20W upgraded to tropical storm, could give Okinawa rainy, gusty weather Wednesday; Tropical Storm Jebi remains forecast to pass east of Kanto Plain at mid-afternoon Tuesday. (Joint Typhoon Warning Center)

7 a.m. Saturday, Sept. 28, Japan time: 20W has been upgraded to a tropical storm, and along with Tropical Storm Jebi could give portions of Japan some blustery, showery weather by the middle of next week.

Joint Typhoon Warning Center’s latest forecast track for 20W indicates it could become a Category 1-equivalent typhoon at mid-afternoon Sunday as it curves north. At the end of JTWC’s five-day forecast period, 20W is projected to be about 310 miles west-southwest of Kadena Air Base, quite a ways away, as a Category 3-equivalent typhoon.

Kadena’s extended forecast calls for gusty winds, showers and isolated thunderstorms gradually ramping up by the middle of next week. More specifics should become apparent as 20W continues developing with the start of the new week.

Jebi is projected to have a brief life as a Category 1-equivalent typhoon early Tuesday morning as it curves northeast, passing about 170 miles east-southeast of Yokosuka Naval Base at mid-afternoon Tuesday as severe tropical storm.

Yokosuka’s extended forecast calls for 30-mph gusts Sunday and Monday; expect that to be updated as the new week begins and Jebi edges closer.