Map: Tracking Tropical Storm Debby

Debby was a tropical storm in the Gulf of Mexico Saturday evening Eastern time, the National Hurricane Center said in its latest advisory.

The tropical storm had sustained wind speeds of 40 miles per hour.

Debby is the fourth named storm to form in the Atlantic in 2024.

Where is flooding possible?

Storm surge is the ocean water pushed ashore by the storm’s winds and has historically been the leading cause of death from hurricanes. If the surge occurs during high tide, it can have far-reaching effects.

What does the storm look like from above?

Satellite imagery can help determine the strength, size and cohesion of a storm. The stronger a storm becomes, the more likely an eye will form in the center. When the eye looks symmetrical, that often means the storm is not encountering anything to weaken it.

Tracking Debby’s rainfall

When a storm comes close enough to land, signals from the United States radar network will begin to bounce off the rainfall within a tropical cyclone, making it easier to locate the more intense section of the storm and the heaviest rainfall.

Flash flooding can occur well inland and away from the storm’s center. Even weaker storms can produce excessive rainfall that can flood low-lying areas.

In late May, the National Oceanic and Atmospheric Administration predicted that there would be 17 to 25 named storms this year, an above-normal amount.

This season follows an overly active year, with 20 named storms — including an early storm later given the official name of “Unnamed.” It was the eighth year in a row to surpass the average of 14 named storms. Only one hurricane, Idalia, made landfall in the United States.

Typically, the El Niño pattern that was in force last season would have suppressed hurricanes and reduced the number of storms in a season. But in 2023, the warm ocean temperatures in the Atlantic blunted El Niño’s usual effect of thwarting storms.

The warm ocean temperatures that fueled last year’s season returned even warmer at the start of this season, raising forecasters’ confidence that there would be more storms this year. The heightened sea surface temperatures could also strengthen storms more rapidly than usual.

To make matters worse, the El Niño pattern present last year is also diminishing, most likely creating a more suitable atmosphere for storms to form and intensify.

Hurricanes need a calm environment to form, and, in the Atlantic, a strong El Niño increases the amount of wind shear — a change in wind speed and/or direction with height — which disrupts a storm’s ability to coalesce. Without El Niño this year, clouds are more likely to tower to the tall heights needed to sustain a powerful cyclone.