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Hurricane Season 2012: Tropical Storm 09S (Southern Indian Ocean)
01.25.12
 
Aqua satellite passed over Tropical Storm 09S on January 25 at 7:05 UTC (2:05 a.m. EST) › View larger image
When NASA's Aqua satellite passed over Tropical Storm 09S on January 25 at 7:05 UTC (2:05 a.m. EST) the AIRS instrument measured the temperatures of the low pressure area's cloud tops. Thunderstorm cloud tops around the entire center of circulation and in some of the bands of thunderstorms that circled the center from northwest to northeast were colder than -63 Fahrenheit (-52.7 Celsius).
Credit: NASA/JPL, Ed Olsen
NASA Sees Development of Tropical Storm 09S in Southern Indian Ocean

NASA's Aqua satellite passed over the low pressure system called System 97S on Jan. 24 and observed a large area of strong thunderstorms around its center that hinted at further development. On Jan. 25, the low strengthened into the ninth tropical depression and now a tropical storm of the Southern Indian Ocean.

NASA's Aqua satellite passed over Tropical Storm 09S on January 25 at 7:05 UTC (2:05 a.m. EST), and the Atmospheric Infrared Sounder (AIRS) instrument measured the cloud top temperatures. Just as they appeared in infrared imagery on January 24, thunderstorm cloud tops around the entire center of circulation and in some of the bands of thunderstorms that circled the center from northwest to northeast were colder than -63 Fahrenheit (-52.7 Celsius). Temperatures that cold indicate uplift (and evaporation) of air is very strong, and it pushes the cloud tops to the top of the troposphere. When cloud tops get that high, they tend to drop heavy rainfall (around 2 inches/50 mm per hour).

AIRS infrared imagery revealed that the convection continues to strengthen and during the early hours on January 25, bands of thunderstorms were developing around the center.

Although Tropical Storm 09S has moved in a westerly direction over the last couple of days, a weather system (elongated area of high pressure, called a ridge) will begin pushing it eastward toward Western Australia late on January 25. The Joint Typhoon Warning Center has forecast Tropical Storm 09S (TS09S) to come closest to the coastline of Western Australia by January 29 and 30, 2012.

At 1500 UTC (10 a.m. EST) on January 25, TS09S had maximum sustained winds near 35 knots (40 mph/~65 kph). It was located near 16.0 South latitude and 107.8 East longitude, about 515 nautical miles (~592 miles/~953 km) northwest of Learmonth, Australia. The storm was still moving to the west at 5 knots (~6 mph/9 kph), but is expected to change course to the east-southeast.

The Joint Typhoon Warning Center expects that Tropical Storm 09S will continue to strengthen over the next couple of days and could reach Cyclone status.

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center, Greenbelt, Md.



Jan. 24, 2012

Aqua satellite passed over System 97S on January 24 at 1:23 a.m. EST › View larger image
When NASA's Aqua satellite passed over System 97S on January 24 at 1:23 a.m. EST the AIRS instrument measured the temperatures of the low pressure area's cloud tops. Thunderstorm cloud tops around the entire center of circulation and in some of the bands of thunderstorms that circled the center from northwest to northeast were colder than -63 Fahrenheit (-52.7 Celsius).
Credit: NASA/JPL, Ed Olsen
NASA Sees Developing Cyclone Near Western Australia

NASA's Aqua satellite saw icy cold cloud top temperatures in the low pressure area called System 97S on January 24, which indicates there's a lot of power in the organizing storm system.

On January 24, 2012, the low pressure area called System 97S was located about 340 miles (~547 km) north-northwest of Learmonth, Western Australia. The Joint Typhoon Warning Center (JTWC) noted that "formation of a significant tropical cyclone is possible within 155 nautical miles (178.4 miles/287 km) either side of a line from 16.6 (South) 112.7 (East) to 17.4 (South) and 107.3 (East) within the next 12 to 24 hours." The center of circulation appears to be near 16.8 South latitude and 112.7 East longitude.

When NASA's Aqua satellite passed over System 97S on January 24 at 06:23 UTC (1:23 a.m. EST) the Atmospheric Infrared Sounder (AIRS) instrument measured the temperatures of the low pressure area's cloud tops. Thunderstorm cloud tops around the entire center of circulation and in some of the bands of thunderstorms that circled the center from northwest to northeast were colder than -63 Fahrenheit (-52.7 Celsius). Those cold temperatures represent strong uplift, hinting System 97S could develop into a tropical depression in the next day or two. AIRS data also showed that System 97S appeared almost symmetrical.

JWTC forecasters noted that the current data on System 97S doesn't justify issuing a tropical depression number yet, but sustained winds are estimated between 28 and 32 knots (~32 to 37 mph / ~52 to 59.6 kph) and just near depression status. System 97S is moving west-southwest at 21 knots (24 mph/~39 kph) away from land. JWTC noted that the likelihood for development into a tropical depression is high.

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center, Greenbelt, Md.