When a King Tide Isn't so royal

Photo of Hollywood Beach taken during the "King Tide" on 6 December 2017

I love me some King Tides, and I love that we've built programs around appreciating and even viewing these sorts of events.  The concept is that we can use these high water events to understand future conditions, or learn something about the complex suite of processes that drives variations in marine water level in our neck of the woods.  I'm 100% in to both of those concepts.

Predicted water level due to astronomical tides in Port Angeles, Washington for the winter 2017-2018

The predicted marine water levels due to the astronomical tides for this winter in Port Angeles, WA (relative to Mean Lower Low Water, or MLLW) are shown above, and four "King Tide" periods stand out as the three humps on the top of the curve, where predicted water level exceeds 7.5 feet.  For reference, the mean higher high water (essentially the daily average high tide) elevation here is 7.0 feet relative to mean lower low water.  So these are pretty high water events.

Predicted (blue) and measured (red) water level at Port Angeles on 6 December 2017

So yesterday's predicted high water level for Port Angeles was 7.8 feet - thats pretty good - and i went down and snapped a pic looking east from the Feiro Marine Life Center (check it out above).  And I have to say, it was pretty unexciting.  What gives?  The measured water level yesterday was considerably lower than predicted...by a full foot.  So the actual water level actually was even lower than the daily high tide.

Predicted (blue), measured (green) and the difference between the two (purple) for Port Angeles for the last year

If we look back even further, and look at a whole year of water level data, we can see that, in fact, water level has reached that 7.5 ft threshold on numerous occasions.  The highest water level in the last year occurred on February 9 of this year.  This one was particularly cool because this particular event was the opposite of what happened yesterday.  It was an astronomical King Tide, with a predicted water level of 7.7 feet...but what actually hit the shoreline was an impressive actual water level of 9.2 feet...which is getting close to the highest observed water for this station (dating back to 1979) of 10.5 feet.  Sadly, no pictures.

Predicted (blue), and measured (green) water level in Port Angeles, WA, and the difference between the two (purple) for February 9, 2017

My take away, though, is that to really get the good King Tide photos its worthwhile looking watching your local tide gauge, and in particular paying attention to what we call the NTR, or "non-tidal residual", which is the difference between the observed and predicted water level (the purple lines on my plots).  If that NTR is high, like 1 ft plus in our area, then get out there!  Heck, if its really high (like 2+ ft), then get out there at any high tide.