Tag Archives: 13W

Tropical Storm Ampil Moves Over Okinawa

Tropical Storm Ampil moved over Okinawa on Friday night.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Ampil was located at latitude 27.3°N and longitude 127.4°E which put it about 25 miles (40 km) north-northwest of Okinawa.  Ampil was moving toward the northwest at 21 m.p.h. (34 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 990 mb.

Drier air continued to circulated around Tropical Storm Ampil on Friday and the drier air prevented Ampil from intensifying.  Several bands of stronger thunderstorms were occurring northeast of the center of circulation and the strongest winds were occurring in those bands.  The bands in other parts of Tropical Storm Ampil consisted primarily of the showers and low clouds.  There was a distinct low level center of circulation, but there were few thunderstorms near the center.  Winds to tropical storm force extended out about 160 miles (260 km) from the center.

Tropical Storm Ampil is unlikely to intensify significantly before it makes landfall in China.  Ampil will move over water where the Sea Surface Temperature is near 28°C.  So, there will be enough energy in the ocean to support intensification.  There is a chance for some intensification on Saturday, if more thunderstorms develop near the center of circulation.  However, the drier air will inhibit the formation of taller thunderstorms and that will limit possible intensification..

Tropical Storm Ampil will move south of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Ampil quickly toward the northwest.  On its anticipated track Tropical Storm Ampil will move quickly away from Okinawa and the Ryukyu Islands.  Ampil could approach the coast of China near Shanghai in about 24 hours.  Tropical Storm Ampil will bring gusty winds and locally heavy rain to the region of China around Shanghai.

Elsewhere over the Western North Pacific Ocean Tropical Depression 13W formed west of northern Luzon.  At 11:00 p.m. EDT on Friday the center of Tropical Depression 13W was located at latitude 18.0°N and longitude 118.9°E which put it about 140 miles (225 km) west of Laoag, Philippines.  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 998 mb.  The depression could bring locally heavy rain and cause flash floods over Luzon during the weekend.

Tropical Storms Lionrock and Kompasu Spin Up Near Japan

A large cyclonic atmospheric gyre near Japan spun up two more tropical storms at the end of the week.  The Japan Meteorological Agency named two smaller circulations within the larger gyre Tropical Storm Lionrock and Tropical Storm Kompasu.

At 2:00 p.m. EDT on Saturday the center of Tropical Storm Kompasu was located at latitude 37.8°N and longitude 142.3°E which put it about 75 miles (120 km) east of Sendai, Japan.  Kompasu was moving toward the northwest at 26 m.p.h. (42 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 996 mb.

At 2:00 p.m. EDT on Saturday the center of Tropical Storm Lionrock was located at latitude 30.6°N and longitude 135.7°E which put it about 530 miles (860 km) east-northeast of Okinawa.  Lionrock was moving toward the west-southwest at 8 m.p.h. (13 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 994 mb.

Tropical Storm Kompasu is located farther north and it is beginning to make a transition into an extratropical cyclone.  Kompasu is moving over water where the Sea Surface Temperature (SST) is near 26°C, but it is moving rapidly toward cooler SSTs.  Most of the thunderstorms are in a single primary rainband that wraps around the southern part of the circulation.  An upper level trough west of Japan is pulling southwesterly winds across the top of Tropical Storm Kompasu and the vertical wind shear is increasing.

The upper level trough is expected to turn Tropical Storm Kompasu toward the northeast.  On its anticipated track Tropical Storm Kompasu will move across Hokkaido in about 18 hours.  It will bring locally heavy rain and some wind.

Tropical Storm Lionrock is more well organized.  Several spiral bands of thunderstorms are wrapping around the southern and east sides of the center of circulation.  There is drier air in the western portion of the circulation and there are few thunderstorms in that part of Lionrock.  The thunderstorms east of the center are generating upper level divergence that is pumping mass toward the northeast away from core of Tropical Storm Lionrock.

Tropical Storm Lionrock is in an environment that is somewhat favorable for additional intensification.  It is moving over water where the SST is near 30°C.  The upper level trough west of Japan is generating some vertical wind shear.  The drier air in the western part of the circulation will also inhibit intensification, but Lionrock could gradually get better organized.  Upper level outflow from stronger Tropical Storm Mindulle, which is southwest of Lionrock, could produce enough vertical wind shear to weaken Lionrock at times.

The large atmospheric gyre is steering Tropical Storm Lionrock toward the west-southwest.  Lionrock could be pulled more toward the south as the larger, stronger Tropical Storm Mindulle passes east of it.  Tropical Storm Lionrock is expected to remain south of Japan during the next several days.  An alternative scenario would be for Tropical Storm Mindulle to intensify into a typhoon and grow large enough to absorb the circulation of Lionrock.