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Hurricane Season 2010: Tropical Storm Imani (Southern Indian Ocean)
03.26.10
 
March 26, 2010

MODIS image of Imani> View larger image
On March 26, NASA's Aqua satellite captured a visible image of Imani at 0836 UTC and showed that the northern half of the tropical cyclone contained very scattered thunderstorms which is conducive to strong wind shear in that quadrant of the storm. Credit: NASA JTWC
Imani on the Weakening on Weekend

This isn't a good weekend for keeping tropical cyclones alive, as Tropical Storm Omais is becoming extra-tropical in the northwestern Pacific Ocean and Tropical Storm Imani appears doomed over the weekend in the Southern Indian Ocean.

Imani was still hanging onto tropical storm status on March 26 at 0900 UTC (5 a.m. EDT) with maximum sustained winds near 52 mph (45 knots), but the storm is running into vertical wind shear – basically a tropical cyclone killer. Imani was located about 810 nautical miles southwest of the Cocos Islands, near 21.3 South and 86.4 East. It was slugging southward at 3 mph (2 knots).

On March 26, NASA's Aqua satellite passed over Imani at 0836 UTC and the Moderate Resolution Imaging Spectroradiometer instrument onboard captured a visible image of the storm. It showed that the northern half of the tropical cyclone contained very scattered thunderstorms which is conducive to strong wind shear in that quadrant of the storm.

Satellite imagery revealed that its low-level circulation center is now "fully exposed" on the north side of the storm, and that there is weak and sheared-off convection (winds coming in block thunderstorms from forming by pushing rising air away). That wind shear is forecast to increase, so Imani's chances of weakening are also increased. Imani is expected to become a depression over the weekend.

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



March 25, 2010

Imani developed a > View larger image
NASA's Aqua satellite captured a visible image of Cyclone Imani on March 25 at 0747 UTC (3:47 a.m. EDT, showing Imani developed a "tail" of clouds stretching southeast of its center. The white area is outside of the satellite's "vision."
Credit: NASA/JPL, Ed Olsen
Imani Reaches Cyclone Status "By the Tail"

Just like the old song by Buck Owens, "Tiger by the Tail," NASA satellite imagery showed that Imani appears to have developed a "tail" of clouds extending southeast from its center. It has indeed become a "tiger" because it is now a category one cyclone on the Saffir-Simpson Scale as it continues to move through the Southern Indian Ocean.

The Atmospheric Infrared Sounder instrument on NASA's Aqua satellite captured a visible image of Cyclone Imani on March 25 at 0747 UTC (3:47 a.m. EDT) and it showed Imani developed a "tail" of clouds, extending to its southeast.

This morning, March 25, at 0900 UTC (5 a.m. EDT) Imani had maximum sustained winds near 80 mph (70 knots). Cyclone-force winds extended up to 30 miles from its center, while tropical storm-force winds extended as far as 85 miles from its center. Cyclone Imani was located about 780 nautical miles southwest of the Cocos Islands near 19.1 South and 85.5 East. It was moving south-southeast near 9 mph (8 knots) and kicking up 16 foot-high seas.

Satellite imagery has given an insight into what is happening within Cyclone Imani as well as its visible appearance. Multispectral satellite imagery showed a strengthening central convection (rapidly rising air that forms the thunderstorms that power a tropical cyclone) in the northwestern quadrant of the storm. In the southwestern quadrant, however, it’s a different story. An upper level trough (an elongated area of low pressure) nearby has sheared or cut-off convection. That wind shear will strengthen over the next day and a half that will cause Imani to dissipate within two days.

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



March 24, 2010

MODIS image of Tropical Storm Imani › View larger image
NASA's Terra satellite captured an image of Tropical Storm Imani on March 24 at 4:25 UTC, and it showed a storm with good symmetry, indicating that it is well-organized. The image even hinted of an eye forming in the storm's center.
Credit: NASA MODIS Rapid Response Team
Map of the path of Tropical Storm Imani › View larger image
This graphic from the Joint Typhoon Warning Center shows that Tropical Storm Imani's path over the last couple of days looks like a question mark. Credit: JTWC
Tropical Storm Imani Making a Question Mark in the Southern Indian Ocean

Over the last week, the path that Tropical Storm Imani, formerly tropical cyclone 21S, is making in the Southern Indian Ocean resembles a question mark. However, there is no question in the minds of forecasters that Imani is headed south to finish out the "question mark" shape.

The Moderate Resolution Imaging Spectroradiometer or MODIS instrument on NASA's Terra satellite captured Tropical Storm Imani at 0425 UTC (12:25 a.m. EDT) today, when it was near the "middle of the question mark" track that it is taking. It showed a storm with good symmetry, indicating that it is well-organized. The image even hinted of an eye forming in the storm's center.

At 0900 UTC (5 a.m. EDT) today, March 24, Tropical Storm Imani had maximum sustained winds near 63 mph (55 knots). Tropical storm-force winds extended out up to 55 miles from the center, making the storm about 110 miles in diameter. It was located about 745 miles west-southwest of Cocos Island, near 15.7 south and 86.3 East. It was moving southwest near 13 mph (11 knots).

Imani has strengthened a little and poses no threat to land. It is forecast to intensify more for another day before moving into an area of increasing vertical wind shear, which will weaken it.

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















March 23, 2010

This NASA Aqua image confirmed that 21S is a compact storm, about 90 miles in diameter. > View larger image
This NASA Aqua satellite visible image from March 23 at 0805 UTC (4:05 a.m. EDT) confirmed that 21S is a compact storm, about 90 miles in diameter.
Credit: NASA JPL, Ed Olsen
NASA's Aqua Satellite Sees a Tight Tropical Storm 21S

The Southern Indian Ocean is still warm enough to enable tropical cyclones to form, and Tropical Cyclone 21S did just that today. NASA's Aqua satellite captured infrared and visible images of 21S and the infrared showed some limited areas of strong convection, while the visible image showed a very small, compact storm.

At 900 UTC (5 a.m. EDT) today, March 23, Tropical Cyclone 21S was located about 505 miles west of Cocos Island near 12.9 degrees South latitude and 88.3 degrees East longitude.

Tropical Storm 21S has maximum sustained winds near 46 mph (40 knots) and tropical storm-force winds extend out to about 45 miles from the center. Today's NASA Aqua satellite visible image confirmed that 21S is a compact storm, about 90 miles in diameter.

The tropical storm was moving southwest at 8 mph (7 knots). The storm is not expected to reach cyclone strength, although it will likely strengthen a little more before encountering adverse atmospheric conditions. Tropical Storm 21S is expected to be short-lived as vertical wind shear is expected to weaken it over the next couple of days. 21S poses no threat to any land areas.

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