Tropical Storm Debby, the fourth named storm of the Atlantic hurricane season, formed in the central Gulf of Mexico on June 23, 2012. It was the earliest date on record for the fourth named storm in a season.
Debby began as an area of low pressure that moved out of the northwestern Caribbean and into the Gulf. After forming on the afternoon of June 23, Debby moved very slowly under the influence of weak steering currents. The storm drifted slowly northward before turning northeast on the morning of June 24. Despite its lack of wind intensification, Debby lashed Florida with heavy rain as well as tornadoes.
The Tropical Rainfall Measuring Mission (TRMM) captured this image of Debby when it passed over the storm at 11:51 Universal Time (6:51 AM Central Daylight Time) on June 24, 2012. At the time of this image, Debby was a moderate tropical storm with sustained winds reported at 60 mph by the National Hurricane Center.
The image shows a top-down view of the rain intensities within Debby. Rain rates in the center of the swath are from the TRMM Precipitation Radar (PR), while those in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) and visible data from the TRMM Visible Infrared Scanner (VIRS).
TRMM reveals that most of the rain associated with Debby was well away from the center, which is marked by a white dot. A large area of moderate rain (shown in green) north and east of the center extends from near Tampa Bay all the way around to near Panama City. A large band of intense rain (shown in darker red) lies just off shore, while light (blue areas) to moderate rain covers a broad area of the Florida peninsula. Curved red symbols mark the locations of tornado reports.
Storm speed is what matters most when it comes to rainfall; the slower the storm, the more time it has to rain over a given area. Debby dumped nearly 7 inches of rain on Gainesville, Florida on June 24, the second highest one-day total on record. Numerous other reports of 6 to 10 inches (15 and 25 centimeters) of rainfall were reported.
TRMM is a joint mission between NASA and the Japanese space agency JAXA.