By Isaac Schultz Published March 10, 2025 | Comments (0) | A map showing the salinity of the sea surface (the greener, the more saline) and the path of Hurricane Idalia, color-coded to show its category. Image: Lauren Dauphin, using sea surface salinity data courtesy of JPL and the SMAP Science Team and the Multiscale Ultrahigh Resolution (MUR) project A previously overlooked factor may have contributed to the debilitating strength of Hurricane Idalia, which cost the United States billions of dollars when it struck in August 2023. According to a team of researchers that studied the climatic conditions around the storm, the typical cocktail of weather conditions that feed a hurricane doesnt add up in Idalias case. The teams research analyzing the storms evolution was published last month in Environmental Research Letters. The team found that the usual suspectswarm sea surface temperatures, ocean heat beneath the surface, and low vertical wind shear all played a role in Idalias intensification. But the team found that a freshwater plumeincluding river discharge into the Gulfcreated a density gradient between the surface water and deeper, cooler water, allowing Idalia to continue to draw strength from the warmth of the Gulfs surface. Wind wants to mix the water, bringing cold water up to the surface and warm water down to the depths, said marine scientistChuanmin Hu, one of the studys authors, in a NASA Earth Observatory release. But the density gradient between surface fresh water and deeper salty water makes this difficult. Plumes from rivers have historically contributed to the intensification of hurricanes; according to the release, more than two-thirds of storms between 1960 and 2000 that hit Category 5 strength at some point in their cycles passed over the historical region of freshwater plumes.If you have a persistent river plume in the right location at the right time, Hu said, you may have a perfect storm. Hurricane Idalia carved through Floridas Big Bend before charting a northeasterly course across the American Southeast. The storm quickly swelled from a Category 1 to Category 4 storm, subsiding only slightly into a Category 3 hurricane when it made landfall on August 30, 2023, with maximum sustained winds of nearly 125 miles (205 kilometers) per hour.A map showing the salinity of the sea surface (the greener, the more saline) and the path of Hurricane Idalia, color-coded to show its category. Image: Lauren Dauphin, using sea surface salinity data courtesy of JPL and the SMAP Science Team and the Multiscale Ultrahigh Resolution (MUR) project The hurricane raised concerns about gas contamination, cut off power for hundreds of thousands of people, and even dropped a tree on the Tallahassee home of Governor Ron DeSantis. The storm shaped up to be the costliest of 2023, tallying a whopping $3.6 billion in damages. The storm departed over the Atlantic on August 31 after cutting across Georgia and the South Carolina coast. The analysis of contextual factors in Idalias formation could help researchers better understand the conditions that foster extreme storms in the future. Consider Hurricane Milton, which shattered records in October 2024 when it intensified from a Category 1 storm to a Category 5 storm in just 7 hours, after feeding on very warm waters in the western Gulf. Category 5 storms are the highest intensity on theSaffir-Simpson hurricane wind scale; to be a Category 5 storm, a system must achieve wind speeds greater than 157 miles per hour (253 kilometers per hour). When Milton touched down in central Florida as a Category 3 storm, it spawned at least three dozen tornadoes across the Sunshine State. As ocean temperatures continue to break records for warmth, we should expect more extreme and rapidly evolving hurricanes. Hopefully, similar research to the Idalia study will lead to improved forecast models,so that authorities can be prepared for these storms landfall. Hurricane season will resume on June 30 and run through November 30.Daily NewsletterYou May Also Like By Matt Novak Published March 3, 2025 By Isaac Schultz Published February 28, 2025 By Isaac Schultz Published February 19, 2025 By Margherita Bassi Published February 12, 2025 By Isaac Schultz Published February 11, 2025 By Passant Rabie Published January 21, 2025