As the 2006 Atlantic hurricane season neared the typical peak of storm activity in mid-September, Hurricane Florence was making its way northward through the western Atlantic near Bermuda. Although Florence was the sixth named storm of the season, no major hurricanes had occurred as of mid-September. Before Florence, only Ernesto had managed to briefly reach minimal hurricane intensity. Florence formed from a tropical depression (low pressure area) on September 3, and it became the second hurricane of the season as it approached Bermuda. It had not exceeded Category 1 intensity, nor was it projected to become more powerful, as of September 12.
The image above shows the hurricane not long after it had passed Bermuda. The image was taken at 7:05 p.m. local time (23:05 UTC) on September 11, 2006, by the Tropical Rainfall Measuring Mission (TRMM) satellite. Rain rates in the center swath are from the TRMM Precipitation Radar, while those in the outer swath are from the TRMM Microwave Imager. The rain rates are overlaid on infrared data from the TRMM Visible Infrared Scanner. The data shows rain bands circling a rather large eye, which contains an area of intense rain (dark red arc) in the northwest eyewall. The southeastern part of the eyewall, however, appears ragged. Most of the rain was ahead of the storm (the broad blue and green area indicating light to moderate rain, respectively).
The TRMM satellite was placed into service in November 1997. From its low-earth orbit, TRMM provides valuable images and information on storm systems around the tropics using a combination of passive microwave and active radar sensors, including the first precipitation radar in space. TRMM is a joint mission between NASA and the Japanese space agency, JAXA.