Florida’s East Coast Faces More Coastal Flooding as King Tides Ease
Just because the king tides are starting to ease does not mean that the threat of flooding is over along the Atlantic coastline. Forecasters are warning that persistent onshore winds will keep water levels high well into next week. Here is a look at what you can expect in the days ahead along this stretch of battered coastline.
Threat of Coastal Flooding and Erosion Persists Along Atlantic Coastline
Lingering onshore winds will continue to create rough surf conditions and beach erosion through the early part of next week for much of the East Coast. Although water levels will begin to trend downward this weekend, minor coastal flooding will continue to be an issue.
The flooding started early in the week when a full moon generated higher high tides and lower low tides. The term "king tide" is used to describe exceptionally high tides that often happen when a full or new moon lines up with the moon's closest approach to Earth.
Strong rip currents will also remain a concern despite the diminishing high tides. This threat will be the greatest along Florida's east coast. The forecast of strong onshore winds will strengthen thanks to the clash of the area of high pressure coming together off the mid-Atlantic coast and the zone of low pressure currently hovering over the Caribbean.
These persistent winds threaten the coastline by sending large volumes of ocean water either toward or away from a shoreline. This movement not only generates high waves, but it also changes the water levels along the coast.
The strong onshore winds push water against the coastline and into the nearby bays. This impact is elevated when the winds find a large zone of open water to pick up steam. The winds also work to slow the natural drainage of water from tidal waterways and bays, amplifying the flooding issues.
Low-tide levels exacerbated by potent onshore winds can sometimes exceed the forecast astronomical high tide levels. This scenario can send coastal water levels several feet over what had been expected. The relative strength of the winds, how long they whipped around, and the depth of water near the coastline all factor into how high these water levels will reach.
Acute Weather Events Produce Surge Known as a Storm Tide
Severe weather events such as hurricanes and nor'easters also produce what is known as storm surge, a rise in the water above the expected astronomical tide driven by storms. Meteorologists call the combination of the natural astronomical tide pairing with storm surge a storm tide.
The severity of the flooding is influenced by surge height, the timing of the tide with the peak of the storm, and local conditions. For example, potent winds blowing out from land toward the water can actually direct water away from the coast. This naturally lowers water levels below the forecast tide levels. Although this is generally better than too much water inundating the coastline, it can trigger what is known as blowout tides. This specific type of tide can leave small watercraft stranded in the shallow water.
Changes in water temperature may also impact tide levels. Average sea levels typically peak in the late summer or early fall months along the East Coast, precisely because this is when water temperatures reach their highest levels. Sea levels inherently rise during these months because water expands as it warms.
This problem is not unique to the East Coast. A strengthening El Niño is sending ocean waters soaring in the Pacific. These warmer-than-average sea surface temperatures and the formation of Kelvin waves are boosting water levels along the coast of California, particularly in the southern part of the state.
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