December 23 – 24 will bring us another round of King Tides, so this is a good time to explain what King Tides are.
Define King Tide:
The term “King Tide” is not a scientific term; it is used to describe the highest and lowest tides that naturally occur each year. In some cases, they may barely even be noticed. Low King Tides usually don’t cause a problem, so the interest is in the high King Tides. These abnormally high tides may cause flooding of low-lying areas and disruption to normal daily routines. This is particularly true when a King Tide event coincides with significant precipitation and winds and therefore may cause problems with water drainage and runoff.
What causes a King Tide?
The sun and moon create a gravitational pull on the oceans. When there is a full or new moon and the moon is closest to the Earth on its elliptical path, it creates a “bulge” on the side of the Earth that faces the sun/moon and the side directly opposite.
There are usually two high and two low tides every day. The moon rotates on a lunar day which is different than the 24-hour solar day we use. A lunar day is the time it takes the moon to complete one rotation around the earth with respect to the sun. A lunar day is 24 hours and 50 minutes. That means there is a high tide every 12 hours and 25 minutes.
How high are King Tides?
In Charleston, the average high tide is about 5.5 feet. Flood stage for our area is about 7 feet and during a King Tide, the tide can be higher than this.
When are the next King Tides?
In addition to the December 23 – 24 event, we will also have King Tides on:
- January 21 – 23
- February 19 – 20
It is important to be aware of when King Tides occur as well as the events that may make the tides even higher. Rain before and during high tides can saturate the ground as well as cause an issue with drains. When there is significant wind off the ocean, such as the gale force winds we had a few weeks ago, the problem can be made worse.
Don’t attempt to drive through deep water. Not only may it damage your car, but the road/bridge foundation may be compromised.
Remember, be prepared; stay safe.
–Tidelines Editors
(Photo credit: nckingtides.web.unc.edu)