Minor coastal flooding is likely to continue for at least another day or two along Palmetto State beaches, primarily caused by a phenomenon known as the “spring tide”.
The spring tide is not named for the season; it refers to a larger than average tidal range where high tide levels are high and low tide levels are low. A particularly high spring tide has become colloquially referred to as a “King Tide”. King Tides occur when the earth, sun, and moon are lined up and in relatively close proximity to one another, especially during the new moon phase, during the fall and early winter months.
The National Weather Service has issued Coastal Flood Warnings for the Lowcountry coastline through early Monday afternoon for moderate to major coastal flooding around the time of high tide. Coastal Flood Advisories are in effect for the Grand Strand through midday Monday. Coastal Flood Advisories are typically issued when minor to locally moderate coastal flooding is likely.
The Charleston tide gauge is recording some of its highest tides on record, including a top 10 height for a non-tropical system on Sunday.
High tide peaked at 8.19 ft MLLW at the Charleston Harbor @noaaocean tide gauge at 10:12am. This ranks as the 14th highest tide on record and the 9th highest non-tropical tide. Historic crest rankings and other info available here https://t.co/cnhf6HV1My. #scwx #chswx pic.twitter.com/Yplof9Wy6I
— NWS Charleston, SC (@NWSCharlestonSC) October 18, 2020
Persistent and strong easterly winds as a result of high pressure over New England and the Mid Atlantic states is also pushing water toward the Atlantic coastline. This weather pattern is forecast to continue for a few more days; however, high tide levels should begin to ease as we move farther away from the new moon phase. Forecasts continue to show minor flooding lasting until at least Wednesday in the Charleston area.
Other factors such as water level rises from climate change and increased development near the coast in recent decades are likely contributing to exposure from the flooding, as well.