Tropical Storm Jebi formed west of the Northern Marianas on Friday.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Jebi was located at latitude 18.7°N and longitude 144.6°E which put the center about 60 miles (95 km) west-northwest of Agrihan. Jebi was moving toward the north-northwest at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 45 m.p.h. (65 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1001 mb.

A low pressure system west of the Northern Marianas strengthened on Friday and the Japan Meteorological Agency designated the system as Tropical Storm Jebi.  The circulation around Tropical Storm Jebi was poorly organized.  Thunderstorms were occurring in the southeastern quadrant of Jebi’s circulation.  There were no thunderstorms near the center of Tropical Storm Jebi.  Bands in the other parts of Jebi’s circulation consisted primarily of showers and lower clouds.

Tropical Storm Jebi will move through an environment somewhat favorable for intensification during the next 24 hours.  Jebi will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southeastern part of an upper level ridge south of Japan.  The upper level ridge will produce northeasterly winds that will blow toward the top of Jebi’s circulation.  Those winds will cause moderate vertical wind shear.  The wind shear will inhibit intensification.  Tropical Storm Jebi could intensify a little during the next 24 hours, if the wind shear does not get any stronger.

Tropical Storm Jebi will move around the western side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Jebi toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Jebi will move slowly away from the Northern Marianas.  Jebi could approach Iwo To in 36 hours.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 20W formed south-southeast of Taiwan.  At 11:00 a.m. EDT on Friday the center of Tropical Depression 20W was located at latitude 19.6°N and longitude 125.8°E which put the center about 430 miles (690 km) south-southeast of Taipei, Taiwan.  The tropical depression was moving toward the southwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1001 mb.