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Typhoon Shanshan Brings Wind and Rain to Kyushu

Typhoon Shanshan brought wind and rain to Kyushu on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Typhoon Shanshan was located at latitude 31.6°N and longitude 130.2°E which put the center about 35 miles (55 km) west of Kagoshima, Japan.  Shanshan was moving toward the north at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 957 mb.

Typhoon Shanshan brought wind and rain to Kyushu on Wednesday.  The eastern side of the eyewall of Shanshan moved over Makurazaki, Japan.  A weather station in Makurazaki reported a sustained wind speed of 69 m.p.h. (111 km/h).  The weather station also reported 8.42 inches (214 mm) of rain.  A weather station in Kaseda reported 10.95 inches (278 mm) of rain.  A weather station in Ibusuki reported 9.33 inches (237 mm) of rain.

Typhoon Shanshan was weakening gradually when it reached the west coast of Kyushu.  An upper level trough over northeastern Asia was producing southwest winds that were blowing toward the top of Shanshan’s circulation.  Those winds caused more vertical wind shear.  The increase in wind shear caused Typhoon Shanshan to start to weaken.

An eye was no longer visible at the center of Typhoon Shanshan on conventional satellite images.  The former eye was still being detected by radars operated by the Japan Meteorological Agency.  There were breaks in the ring of thunderstorms that surrounded the former eye.  The strongest winds were still occurring in that broken ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Shanshan.

The circulation around Typhoon Shanshan was still symmetrical.  Winds to typhoon force extended out 30 miles (50 km) from the center of Shanshan’s circulation.  Winds to tropical storm force extended out 125 miles (200 km) from the center of Typhoon Shanshan.

The Hurricane Intensity Index (HII) for Typhoon Shanshan was 16.5.  The Hurricane Size Index (HSI) was 11.8 and the Hurricane Wind Intensity Size Index (HWISI) was 28.3.  Typhoon Shanshan was similar in intensity to Hurricane Idalia when Idalia hit Florida in 2023.  Shanshan was bigger than Idalia was.

Typhoon Shanshan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Shanshan toward the north during the next 12 hours.  The upper level trough over northeastern Asia will steer Shanshan toward the northeast on Thursday.  On its anticipated track, the center Typhoon Shanshan will move near the west coast of Kyushu during the next 12 hours.  Shanshan will move inland over Kyushu on Thursday.

Typhoon Shanshan will weaken gradually as it moves inland over Kyushu.  Even though Shanshan will weaken it will still produce strong winds and drop heavy rain over much of Kyushu.  Heavy rain is likely to cause flash floods in some locations,