Hurricane Rosa brought widespread flooding to northwestern Mexico and the Southwestern United States in late September 2018, and was the first tropical cyclone to make landfall in Baja California since Nora in 1997. The seventeenth named storm, tenth hurricane, and seventh major hurricane of the 2018 Pacific hurricane season; Rosa originated from an Atlantic tropical wave that crossed the West African coast on September6. The wave proceeded westward across the Atlantic, traversing Central America before entering the Gulf of Tehuantepec on September 22. There, the weather system acquired cyclonic features and became a tropical storm on September 25. Within a favorable atmosphere, Rosa entered a period of rapid intensification on September 27, peaking as a Category4 hurricane with maximum sustained winds of a day later. Over the next few days, Rosa turned north and then northeast while steadily weakening, making landfall in Baja California as a tropical depression on October 2. After crossing over into the Gulf of California, the remnant system split apart and merged with an upper-level low off the coast of California by October 3. Rosa prompted the issuance of tropical storm watches and warnings along the coast of Baja California, as well as various flood watches and warnings throughout the Southwestern United States. The impact of Rosa was relatively minor, as a combination of wind shear and cooler seas had weakened the storm significantly by the time it made landfall. Widespread flooding throughout northwestern Mexico, mainly in Sonora and Baja California, led to one drowning and minor damage. In Arizona, rainfall peaked at and caused flash floods that killed two people. Flood damage from Rosa and its remnants totaled $50 million (2018 USD) in the Southwestern United States and $530,000 in Baja California. Meteorological history Hurricane Rosa originated from a vigorous tropical wave that departed from the west coast of Africa on September 6. The wave traveled across the tropical Atlantic with minimal associated convection and became difficult to track after interacting with a mid-level trough in the Caribbean Sea. The National Hurricane Center (NHC) issued a Tropical Weather Outlook on September 19, anticipating that an area of low pressure would form in the Gulf of Tehuantepec over the weekend. The wave crossed Central America and entered the gulf on September 22, where it produced a surface circulation with convective activity aloft. Though broad in structure, the system consolidated as it proceeded slightly north of west.