Super Typhoon Chaba moved north on Monday and it threatened to bring strong winds and heavy rain to Japan and South Korea.  At 5:00 p.m. EDT on Monday the center of Super Typhoon Chaba was located at latitude 27.5°N and longitude 126.5°E which put it about 100 miles (160 km) west-northwest of Okinawa.  Chaba was moving toward the north at 11 m.p.h. (18 km/h).  The maximum sustained wind speed was 155 m.p.h. (250 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 925 mb.

Typhoon Chaba is a compact well organized storm.  It has a clear circular eye surrounded by a ring of strong thunderstorms.  Winds to typhoon force extend out about 35 miles (55 km) from the center of circulation.  Additional rainbands are rotating around the core of Typhoon Chaba.  Thunderstorms at the core of Chaba are generating upper level divergence which is pumping mass out in all directions.

The Hurricane Intensity Index (HII) for Typhoon Chaba is 33.3.  The Hurricane Size Index (HSI) is 11.6 and the Hurricane Wind Intensity Size Index (HWISI) is 44.9.  These indices indicate that Typhoon Chaba is stronger, but slightly smaller than Hurricane Matthew which is over the Caribbean Sea.

Although Typhoon Chaba is still in a very favorable environment, it has probably peaked in intensity.  Chaba was the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale earlier today.  Chaba is currently moving over water where the Sea Surface Temperature (SST) is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Typhoon Chaba is likely to weaken gradually during the next 24 hours.  In about a day or so, Chaba will move over cooler SSTs.  In addition, when Chaba moves farther north it will move closer to the upper level westerly winds in the middle latitudes.  A combination of cooler SSTs and more vertical wind shear will increase the rate at which Typhoon Chaba will weaken.

Chaba is moving around the western end of a subtropical ridge which is steering the typhoon toward the north.  That general motion is expected to continue for about another 24 hours.  In about a day or so the westerly winds of the middle latitudes are expected to turn Chaba quickly toward the northeast.  On its anticipated track the core of Typhoon Chaba will pass west of the northern Ryukyu Islands.  Chaba could be near Jeju, South Korea and western Kyushu in 24 hours.

Chaba is a very strong typhoon.  Although it will weaken, Typhoon Chaba will bring strong winds and heavy rain to parts of South Korea and Japan.