Typhoons Lekima and Krosa Threaten Japanese Islands

Typhoons Lekima and Krosa threatened Japanese islands on Wednesday.  Typhoon Lekima posed a serious threat to the southern Ryukyu Islands and Typhoon Krosa was headed for Iwo To.  At 5:00 p.m. EDT on Wednesday the center of Typhoon Lekima was located at latitude 22.4°N and longitude 126.0°E which put it about 190 miles (305 km) southeast of Ishigaki, Japan.  Lekmia was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 925 mb.

Typhoon Lekima rapidly intensified into the equivalent of a major hurricane on Wednesday.  A small distinct eye was at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of the circulation.  Storms near the core were generating strong upper level divergence which was pumping mass away from the typhoon in all directions.

Typhoon Lekima had a large circulation.  Winds to typhoon force extended out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extended out about 210 miles (335 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Lekima was 23.6.  The Hurricane Size Index (HSI) was 21.6 and the Hurricane Wind Intensity Size Index (HWISI) was 44.7.   Those indices indicated that Typhoon Lekima was capable of causing widespread major damage.

Typhoon Lekima will move through an environment favorable for intensification during the next 24 hours.  Lekima will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will not be a lot of vertical wind shear.  Typhoon Lekima could intensify further during the next day or so.  It is possible that a rainband could wrap around the existing eye and eyewall.  If a rainband wraps around the core of Lekima then an eyewall replacement cycle could cause weakening.

Typhoon Lekima will move around the western end of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Lekima toward the northwest on Thursday.  On its anticipated track Typhoon Lekima will reach Ishigaki and the southern Ryukyu Islands in less than 24 hours.  Lekima will be capable of causing major damage to the southern Ryukyu Islands.  Typhoon Lekima will move more toward the north when it moves around the end of the subtropical ridge.  The center of Lekima could be northeast of Taiwan within 36 hours.  Typhoon Lekima could reach the east coast of China in less than three days.

At 5:00 p.m. EDT on Wednesday the center of Typhoon Krosa was located at latitude 22.1°N and longitude 140.8°E which put it about 210 miles (340 km) south of Iwo To.  Krosa was moving toward the north-northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 970 mb.

Former Tropical Storm Krosa strengthened into a typhoon on Wednesday.  The inner portion of a rainband wrapped around the center of circulation and an eye formed.  The inner part of the rainband closed around the eye and a circular ring of thunderstorms formed a closed eyewall.  The strongest winds were occurring in the eyewall.  Several bands of showers and thunderstorms were revolving around the core of Typhoon Krosa.  Storms near the center were pumping mass away to the east of the typhoon.

The circulation around Typhoon Krosa was also large.  Winds to typhoon force extended out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extended out about 225 miles (360 km) from the center.  The Hurricane Intensity Index for Typhoon Krosa was 11.5.  The Hurricane Size Index was 22.5 and the Hurricane Wind Intensity Size Index was 34.0.

Typhoon Krosa will move through an environment mostly favorable for intensification.  Krosa will move over water where the Sea Surface Temperature is near 29°C.  Upper level divergence from Typhoon Lekima which is to the west of Typhoon Krosa could cause some vertical wind shear.  The wind shear will not be great enough to prevent intensification, but it could slow the rate at which Typhoon Krosa strengthens.

Typhoon Krose will move into a region where the steering winds are weaker.  Typhoon Krosa is forecast to move slowly toward the north during the next two or three days.  On its anticipated track the center of Typhoon Krosa could be near Iwo To in about 48 hours.