232
FXUS66 KSEW 191524 AAC
AFDSEW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SEATTLE WA
824 AM PDT MON OCT 19 2026
SYNOPSIS
UPPER LEVEL LOW OFF THE COAST NEAR 130W WILL MOVE SOUTH ENDING
UP OFF THE CENTRAL CALIFORNIA COAST TUESDAY. SOUTHWESTERLY FLOW
ALOFT OVER THE AREA WEDNESDAY. FRONT DISSIPATING OVER WESTERN
WASHINGTON THURSDAY WITH THE TRAILING UPPER LEVEL TROUGH MOVING
THROUGH THURSDAY NIGHT INTO FRIDAY. LOTS OF UNCERTAINTY IN THE
WEEKEND FORECAST WITH A FEW MODEL SOLUTIONS SHOWING A STRONG
FRONT MOVING INTO THE AREA.
SHORT TERM /TODAY THROUGH WEDNESDAY/
SATELLITE IMAGERY SHOWS HIGH CLOUDS OVER WESTERN WASHINGTON THIS
MORNING WITH AN UPPER LEVEL LOW ALONG 130W WEST OF HOQUIAM.
TEMPERATURES AT 3 AM/10Z IN THE 40S AND LOWER 50S.
UPPER LEVEL LOW MOVING SOUTH TODAY WITH SOUTHWESTERLY FLOW
ALOFT KEEPING HIGH CLOUDS OVER THE AREA. THERE ARE SOME
TEMPERATURE DEW POINT SPREADS NEAR 0 EARLY THIS MORNING SO EVEN
WITH THE CLOUD COVER PATCHY FOG POSSIBLE UNTIL MID MORNING.
HIGHS IN THE UPPER 50S TO MID 60S.
UPPER LEVEL LOW CONTINUING TO MOVE SOUTH TONIGHT AND TUESDAY
ENDING UP OFF THE CENTRAL CALIFORNIA COAST. AS THE LOW MOVES
FARTHER AWAY HIGH CLOUD COVER WILL THIN OUT OVERNIGHT INTO
TUESDAY. THINNER CLOUD COVER OVERNIGHT PLUS LIGHT SURFACE
GRADIENTS WILL LEAD TO MORE FOG COVERAGE TUESDAY MORNING. THE
LAYER WILL BE SHALLOW ENOUGH TO DISSIPATE BY NOON. LOWS TONIGHT
MOSTLY IN THE MID 30S TO MID 40S WITH LOCAL LOWS NEAR FREEZING
OVER THE SOUTHWEST INTERIOR AND NEAR THE HOOD CANAL. HIGHS
TUESDAY IN THE UPPER 50S TO MID 60S.
UPPER LEVEL LOW WELL TO THE SOUTH WITH A DEVELOPING UPPER LEVEL
TROUGH WELL TO THE NORTH TUESDAY NIGHT AND WEDNESDAY LEAVING
MOSTLY CLEAR SKIES OVER WESTERN WASHINGTON. LOW LEVEL FLOW
TURNING OFFSHORE BUT NOT STRONG ENOUGH TO PREVENT AREAS OF FOG
FROM DEVELOPING EARLY WEDNESDAY MORNING. WHAT FOG THAT DOES FORM
WILL DISSIPATE BY MIDDAY. LOWS IN THE 30S AND LOWER 40S. HIGHS
IN THE LOWER TO MID 60S. FELTON
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
EXTENDED MODELS IN GOOD AGREEMENT EARLY ON WITH A WEAKENING
FRONT DISSIPATING OVER THE AREA THURSDAY FOR A CHANCE OF SHOWERS.
TRAILING UPPER LEVEL TROUGH MOVING THROUGH THURSDAY NIGHT INTO
EARLY FRIDAY WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA
FOR A DRY FRIDAY.
CONFIDENCE IN THE FORECAST FOR THE WEEKEND PRETTY LOW AT THIS
POINT. MODEL RUN TO RUN CONSISTENCY TERRIBLE WITH SOLUTIONS ALL
OVER THE PLACE FOR A DEVELOPING SYSTEM OFF THE COAST. PREVIOUS
RUN HAD A FEW WINDY SOLUTIONS FOR SATURDAY INTO SUNDAY WITH
RAIN. SOME OF THE ECMWF ENSEMBLES STILL POINTING AT A WINDY
COAST AND NORTHWEST INTERIOR SCENARIO. GFS SOLUTIONS MUCH WEAKER
WITH THE OPERATIONAL RUN ABOUT 20 MB WEAKER WITH THE SURFACE
LOW ASSOCIATED WITH THE FRONT VERSUS THE ECMWF. WITH ALL THE
UNCERTAINTY WEEKEND FORECAST A BROADBRUSH CHANCE OF RAIN/RAIN
LIKELY. DO NOT HAVE ANY IMPACTFUL WINDS IN THIS FORECAST
PACKAGE. PRETTY CONFIDENT THE WEEKEND FORECAST IS GOING TO
CHANGE A FEW TIMES BEFORE FRIDAY.
HIGHS IN THE MID TO UPPER 50S THOUGH THE PERIOD WITH LOWS IN
THE 30S AND LOWER 40S. FELTON
AVIATION
SOUTHWESTERLY FLOW ALOFT IS EXPECTED TODAY AS AN
UPPER TROUGH DIGS SOUTHWARD OFFSHORE. FLOW ALOFT THEN TURN MORE
VARIABLE INTO EARLY TUESDAY. MID TO HIGH LEVEL CLOUDS THIS
MORNING IS LIMITING AREAL COVERAGE OF LOW CLOUDS AND FOG WITH
THE EXCEPTION OF MORE FOG PRONE LOCATIONS IN THE SOUTHWEST
INTERIOR, SOME RIVER VALLEYS, AND EXTREME SOUTHERN PUGET SOUND
FOR THE POTENTIAL OF IFR/LIFR CONDITIONS. IMPACTED TERMINALS
EXPECTED TO IMPROVE BY 18Z FOR WIDESPREAD VFR CONDITIONS. WINDS
WILL SHIFT MORE SOUTHERLY MONDAY MORNING THEN TRANSITION BACK
NORTHERLY IN THE EVENING. MORE WIDESPREAD LOW CLOUDS/FOG A
POSSIBILITY LATE TONIGHT INTO TUESDAY MORNING.
KSEA...CONFIDENCE LEANS TOWARD VFR CONDITIONS CONTINUING TODAY. MID-
HIGH CLOUDS OVERHEAD SHOULD LIMIT FOG DEVELOPMENT THIS MORNING.
SURFACE WINDS LIGHT THIS MORNING. WINDS WILL SHIFT MORE
NORTHWESTERLY AFTER 19Z-21Z AT 5-8 KT AND REMAINING INTO THE
EVENING. 33/41
MARINE
A LOW PRESSURE SYSTEM PASSING SOUTHWARD WELL OFFSHORE
WILL KEEP WINDS NORTHERLY OR WEAKLY OFFSHORE FOR TODAY. WEAK
HIGH PRESSURE WILL REMAIN ACROSS THE WATERS INTO THE MIDDLE OF
THE WEEK FOR A PERIOD OF BENIGN CONDITIONS. A LARGER SWELL TRAIN
NEAR 10-12 FEET GENERATED BY ACTIVE WEATHER WELL OFFSHORE IS
EXPECTED TO REACH THE COASTAL WATERS AROUND THURSDAY ALONG WITH
AN INCREASE IN ONSHORE FLOW. A FRONT MAY REACH THE WATERS TOWARD
THE END OF THE WEEK BUT MUCH UNCERTAINLY EXISTS IN REGARDS TO
CURRENT TRACK AND INTENSITY.
41
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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