026
FXUS66 KSEW 200309
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
809 PM PDT MON OCT 19 2026
SYNOPSIS
DRY WEATHER WILL CONTINUE ACROSS MUCH OF THE REGION THROUGH THE
END OF THE WEEK AS A COUPLE DISTURBANCES BYPASS THE REGION.
TEMPERATURES WILL REMAIN MILD THROUGH THE FIRST HALF OF THE
WEEK, THOUGH A FEW AREAS NEXT COUPLE OF MORNINGS MAY SEE SOME
INSTANCES OF PATCHY FOG. THE NEXT CHANCE OF PRECIPITATION COMES
WITH A POTENTIAL FRONT MOVING THROUGH NEXT WEEKEND, WITH SNOW
LEVELS DROPPING TO AROUND 4000 FEET.
SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/
THE LATEST FORECAST REMAINS ON TRACK THIS EVENING WITH NO
UPDATES. A LARGE TROUGH OFFSHORE IS DIGGING ITS WAY SOUTH
TOWARDS CALIFORNIA TODAY. THE SURFACE LOW PRESSURE SYSTEM
ASSOCIATED WITH THE TROUGH WILL ALSO BYPASS THE REGION TO THE
SOUTH TODAY INTO TUESDAY. THE WEATHER WILL REMAIN LARGELY QUIET
THANKS TO THE LOW AND TROUGH MISSING THE REGION, AND ALSO A WEAK
UPPER LEVEL RIDGE DEVELOPING IN WESTERN CANADA TODAY INTO
WEDNESDAY. CAN'T RULE OUT SOME PATCHY FOG POTENTIAL WITH THE
HIGH CLOUD DECK THINNING OUT AND CALM OR LIGHT/VARIABLE WINDS,
BUT THE COVERAGE WILL LIKELY BE LIMITED TO THE VALLEYS WHERE IT
IS COOLER TONIGHT. SOME FROST MAY ALSO MIX IN, PARTICULARLY IN
THE SOUTH INTERIOR. THE HIGH CLOUDS WILL DISSIPATE LATE TUESDAY,
WHICH SHOULD HELP BUMP UP HIGH TEMPERATURES A FEW DEGREES, AS
WELL AS INTO WEDNESDAY. THE BEST CHANCE FOR A 70 WILL BE IN THE
SOUTH INTERIOR.
LONG TERM /THURSDAY THROUGH MONDAY/
HIGH PRESSURE FROM WEDNESDAY WILL MOVE EAST ON THURSDAY. A
TROUGH WITH A WEAK COLD FRONT WILL PASS THROUGH THURSDAY INTO
FRIDAY. THE BEST CHANCE OF PRECIPITATION WILL BE FOR AREAS EAST
OF I-5, UP TO THE CASCADES. TEMPERATURES WILL COOL DOWN A FEW
DEGREES THURSDAY AND FRIDAY, WITH MORE 50S FOR HIGHS, AND SOME
30S IN THE VALLEYS AND MOUNTAINS (WHICH MAY ALSO SEE A COUPLE
20S). THE MODELS INTO NEXT WEEKEND REMAIN IN DISAGREEMENT AS TO
WHEN AND WHERE ANOTHER POTENTIAL LOW WILL TRACK THROUGH THE
REGION. SOME HAVE THE SYSTEM MOVING NORTH UP INTO CANADA, AND
OTHERS HAVE IT DEEPENING OFF THE COAST OF B.C. THIS WILL KEEP
PRECIPITATION CHANCES SOMEWHAT A "TOSSUP" GOING INTO THE
WEEKEND, ALTHOUGH SNOW LEVELS EITHER WAY ARE EXPECTED TO DROP TO
4,000 TO 5,000 FT GOING INTO WEEKEND.
HPR
AVIATION
AN UPPER LEVEL LOW WILL SPIN OFFSHORE TO OUR SW TONIGHT, WITH DRY
AND STABLE WEATHER OVER WESTERN WA. THE FLOW ALOFT IS SOUTHERLY.
VFR CONDITIONS EXPECTED TONIGHT INTO TUESDAY MORNING. THE EXCEPTION
BEING WHERE POCKETS OF SHALLOW FOG DEVELOPS, ESPECIALLY OVER THE
SOUTH SOUND. LOW CLOUDS WILL BURN OFF MID TO LATE MORNING WITH VFR
CONDITIONS EXPECTED ON TUESDAY. 33/29
KSEA...VFR CONDITIONS EXPECTED THROUGH THE PERIOD. N WINDS 6-8 KT,
BECOMING NE AT 7-11 KT BY 12-15Z TUE DECREASING IN THE EVENING TO 4-
6 KT AFTER 03Z. LIGHT AND VARIABLE WINDS TUESDAY NIGHT INTO
WEDNESDAY MORNING.
33/29
MARINE
NORTHERLY FLOW WILL PREVAIL OVER THE WATERS WITH LOW PRESSURE
SPINNING OFF NORTHERN CA. WEAK HIGH PRESSURE WILL RESULT IN
GENERALLY LIGHT WINDS THROUGH MID WEEK. ONSHORE FLOW WILL INCREASE
ON THURSDAY/THURSDAY NIGHT AS A COLD FRONT MOVES INLAND. SEAS
WILL RISE ON THURSDAY NIGHT AND FRIDAY WITH SWELLS REACHING
10-15 FEET. WINDS WILL TURN OFFSHORE THIS WEEKEND AS DEEPER LOW
PRESSURE SPINS OVER THE OFFSHORE WATERS.
33
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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