Taking the measure of future king tides

By Dave Wilkinson
Posted 8/15/17

One of the joys of living in a coastal community is to simply watch the water as it is constantly changing, driven by our place and time in the solar system, continuously evolving weather systems and …

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Taking the measure of future king tides

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One of the joys of living in a coastal community is to simply watch the water as it is constantly changing, driven by our place and time in the solar system, continuously evolving weather systems and the complexity of the coastline itself.

A special treat – and sometimes hazard – is the king tide, occurring multiple times throughout the year, but most dramatically in the winter season. These exceptionally high tides cause flooding, debris in the streets, beach and bluff erosion, and damage to shoreline structures.

King tides also offer a chance to visualize the effects of a rising sea level. As observed at the local tide station located at the Port Townsend ferry dock, sea level has been rising steadily at a rate of 0.6 foot per 100 years over the past 44 years.

Climate models project future sea level rise of 2 feet or more by 2100, more than tripling the previous rate. The high water levels of today’s king tides let us see what the “new normal” everyday high tide will be in the not-so-distant future. Watching king tides at any particular shoreline area lets you identify potential areas of concern and adapt to future conditions.

For example, a king tide on March 10, 2016 was amplified by wind and low pressure from a passing weather system. The high tide was predicted to be about 9 feet, but the actual water level was more than 11 feet.

Puddles of seawater and piles of debris were left on downtown streets and in parking lots. At the expected rate of sea level rise, this will be routine almost monthly. Any storm surge coinciding with high tides will likely render inundated streets impassable, damage shoreside buildings and require substantial cleanup.

Local climate action groups are facilitating this “crystal ball” view of the future by photo-documenting king tide events and posting the pictures on a website set up by Washington Sea Grant. You can view photos of local high-water events at the Boat Haven marina, the Salmon Club boat ramp and the Northwest Maritime Center dock by logging on to tinyurl.com/y7ncdz5h.

You will find that many of our neighboring communities are also monitoring areas vulnerable to king tides.

One doesn’t need to look far in Port Townsend to see a variety of locations that will be impacted by sea level rise. It is a challenge that we face together, as our municipalities, local businesses, nonprofits, port, shoreline property owners, etc. all consider how to best prepare for these impacts.

The good news is that the king tides are giving us early warning signals. If we heed them now, we can minimize damage and costs in the long term.

Do your part by informing yourself and engaging with your local organizations. You can learn more about climate change by visiting the Port Townsend Marine Science Center, or going online to Local 20/20 at

L2020.org and NOAA at

climate.gov. And you can see more detailed sea level rise projections for this area at

noprcd.org.

(Dave Wilkinson teaches marine meteorology at Northwest sailing schools and participates in local climate action groups.)

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