Tropical Depression 11S forms in the southern Indian Ocean

The eleventh tropical depression formed today in the Southern Indian Ocean south of Port Louis. It will continue on a southeasterly track and move into open ocean.

At 4 a.m. ET (09:00 UTC) on January 28, Tropical Depression 11S (TD 11S) had maximum sustained winds near 39 mph (35 knots). It was located about 180 nautical miles east of La Reunion, near 21.7 degree South latitude and 58.9 degrees East longitude. TD 11S is moving southward near 6 mph (5 knots).

La Reunion Island is a French island located in the Southern Indian Ocean, east of Madagascar and about 120 miles southwest of the island of Mauritius.

At 11:20 p.m. ET January 27, the Tropical Rainfall Measuring Mission, or TRMM satellite captured Tropical Depression 11S's rainfall, as it was centered east of La Reunion Island. Although most of the rainfall was light to moderate there were some areas of heavy rain of over 2 inches per hour. For more information on the TRMM satellite, go to: www.trmm.nasa.gov.

Despite being in an area of low wind shear, TD 11S has a fully exposed low-level circulation center, which opens the storm's circulation up to wind shear and dry air. Low wind shear helps a storm strengthen, while open circulation lends itself to weakening a storm.

Over the next day or two, however, TD 11S is expected to redevelop and convection (rapidly rising air that forms thunderstorms) and strengthen as it moves over warm sea surface temperatures. After it strengthens, then over the weekend, it is expected to become extra-tropical while remaining over open ocean.