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Hurricane Season 2010: Tropical Cyclone 24S (Southern Indian Ocean)
04.22.10
 
April 22, 2010

TRMM's analysis of rainfall within Tropical Storm 24S on April 22 at 0708 UTC showed areas of light to moderate rainfall. > View larger image
TRMM's analysis of rainfall within Tropical Storm 24S on April 22 at 0708 UTC (3:08 a.m. EDT) showed areas of light to moderate rainfall. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour.
Credit: NASA/SSAI, Hal Pierce
91S Becomes Tropical Cyclone 24S as NASA's TRMM Captures its Rainfall

NASA's Tropical Rainfall Measuring Mission or TRMM satellite has been flying over the low pressure area known as System 91S in the Southern Indian Ocean and providing estimates of rainfall within the storm. The storm has now strengthened enough to be reclassified as the twenty-fourth southern hemispheric tropical cyclone, "24S."

TRMM, managed by NASA and the Japanese Space Agency (JAXA) passed over System 91S early today, April 22 at 3:08 Eastern Daylight Time (0708 UTC) and captured a look at the rainfall rates in the storm. TRMM found that there were some areas of light to moderate rainfall between .78 to 1.57 inches per hour.

Rain rates are created from different instruments aboard TRMM. The rain rates in the center of TRMM images are derived from the TRMM Precipitation Radar, the only space borne radar of its kind, while those in the outer portion are from the TRMM Microwave Imager. The rain rates are then overlaid on infrared data from the TRMM Visible Infrared Scanner to create the entire image. The images are created at NASA's Goddard Space Flight Center, in Greenbelt, Md.

At 11 a.m. EDT (1500 UTC) this morning, April 22, Tropical Cyclone 24S had maximum sustained winds near 35 knots (40 mph) making it of tropical storm strength. 24S was about 570 nautical miles north of Learmonth, Australia, near 13.1 South and 115.4 East. It was moving in a southerly direction at 6 mph (5 knots) but it is forecast to turn westward and head into open waters and away from Australia.

Animated infrared satellite imagery shows increased central convection (thunderstorm development) and improved banding of thunderstorms around the center of the cyclone. Because 24S is in an environment of low vertical wind shear, it is expected to further intensify for a couple of days. After that, the wind shear will kick up again and weaken the storm.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center



April 21, 2010

This AIRS satellite image shows some high, strong thunderstorms with temperatures colder than -63 Fahrenheit. > View larger image
This NASA infrared AIRS satellite image on April 21 shows some high, strong thunderstorms (purple) in System 91 with temperatures colder than -63 Fahrenheit.
Credit: NASA/JPL, Ed Olsen
System 91 Looking Good for Tropical Cyclone Development

NASA's infrared satellite imagery indicates that the low pressure area currently known as "System 91S" in the Southern Indian Ocean has some punch in it, as it has high, cold cloud tops and some strong thunderstorms.

System 91S has shown increasing organization of its low-level circulation center over the last 12 hours, and favorable conditions for development. The vertical wind shear (winds that can tear a storm apart if strong enough) has decreased, so the potential for 91S to develop into a tropical cyclone is good in the next 24 hours.

The Atmospheric Infrared Sounder (AIRS), instrument that flies aboard NASA's Aqua satellite, captured an infrared image of System 91S today, April 21, and it revealed some strong, high thunderstorms around the storm's center. Infrared imagery is false-colored and higher cloud tops of stronger storms are depicted in purple in the AIRS images. Today's image revealed a lot of purple (high, strong thunderstorms) especially to the east and south of the storm's center. Those highest thunderstorms are as cold as or colder than 220 Kelvin or minus 63 degrees Fahrenheit (F).

At 08:30 UTC (4:30 a.m. EDT) the circulation center of 91S appeared to be near 10.1 degrees South latitude and 116.4 East longitude, and had maximum sustained winds near 30 knots (33 mph). 91S was moving west-southwest near 3 knots (4 mph) and it is currently about 630 nautical miles north-northwest of Port Hedland, Australia.

Forecasters will be watching 91S as it continues to organize. It now has a good chance of becoming a tropical storm in the next 24 hours.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center