A group of hurricane experts have published a research report discussing the recently observed phenomenon of hurricanes rapidly intensifying, growing from a weak tropical storm or Category 1 status to Category 4 or 5 in a brief period. Rapid intensification is generally measured by comparing the strength of a hurricane over a 24-hour period. A change in storm wind speed of greater than 35 mph in 24 hours is generally the cutoff. The researchers found that rapid intensification has been seen repeatedly in the Atlantic in recent years. It happened before Hurricane Harvey struck Texas and before Hurricane Michael pummeled the Gulf Coast with little warning last fall. Jim Kossin, one of the report’s authors and a hurricane expert with the National Oceanic and Atmospheric Administration (NOAA), said that more rapidly intensifying storms means both that there are more strong storms overall, but also that there are more risky situations near land. “Rapid intensification is exceedingly dangerous because people, they’re not warned adequately, they’re not prepared, many of them don’t evacuate,” he said. Read the report at Nature Communications and an article describing its findings at The Washington Post.