Tropical Storm Winona originated from a monsoon trough that was displaced 550 km (340 mi) north of its climatological position.
An area of enhanced convection developed within the monsoon trough in the East China Sea around 00:00 UTC on August 4.
Six hours later, the Joint Typhoon Warning Center (JTWC) started tracking the system as a weak low-pressure area developed.
At 18:00 UTC, the Japan Meteorological Agency (JMA) classified the system as a tropical depression.
Initially, strong wind shear left the center to the north of persistent convection.
Following a Dvorak classification of T1.0/50 km/h (30 mph), the JTWC issued a Tropical Cyclone Formation Alert (TCFA) at 11:00 UTC on August 5.
Twenty four hours later, the JTWC started issuing warnings on the system, designating the system as a tropical depression, after the system's convection structure improved and thunderstorm activity increased in coverage.
The depression initially moved northeast, skirting past the southern tip of Kyushu, only to turn southeast under the influence of the monsoonal flow.
On the evening of August 6, the JMA upgraded the depression into a tropical storm.

Winona was in between two subtropical ridges – one in the Luzon Strait and one south of Tropical Storm Vernon.
Early on August 7, the JTWC upgraded the system into a tropical storm, naming it Winona.
Wind shear began to relax; consequently, the storm's low-level center moved under the deep convection.
By 00:00 UTC on August 8, Winona abruptly turned north in response to a building ridge to its southeast.
Strengthening was aided by the development of dual upper-level outflow channels.
Early on August 8, the JMA reported that Winona strengthened into a severe tropical storm.
By this time, Winona was expected by both agencies to move over northeastern Japan, but Winona tracked further south than predicted, maintaining a northward course in the direction of Japan.
At noon on August 9, the JMA estimated that Winona peaked in intensity with winds of 115 km/h (70 mph) and a barometric pressure of 975 mbar (28.8 inHg).
Meanwhile, the JTWC upgraded Winona into a typhoon; simultaneously, the agency estimated that the typhoon reached peak intensity, with winds of 120 km/h (75 mph) over 330 km (205 mi) east-southeast of Tokyo.
Early on August 10, Winona made landfall close to Hamamatsu near peak intensity.
After landfall, it began to accelerate northeastward and by 12:00 UTC, Winona was embedded in the mid-latitude westerlies and started a transition into an extratropical cyclone.
Eighteen hours later, at 06:00 UTC on August 11, the JMA declared Winona an extratropical cyclone; the JTWC followed suit several hours later.
On August 14, the JMA ceased tracking the system.
Tropical Storm Winona originated from a monsoon trough that was displaced 550 km (340 mi) north of its climatological position. An area of enhanced convection developed within the monsoon trough in the East China Sea around 00:00 UTC on August 4. Six hours later, the Joint Typhoon Warning Center (JTWC) started tracking the system as a weak low-pressure area developed. At 18:00 UTC, the Japan Meteorological Agency (JMA) classified the system as a tropical depression. Initially, strong wind shear left the center to the north of persistent convection. Following a Dvorak classification of T1.0/50 km/h (30 mph), the JTWC issued a Tropical Cyclone Formation Alert (TCFA) at 11:00 UTC on August 5. Twenty four hours later, the JTWC started issuing warnings on the system, designating the system as a tropical depression, after the system's convection structure improved and thunderstorm activity increased in coverage. The depression initially moved northeast, skirting past the southern tip of Kyushu, only to turn southeast under the influence of the monsoonal flow. On the evening of August 6, the JMA upgraded the depression into a tropical storm.
Winona was in between two subtropical ridges – one in the Luzon Strait and one south of Tropical Storm Vernon. Early on August 7, the JTWC upgraded the system into a tropical storm, naming it Winona. Wind shear began to relax; consequently, the storm's low-level center moved under the deep convection. By 00:00 UTC on August 8, Winona abruptly turned north in response to a building ridge to its southeast. Strengthening was aided by the development of dual upper-level outflow channels. Early on August 8, the JMA reported that Winona strengthened into a severe tropical storm. By this time, Winona was expected by both agencies to move over northeastern Japan, but Winona tracked further south than predicted, maintaining a northward course in the direction of Japan. At noon on August 9, the JMA estimated that Winona peaked in intensity with winds of 115 km/h (70 mph) and a barometric pressure of 975 mbar (28.8 inHg). Meanwhile, the JTWC upgraded Winona into a typhoon; simultaneously, the agency estimated that the typhoon reached peak intensity, with winds of 120 km/h (75 mph) over 330 km (205 mi) east-southeast of Tokyo. Early on August 10, Winona made landfall close to Hamamatsu near peak intensity. After landfall, it began to accelerate northeastward and by 12:00 UTC, Winona was embedded in the mid-latitude westerlies and started a transition into an extratropical cyclone. Eighteen hours later, at 06:00 UTC on August 11, the JMA declared Winona an extratropical cyclone; the JTWC followed suit several hours later. On August 14, the JMA ceased tracking the system.
Tropical Storm Winona (1990)