A center of circulation developed within a large area of thunderstorms a few hundred miles south of Japan and the system has been designated Tropical Storm Etau.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Etau was located at latitude 25.3°N and longitude 138.5°E which put it about 720 miles (1160 km) south-southeast of Osaka, Japan.  Etau was moving toward the north at 11 m.p.h. (18 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 998 mb.

Although Tropical Storm Etau does have a low level center of circulation, most of the stronger thunderstorms are located north-northwest of the center.  Etau is moving over water where the Sea Surface Temperatures are warm enough to support intensification.  However, a large upper level trough west of Japan is producing southwesterly winds over the top of the tropical storm.  The circulation appears to be tilting toward the north with height because  of vertical wind shear.  Tilted tropical cyclones are unable to efficiently convert energy to wind speed and intensify.  Etau could intensify a little during the next 24 hours, but then it will run into much stronger upper level winds associated with the upper level trough.  Stronger vertical wind shear will cause Etau to begin to weaken before it reaches Japan.

A subtropical ridge east of Etau is steering it toward the north-northwest and that general motion is expected to continue for the next several days.  On its anticipated track Etau will approach the coast of Japan near Honshu and Shikoku.  Landfall somewhere between Nagoya and Kochi could occur in about 36 hours.  Etau’s biggest impact will be to increase rainfall as it moves inland.