The National Weather Service has released a flood watch for King and Pierce counties from Saturday afternoon to Sunday night.
Flood Watch
FLOOD WATCH...UPDATEDNATIONAL WEATHER SERVICE SEATTLE WA
1234 PM PST FRI DEC 19 2014
WAC009-027-031-033-041-045-053-057-061-067-073-200845-
/O.EXT.KSEW.FA.A.0015.141221T0000Z-141222T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLALLAM-GRAYS HARBOR-JEFFERSON-KING-LEWIS-MASON-PIERCE-SKAGIT-
SNOHOMISH-THURSTON-WHATCOM-
1234 PM PST FRI DEC 19 2014
...FLOOD WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH LATE
SUNDAY NIGHT...
* PORTIONS OF WESTERN WASHINGTON...INCLUDING THE FOLLOWING
COUNTIES... GRAYS HARBOR...CLALLAM...JEFFERSON...SKAGIT...
WHATCOM...KING...LEWIS...MASON...PIERCE...SNOHOMISH...THURSTON.
* FROM SATURDAY AFTERNOON THROUGH LATE SUNDAY NIGHT
* HEAVY RAIN IS FORECAST OVER WESTERN WASHINGTON SATURDAY AND
SUNDAY...ESPECIALLY IN THE MOUNTAINS. STRONG WESTERLY FLOW
ALOFT WILL BRING HEAVY RAIN AT TIMES TO THE COAST AND OLYMPICS
ON SATURDAY. HEAVY RAIN WILL SPREAD INTO THE CASCADES SATURDAY
AFTERNOON. MODELS CURRENTLY TAPER RAIN OVER THE OLYMPICS ON
SUNDAY BUT KEEP HEAVY RAIN GOING IN THE CASCADES THROUGH SUNDAY
NIGHT...ESPECIALLY OVER THE CASCADES FROM ABOUT KING COUNTY
SOUTH. THE TOTAL MODEL RAINFALL OVER ABOUT 48 HOURS FROM
SATURDAY MORNING THROUGH SUNDAY NIGHT AMOUNTS TO AROUND THREE
TO SIX INCHES OVER THE OLYMPICS AND CENTRAL CASCADES WITH A
NINE- INCH BULLS-EYE OVER MOUNT RAINIER. RAINFALL OVER THE
LOWLANDS WILL GENERALLY BE AN INCH OR LESS AS THE WESTERLY FLOW
CAUSES A RAINSHADOW EAST OF THE OLYMPICS.
* THESE RAINFALL AMOUNTS ARE ENOUGH TO CAUSE FLOODING. AT THIS
TIME THE RIVERS MOST LIKELY TO FLOOD ARE THE ONES FLOWING OFF
THE CASCADES OF KING...PIERCE...AND LEWIS COUNTIES...AS WELL AS
THE UNUSUALLY FLOOD-PRONE SKOKOMISH RIVER IN MASON COUNTY. ANY
FLOODING WOULD LIKELY BEGIN SATURDAY NIGHT ON THE OLYMPICS AND
SUNDAY FOR THE CASCADES...WITH CRESTS SUNDAY NIGHT OR MONDAY.
THE EXACT POSITION OF THE STREAM OF MOISTURE IS UNCERTAIN SO
THIS OUTLOOK COVERS THE ENTIRE OLYMPIC PENINSULA AND ALL OF THE
CASCADES RIVERS.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A FLOOD WATCH MEANS CONDITIONS ARE FAVORABLE FOR FLOODING BUT
FLOODING IS NOT IMMINENT OR OCCURRING. MONITOR THE LATEST
FORECASTS FROM THE NATIONAL WEATHER SERVICE AND BE READY TO ACT
QUICKLY IF FLOODING IS OBSERVED OR A WARNING IS ISSUED.