Typhoon Yunya (1991)

Typhoon Yunya (Diding)

Typhoon (JMA scale)
Category 3 (Saffir–Simpson scale)
Typhoon Yunya on June 13 near the Philippines
Formed	June 11, 1991
Dissipated	June 17, 1991
Highest winds	10-minute sustained: 150 km/h (90 mph) 1-minute sustained: 195 km/h (120 mph)
Lowest pressure	950 hPa (mbar); 28.05 inHg
Fatalities	4–7 direct, ~300 indirect
Areas affected	Philippines, Taiwan
Part of the 1991 Pacific typhoon season

Typhoon Yunya, known in the Philippines as Typhoon Diding, was a strong tropical cyclone that weakened before impacting the Philippines at the time of the colossal eruption of Mount Pinatubo in June 1991. 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 195 km/h (120 mph); 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. Four people were killed as a direct result of the storm and three others were listed as missing. Although the storm itself caused significant damage, the worst effects were related to the system's heavy rains mixing with volcanic ash from Pinatubo. The combined effects of both natural disasters created numerous large lahars that killed 250–300 people.

On June 11, 1991, a tropical disturbance developed east of East Samar, Philippines. Situated to the southwest of a Tropical Upper Tropospheric Trough, the system experienced little 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 1500 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 1815 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 110 km/h (70 mph). Although 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.