NASA - National Aeronautics and Space Administration

October 28, 2010

NASA Satellite Sees Tropical Depression 1S Dissipating in Southern Indian Ocean

› View larger image
TRMM captured the waning rainfall rates of TD01S on Oct. 28 at 0045 UTC (Oct. 27 at 8:45 p.m. EDT). The rainfall appears to be mostly on the southern side of the storm, although the storm's northeastern quadrant was not visible from TRMM's orbit. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour.
Credit: NASA/SSAI, Hal Pierce The first tropical cyclone of the Southern Indian Ocean is running into wind shear and is expected to dissipate in the next day or two as a NASA satellite showed rainfall in the system is weakening.

The Tropical Rainfall Measuring Mission (TRMM) satellite, managed by NASA and the Japanese Space Agency flew over Tropical Depression 01S (TD01S) and captured the storm's waning rainfall rates on Oct. 28 at 0045 UTC (Oct. 27 at 8:45 p.m. EDT). The rainfall appeared to be mostly on the southern side of the storm, although the storm's northeastern quadrant was not visible from TRMM's orbit. The heaviest rainfall appeared to be around .78 inches per hour. TRMM data also showed the highest thunderstorms in TD01Swere near 7 kilometers (4 miles) high and falling. Cloud tops that keep lowering are a strong indication that the strength of convection is waning within the storm.

At 0900 UTC (5 a.m. EDT) on Oct. 28, Tropical Depression 01S had maximum sustained winds near 29 mph. It was located about 650 nm east-southeast of Diego Garcia, near 13.5 South latitude and 81.3 East longitude. TD01S is moving westward near 16 mph.

Animated multispectral imagery shows the convection (rapidly rising air that forms the thunderstorms that make up a tropical cyclone) decreased and most of the convection is now moves to the southwest of the depression's center. TD01S's center is now exposed to outside winds, which could weaken it further. TD01S is moving into an area with stronger wind shear, which will further weaken the tropical cyclone (general name for a tropical depression, storm, or hurricane).

Forecasters at the Joint Typhoon Warning Center, who forecast for the storm, expect that it will dissipate by Oct. 29.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD

---

October 27, 2010

Tropical Storm 1S Hanging Onto Tropical Storm Status

› View larger image
The TRMM satellite passed over Tropical Depression 1S in the southwestern Indian Ocean at 1050 UTC (6:50 a.m. EDT) on Oct. 26 and measured light to moderate rainfall within the system. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour.
Credit: NASA/SSAI, Hal Pierce Tropical Storm 1S is maintaining tropical storm strength as it continues on its track in a south-southwesterly direction through the Southern Indian Ocean.

On Oct. 27 at 0900 UTC (5 a.m. EDT), Tropical Storm 1S had maximum sustained winds near 39 mph, the threshold for tropical storm strength. It was far away from land areas, some 825 nautical miles southeast of the island of Diego Garcia, near 12.5 South and 85.1 East. It was encountering a stronger vertical wind shear, so it has been unable to strengthen and is going to start running into cooler waters will which further reduce its chance to intensify.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD

---

October 26, 2010

TRMM Satellite Sees So. Indian Ocean's First Tropical Storm of the Season

› View larger image
The TRMM satellite passed over Tropical Depression 1S in the southwestern Indian Ocean at 1050 UTC (6:50 a.m. EDT) on Oct. 26 and measured light to moderate rainfall within the system. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour.
Credit: NASA/SSAI, Hal Pierce The Southern Indian Ocean tropical cyclone season has started early this year, as the first tropical depression formed today and quickly grew into a tropical storm as NASA's TRMM satellite captured its rainfall.

The Tropical Rainfall Measuring Mission (TRMM) satellite passed over Tropical Depression 1S in the southwestern Indian Ocean at 1050 UTC (6:50 a.m. EDT) on Oct. 26 and measured light to moderate rainfall within the system. TRMM is a joint satellite mission between NASA and the Japanese Space Agency, JAXA, and the TRMM data was used to create a rainfall image at NASA's Goddard Space Flight Center in Greenbelt, Md.

The southwest Indian Ocean tropical cyclone season doesn't officially begin until November 15 but Meteo France upgraded this low pressure center to a tropical depression today. The Joint Typhoon Warning Center upgraded it to a tropical storm a little later.

At 1500 UTC (11 a.m. EDT), Tropical Storm 1S was far away from land, about 850 nautical miles east-southeast of Diego Garcia near 11.3 South and 86.3 East. It had maximum sustained winds near 39 mph, and was moving southward near 8 mph.

Satellite data shows that vertical wind shear has weakened, which has allowed for convection to strengthen. Convection is rapidly rising air that develops the thunderstorms that power the tropical cyclone. Satellite data also shows banding of thunderstorms around the low-level center, which is indicative of strengthening.

Tropical storm One is predicted to move harmlessly toward the southwest over open waters and strengthen slowly in the next couple of days.

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