OK, so are the effects of a “King Tide” on real estate in Palm Beach County and specifically I will look at Northern Palm Beach County.
First, what is a “King Tide”? What we now call a “King tide” is defined by NOAA as “The king tide is the highest predicted high tide of the year at a coastal location. It is above the highest water level reached at high tide on an average day. King tides are also known as perigean spring tides“
Are “King Tides” new? No, these are natural and calculable occurrence caused by an alignment of the sun and the moon. When the sun and moon are in alignment – as is the case with a new or full moon – their combined gravitational pull results in exceptionally high tides, known as Spring Tides. These Spring Tides become King Tides when the moon is in its perigee due to the stronger gravitational force of the moon on the earth’s oceans.
As for the effect on real estate. it is real IMO. The king tides basically scare the hell out of people. When one is driving along the river in Jupiter or on the road out to Singer Island and the water is over or within inches of the road then this gets people thinking about rising sea levels and things to come. Read THIS POST to see how the sea level has increased in the last 100 years at the Lake Worth Pier.
How much higher is a “King Tide” than a “normal” high tide? First we must look at the locations where the tide predictions are ‘harmonic’ such as the Lake Worth Pier. Think of these as the main tide stations. Places like the PGA Bridge do publish tide predictions but they are based upon adjustments to the main tide stations like the pier. OK, so the Mean Higher High Water (MHHW) level at the Lake Worth Pier is +3.06 ABOVE the Mean Low Lower Water (MLLW). (The MLLW is +2.51 ft by the NAVD 88 Datum.)
As I type this post on 1 October 2019 there is a coastal flood watch because of the king tides and the 10.45 AM high tide is predicted to be +3.96 ft above the MLLW. Thus the high tide at 10.45 AM today is to be 0.9 ft HIGHER than the Mean Higher High Water. By the way, the Highest Astronomical Tide (HAT) at the pier was +4.32 back in November 1998 WHICH IS 1.81 FT ABOVE THE NAVD 88 DATUM. BUT THE REALLY INTERESTING THING IS THAT THE ACTUAL RECORDED SEA LEVEL AT THE PIER AS I TYPE THIS IS ABOUT 1 FOOT HIGHER THAN THE PREDICTIONS FOR TODAY OR ABOUT +2.5′ BY THE NAVD 88 DATUM. THIS “KING TIDE” IS ABOUT 2.5 FT HIGHER THAN WHAT WE NOW USE AS “SEA LEVEL”. 10/28/19 – READ THIS to find out why.
I just thought of this. I have a waterfront property listed for sale and I know from a recent survey that the top of the sea wall there is +3.0 ft NAVD 88. Now this is up inside the ICW but the sea level did get up to about this +2.5′ level in the last few days. It never overflowed the dock, which is about the same height as the wall, but the point is that this assertion that the “King Tide” is about +2.5′ by the NAVD 88 datum which we now call “Sea Level” is correct.
