Decreased wind shear aided in intensification, and it is estimated that the depression strengthened into a tropical storm on August 17.

Continuing to intensify, Zola turned northwest in response to a subtropical ridge to its east before obtaining typhoon intensity on August 20.

Thunderstorm activity began to persist east of Yancy, but further development was slow to occur because of strong vertical wind shear.

Early on August 15, the Joint Typhoon Warning Center (JTWC) started watching a persistent area of disturbed weather west of Guam.

[1] Initially, the disturbance tracked west-northwest[2] and then eastward, but further development was inhibited by strong vertical wind shear.

[1] At 00:00 UTC on August 16, the Japan Meteorological Agency (JMA) upgraded the disturbance into a tropical depression.

Banding quickly wrapped around the center around a low-level circulation[3][nb 3] as the disturbance passed through the Mariana Islands.

[1][nb 4] The depression turned west-northwest in response to a shortwave trough that tracked north of the system.

[1] Tropical Storm Zola continued northwest and tracked through region of divergence aloft, which aided intensification.

The cyclone subsequently resumed intensification while turning northwest in response to a subtropical ridge between China and Japan.

Following the appearance of a ragged 45 km (30 mi) eye on weather satellite imagery and a Dvorak classification of T4.0/120 km/h (75 mph),[1] Zola was classified as a typhoon at 00:00 UTC on August 20 by the JTWC.

[3] Further intensification was aided by a tropical upper tropospheric trough that provided an excellent poleward outflow channel.

[1] Around this time, the JMA estimated that Zola peaked in intensity, with winds of 135 km/h (85 mph) and a minimum barometric pressure of 975 mbar (28.8 inHg).

[12] Near where the storm moved over Shikoku island, in Kōchi Prefecture, three people suffered injuries.

[20] Storm surge and torrential rains resulted in heavy damage to Hiroshima prefecture.

The main roads in the cities of Sada and Izumo were deemed impassable during the height of the storm.