A tropical depression building off the coast of Florida is an early sign of a hurricane season projected to be the most active in years, even as the coronavirus pandemic continues to threaten the U.S.
Scientists with Penn State University’s Earth Systems Science Center are forecasting more tropical activity in 2020 than in any year since 2010. Their statistical model estimates a range of 15 to 24 named storms, with a best guess of 20. Tropical cyclones are given names when they generate wind speeds of at least 39 miles per hour.
“If you’ll forgive the expression, this year we have a sort of perfect storm of factors,” Penn State atmospheric scientist Michael Mann said in an email this week.
As of late Monday, a tropical disturbance south of Florida had a 20 percent chance of forming a cyclone, according to the National Hurricane Center. The storm comes ahead of June 1, considered the official start to hurricane season.
Mann said that “bathtub levels of warmth in the tropical Atlantic” and incipient La Niña conditions have led to reduced wind shear in the tropical Atlantic and Caribbean. That’s made the weather in these regions more likely to generate cyclones, he said.
As of Monday night, the San Antonio area had received two to three inches of rainfall over a 24-hour period, from thunderstorms that caused flash flooding Sunday night. At its peak, the storm caused more than 63,000 outages in the Bexar County area.
Strong storms could worsen situations in communities already struggling with the pandemic.
High winds could cut power to hospitals and care facilities, and people fleeing destruction and flooding could be crowded into safe sites.
San Antonio and Bexar County officials say they are preparing. On May 19, local, state, and federal agencies held their annual half-day seminar on hurricane preparedness.
The event included table-top exercises that layered a hurricane on top of the pandemic. A San Antonio Fire Department spokesman said attendees discussed social distancing in emergency shelters, security for evacuees, and coronavirus testing.
“We’re prepared for any kind of scenario,” San Antonio Mayor Ron Nirenberg said during a May 19 briefing. “The work that we’ve done together over the last couple of months over the response of this pandemic has put us in a good position to be ready to handle a hurricane at the same time.”
San Antonio has seen heavy flooding wrought by hurricanes and was even threatened by inundation from Hurricane Harvey in 2017 before that storm veered toward Houston. Harvey dropped unprecedented amounts of rain over Harris County, a record that climate scientists have linked to human-caused global warming.
Mann, a climate scientist well-known for his presentation of the hockey-stick graph showing spiking levels of carbon dioxide, said there is conflicting information in the scientific literature about whether climate change is making hurricanes more frequent. More evidence exists that warming is making them more intense and prone to record-breaking rainfall.
“In my view, it isn’t a coincidence that we’ve seen both the most intense storms and the greatest flooding in history during the past few years when ocean temperatures have been at their warmest,” Mann said.