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.
Source: NASA's Goddard Space Flight Center (news : web)
Explore further: The next Napa earthquake could be much bigger, scientists find