Otto (2016)

Otto formed as a tropical depression at 1800 UTC on 20 November 2016 in the southwestern Caribbean Sea about 105 nautical miles north of Colón, Panama. The system became a tropical storm on 21 November and gradually strengthened before a burst of deep convection late on 23 November led to rapid intensification. Otto reached its peak intensity on 24 November while moving westward toward Central America, then crossed southern Nicaragua and northwestern Costa Rica and emerged into the eastern North Pacific on 25 November. The system weakened over the Pacific and became a remnant trough by 26 November.

The cyclone made landfall in extreme southern Nicaragua in the Indio Maíz Biological Reserve around 1730 UTC 24 November, about 10 n mi northwest of the Nicaragua–Costa Rica border, with estimated winds of 100 kt (115 mph). It continued inland, weakened to a Category 1 hurricane, passed over extreme northern Costa Rica, and emerged off the Pacific coast near the Gulf of Papagayo around 0330 UTC 25 November as a tropical storm.

Otto’s maximum sustained winds at peak were estimated at 100 kt (115 mph) with a minimum central pressure near 975 mb, making it a Category 3 major hurricane at landfall. Aircraft measured peak SFMR winds of 90 kt and flight-level winds up to 108 kt during final penetrations; satellite estimates briefly suggested even higher values, but the best-track peak is 100 kt.

The storm produced heavy rainfall and coastal inundation. In Costa Rica, several stations reported more than 8 inches of rain in the event; the highest 24-hour total reported was 11.77 inches at the Miravalles Volcano site (3-day total 12.11 inches). Northern and northwestern Costa Rica reported widespread 3–10+ inch totals (examples: Fortuna 8.97 in, Bijagua 10.41 in, La Maritza 8.59 in). Southern and southwestern Nicaragua reported 3–6 inches, with El Castillo reporting 6.35 inches. Storm surge likely caused significant inundation along parts of the southern Nicaraguan coast and possibly extreme northeastern Costa Rica, though no direct surge observations were received.

Otto caused 18 direct fatalities in Central America: eight deaths in Panama (including landslides, flooding, and a ship sinking with presumed loss of two sailors) and ten deaths in Costa Rica, primarily from flash floods and landslides in northern and northwestern provinces. Nicaragua reported no storm-related deaths. Extensive freshwater flood damage, landslides, damaged roads and bridges, widespread power outages, and agricultural losses occurred; media reports indicate about $15 million in damage to Costa Rica’s coffee industry and thousands displaced or evacuated.

Noteworthy aspects include several late-season records: Otto was the latest-forming hurricane in the Caribbean Sea on record (surpassing Hurricane Martha by one day), the latest hurricane on record in the Caribbean Sea, and produced the latest hurricane landfall in the Atlantic basin in a calendar year (24 November). Otto was also the southernmost hurricane landfall in Central America and the only known hurricane to cross directly over Costa Rica. Forecast track guidance consistently showed landfall in southern Nicaragua, and NHC track forecasts were generally accurate through 72 hours, but the rapid intensification to major hurricane strength and the quick post-landfall decay in the eastern Pacific were not fully anticipated.