Climate Shift Index Alert•September 23, 2024

Climate change amplifying ocean heat along the projected path of Potential Tropical Cyclone Nine [Hurricane Helene]

UPDATE: October 2, 2024
After Climate Central released the alert below on September 23, Potential Tropical Cyclone Nine was named Tropical Storm Helene by the National Hurricane Center. Rapidly intensifying over unusually warm Caribbean Sea and Gulf of Mexico waters, the storm became a hurricane (Hurricane Helene) and reached Category 4 strength before making landfall. Using the **Climate Shift Index: Ocean, we can confirm that these unusually elevated sea surface temperatures were made at least 200-500 times more likely due to climate change. See the Ocean CSI map here**. Our partners at World Weather Attribution also conducted a rapid attribution study on Hurricane Helene, finding that climate change was a key driver of the hurricane and its impacts. On September 26, Hurricane Helene made landfall near Perry, Florida with 120 mph winds, and generated record storm surge, extensive flooding, and widespread power outages. Its unusually large wind field and rapid forward motion allowed Helene to maintain tropical storm characteristics while carrying record-level moisture across the southeastern U.S., ultimately causing historic and devastating flash flooding in the Appalachian states of North Carolina, South Carolina, Tennessee, and Georgia.

UPDATE: October 2, 2024

After Climate Central released the alert below on September 23, Potential Tropical Cyclone Nine was named Tropical Storm Helene by the National Hurricane Center. Rapidly intensifying over unusually warm Caribbean Sea and Gulf of Mexico waters, the storm became a hurricane (Hurricane Helene) and reached Category 4 strength before making landfall.

Using the Climate Shift Index: Ocean, we can confirm that these unusually elevated sea surface temperatures were made at least 200-500 times more likely due to climate change. See the Ocean CSI map here. Our partners at World Weather Attribution also conducted a rapid attribution study on Hurricane Helene, finding that climate change was a key driver of the hurricane and its impacts.

On September 26, Hurricane Helene made landfall near Perry, Florida with 120 mph winds, and generated record storm surge, extensive flooding, and widespread power outages. Its unusually large wind field and rapid forward motion allowed Helene to maintain tropical storm characteristics while carrying record-level moisture across the southeastern U.S., ultimately causing historic and devastating flash flooding in the Appalachian states of North Carolina, South Carolina, Tennessee, and Georgia.

September 23, 2024

Today, the National Hurricane Center initiated forecasts for Potential Tropical Cyclone Nine, which is expected to strengthen into a hurricane as it moves into the Gulf of Mexico. Exceptionally warm sea surface temperatures along the system’s projected path, through the Northern Caribbean and Eastern Gulf of Mexico, have been made at least 200 to 500 times more likely due to human-caused climate change.

Climate Shift Index: Ocean alert September 2024

Note: This is NOT a storm forecast. Visit the National Hurricane Center for the latest updates and information on how the storm is evolving. For more information on the Climate Shift Index: Ocean, refer to the FAQs.

What do experts say?

Dr. Daniel Gilford, Meteorologist and Climate Scientist at Climate Central, said: “Unseasonably hot ocean temperatures made hotter by human-caused climate change will offer the storm plenty of fuel to intensify once it becomes better organized.”

How do we know climate change is influencing this heat?

The Climate Shift Index: Ocean is grounded in peer-reviewed methodology and high-quality data. It quantifies the influence of climate change on sea surface temperatures.

The Ocean CSI indicates how human-caused climate change has influenced the likelihood of daily sea surface temperatures occurring at nearly any location around the world’s oceans.

To request an interview with a Climate Central scientist, please contact Abbie Veitch at aveitch@climatecentral.com.