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Friday, September 22, 2023
Sept. 22, 2023

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King tides coming to Puget Sound area and Seattle

Officials don’t expect repeat of December flooding


SEATTLE — Communities across the Puget Sound area are preparing for high waters and potential flooding as king tides are forecast to raise waters in the early mornings of today through Wednesday.

Next week’s king tides, or the highest tides of the year, come less than a month after a king tide brought the worst flooding that Seattle’s South Park neighborhood had seen in years, leaving at least 13 homes flooded on Dec. 27.

On a smaller scale, seawater swamped shoreside parks and homes in King, Whatcom and Snohomish counties.

The National Oceanic and Atmospheric Administration does not expect the upcoming king tides today, Tuesday and Wednesday to cause heavy flooding.

The widespread flooding on Dec. 27 was caused by a storm system that delivered strong winds and heavy rains across the region, as well as an unusually low sea level pressure.

The low pressure caused the water in Puget Sound to bulge upward, creating a strong storm surge, NOAA said.

The sea level pressure at Seattle Tacoma Airport was 978.3 mb on Dec. 27, the seventh lowest on record. This pressure alone is estimated to have contributed over a foot of surge waters, according to NOAA.

For the upcoming king tide event, many of those factors will not come together again, NOAA officials said in an online webinar.

High tides are predicted through Jan. 27 with king tides the mornings of Jan. 23-25. These king tides will be coupled with a higher-than-normal surface pressure, which will have the opposite effect of December’s king tides and reduce storm surge levels.

This round of king tides also does not include “much in the way of winds, wind-driven waves, river levels, heavy precipitation, snow melt or anything else that would contribute to higher than usual water levels,” said Reid Walcott, a meteorologist with NOAA.

“While some minor tidal overflow is possible due to just the astronomical tides themselves, the water levels are not expected to reach anywhere close to the levels seen Dec. 26 and 27,” Walcott said.

To prepare for the next round of king tides and potential flooding, Seattle Public Utilities, Seattle Department of Transportation and the Finance and Administrative Branch have set up temporary flood barriers (concrete blocks, jersey barriers and sandbags) along the Duwamish River and in South Park.

In addition to temporary flood barriers, SPU is also in the process of improving drainage and building a pump station in South Park, where high waters are common as it is situated on a river floodplain.

When complete next year, the station will pump stormwater from South Park’s lower industrial basin into the Lower Duwamish Waterway, preventing water backing up in pipes during high tide to cause flooding, SPU said online.

Other drainage-related projects in South Park include added stormwater infrastructure and the South Park Drainage and Roadway Partnership with the Seattle Department of Transportation, which will be completed this year, SPU said.

A state-led project encourages people to upload photos of king tides or other high-water events online at mycoast.org/wa. The documentation helps scientists, local planners and others understand how sea-level rise and storm surges affect local infrastructure and ecosystems.

NOAA catalogs king tides in the U.S. and other tide predictions for states and regions at tidesandcurrents.noaa.gov. The agency also publishes seasonal projections for high tides.

But before high tides and king tides arrive through Friday, you can make the most of low tides sucking water away from beaches, revealing beaches teeming with life.

Low tides offer a magical time to discover Puget Sound’s multitude of marine plants and animals.