Max — 2023

A small tropical cyclone formed in the eastern North Pacific from a disturbance that tracked westward across Central America and developed a well-defined center on 8 October 2023. The system became a tropical depression by 1800 UTC 8 October about 125 nautical miles south of Zihuatanejo, Mexico, and strengthened to Tropical Storm Max six hours later. Max moved slowly northward toward the southwestern coast of Mexico, rapidly intensified on 8–9 October while over very warm water, and dissipated over the mountains of Mexico by 0600 UTC 10 October. Max made landfall near Puerto Vicente, Guerrero, Mexico, around 1800 UTC 9 October 2023. The storm’s landfall coincided with its peak intensity; it weakened quickly over the mountainous terrain and was no longer a tropical cyclone by the morning of 10 October. The storm’s maximum sustained winds were estimated at 60 knots (about 69 mph) at peak, with an estimated minimum central pressure of 990 mb. Those peak conditions correspond to a strong tropical storm (below hurricane strength). Max was small in size, with tropical-storm-force winds extending roughly 50 nautical miles from the center and an estimated radius of maximum winds of about 10 nautical miles at landfall. Max produced very heavy rainfall along the central coast of Guerrero. Measured totals included 312.2 mm (12.29 inches) at San Jerónimo, 300.0 mm (11.81 inches) at Laguna de Coyuca, and 298.0 mm (11.73 inches) at Atoyac. An automated station at Puerto Vicente recorded sustained winds of 35 kt with a gust to 63 kt and a lowest sea level pressure of 997.0 mb near landfall. Reports of storm surge heights were not given in the report for specific locations. The storm caused two direct fatalities by drowning in Guerrero: one man swept away in Nuxco and another who drowned when a transport van fell into a sinkhole on the Acapulco–Zihuatanejo Highway. Media sources reported more than 90 homes flooded and many downed trees in Guerrero; emergency declarations were issued for the municipalities of Benito Juárez, Atoyac de Álvarez, Tecpan de Galeana, and Coyuca de Benítez. Many of the communities affected by Max were later severely hit again by Hurricane Otis later in October. Forecasts had mixed performance: the timing of Max’s formation was well predicted up to several days in advance, but the precise location of genesis was less accurate. Short-duration rapid intensification on 8–9 October was not anticipated and led to larger-than-normal intensity forecast errors, although the official forecasts still generally performed better than most individual models at 12–24 hours.