Typhoon Yunya, known in the Philippines as Typhoon Diding, was a strong tropical cyclone whose landfall in the Philippines coincided with the 1991 eruption of Mount Pinatubo. A small tropical cyclone, Yunya rapidly developed from a tropical disturbance near East Samar on June 11. By June 13 the storm had reached typhoon status as it moved west-northwest near the Philippines. Yunya attained its peak intensity the following day with estimated winds of ; however, strong wind shear soon impacted the typhoon and caused it to rapidly decay. The storm struck southern Luzon early on June 15 as a minimal typhoon before moving over the South China Sea later that day. After turning north and weakening to a tropical depression, the system brushed the southern tip of Taiwan on June 16 before dissipating the following day. Across the Philippines, Yunya produced heavy rains that triggered significant flooding. Hundreds of homes and several bridges were washed away by swollen rivers. Six people were killed as a direct result of the storm, 2,013 homes were destroyed, and 24 others were damaged. Although the storm itself caused significant damage, the worst effects were related to the system's heavy rains mixing with volcanic ash from Mount Pinatubo, creating massive lahars that killed 320 people. Meteorological history On June 11, 1991, a tropical disturbance developed east of East Samar. Situated to the southwest of a tropical upper tropospheric trough, the system experienced low wind shear and gradually intensified as it moved northwestward. The following day, the Japan Meteorological Agency (JMA) began monitoring the system as a tropical depression. At 15:00 UTC on June 12, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert on the depression. Around this time, the storm began a period rapid development and a tiny central dense overcast formed. At 18:15 UTC, the USNS Spica sailed directly through the storm, measuring a barometric pressure of 989.5 mbar (hPa; 29.22 inHg) and peak winds of . Although Yunya was already a tropical storm, the JTWC did not issue their first advisory on the system until early on June 13, at which time they assigned it the name Yunya. Based on the measurements provided by the USNS Spica, the storm was analyzed as a midget cyclone with a gale diameter of . Initially, the storm tracked northwestward at . Throughout June 13, subsidence around the periphery of Yunya allowed the system