056
FXUS66 KSEW 192104
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
204 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/
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.
HIGH CLOUDS WILL REMAIN OVERHEAD THIS AFTERNOON INTO EARLY
TUESDAY. 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.
POCKETS OF SHALLOW FOG EXPECTED OVERNIGHT, ESPECIALLY OVER THE
SOUTH SOUND. LOW CLOUDS WILL BURN OFF MID TO LATE MORNING WITH
VFR CONDITIONS EXPECTED. 33
KSEA...VFR CONDITIONS EXPECTED THROUGH THE PERIOD. N WINDS
AROUND 5 KT, BECOMING NE 5-10 KT BY 12-15Z TUE. 33
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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