English: Southern Florida was swamped under widespread flooding in early November 2021, thanks to king tides and a powerful storm that struck the southeast from November 5-6. The storm fit the definition of a nor’easter, which are storms more commonly associated with New England. To classify as a nor’easter, the strong wind must blow inland from the Atlantic Ocean and must blow from the northeast.

Nor’easters typically develop within 100 miles of the East Coast of the United States and in the latitudes between Georgia and New Jersey. They are uncommon in Florida but when they do strike here, they tend to be weaker than more northerly storms.

By November 5, the unusual and powerful storm was at full force over the Florida, dumping as much as 8 inches (20 cm) of rain to parts of the state. Wind gusts ranged between 50-70 mph (80-112 km/h) from Florida’s First Coast to Hilton Head Island, South Carolina, according to The Weather Channel.

The powerful onshore winds drove the storm surge onshore just as tides reached their near-highest level of the year. These “king tides” arrive when the new moon aligns with the moon’s closest approach to Earth. This close approach is called a “perigee”, and the powerful tides created by the close approach are called “perigean spring tides” or “king tides”. Even without storm surge, king tides can increase normal tidal range by a couple of inches.

With the average elevation of South Florida only 6 feet above sea level, and many areas at 3 feet above sea level, South Florida is at high risk of for flooding and significant risk for rising sea level driven by climate change. According to NASA’s Jet Propulsion Laboratory, in 2017 it was estimated that more than ten percent of Florida’s population live at elevations of 4 inches or less above the high tide level. Single events like this one strong storm can cause widespread flooding, which may last for days or weeks due to difficulties in drainage of the low-lying region. The southeast Florida counties are collaborating through the regional Climate Change Compact to try to prepare for substantially higher seas by 2060.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of South Florida on November 8, only two days after the end of the storm.

The coasts along the Atlantic Ocean and Gulf of Mexico, along with the Florida Bay (between the Keys and the mainland) are stained with the tan, green, and blues that is typical of run-off after a heavy storm. Some of the tint, especially in Florida Bay, may also come from a bloom of microscopic plant-like organisms known as phytoplankton. The deep green and tan area at the southwestern tip of Florida is the Everglades. This large wetland, also known as the River of Grass, helps protect low-lying terrain from the advancing ocean as well as providing a refuge for unique wildlife. The gray pixels stretching up the southeast coast mark the sprawling Miami metropolitan area. The metro area encompasses the three most populous counties in Florida and many cities, including Miami, Fort Lauderdale, West Palm Beach, Hialeah, Hollywood, and Boca Raton.