Tropical Storm Idalia formed on Sunday, becoming the latest named storm of the 2023 Atlantic hurricane season, and one that threatens to bring heavy rains to Florida, Georgia and the Carolinas, forecasters said.
The National Hurricane Center, in an advisory on Sunday when the storm was still designated as a tropical depression, noted that from Tuesday into Wednesday, parts of the west coast of Florida, the Florida Panhandle and southern Georgia could get up to six inches of rain, with higher isolated totals of 10 inches.
Heavy rainfall was also expected to spread into portions of the Carolinas by Wednesday into Thursday, the center said.
“There is an increasing risk of life-threatening storm surge, flooding from heavy rainfall and hurricane-force winds along portions of the west coast of Florida and the Florida Panhandle beginning as early as Tuesday,” the center said.
The Florida Division of Emergency Management told residents to keep their gas tanks halfway full in case emergency evacuation orders were issued.
Gov. Ron DeSantis of Florida signed an executive order on Saturday declaring a state of emergency in 33 counties in preparation for the storm.
“I encourage Floridians to have a plan in place and ensure that their hurricane supply kit is stocked,” he said.
The Hurricane Center estimated that the storm had sustained winds of 40 miles per hour with higher gusts.
In late May, the National Oceanic and Atmospheric Administration predicted that there would be 12 to 17 named storms this year, a “near-normal” amount. On Aug. 10, NOAA officials revised their estimate upward, to 14 to 21 storms.
There were 14 named storms last year, after two extremely busy Atlantic hurricane seasons in which forecasters ran out of names and had to resort to backup lists. (A record 30 named storms took place in 2020.)
This year features an El Niño pattern, which arrived in June. The intermittent climate phenomenon can have wide-ranging effects on weather around the world, and it typically impedes the number of Atlantic hurricanes.
In the Atlantic, El Niño increases the amount of wind shear, or the change in wind speed and direction from the ocean or land surface into the atmosphere. Hurricanes need a calm environment to form, and the instability caused by increased wind shear makes those conditions less likely. (El Niño has the opposite effect in the Pacific, reducing the amount of wind shear.)
At the same time, this year’s heightened sea surface temperatures pose a number of threats, including the ability to supercharge storms.
That unusual confluence of factors has made solid storm predictions more difficult.
“Stuff just doesn’t feel right,” Phil Klotzbach, a hurricane researcher at Colorado State University, said after NOAA released its updated forecast in August. “There’s just a lot of kind of screwy things that we haven’t seen before.”
There is solid consensus among scientists that hurricanes are becoming more powerful because of climate change. Although there might not be more named storms overall, the likelihood of major hurricanes is increasing.
Climate change is also affecting the amount of rain that storms can produce. In a warming world, the air can hold more moisture, which means a named storm can hold and produce more rainfall, like Hurricane Harvey did in Texas in 2017, when some areas received more than 40 inches of rain in less than 48 hours.
Rebecca Carballo contributed reporting.
Rebecca Carballo contributed to this report.