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Hurricane Season 2009: Tropical Storm Cleo (Southern Indian Ocean)
12.11.09
 
December 11, 2009

Hurricane Cleo› Larger image
TRMM flew over Cleo on Dec. 10 at 20:23 UTC. There was one small area of heavy rainfall, in its northwestern side (in red) of about 2 inches per hour.
Credit: NASA/SSAI, Hal Pierce
TRMM Satellite Sees Cyclone Cleo Coming to a Close

Rainfall in the once-known Cyclone Cleo has really diminished over the last 24 hours, and the Tropical Rainfall Measuring Mission or TRMM satellite has confirmed it. Cleo is fading and the Joint Typhoon Warning Center has acknowledged its demise, in its final warning on the storm today.

At 4 a.m. ET today, December 11, Cleo's maximum sustained winds were down to 40 mph, and waning fast. That make Cleo a weak tropical storm at the moment, but it is expected to dissipate in the next day or two, because of hostile atmospheric conditions (wind shear). Cleo's center was located about 480 miles southwest of Diego Garcia, near 13.9 degree South latitude and 67.7 East longitude.

The TRMM satellite, managed by both NASA and the Japanese Space Agency known as JAXA flew over Cleo on December 10 at 20:23 UTC (3:23 p.m.ET) when it was still showing one small area of heavy rainfall, in its northwestern side.

Satellite data has also confirmed that Cleo's low level center of circulation is now fully exposed, and that deep convection (heavy rainfall) that TRMM noticed yesterday is nearly gone. Cleo is not expected to regenerate because it's battling wind shear and dry air – two factors that will lead to the storm's dissipation over the next day or two.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



December 10, 2009

NASA's Terra satellite captured this image of Cleo  in the southern Indian Ocean on December 8. > View larger image
NASA's Terra satellite captured this image of Cleo in the southern Indian Ocean on December 8 at 05:35 UTC (12:35 a.m. ET) when it was still a cyclone.
Credit: NASA MODIS Rapid Response
Cyclone Cleo Back Down to Tropical Storm Status

Cleo has run into wind shear and it has weakened it from a cyclone to a tropical storm. Cleo's maximum sustained winds are now down to 69 mph, and expected to continue falling. NASA's TRMM satellite noticed that an opening in the storm's circulation is one of the reasons Cleo has weakened quickly.

On December 10 at 09:00 UTC (4 a.m. ET) Tropical Storm Cleo) was located approximately 380 nm south-southwest of the island of Diego Garcia, near 13.5 degrees South latitude and 70.3 East longitude. Cleo was moving west-southwestward at 7 mph.

NASA and the Japanese Space Agency's Tropical Rainfall Measuring Mission or TRMM satellite flew over Cleo early this morning and confirmed that Cleo's low level circulation center is becoming exposed to the north. Open circulation leads to weakening, and Cleo has weakened more quickly than expected.

TRMM noticed that Cleo's deepest convection has contracted toward its center and has thinned significantly.

An elongated area of low pressure, or a trough located to Cleo's west is impacting the storm, and increased vertical wind shear. Wind shear can weaken and tear a storm apart. In addition, Cleo continues to move toward cooler waters, another factor that will zap its strength. Over the next several days, Cleo is forecast to become extra-tropical.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



December 9, 2009

The red areas in the image depict heavy rainfall at almost 2 inches per hour. > View larger image
This TRMM image of Cleo's rainfall was captured on December 8 at 2035 UTC. The red areas in the image depict heavy rainfall at almost 2 inches per hour.
Credit: NASA/SSAI, Hal Pierce
NASA's Aqua satellite captured this visible image of Cyclone Cleo in a classic hurricane-style pinwheel shape. > View larger image
NASA's Aqua satellite captured this visible image of Cyclone Cleo on Dec. 9 at 0853 UTC, in a classic hurricane-style pinwheel shape. However, the eye is not clearly visible.
Credit: NASA JPL, Ed Olsen
NASA's Aqua satellite captured high, cold (purple) thunderstorm cloud tops of Cleo (bottom center). > View larger image
NASA's Aqua satellite captured high, cold (purple) thunderstorm cloud tops of Cleo (bottom center) in this infrared image December 9. Those cloud tops are as cold as -63F. Southern India and the island of Sri Lanka are pictured here to the northeast of Cleo.
Credit: NASA JPL, Ed Olsen
Cyclone Cleo Has Reached Its Maximum Wind Speed

NASA Satellites noticed that Tropical Cyclone Cleo had reached its maximum strength, and was now moving into areas that will weaken it. Cleo's maximum sustained winds were near 115 mph (100 knots), with gusts to (138 mph) 120 knots today, December 9, 2009.

Two NASA satellites, Aqua and the Tropical Rainfall Measuring Mission or TRMM satellite captured three different views of Cleo earlier today. The Atmospheric Infrared Sounder (AIRS) instrument on Aqua captured an infrared and visible image of Cleo, while TRMM was able to see the rate of rainfall within the storm.

At 4 a.m. today, Cyclone Cleo was located about 275 miles south of Diego Garcia, near 11.9 South latitude and 73.3 East longitude. It was moving west-southwest near 8 mph. Tropical storm-force winds extend out to 115 miles from its center, so the storm is larger than 230 miles in diameter. Hurricane-force winds of more than 74 mph extend as far as 45 miles from the center.

The AIRS instrument on NASA's Aqua satellite captured an infrared image of high, cold thunderstorm cloud tops around the center of Cleo's circulation on December 9. Those cloud tops were as cold as -63F and are the strongest areas of convection. Once the storm starts to weaken, however, the cloud top heights will drop and AIRS will notice that those cloud tops will be warmer than they are today.

The TRMM satellite confirmed those areas of strongest convection with its rainfall mapping capabilities. On December 8 at 2035 UTC (3:35 p.m. ET) TRMM noticed heavy rainfall in those same areas of strong convection, where rain was falling at almost 2 inches per hour.

Cleo isn't threatening any landmasses, but it is churning up 30-foot high waves in the Southern Indian Ocean.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center





















December 8, 2009

This is a visible image of Cleo (left) on December 8 at 08:15 UTC from the MODIS instrument on NASA's Aqua satellite. > View larger image
This is a visible image of Cleo (left) on December 8 at 08:15 UTC from the MODIS instrument on NASA's Aqua satellite. The blue longitude line helps show the curvature of the Earth.
Credit: NASA MODIS Rapid Response Team
NASA Captures a Visible Image of Cleo's New Eye

The Moderate Imaging Spectroradiometer or MODIS instrument that flies on NASA's Aqua satellite has amazing resolution from space, and captured Cleo's cloudless eye early this morning. Cleo has intensified from a Tropical Storm into a Cyclone.

MODIS captured an image of Cleo today, December 8 at 08:15 UTC (03:15 a.m. ET) as it passed overhead from its orbit in space. The development of an eye is an indication that Cleo strengthened overnight, and is now a tropical cyclone. Cleo has sustained winds near 109 mph (95 knots) with higher gusts. Hurricane-force winds only extend out to 25 miles from the center right now, while tropical storm-force winds extend as far as 65 miles. Cleo is at the top end of the Category Two Saffir-Simpson scale. Category three cyclones have sustained winds from 111-130 mph.

Cleo was located 340 miles southeast of Diego Garcia, near 10.8 degrees South latitude and 76.4 degrees East longitude. It was moving west-southwest near 12 mph. Currently, Cleo isn't threatening any landmasses.

Because Cleo is in a favorable area for strengthening, it is expected to reach Category 3 status later today or tomorrow. The current forecast track takes Cleo passing well to the north of La Reunion and Mauritius.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



December 7, 2009

TRMM reveals rain rates in various areas around Cleo's center near 1 inch/hour (yellow/orange). > View larger image
This image of Tropical Storm Cleo from Dec. 7 at 0641 UTC is a combination from NASA's TRMM satellite and the EUMETSAT's Meteosat-7. TRMM reveals rain rates in various areas around Cleo's center near 1 inch/hour (yellow/orange). Meteosat-7 provided the cloud image.
Credit: JTWC
NASA's TRMM Satellite Sees Tropical Storm Cleo Form in Southern Indian Ocean

The Tropical Rainfall Measuring Mission or TRMM satellite captured the birth of Tropical Storm Cleo in the southern Indian Ocean today, December 7.

TRMM is managed by both NASA and the Japanese Space Agency, and provides rainfall estimates of tropical systems from its orbit in space. Data from TRMM earlier today revealed that there are some areas around Cleo's circulation where rain is falling at about one inch per hour.

At 1200 UTC (7 a.m. ET) today, Cleo had maximum sustained winds near 52 mph with higher gusts. Cleo was centered approximately 425 nautical miles east-southeast of the island of Diego Garcia, near 9.1 South latitude and 79.4 East longitude. Diego Garcia is a coral atoll and the largest island of the Chagos Archipelago. It is located in the Indian Ocean, about 1,000 miles south of the southern coast of India. Cleo was moving west near 13 mph.

Cleo strengthened quickly because of light wind shear and very warm ocean waters. Those two factors enable a tropical cyclone to strengthen, and are available in Cleo's path so the storm is expected to continue intensifying.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center