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Hurricane Season 2005: Tropical Storms Delta and Epsilon
TRMM image of Tropical Storm Delta on November 23, 2005.With every new storm, the 2005 Atlantic hurricane season continues to set new records. With the formation of tropical storms Delta and Epsilon, the record for number of named storms in the Atlantic is now at 26, which shatters the previous mark of 21 set back in 1933. Although hurricane season officially ends on November 30, storms can form in December although they are relatively rare. Considering the magnitude of the record-breaking 2005 hurricane season, it is not surprising that on the last day of the official season there is an active storm in the Atlantic--Epsilon.

Tropical Storm Delta, the 25th named storm of the season, started out as a non-tropical area of low pressure about 1150 miles southwest of the Azores in the eastern Atlantic. This low pressure center acquired tropical characteristics as a result of persistent deep convection, and on 23 November 2005, Tropical Storm Delta was born.

TRMM image of Tropical Storm Delta on November 28, 2005. The Tropical Rainfall Measuring Mission (TRMM) satellite has continued to monitor the extraordinary activity in the Atlantic. Armed with an array of sensors, TRMM provides unique images and information on tropical cyclones over the global Tropics. This first image was taken by TRMM (above right) at 4:32 pm EDT on 23 November 2005 and shows the horizontal distribution of the rain intensity within Delta. Rain rates in the central part of the swath are from the TRMM Precipitation Radar (PR), the only radar that can measure rainfall from space. Rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM reveals that Delta is rather small, but the circulation is fairly well developed as evidenced by the nearly closed eye (semicircular green area) and curvature in the rain field. At the time of the image, Delta was a tropical storm with sustained winds estimated at 58 mph by the National Hurricane Center (NHC).

Initially the storm headed south before veering off to the northeast. As the system was approaching the Canary Islands off of the coast of Africa, it began to merge with a front and became more extratropical in nature. This next image from TRMM (above left) was taken at 1:38 pm EDT on November 28 just as Delta was passing north of the Canary Islands. The storm center (shown by the symbol) is now completely exposed and all of the rain is ahead of the center. A large band of heavy (dark red area) to moderate (green) rain shows where Delta's circulation is interacting with the front.

TRMM image of Tropical Storm Epsilon on November 30, 2005.Epsilon, the 26th named storm of the season, also formed from a midlatitude low pressure center on 29 November 2005 in the central Atlantic about 840 miles east of Bermuda. This final image from TRMM (right) was taken of Epsilon at 7:05 pm EDT, November 29, 2005. Epsilon is a very small storm. Areas of moderate rain (green areas) and an area of heavy rain (red dot) are present near the center. However, there is yet little curvature in the rain features, and no eye is present as Epsilon is still in the formative stages at this time. At the time of this image, Epsilon had sustained winds estimated at 52 mph by NHC. TRMM is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC).

For the latest advisories on hurricanes, please visit the National Hurricane Center website at:

Steve Lang
Goddard Space Flight Center