A pair of active cyclones in the West Pacific has resulted in winds and heavy rain for both Taiwan and the Philippines. The first storm, Pabuk, made landfall on the southern tip of Taiwan bringing gusty winds and rain but little damage. The second storm, Wutip, is also expected to affect Taiwan. Neither storm is very strong: Pabuk reached minimal typhoon intensity while Wutip has remained a tropical storm. Despite neither storm passing directly over the Philippines, they are being blamed for 11 deaths there as a result of flooding due to enhanced monsoon rains.

Pabuk (known as "Chedeng" in the Philippines) formed into a tropical storm on the 5th of August in the central Philippine Sea and took a general westward track. The Tropical Rainfall Measuring Mission (TRMM) satellite captured this first image of Pabuk on the 5th of August 2007 at 15:13 UTC as it was passing through the Philippine Sea well east of Taiwan. The image shows the horizontal distribution of rain intensity within the storm as seen from the TRMM satellite. Rain rates in the center swath are from the TRMM Precipitation Radar (PR), a first-of-its-kind space-borne precipitation radar, while rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). From this image it is apparent that Pabuk's circulation is still rather immature. The storm is asymmetrical with the vast majority of the rain occurring south and east of the center as shown by the blue, green and red areas denoting light, moderate and heavy rain, respectively. At the time of this image, the Joint Typhoon Warning Center estimated the maximum sustained winds to be 45 knots (52 mph), a moderate tropical storm. Pabuk continued to track to the west and slowly gained strength, reaching minimal typhoon intensity on the 7th as it began to approach Taiwan.

Click to See a FLYBY animation (1.3 mb) using TRMM PR.

The next image was taken by TRMM at 14:56 UTC on the 7th and shows not only Pabuk just as it was about to pass over southern Taiwan but also the precursor to what would become Tropical Storm Wutip. The area of very heavy rain (dark red area) just to the southeast of the southern tip of Taiwan is associated with the southwest portion of Pabuk's eyewall. The center of Pabuk falls just within the TMI swath. The other area of heavy rain due east of Luzon is associated with a tropical depression (TD 08W) that would later become Wutip. The TRMM PR has the ability to look at precipitation structures in the vertical. This next image is coincident with the previous image and shows a 3D view of both systems. The PR reveals that the areas of intense rain visible in the previous image are associated with deep convective towers (shown in red). These areas of deep convection release heat into the storms. This heating, known as latent heating, is what drives their circulations. At the time of these images, Pabuk's sustained winds were estimated at 60 knots (69 mph, a strong tropical storm) and TD 08W's at 30 knots (35 mph).

After passing over southern Taiwan, Pabuk continued westward toward China. This final image from TRMM was taken at 07:26 UTC on August 8th as Pabuk was approaching the the southeast coast of China. The bulk of the rain is now ahead of the system. Although an area of heavy rain is present on the southwest corner of the eye, the eye is open, an indication of a weakened system.

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Images and animations produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC)