOUT THE
AFTERNOON.
MAZURKIEWICZ/41
MARINE
SURFACE HIGH PRESSURE DEVELOPING OFFSHORE IN THE NORTHEASTERN
PACIFIC. ONSHORE FLOW CONTINUES OVER THE AREA WATERS AS WELL FOR
THE SMALL CRAFT ADVISORY IN THE STRAIT OF JUAN DE FUCA FOR
ENHANCED WESTERLIES. A STRONGER FRONTAL SYSTEM WILL APPROACH THE
AREA WATERS LATE TUESDAY INTO WEDNESDAY FOR BREEZY CONDITIONS
AND ELEVATED SEAS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR
ALL OF THE COASTAL WATER ZONES STARTING EARLY TUESDAY AS S/SW WINDS
INCREASE AHEAD OF THE FRONT. MORE WIDESPREAD HEADLINES ARE
LIKELY FOR THE INTERIOR WATERS AS WE GET CLOSER, ALONG WITH THE
POTENTIAL FOR SOME GALE STRENGTH WINDS ESPECIALLY IN THE STRAIT.
COASTAL SEAS 6 TO 8 FEET THROUGHOUT THE REMAINDER OF TODAY, WITH
SEAS INCREASING UPWARD TO 9 TO 12 FEET BY TUESDAY AFTERNOON.
SEAS LOOK TO REMAIN ABOVE 10 FEET THROUGH THURSDAY BEFORE
DECREASING BY FRIDAY TO 3 TO 5 FEET.
MAZURKIEWICZ
HYDROLOGY
NO RIVER FLOODING EXPECTED OVER THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY
EVENING FOR CASCADES OF PIERCE AND LEWIS COUNTIES-
CASCADES OF SNOHOMISH AND NORTHERN KING COUNTIES-CASCADES
OF SOUTHERN KING COUNTY-CASCADES OF WHATCOM AND SKAGIT
COUNTIES.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT TUESDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 5 AM PDT WEDNESDAY
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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