The entire island, only 17 km (11 mi) in length, experienced typhoon force winds, and 90% of the structures were damaged or destroyed.

Damage was most severe in southeastern Yap, where the eyewall struck and winds exceeded 185 km/h (115 mph), but the center of the typhoon passed south of the island.

[1] The origins of Typhoon Sudal were from a persistent area of convection, or thunderstorms, southeast of Pohnpei in the Federated States of Micronesia toward the end of March 2004.

[1] On April 2, the Japan Meteorological Agency (JMA) classified the system as a weak tropical depression near Chuuk in the FSM.

On April 6, an eye feature began forming, and the JTWC upgraded Sudal to typhoon strength about 540 km (340 mi) southeast of Guam, a small island under possession of the United States.

[1] Around that time, the typhoon turned toward the northwest, and initially it was thought that Sudal would pass safely north of Yap in the FSM.

On April 8, the typhoon intensified rapidly; the JTWC reported 1-minute winds of 215 km/h (130 mph), or the equivalent of a Category 4 on the Saffir–Simpson hurricane scale.

Weakening slightly as its forward motion slowed, Typhoon Sudal passed about 45 km (28 mi) south of Yap at 0000 UTC on April 9, which was its closest approach to the island.

[1] Intensification continued throughout the day on April 9, with the appearance of concentric eyewalls on satellite imagery; such a feature is indicative of an intense tropical cyclone.

Early on April 10, the JTWC estimated that Sudal attained peak 1-minute sustained winds of 240 km/h (150 mph), making the cyclone a super typhoon.

[2] Also on that day, Sudal entered the area of warning responsibility of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), which provided the name "Cosme" for local advisories.

On April 12, Sudal turned toward the north and northeast through a weakness in the ridge, and its eye increased to a diameter of about 85 km (53 mi).

[1] Early on April 15, Sudal passed very near the uninhabited Japanese island of Iwo Jima as a rapidly weakening typhoon; at the time, its circulation center was exposed from the deepest convection.

As an extratropical storm, Sudal continued northeastward until losing its identity early on April 18, well east of Japan and far south of the Aleutian Islands.

The small Ngulu Atoll received gale-force winds and heavy rainfall, which destroyed half of the island's water storage tanks.

On the day before the typhoon struck, storm shelters were opened in schools and government buildings that could withstand the winds of Sudal.

In anticipation of significant damage, Yap officials sent a request to the FSM government for emergency aid to clean up after the storm.

[10] Over 90% of the structures on the island were damaged or destroyed, including the hospital, airport, most government facilities, and the water, power and communications systems.

The Guam Memorial Hospital dropped a package of medical supplies to Yap, although planes containing aid flying onto the island were disrupted by the damaged runway.

[16] About a day after Sudal's passage, the runway was cleared and repaired, which allowed a United States Coast Guard plane to provide relief supplies, including building materials.

[18] The United States Army Corps of Engineers arrived on Yap to coordinate debris removal and installing generators.

About 60 FEMA personnel worked at the hospital, who required additional items, such as their own supply of water and food, to prevent them from acquiring local diseases.

The hospital remained damaged with a temporary roof, and although private businesses quickly re-opened, government buildings took longer to be rebuilt; this was due to the lengthy process of receiving aid from FEMA.