Typhoon Ivan

Meteorological history

Typhoon Ivan originated from an area of disturbed weather near the equator during the first week of October 1997. Two equatorial troughs, one in the Northern Hemisphere and one in the Southern Hemisphere developed from this system. Three resultant areas of low pressure formed; one in the Southern Hemisphere developed into Tropical Cyclone Lusi on October 8, and two north of the equator steadily tracked westward. The eastern low developed into Typhoon Joan, while the western cyclone became the system that would intensify into Typhoon Ivan. Situated in an environment without significant convective activity, this system initially struggled to become organized. However, the disturbance began to mature, and by October 11, the Joint Typhoon Warning Center (JTWC) discovered a low-level circulation center, prompting the issuance of a Tropical Cyclone Formation Alert the following day.

The system quickly tracked toward the west-northwest at a forward speed of 33 km/h (21 mph). The JTWC issued their first advisory on the storm early on October 13, designating it Tropical Depression 27W. Around this time, the Japan Meteorological Agency (JMA) also classified the cyclone as a tropical depression.

Convective banding features developed late on October 13. The JTWC upgraded the depression to a tropical storm and gave it the name Ivan. Early the next day, the JMA also upgraded Ivan to a tropical storm. Later on October 14, Ivan passed roughly 100 km (65 mi) south of Guam and subsequently intensified. Several hours afterwards, the JMA upgraded Ivan to a typhoon. During a 24-hour span, Ivan's winds increased from 120 km/h (75 mph) to 270 km/h (165 mph), making it a Category 5 super typhoon, the eighth of the season. Late on October 17, Ivan attained its peak intensity with winds of 295 km/h (185 mph) and an official barometric pressure of 905 hPa (mbar). However, the JTWC reported an unofficial pressure of 872 hPa (mbar), which would tie Ivan for the second strongest tropical cyclone worldwide with Typhoons Gay, Angela, Joan , Keith and Zeb, and Hurricane Patricia.

Due to the storm's proximity to Typhoon Joan, forecast models anticipated Ivan to re-curve before reaching the Philippines; however, the storm maintained its track and did not take the northward turn until impacting the country. The typhoon began to slow and weaken, and on October 20, its center made landfall in extreme northern Luzon with winds of 220 km/h (140 mph). After emerging into the Luzon Strait, Ivan turned to the north-northeast and weakened to a tropical storm. On October 22, the storm briefly re-attained typhoon status before accelerating in forward speed. The system steadily weakened and the JTWC issued their final advisory on the storm on October 24. The JMA continued to monitor Ivan as a tropical cyclone for another day before classifying it as extratropical. The remnants of the powerful typhoon eventually dissipated on October 26.

Preparations and impact

Thousands of people evacuated from northern areas of the Philippines as Ivan approached. Power was shut off prior to the storm to reduce the risk of electrocution. Four flights were cancelled in Taiwan, Hong Kong, and the Philippines due to the storm. Residents in Taiwan were advised to take precautions for Typhoon Ivan, though autumn typhoons are rare in the island. Vessels were urged to stay at port due to rough seas throughout the Philippines. Disaster agencies were put on high alert; relief supplies were then stockpiled, the navy was placed on standby, and military search and rescue vehicles were prepped.

On October 20, Ivan made landfall in the northern Philippines, producing torrential rains that triggered waist-deep flooding in localized areas. Severe crop losses were reported throughout northern Luzon. One person drowned in floodwaters in Cagayan. Elsewhere in the country, two other people drowned in floodwaters. Numerous power lines and trees were downed throughout the region, rain-triggered landslides blocked several roads. Throughout the country, a total of 14 people were killed and two others were listed as missing. Poultry farms and fisheries sustained significant damage; an estimated $3.6 million in losses resulted from lost stocks in the two businesses. Several thousand animals drowned during the storm. Total damage was estimated at $9.6 million (1997 USD; $13.1 million 2009 USD). A total of 1,779 homes were destroyed, 13,771 others were damaged and 4,600 hectares of croplands were inundated by Typhoon Ivan. Rainfall from the storm was considered to be helpful as the area impacted had been suffering from below average rainfall for several months. Minor damage was also reported in the Marshall Islands. The island of Tiyan recorded 5.26 in (134 mm) of precipitation, contributing to above-average rainfall during the month of October.