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Hurricane Season 2010: Tropical Storm Chanthu (Northwestern Pacific Ocean/South China Sea)
07.22.10
 
July 22, 2010

MODIS captured this visible image of Chanthu on July 22 (11:25 a.m. local time/China) just before landfall in southeastern China > View larger image
The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument that flies on NASA's Terra satellite captured this visible image of Chanthu at 03:25 UTC on July 22 (11:25 a.m. local time/China) just before landfall in southeastern China.
Credit: NASA Goddard/MODIS Rapid Response Team
Chanthu's center as it was approaching China on July 21 at 17:53 UTC (1:53 p.m. EDT); that area shifted to the south after landfall. > View larger image
This infrared image from NASA's Aqua satellite captured the high, cold, thunderstorm clouds (purple) located mostly east of Tropical Storm Chanthu's center as it was approaching China on July 21 at 17:53 UTC (1:53 p.m. EDT). That area shifted to the south after landfall.
Credit: NASA JPL, Ed Olsen
NASA Infrared Imagery Shows Chanthu Weakening After Landfall in Southeastern China

Tropical Storm Chanthu came ashore in southeastern China and continues to move inland. NASA captured both visible and infrared satellite data that showed the storm is weakening in both form and cloud temperatures.

Typhoon Chanthu was the third typhoon of the season. It made landfall at Wuchuan City, in southern China's Guangdong Province at around 1:45 p.m. local time on Thursday. At the time of landfall, Chanthu's maximum sustained winds were reported near 78 mph (126 km) per hour. Potou Town of Zhanjiang City received 3.07 inches (78.2 mm) of rainfall. No casualties or damages have been reported so far.

On July 22 at 1500 UTC (11 a.m. EDT/11 p.m. local time China), Chanthu was again a tropical storm with maximum sustained winds near 62 mph (55 knots) and weakening. It was located approximately 45 nautical miles northwest of Zhanjiang, China, near 21.9 North and 109.7 East. It was moving northwest near 10 mph (9 knots).

NASA's Atmospheric Infrared Sounder (AIRS) instrument captured infrared imagery of Chanthu, and indicated that the system has begun to weaken due to land Interaction. The infrared imagery shows lower (less cold) cloud tops, indicating weakening convection. Chanthu's low-level circulation center has also now become partially-exposed. Satellite imagery shows that the deep convection is limited to the southern area around the center.

In addition to AIRS, the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument that flies on NASA's Terra satellite captured a visible image of Chanthu at 03:25 UTC on July 22 (11:25 a.m. local time/China) just before landfall in southeastern China. The image showed a cloud-filled eye.

Chanthu is being guided around the edge of an elongated area of high pressure as it continues moving inland. It is forecast to continue moving west-northwest and is expected to dissipate in the next 12-24 hours just north of Vietnam.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center





July 21, 2010

NASA's Aqua satellite captured this visible image of Tropical Storm Chanthu approaching China on July 21. > View larger image
NASA's Aqua satellite captured this visible image of Tropical Storm Chanthu approaching China at 05:45 UTC (1:45 a.m. EDT) on July 21.
Credit: NASA/MODIS Rapid Response Team
The TRMM satellite captured heavy rain (~2 inches per hour) seen in red in Tropical Storm Chanthu on July 20 > View larger image
The TRMM satellite captured heavy rain (~2 inches per hour) seen in red in Tropical Storm Chanthu on July 20 at 1316 UTC.
Credit: NASA/SSAI, Hal Pierce
NASA Satellites Tracking Rain-packed Tropical Storm Chanthu as it Heads Toward China

NASA satellite imagery of Tropical Storm Chanthu revealed a large area of moderate to very heavy rainfall as it nears the southeast China coast.

The Tropical Rainfall Measuring Mission (TRMM) satellite flew over Tropical storm Chanthu on July 20 at 1316 UTC (9:16 a.m. EDT) as it churned in the South China Sea. The data it captured helped create a TRMM rainfall analysis to understand the rates in which rain was falling throughout the storm. TRMM is a joint mission between NASA and the Japanese space agency JAXA.

The rainfall analysis was derived from Precipitation Radar (PR) and TRMM Microwave Imager (TMI) data and was overlaid on a TRMM infrared image from Visible and Infrared Scanner (VIRS) data. The rainfall analysis showed a large area of moderate to very heavy rainfall (as much as 2 inches per hour) in Chanthu's southwest quadrant.

Forecasters at the Joint Typhoon Warning Center, the organization that forecasts tropical cyclones in that region, noted "Recent animated multispectral satellite imagery shows spiral banding tightening around a small but persistent area of central convection."

NASA's Aqua satellite captured a visible image of Tropical Storm Chanthu approaching China at 05:45 UTC (1:45 a.m. EDT) on July 21 and it had the signature shape of a tropical storm. No eye was visible.

At 1500 UTC (11 a.m. EDT) on July 21, Tropical Storm Chanthu had maximum sustained winds near 55 knots (63 mph). It was moving north-west at 6 mph (5 knots). At that time, it was about 210 miles south-southwest of Hong Kong, near 19.5 North and 112.2 East.

Chanthu is forecast to pass just north of Hainan Island and make landfall near Luichow Peninsula in the southern China mainland in the evening hours (local time) on July 22 (or mid-morning EDT).

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



July 20, 2010

AIRS infrared imagery of Chanthu from July 19 at 18:05 UTC showed strong convection (purple) from northeast to southwest > View larger image
NASA's AIRS instrument infrared imagery of Chanthu from July 19 at 18:05 UTC showed strong convection (purple) from northeast to southwest.
Credit: NASA/JPL, Ed Olsen
NASA Infrared Image of Tropical Storm Chanthu Shows Convection Missing on West Side

The fourth tropical depression of the western Pacific Ocean strengthened into a tropical storm and was named Chanthu today. Infrared imagery from the Atmospheric Infrared Sounder (AIRS) instrument that flies aboard NASA's Aqua satellite captured areas of strong convection from northeast to southwest, but convection isn't showing on the storm's west side.

At 1500 UTC (11 a.m. EDT) on July 20, Tropical Storm Chanthu's maximum sustained winds were near 46 mph (40 knots). Chantu was located about 240 nautical miles south of Hong Kong, China, near 18.6 North and 114.3 East. It was moving west-northwestward near 8 mph (7 knots), and is forecast to make a landfall south of Hong Kong by 1800 UTC (3 p.m. EDT) tomorrow, July 21 or 3 a.m. local time/Hong Kong on July 22.

The Hong Kong Observatory has posted Standby Signal, No. 1. That means that a tropical cyclone now centred within about (~500 miles) 800 kilometers of Hong Kong.

Infrared imagery from NASA's AIRS instrument on July 19 at 18:05 UTC (2:05 p.m. EDT) showed strong convection (rapidly rising air that forms the thunderstorms that power a tropical cyclone) from northeast to southwest. By July 20, convection had become fragmented, which indicated to forecasters at the Joint Typhoon Warning Center (JTWC) that any further strengthening will be limited.

The JTWC forecast notes that although the eastern side of the storm is showing convection, the western side is lacking it. This morning's JTWC report noted "Convection has been somewhat dampened on the western periphery of the circulation due to an upper level trough (elongated area of low pressure) positioned over the extreme-western South China Sea."

Two factors will play into the strength of Tropical Storm Chanthu over the next two days as it nears landfall: dry air and increased wind shear. Both of those factors will help weaken Chantu on its journey to a landfall in China.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



July 19, 2010

AIRS saw an area of very high thunderstorm (purple) cloud tops from northeast to southwest around the center of TD4W. > View larger image
NASA's Aqua satellite's AIRS instrument infrared image on July 18 at 0723 UTC saw an area of very high thunderstorm (purple) cloud tops from northeast to southwest around the center of TD4W.
Credit: NASA/JPL, Ed Olsen
NASA Infrared Image Sees Tropical Depression 4 Form in South China Sea

Tropical Depression 04W formed out of disturbance 98W this weekend after this passed over Luzon, the Philippines. NASA's Aqua satellite captured an infrared image that showed strong convection and thunderstorms in its center, helping confirm its organization into a tropical depression.

The Atmospheric Infrared Sounder (AIRS) instrument uses infrared capabilities to take the temperature of various factors associated with a tropical cyclone, from cloud top temperatures which indicate strength of thunderstorms within (colder cloud tops indicate higher, stronger thunderstorms) to sea surface temperatures (those greater than 80 Fahrenheit help power tropical cyclones). When NASA's Aqua satellite flew over Tropical Depression 04W (TD4W) on July 18 at 0723 UTC (3:23 a.m. EDT), it saw an area of very high thunderstorm cloud tops from northeast to southwest around the center of TD4W. Those temperatures were colder than -63 Fahrenheit and indicate strong convection (rapidly rising air that forms thunderstorms).

At 1500 UTC (11 a.m. EDT) on July 19 TD4W had still not consolidated and strengthened into a tropical storm. However, the sea surface temperatures in the South China Sea are warm enough to enable strengthening, as long as the wind shear remains low (which is it expected to do). TD4W had maximum sustained winds near 34 mph (30 knots) and higher gusts. It was located about 285 nautical miles west-northwest of Manila, the Philippines, near 15.9 North and 115.9 East. It was moving west-northwestward near 11 mph (10 knots).

TD4W is expected to strengthen into a tropical storm and move toward the northwest for a landfall south of Hong Kong in a couple of days.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center