Tropical Storm Sanba exploded in intensity between Sept. 12 and 13, becoming a major Category 4 Typhoon on the Saffir-Simpson Scale. NASA's Aqua satellite captured infrared data that showed a large area of powerful thunderstorms around the center of circulation, dropping heavy rain over the western North Pacific Ocean.
NASA's Aqua satellite passed over Super Typhoon Sanba on Sept. 13 at 0447 UTC (12:47 a.m. EDT). The Atmospheric Infrared Sounder (AIRS) instrument captured an infrared image of Sanba and found an eye about 20 nautical miles (23 miles/37 km) wide, surrounded by a thick area of strong convection (rising air that forms the thunderstorms that make up the storm) and strong thunderstorms. Forecasters at the Joint Typhoon Warning center noted that the AIRS imagery showed that there was "no banding outside of this ring, consistent with an annular typhoon."
On Sept. 13 at 1500 UTC (11 a.m. EDT), Sanba's maximum sustained winds were near 135 knots (155 mph/250 kmh). Sanba had higher gusts into the Category 5 typhoon category. The Saffir-Simpson scale was slightly revised earlier in 2012, so a Category 4 typhoon/hurricane has maximum sustained winds from 113 to 136 knots (130 to 156 mph /209 to 251 kmh). A Category 5 typhoon's maximum sustained winds begin at 137 knots (157 mph /252 kmh).
Sanba was located about 600 nautical miles (690 miles/1,111 km) south of Kadena Air Base, near 16.8 North latitude and 129.5 East longitude. It was moving to the north at 9 knots (10.3 mph/16.6 kmh) and generating wave heights of 40 feet.
Sanba is expected to continue on a north-northwesterly track through the western North Pacific and move through the East China Sea, passing close to Kadena Air Base, Okinawa, Japan on Sept. 15.
Explore further: Thousands of intense earthquakes rock Iceland