image: On July 6, RapidScat measured the Chan-Hom's sustained surface winds and saw strongest winds were near 25 meters per second/55.9 mph/90 kph) from north of the center to east and around to the southwestern quadrant. view more
Credit: NASA JPL/Doug Tyler
Typhoon Chan-Hom's strongest winds wrapped from north to south, around the eastern side of the storm, according to surface wind data from NASA's RapidScat instrument. Winds in the western quadrant were not as strong as they were in the other quadrants on July 6 and July 7.
Typhoon Chan-Hom continues to strengthen as it moves through the Northwestern Pacific Ocean. On July 6, the RapidScat instrument that flies aboard the International Space Station (ISS) measured the storm's sustained surface winds as the ISS passed overhead. RapidScat took measurements from 4:54 to 6:26 UTC (12:54 to 2:26 a.m. EDT). Data showed the strongest winds were near 25 meters per second (mps) (55.9 mph/90 kph) from north of the center, wrapping around the east and around to the southwestern quadrant. Only sustained winds in the northwestern quadrant were below that threshold.
On July 7, that northwestern quadrant still appeared to be the weakest part of the storm. The Joint Typhoon Warning Center noted that a satellite imager taken at 12:05 UTC (8:05 a.m. EDT) from the AMSU-B instrument "continues to show a microwave eye and the lack of deep convection on the northern side of the low-level center." The Advanced microwave sounding unit (AMSU) is a multi-channel microwave radiometer installed on meteorological satellites. The instrument examines several bands of microwave radiation from the atmosphere to perform atmospheric sounding of temperature and moisture levels.
The Atmospheric Infrared Sounder or AIRS instrument aboard NASA's Aqua satellite gathered infrared temperature data on Chan-Hom on July 6 at 16:47 UTC (12:47 p.m. EDT). The infrared data shows a large area of high thunderstorm cloud tops, indicating strong uplift in the storm. The coldest cloud top temperatures were near -81 Fahrenheit or -63 Celsius. Cloud top temperatures that cold are high into the troposphere and capable of generating heavy rain.
At 1500 UTC (11 a.m. EDT) on July 7, Typhoon Chan-Hom's maximum sustained winds were near 80 knots (92.0 mph/148.2 kph) and the storm continued to strengthen. Chan-Hom was centered near 18.7 North latitude and 135.0 East longitude, about 506 nautical miles (582 miles/937 km) southwest of Iwo to, and has tracked westward at 10 knots (11.5 mph/18.5 kph).
Typhoon Chan-Hom is forecast to continue heading for southeastern China after passing south of Iwo To. Chan-Hom is expected to develop into a super typhoon. China's National Meteorological Centre (CNMC) noted that Chan-Hom is the ninth typhoon of the year. At 5:00 a.m. (local time, Shanghai) today, it was centered about 1,620 km (1,007 miles) southeast of Diaoyu Island of China.
CHMC expects Chan-Hom to enter southeastern East China Sea on the night of July 9, approaching coast of Zhejiang and Fujian. Late on July 10 and early July 11, Chan-Hom is forecast to make landfall in those areas. For updated warnings and watches from the China Meteorological Service, visit: http://www.cma.gov.cn/en/WeatherWarnings/.
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