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Hurricane Season 2012: Tropical Cyclone 15S (Southern Indian Ocean)
03.05.12
 
Tropical Cyclone 15S Now Off the Books

Tropical Cyclone 15S had a short and difficult life in the Southern Indian Ocean, and as of March 5 it was off the books.

On March 2, it appeared that Tropical Cyclone 15S had a chance for regeneration. It was a tropical depression for a day before that. At 1800 UTC (1 p.m. EST) on March 2, System 15S was located near 16.4 South and 63.2 East, about 400 miles northeast of Port Louis, Mauritius. At that time, the remnants had a medium chance of regeneration, but that changed the next day, as wind shear increased.

On March 3, the remnants of tropical cyclone 15S were still about 400 nautical miles northeast of Port Louis, Mauritius. It had only moved slightly from the previous day and were centered near 16.3 South and 63.3 East. At that time, it had a low chance of regeneration. By March 4 at 0730 UTC (2:30 a.m. EST), the forecasters at the Joint Typhoon Warning Center noted "System 15S is no longer suspect for tropical cyclone formation."

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center



Mar. 2, 2012

TRMM 3-D image of the remnants of Tropical Cyclone 15S' structure. › View larger image
TRMM's Precipitation Radar was used to create a 3-D image of the remnants of Tropical Cyclone 15S' structure. Powerful thunderstorm towers in the middle of the storm were seen to reach heights of over 17.5 (~10.9 miles).
Credit: NASA/SSAI, Hal Pierce
TRMM shows rainfall in the remnants of Tropical Cyclone 15S on March 2. › View larger image
This image from NASA's TRMM satellite shows rainfall in the remnants of Tropical Cyclone 15S on March 2. Numerous intense storms were dropping rainfall at a rate of over 50mm per hr / ~2 inches (red). Light to moderate rainfall is depicted in blue and green was falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
NASA's TRMM Satellite Sees Remnants of Tropical Cyclone 15S's "Difficult Childhood"

Tropical Cyclone 15S has had a difficult "childhood." It was born on March 1 and immediately dealt with a harsh environment. The cyclone weakened within 24 hours to a remnant low pressure area, and NASA's TRMM satellite revealed there was still some strength remaining in the storm.

The Tropical Rainfall Measuring Mission (TRMM) satellite passed over the remnants of Tropical Cyclone 15S in the South Indian Ocean on March 2, 2012 at 0140 UTC (8:40 p.m. EST, March 1). A rainfall analysis from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments showed very heavy rainfall of over 50mm/hr (~2 inches) was occurring near the center of the storm's circulation.

TRMM's Precipitation Radar (PR) was used to create a 3-D image of the remnants of Tropical Cyclone 15S' structure. Powerful thunderstorm towers in the middle of the remnant low were seen to reach heights of over 17.5 (~10.9 miles). "Another indication of heavy rainfall was that radar reflectivity values of 53.770 dBz were found in this area of the tropical cyclone," said Hal Pierce of the TRMM satellite team at NASA's Goddard Space Flight Center in Greenbelt, Md. where the images were created.

The Joint Typhoon Warning Center issued their final warning on Tropical Cyclone 15S on March 1 at 2100 UTC (4 p.m. EST) when its maximum sustained winds were near 30 knots (34.5 mph/55.5 kph). It was located about 460 nautical miles (529 miles/852 km) northeast of Port Louis, Mauritus at that time. That's near 15.3 South and 63.7 East.

On March 2, Tropical Cyclone 15S's remnants were located near 16.4 South and 63.2 East, approximately 400 nautical miles (460 miles/~741 km) northeast of Port Louis, Maritius. Infrared satellite imagery showed that strong convection (rising air that forms the thunderstorms that make up a tropical cyclone) was occurring near the center of the low pressure area. In the southwestern quadrant of the low, however, the air was sinking (subsidence) so thunderstorm development was being prevented.

Satellite data also showed that the low-level center was elongated from northwest to southeast, as a result of an upper level trough (elongated area) of low pressure.

The remnants of Tropical Cyclone 15S are expected to keep tracking west and may re-develop as wind shear weakens and it moves through warm sea surface temperatures. The Joint Typhoon Warning Center gives the remnants a medium chance of regaining tropical depression status over the weekend of March 3 and 4, 2012.

Text Credit: Hal Pierce/Rob Gutro
SSAI/NASA Goddard Space Flight Center, Greenbelt, Md.



Mar. 1, 2012

MODIS captured this visible image of Tropical Depression 15S on March 1, 2012 at 1002 UTC (5:02 a.m. EST). › View larger image
NASA's Aqua satellite's MODIS instrument captured this visible image of Tropical Depression 15S on March 1, 2012 at 1002 UTC (5:02 a.m. EST) over the Southern Indian Ocean.
Credit: NASA Goddard MODIS Rapid Response Team
NASA Sees Fifteenth Tropical Cyclone Form in Southern Indian Ocean

NASA's Aqua satellite captured a visible image of the birth of Tropical Cyclone 15S over the Southern Indian Ocean.

Tropical Cyclone15S was born on March 1, and when the Aqua satellite passed overhead on March 1, 2012 at 1002 UTC (5:02 a.m. EST) the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument captured a visible image of the storm that showed it as a rounded area of clouds with bands of thunderstorms developing around the center. The storm also appears somewhat elongated as a result of an approaching trough( elongated area) of low pressure.

At 0900 UTC, Tropical Cyclone 15S (TC15S) had maximum sustained winds near 35 knots (~40 mph/~65 kph) making it a tropical storm. It was located about 525 nautical miles northeast of Port Louis, Mauritius, near 15.0 South and 64.4 East. It was moving to the west-south at 16 knots (18.4 mph/29.6 kph).

TC15S is expected to remain at sea over the next couple of days and not affect land areas.

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