963
FXUS66 KSEW 120938
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
238 AM PDT SUN APR 12 2026
SYNOPSIS
ONSHORE FLOW WILL INCREASE TONIGHT AND MONDAY FOR
SHOWERS AND A CONVERGENCE ZONE. THE NEXT SYSTEM WILL BRING
ADDITIONAL LOWLAND RAIN, WINDY CONDITIONS PLUS POSSIBLE HEAVY
MOUNTAIN SNOW ON TUESDAY. UPPER LEVEL LOW OVER WESTERN
WASHINGTON WEDNESDAY FOR CONTINUED COOL CONDITIONS. DRYING
NORTHERLY FLOW ALOFT DEVELOPING THURSDAY INTO THE WEEKEND.
SHORT TERM /TODAY THROUGH TUESDAY/
A BRIEF BREAK IN THE
WEATHER THIS MORNING AND EARLY AFTERNOON AS AN UPPER LEVEL LOW
SHIFTS INLAND TO OUR SOUTH (OVER NORTHERN CA). SHOWERS WILL THEN
INCREASE LATE THIS AFTERNOON AND EVENING, PRIMARILY OVER THE
INTERIOR AND CASCADES, AS LOW LEVEL ONSHORE FLOW INCREASES.
ONSHORE FLOW CONTINUES INTO MONDAY WITH CONVERGENCE ZONE SHOWERS
OVER KING/SNOHOMISH COUNTIES.
COOL, WET AND WINDY CONDITIONS ARE AHEAD AS WE MOVE INTO TUESDAY
WHILE A DEEP UPPER LOW DESCENDS SOUTH FROM B.C. SNOW LEVELS WILL
LOWER TO AROUND 3000 FT WITH SNOW EXPECTED AT ALL CASCADE
PASSES. WINDS WILL BE GUSTY FROM THE S/SW WITH GUSTS TO 25-35
MPH (PEAKING IN THE INTERIOR DURING THE AFTERNOON). 33
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
WET AND COOL
CONDITIONS WILL CONTINUE TUESDAY NIGHT AND WEDNESDAY AS A DEEP
UPPER LOW SPINS OVER WA. SNOW LEVELS WILL LOWER FURTHER, DOWN TO
AROUND 1500-2000 FT, WITH SNOW IN THE CASCADES AND PASSES. MEAN
48 HOUR SNOW TOTALS RANGE FROM 6 TO 12" INCHES WITH HIGHER
AMOUNTS ON THE VOLCANOES. EXPECT COOLER LOWLAND TEMPERATURES
WITH LOWS IN THE 30S AND HIGHS IN THE 40S TO AROUND 50.
DRIER WEATHER IS IN STORE THURSDAY INTO THE WEEKEND WITH HIGH
PRESSURE. LOWS REMAIN CHILLY AND IN THE 30S WITH FREEZING
TEMPERATURES AROUND THE SOUTH SOUND. EXPECT HIGHS IN THE 50S
WITH LOWER 60S BY SATURDAY. 33
AVIATION
VARIABLE TO NORTHERLY WINDS ALOFT AS A WEAK TROUGH
SETS UP OVER WESTERN WASHINGTON. FOG AND LOW CLOUDS HAVE
ALREADY DEVELOPED EARLY THIS MORNING ACROSS MOST OF THE INTERIOR
WITH A SPREAD OF IFR/LIFR CONDITIONS. MOST TERMINAL LOCATIONS
WILL CONTINUE SEEING THESE DETERIORATED CONDITIONS THROUGHOUT
MUCH OF THE MORNING BEFORE SLOWLY IMPROVING TO VFR AROUND
20-22Z. WINDS WILL REMAIN NORTHERLY THROUGHOUT THE AFTERNOON BUT
WILL KEEP SPEEDS GENERALLY 3 TO 6 KNOTS.
KSEA...LIFR CONDITIONS EARLY MORNING AS FOG AND LOW CLOUDS HAVE
DEVELOPED AT THE TERMINAL WITH NORTHERLY WINDS GENERALLY AROUND
3 TO 6 KNOTS AND REMAINING THERE THROUGHOUT THE AFTERNOON.
LATEST GUIDANCE SHOWS A 60-70% CHANCE OF CONDITIONS RETURNING TO
VFR BY 18Z-20Z AS FOG/LOW CLOUDS START TO DISSIPATE. WINDS WILL
START TO TURN MORE SW BY 20Z AND INCREASE SLIGHTLY TO 4 TO 8
KNOTS.
MAZURKIEWICZ
MARINE
SURFACE LOW PRESSURE CONTINUING TO MOVE SOUTHWARD AS A HIGH
PRESSURE SYSTEM DEVELOPS OFFSHORE IN THE NORTHEASTERN PACIFIC.
GENERALLY CALM AND BENIGN NORTHERLY WINDS OVER THE WATERS THIS
AFTERNOON. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
INCREASED WESTERLIES DOWN THE STRAIT OF JUAN DE FUCA LATE SUNDAY
INTO MONDAY. A STRONGER FRONTAL SYSTEM ARRIVING LATE TUESDAY
INTO WEDNESDAY WILL LIKELY YIELD ADDITIONAL HEADLINES AS WE WILL
SEE INCREASED WINDS AND SEAS.
COASTAL SEAS 4 TO 6 FEET THROUGHOUT THE WEEKEND. SEAS WILL THEN
START TO BUILD UPWARDS TO 8 TO 10 FEET BY TUESDAY EVENING AND
REMAINING ELEVATED THROUGH THURSDAY.
MAZURKIEWICZ
HYDROLOGY
NO RIVER FLOODING THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM PDT
MONDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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