Such movements may also be linked to slowing atmospheric circulation, Dr Kossin said. “You won’t really get twists and turns until you have a slow storm,” he says. “They don’t move like karts.”
While Sally’s winds weren’t as intense as the strongest hurricanes – maximum sustained speeds early Wednesday were around 105 mph, about 50% slower than a Category 5 storm – in s lingering longer, the storm may also have increased the storm surge, the wind accumulating water that can quickly inundate coastal areas, often with devastating results.
But storm surges can be influenced by many other factors, including the timing of the tides and the shallow depth of a bay or other body of water. In this case, Sally’s slow speed “contributed more to extreme rainfall flooding than flooding,” said Rick Luettich, a professor at the University of North Carolina and lead developer of the main surge model used by forecasters. .
Dr Luettich said the storm surge was close to projections of about five feet. But another feature of some hurricanes which is linked to warmer oceans, the rapid strengthening of a storm before landing, “gave the water a greater push” than previous forecasts called for, he said. -he says.
Hurricanes are not the only type of storm affected by climate change, nor the only one that can cause catastrophic flooding on the Gulf Coast or in other areas. Record-breaking rain from a low pressure system in August 2016, a big storm that didn’t turn like a hurricane, caused flooding in Baton Rouge, Louisiana. A gauge east of town received 26.5 inches of rain in three days.
That storm triggered an attribution study, research that attempts to determine the extent, if any, of climate change influence on an extreme weather event. He found that climate change had increased the likelihood of such a storm along the Gulf Coast in any given year by 40 percent since 1900. In the current climate, there is a 3 percent chance for a given year of a similar storm.
“The risk of extreme precipitation events in this region has increased,” said Sarah Kapnick, a researcher at NOAA’s Geophysical Fluid Dynamics Laboratory in Princeton, NJ, who worked on the study.