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'Zombie storms' may become common due to climate change with tropical storm Paulette returning from the dead

Above-average sea surface temperatures are one reason why Paulette came back to life, say experts

A tropical storm has come back from the dead, introducing us to a new term: zombie tropical storms. The weather event, which is linked to climate change, is likely to become more common, experts believe.

The tropical storm in question is Paulette, which formed early this month. It made landfall in Bermuda as a Category 1 and strengthened to a Category 2 on September 14, according to CNN. Five-and-a-half days later, it died out. But that was not the end for Paulette. According to the National Hurricane Center, it regained strength and became a tropical storm once again on 21 September, appearing about 300 miles away from the Azores Island. On 23 September, Paulette transformed into a post-tropical cyclone for the second time, the National Hurricane Center said.

We have had events like the zombie storms before, but are rare. In 2004, it was Hurricane Ivan, the National Weather Service tweeted. It made landfall near Gulf Shores and eventually weakened. But then it circled and came back to hit Florida again. "Conditions can become hostile for a tropical storm to maintain its intensity, but if it doesn't dissipate completely, it can revive days later when conditions become more favorable," CNN meteorologist Brandon Miller.

"One of the reasons for Paulette's “coming back to life” is the same reason for an active tropical storm season—above-average sea surface temperatures," Jim Foerster, a meteorologist, wrote in Forbes. In other words, warmer waters provide the necessary energy for a tropical cyclone to grow. It needs a sea surface temperature needs to be above 80F. If temperatures drop below 77F, it weakens because there is not enough energy to maintain the intensity. "With the warmer sea surface temperatures near Portugal, Paulette was able to regain tropical storm strength," he explained.

In addition to warm ocean waters, tropical storms also depend on moist, humid air to form. They develop near the equator, mostly off the coast of Africa, and move towards the west. The US witnessed nine tropical storms this year, breaking records. "This ties 2020 with the 1916 Atlantic #hurricane season for the most named storms to make continental US landfall in an Atlantic hurricane season on record," Philip Klotzbach, a meteorologist at Colorado State University tweeted.

We might have more Zombie storms to come. "2020 is a good candidate to experience a zombie storm because water temperatures are above average over a bulk of the Atlantic Ocean, and obviously we are seeing a record number of storms -- which ups the chances one could regenerate," Miller said. 

Climate change is worsening hurricanes. There has been an "extreme amount of heating of the Gulf (of Mexico), particularly in some of the ocean areas off of the Caribbean," Donald Wuebbles, a professor of atmospheric sciences at the University of Illinois at Urbana-Champaign, told Live Science. Most hurricanes hit the US after passing through the Gulf of Mexico -- a region vulnerable to global warming because the waters are shallow, and hence, warm up with ease, Wuebbles explained.