Chapala began as a cluster of thunderstorms southwest of India on October 25, 2015, spawned by the monsoon trough. For three days, moderate wind shear kept the system disorganized. Then conditions shifted. On October 28, the India Meteorological Department classified the disturbance as a depression. What followed was startling: over thirty-three hours, Chapala's barometric pressure plunged fifty-nine hectopascals as the system underwent rapid intensification. By October 30, the IMD estimated peak three-minute sustained winds of 215 km/h. The American-based Joint Typhoon Warning Center put the number higher, at 240 km/h, ranking Chapala among the strongest cyclones ever recorded over the Arabian Sea -- second only to Cyclone Gonu in 2007. Its eye tightened to just thirty-seven kilometers across as it bore down on the Horn of Africa.

The Yemeni island of Socotra, a UNESCO World Heritage Site renowned for its otherworldly dragon blood trees, lay directly in Chapala's path. On November 1, hurricane-force winds and torrential rain swept the island. Over a thousand families had evacuated to schools set up as shelters, but the storm overwhelmed the island's fragile infrastructure. Power went out entirely. Eighteen thousand people were forced from their homes. At least two hundred were injured. Residents described the rainfall as the worst in living memory. Socotra's isolation -- it sits in the Arabian Sea between Yemen and Somalia -- made relief efforts difficult even under normal circumstances. And circumstances were anything but normal. A week later, Cyclone Megh struck the same island again, compounding the devastation before aid from the first storm had fully arrived.

As Chapala crossed the Gulf of Aden on November 2, it remained ferociously powerful -- the strongest tropical cyclone ever recorded in that body of water. Along the coast of northern Somalia, the storm killed tens of thousands of livestock and destroyed 350 houses. But the worst was still to come. In Mukalla, a port city of roughly 300,000 people, the situation was uniquely dire. Al-Qaeda in the Arabian Peninsula had seized the city during Yemen's civil war and held effective control. Even the evacuation of coastal neighborhoods was organized partly by AQAP militants. Yemen's meteorological agency urged residents to move at least one kilometer inland. About 18,750 people fled their homes on the mainland. Early on November 3, Chapala made landfall near Mukalla as the strongest storm ever to strike Yemen. The city's main hospital flooded and closed. Thirty-five kilometers of roads became impassable under mud.

Across Yemen's mainland, Chapala destroyed 214 homes and damaged 600 more. Eight people died -- a toll that officials attributed to the evacuations -- and sixty-five were injured. But the storm's consequences extended far beyond the immediate damage. Between Chapala and the subsequent Cyclone Megh, twenty-six people were killed and forty-seven thousand displaced. Relief distribution faltered because the hardest-hit areas were under al-Qaeda control, and the ongoing civil war had already crippled communications and supply lines. By January 2016, the standing floodwater in Mukalla had bred an outbreak of dengue fever that sickened over a thousand people and killed seven. In March, the residual moisture triggered a locust plague that spread across Yemen and reached as far as Pakistan. The World Food Programme distributed emergency rations. Medecins Sans Frontieres set up clinics. The International Organization for Migration provided forty-one thousand liters of clean water daily. For a country already enduring one of the world's worst humanitarian crises, Chapala was a compounding catastrophe.