King tides are coming to the Southeast coast: Here's what to know
The seasonal occurrence that can lead to disruptive tidal flooding is due to a combination of astronomical, climatological and meteorological factors.
The full moon has brought king tides and flooding to South Florida. AccuWeather’s Leslie Hudson talks to city officials about how they handle the expected flooding.
A meteorological phenomenon known as 'king tides' is coming to east- and south-facing beaches along the Southeast coast this week and will lead to disruptive coastal flooding, warn AccuWeather meteorologists.
The extra push of water ashore, occurring around high tides through Tuesday from Florida to North Carolina, will be assisted by our moon, despite the fact that it's more than 220,000 miles away from Earth.
"A full moon occurred on Monday, and tides are typically higher than average around that time as the Earth, sun and moon are all aligned," explained AccuWeather Senior Meteorologist Dan Pydynowski. "This causes their gravitational pulls to combine and produce higher tides." The moon will also be approaching perigee, the closest it is to Earth all year long, adding to that pull.
An added complication of a strong onshore flow will only help to worsen tidal flooding.
"A large and nearly stationary area of high pressure off the Northeast coast will produce day after day of easterly flow through the week," Pydynowski said.
While residents along the Southeast coast are no strangers to tidal flooding, even on perfectly sunny days, because of climate change-induced rising sea levels, king tides can push water up to an even higher level.
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Some of the more notorious spots for coastal flooding, including lower-lying beaches, cities and tidal basins such as those found in and near Charleston, South Carolina; Miami Beach, Florida; Myrtle Beach, South Carolina; and Savannah, Georgia; will especially be at risk for inundation early this week.
In Charleston Harbor, high tides typically reach a level of 6-7 feet above mean lower low water (MLLW). During king tides, that water level can reach as high as 7.5 or 8 feet above MLLW, which can lead to flooded roads in Downtown Charleston.
Even ahead of the king tide threat early this week, coastal flood advisories were posted for more vulnerable coastlines this past weekend from the east-central Florida Peninsula to North Carolina, due to the robust onshore flow and the building gravitational pull from the moon.
The threat was not limited to just the Atlantic coastline, but also for those farther inland along tidal rivers, bays and sounds, such as the Cape Fear River, Cooper River, Pamlico Sound, Savannah River and St. Johns River.
Flood waters reflect East Battery as a king tide rolls into the historic Battery causing flooding in Charleston, S.C. Sunday, Nov. 15, 2020. (AP Photo/Mic Smith)
When coastal flooding is forecast, locals often know what action to take, but sometimes visitors and tourists do not. Cars parked on roads vulnerable to flooding will need to be moved to higher ground around times of high tide. In addition, never drive around barricades and onto flooded roads.
In addition to water rising from the ocean and bodies of water, it will be falling from the sky. The easterly flow will come with frequent showers, some with torrential downpours.
"By the second half of the week, the king tides will continue," AccuWeather Climate Change Expert Brett Anderson said. "However, onshore winds will lessen and even become slightly offshore in some areas, which will reduce the risk of coastal flooding."
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