Tracking Tropical Storm Debby (2024)

Debby was a tropical storm over South Carolina early Thursday Eastern time, the National Hurricane Center said in its latest advisory.

The tropical storm had sustained wind speeds of 50 miles per hour. Excessive rainfall was expected to pose the biggest threat as the storm moved inland.

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Forecasters warned that the region was saturated and that creeks and rivers would quickly reach flood stage. Automatic data from river gages across the region show where flooding is already occurring.

As Debby meanders at a walking pace through the Southeast this week, over 10 to 20 inches of rain could fall, with some areas reaching 30 inches.

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.

The forecast path for Debby

What does the storm look like from above?

Satellite imagery can help determine the strength, size and cohesion of a storm.

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

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.