326
FXUS66 KSEW 272123
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
223 PM PDT FRI MAR 27 2026
SYNOPSIS
HIGH PRESSURE UNDER A ZONAL FLOW WILL KEEP WESTERN WASHINGTON
QUIET THROUGH THE FIRST PART OF THE WEEKEND. A TROUGH WILL BRING
THE NEXT CHANCE OF SHOWERS SUNDAY INTO MONDAY, INCLUDING LIGHT
SNOW IN THE MOUNTAINS. THE ZONAL JET WILL SHIFT EASTWARD,
INVITING ADDITIONAL SYSTEMS TO PASS THROUGH NEXT WEEK, WITH
CHANCES OF SHOWERS.
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
IT REMAINS DRY ACROSS WESTERN WASHINGTON THIS AFTERNOON. THE
ZONAL FLOW PATTERN WITH THE UPPER LEVEL JET REMAINS IN PLACE
TODAY, WITH HIGH PRESSURE AT THE SURFACE. HIGH CIRRUS CLOUDS ON
SATELLITE ARE TRACKING INLAND FROM A WEAK FRONT OFFSHORE TO THE
NORTHWEST (OVER NORTH VICTORIA B.C.). TEMPERATURES THIS
AFTERNOON HAVE REACHED THE LOW TO MID 50S, AND SATURDAY IS
SHAPING UP TO BE SIMILAR TO FRIDAY (ALBEIT WITH A FEW MORE
CLOUDS THAT WILL ROLL IN TONIGHT AND LINGER SATURDAY). A COUPLE
PATCHES ARE FOG CAN'T BE RULED OUT SATURDAY MORNING (AS THE
CLOUD DECK IS EXPECTED TO REMAIN HIGH IN ALTITUDE AND THIN IN
COVERAGE, BUT WILL GRADUALLY LOWER THROUGH THE NIGHT).
TEMPERATURES TONIGHT/SATURDAY NIGHT WILL BE A FEW DEGREES WARMER
WITH THE HELP OF THE CLOUD COVERAGE (UPPER 30S-LOW 40S). WINDS
WILL BE LIGHT AND VARIABLE AND CALM AT TIMES THROUGH THE
WEEKEND.
THE NEXT SYSTEM IS EXPECTED TO ARRIVE SUNDAY AND LINGER INTO
MONDAY, AS THE ZONAL JET AND HIGH PRESSURE MOVE OUT OF THE
REGION. A WEAK UPPER LEVEL LOW WILL DROP A TROUGH BEHIND THE JET
STREAK, WHICH WILL BRING THE NEXT CHANCE OF SHOWERS ACROSS THE
REGION (SNOW SHOWERS FOR ELEVATIONS GREATER THAN ROUGHLY 1,500
FT). THE TROUGH WILL DRAG A COLD FRONT ACROSS THE REGION DURING
THE DAY. COOLER AIR WILL SINK IN BEHIND THE FRONT, WITH HIGHS
SUNDAY ONLY REACHING THE UPPER 40S/LOW 50S, AND LOWS DIPPING
BACK TO THE UPPER 20S/LOW 30S. THE MOISTURE AVAILABLE WITH THIS
FRONT IS LIMITED, WHICH WILL KEEP LOWLAND RAIN ACCUMULATIONS TO
SEVERAL HUNDREDTHS TO A FEW TENTHS OF AN INCH, AND THE
MOUNTAINS SEEING LIGHT AMOUNTS OF SNOW (COUPLE INCHES AT THE
PASSES SUNDAY INTO MONDAY - 2-4 INCHES AT HIGHER ELEVATIONS).
THE PEAKS OF THE MOUNTAINS HAVE A 50-60% CHANCE OF HAVING SNOW
ACCUMULATIONS GREATER THAN 6 INCHES (AREAS SUCH AS PARADISE, MT.
BAKER AND GLACIER PEAK).
LONG TERM /MONDAY THROUGH FRIDAY/
THE ENSEMBLES ARE IN GOOD AGREEMENT WITH THE TROUGH SUNDAY
CONTINUING TO PUSH THROUGH THE REGION MONDAY. THE PRECIPITATION
CHANCES DECREASES TO NEAR 0 LATE MONDAY INTO EARLY TUESDAY AS
ANY POST-FRONT CONVERGENCE ZONE ACTIVITY MOVES OUT. BREAKS IN
THE CLOUD COVERAGE ARE LIKELY, WITH TEMPERATURES SLOWLY WARMING
UP MONDAY INTO TUESDAY, WITH HIGHS RETURNING INTO THE LOW TO MID
50S. THE AIR WILL DRY OUT SUBSTANTIALLY MONDAY/TUESDAY WITH
LIGHT EAST/NORTHEAST WINDS MONDAY INTO TUESDAY (SOME AREAS MAY
SEE RH VALUES DIP DOWN TO AS LOW AS 40%).
THE MODEL AGREEMENT CONTINUES MIDWEEK, WITH NEARLY ALL OF THE
MODELS HAVING A MORE VIGOROUS SHORTWAVE TROUGH PASSING THROUGH
WEDNESDAY. THIS SYSTEM (IF IT REMAINS ON TRACK) WILL PRODUCE A
STEADY AMOUNT OF PRECIPITATION FROM LATE TUESDAY THROUGH
THURSDAY. THIS INCLUDES MOUNTAIN SNOW, WITH SNOW LEVELS AROUND
2,000 TO 3,000 FT. PROBABILITIES FOR MORE THAN 8 INCHES OF SNOW
AT THE PASSES WITH THIS SYSTEM REMAINS LOW AT THIS TIME
(15-30%). TEMPERATURES WILL HOLD STEADY FOR THE REMAINDER OF THE
WEEK IN THE UPPER 40S TO LOW 50S, WITH LOWS IN THE UPPER 30S TO
LOW 40S. A FEW AREAS WEDNESDAY MAY SEE BREEZY WINDS UP TO 20-30
MPH FROM THE SOUTHWEST AS THE MIDWEEK SYSTEM PASSES THROUGH.
HPR
AVIATION
VFR CIGS ARE EXPECTED TO PREVAIL THROUGHOUT THE VALID PERIOD FOR ALL
TERMINALS. WINDS ARE EXPECTED TO REMAIN NORTHERLY AT THE SURFACE,
DECREASING FROM 8-10 KTS THIS AFTERNOON, TO 4-6 KTS AFTER 06Z. BY
SATURDAY MORNING, EXPECT WINDS TO TURN WESTERLY FOR INTERIOR
TERMINALS, BECOMING NW IN THE AFTERNOON.
KSEA...VFR CIGS CONTINUING, WITH HIGH CLOUDS STREAMING OVERHEAD FROM
THE NW THROUGHOUT THE AFTERNOON. WINDS ARE BETWEEN 8-10 KTS THIS
AFTERNOON, AND WILL COME DOWN AFTER 06Z TO BETWEEN 4-6 KTS. WINDS AT
THE SURFACE ARE NORTHERLY, BECOMING ENE OVERNIGHT. WHILE STILL VFR,
THERE WILL BE A SCT TO FEW LAYER AT 040 TO 050 SATURDAY MORNING
AFTER 12Z, LINGERING INTO THE EARLY AFTERNOON. WINDS DURING THIS
TIME WILL BECOME WSW AT 4-6 KTS.
21
MARINE
HIGH PRESSURE WILL BE THE DOMINANT FEATURE OVER THE NEXT
SEVERAL DAYS AS NORTH TO NORTHWESTERLY WINDS PREVAIL ACROSS THE
AREA. A WEAK FRONT WILL PASS BY TO THE NORTHWEST INTO EARLY SATURDAY
AND DISSIPATE AS IT DOES SO. A WEAK PUSH DOWN THE STRAIT OF JUAN DE
FUCA WILL ENSUE SATURDAY EVENING. A DISORGANIZED LOW PRESSURE SYSTEM
WILL MOVE ACROSS THE WATERS SUNDAY INTO EARLY MONDAY, BUT STRONGER
HIGH PRESSURE BUILDING BEHIND IT COULD RAISE WINDS THROUGH THE
COASTAL WATERS ABOVE 20-25 KT EARLY ON MONDAY. A STRONGER SYSTEM
LOOKS TO MOVE INTO THE REGION AROUND MID-WEEK, WHICH LOOKS TO BRING
THE NEXT ROUND OF GUSTIER WINDS AND BUILDING SEAS TO THE AREA WATERS.
SEAS GENERALLY REMAIN AROUND 5-8 FT BEFORE INCREASING GOING INTO MID-
WEEK.
21
HYDROLOGY
NO RIVER FLOODING IS EXPECTED IN THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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