Norma — 2023

A broad area of low pressure formed in the eastern Pacific near 98°W on 15 October 2023 and became a tropical depression at 1200 UTC 17 October about 400 nautical miles south-southwest of Manzanillo, Mexico. The system strengthened to Tropical Storm Norma six hours later and moved generally west-northwestward, then turned north as a weakening mid-level ridge slowed it. Norma underwent nearly two days of rapid strengthening and became a major hurricane on 19 October, reaching peak intensity that day before weakening as it approached the southern tip of the Baja California peninsula. The cyclone crossed the peninsula, moved into the Gulf of California, made a final landfall in Sinaloa as a depression, and dissipated over western Mexico on 23 October. Norma made two principal landfalls. The first landfall was near El Pozo de Cota in the state of Baja California Sur around 2015 UTC 21 October, when the storm was estimated to have sustained winds of about 70 knots (a Category 1 hurricane). The second landfall occurred near Eldorado in the state of Sinaloa around 1030 UTC 23 October after Norma had weakened to a tropical depression. The hurricane’s maximum estimated intensity was 115 knots (132 mph) with a minimum central pressure of 939 mb at 1200 UTC 19 October, which corresponds to a Category 4 hurricane on the Saffir–Simpson scale. Aircraft measurements taken shortly after that peak recorded flight-level winds near 111 kt and surface estimates from onboard instruments near 102 kt, indicating the reconnaissance arrived just after peak intensity. Norma produced very heavy rains and some coastal flooding. The highest reported storm total rainfall was 19.21 inches (488.0 mm) at El Quemado, Baja California Sur; San Vicente de la Sierra reported 18.89 in (480.0 mm) and La Palmilla 18.62 in (473.0 mm). Coastal and surf-driven effects included flooded streets and boat damage around Los Cabos and La Paz; the Mexican Navy station near Cabo San Lucas measured sustained winds of 70 kt and a gust to 93 kt. The report lists storm surge and tide impacts locally but gives specific maximum inundation values primarily in coastal observations rather than broad regional totals. There were three indirect deaths in Sinaloa: two from vehicle accidents and one child electrocuted. No deaths or injuries were reported in Baja California Sur. The governor of Baja California Sur estimated about $11.1 million USD in infrastructure damages; Sinaloa’s governor reported about $12.2 million USD in damages and 18 sinkholes from heavy rains. Significant impacts included flooded streets and canals, downed trees and power lines, roughly 10,000 homes without power in Cabo San Lucas, and numerous boats damaged or washed ashore. Notable points include that Norma intensified rapidly to a major hurricane over warm waters and later briefly re-strengthened before weakening prior to landfall. The NHC successfully forecasted the system’s genesis well in advance, and official track forecasts were generally better than recent averages at most forecast intervals, though intensity forecasts had larger-than-average errors at some lead times because the rapid intensification and subsequent weakening were difficult to capture.