Isaac was a Category 1 hurricane in the North Atlantic Ocean as of Friday morning eastern time, the National Hurricane Center said in its latest advisory.

The hurricane had reached winds of 75 miles per hour.

What does the storm look like from above?

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

Where will it rain?

Flash flooding can occur far inland and far away from the center of the storm. Even weaker storms can cause excessive rainfall, which can flood low-lying areas.

Isaac is the ninth storm to form in the Atlantic Ocean in 2024.

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

This season follows an overly active year, with 20 named storms – including an early storm that was later officially named ‘Unnamed’. It was the eighth year in a row that the average of fourteen named storms was exceeded. Only one hurricane, Idalia, made landfall in the United States.

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

The warm ocean temperatures that fueled last year’s season have become even warmer at the start of this season, giving forecasters more confidence that more storms would arrive this year. The increased sea surface temperature could also strengthen storms faster than normal.

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

Hurricanes need a calm environment to form, and in the Atlantic Ocean, a strong El Niño increases the amount of wind shear – a change in wind speed and/or direction with height – reducing a storm’s ability to unite disturbed. Without El Niño this year, clouds are more likely to reach the high altitudes needed to sustain a powerful cyclone.