Tuesday, December 22, 2015

West Coast US Coastal Flooding - high tides and waves

By: Dr Larry P. Atkinson , 11:34PM,GMT on December 22,2015



 
The west coast of the US is experiencing coastal flooding from what I see in the news reports. It appears to be a combination of monthly high tides and high waves. Below I have data from the National Data Buoy Center (NOAA/NDBC) and the ExtraTropical Surge Product from the National Weather Service.




Figure 1. Data from LINK. The red dots are where the upcoming tides are above the 19 year highest astronomical tide.



Figure 2. Plot of astronomical tide (blue), predicted (Black). Right of the red vertical line is predictions. Left is past and thus observations. Note that the storm surge component (orange) is near zero. The anomaly (green) I assume is the effect of the large swells coming ashore. Note the astronomical tides are higher right now exacerbating the flooding.




Figure 3. This figure from a National Data Center Buoy LINK shows that significant wave heights are in the 10 to 22 foot range - quite large.

Finally Surfline has a beautiful animation of global wave heights - the surfers care !  LINK 

Experts on west coast flooding feel free to chime in on this.

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