A low pressure system designated System 91S is spinning in the Southern Indian Ocean, and NASA’s Aqua satellite captured infrared and visible images of it earlier today. Satellite imagery indicates that the system is getting organized and may soon develop into a tropical depression.

At 0600 UTC (1 a.m. EST) on December 15, System 91S was located about 310 miles northwest of Learmonth, Australia near 18.1 South latitude and 110.6 East longitude. Learmonth is located in the extreme western coast of Australia.

When NASA’s Aqua satellite passed over System 91S on Dec. 15 at 06:05 UTC (1:05 a.m. EST) the Atmospheric Infrared Sounder (AIRS) Instrument captured an infrared image that showed a large area of strong convection around the center of the system’s circulation. The cloud tops were as cold as or colder than -63 Fahrenheit, indicating high, strong thunderstorms. The circulation of the low was clearly evident in the visible image from the AIRS instrument.

The strongest surface winds appear to be on the northeastern side of the storm between 25-30 knots (28-34 mph or 46-55 km/hr) where the strong convection is occurring. Minimum estimated pressure is 1000 millibars. System 91S is moving southwest near 5 mph.

Because System 91S continues to intensify and organize it has a good potential for developing into a tropical depression in the next 24 hours.

Tropical Depression 19W was alive as a depression for only two days in the waters of the Northwestern Pacific Ocean basin and as it wanes it still had some strong thunderstorms within, according to NASA’s TRMM Satellite. Those thunderstorms have added to the rainfall flooding woes already being experienced in Vietnam.

Tropical Depression 19W (TD 19W) became a remnant low pressure area on Dec. 13 at 0900 UTC (4 a.m. EST) when its center was located about 225 miles east of Ho Chi Minh, Vietnam near 10.2 North and 110.4 East. At that time, its maximum sustained winds were only near 23 mph (20 knots) and it had higher gusts over 30 mph. It was slowly moving west at 5 mph through the South China Sea (part of the Northwestern Pacific Ocean basin). TD 19W was kicking up wave heights to nine feet in the South China Sea.

Tropical depression 19W was the latest of four tropical cyclones to move over Vietnam this season. The Tropical Rainfall Measuring Mission (TRMM) satellite passed directly above TD 19W on December 13, 2010 at 2038 UTC (3:38 p.m. EST) and collected rainfall data. TRMM’s Precipitation Radar (PR) showed that a few powerful thunderstorms embedded within TD 19W were dropping heavy rainfall off Vietnam’s south-eastern coast. The heaviest rainfall was falling at a rate of about 2 inches per hour over the coastal waters of Vietnam. TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Although TD 19W was very small it’s rainfall added to October’s extreme rainfall amounts that contributed to the worst flooding seen in the country of Vietnam for 20 years. Flooding was widespread in the central provinces of Nghe An, Quang Tri, Quang Binh, Thua Thien Hue, and Ha Tinh. Deadly tropical storms Mindulle and Conson hit Vietnam in July and August. Tropical depression 18W in November also added to Vietnam’s extremely high 2010 rainfall totals.

According to the Joint Typhoon Warning Center, the organization that forecasts tropical cyclones in that area of the world, TD 19W’s remnant s have already moved ashore and are now affecting southern and central Cambodia.