Tropical Storm Chaba strengthened on Thursday as it started to move toward Okinawa.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Chaba was located at latitude 13.8°N and longitude 138.6°E which put it about 1145 miles (1850 km) southeast of Okinawa.  Chaba was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 996 mb.

The circulation of Tropical Storm Chaba showed signs of better organization on Thursday.  A primary rainband wrapped around the western and south sides of the circulation.  Additional bands of thunderstorms were forming on the southern and eastern side of Tropical Storm Chaba.  Thunderstorms near the core of Chaba were generating upper level divergence which was pumping mass out to the west, south and east of the tropical storm.

Tropical Storm Chaba is moving into an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 30°C.  An upper level ridge to the north of Chaba is generating easterly winds which are blowing across the northern portion of the tropical storm.  However, those winds are not causing significant vertical wind shear.  The combination of warm SSTs and little vertical wind shear should allow Tropical Storm Chaba to intensify steadily during the next several days.  It could become a typhoon within 24 to 48 hours.  There is a chance that Chaba could become the equivalent of a major hurricane in three or four days.

A subtropical ridge to the north of Chaba is steering the tropical storm toward the west and that general motion is expected to continue in the short term.  When Chaba gets a little closer to the western end of the ridge, it will start to move toward the northwest and when Chaba reaches the western end of the ridge it will turn toward the north.  On it anticipated track Tropical Storm Chaba could be approaching Okinawa and the Ryukyu islands in about three days.  It could be a powerful typhoon at that time.