The 2008 Atlantic hurricane season has become a lot more active recently, first with the formation of Tropical Storm Cristobal off of the Carolina coast and now with Tropical Storm Dolly in the Gulf of Mexico poised to strike near the border between Texas and Mexico. Dolly, which became a tropical storm in the western Caribbean on the morning (local time) of 20 July 2008, originated from an African easterly wave that had emerged off of the coast of Africa back on the 12th of July before propagating westward across the tropical Atlantic and into the Caribbean. After forming in the western Caribbean, Tropical Storm Dolly maintained a generally west-northwestward track, which took the center across the very northern tip of the Yucatan Peninsula early on the morning (local time) of July 21st. Despite passing over land and being somewhat disorganized, Dolly maintained moderate tropical storm intensity with sustained winds estimated at 45 knots (52 mph) by the National Hurricane Center (NHC). Dolly re-emerged over the warm open waters of the western Gulf of Mexico later on the morning of the 21st. Combined with low atmospheric wind shear, conditions were favorable for intensification. The only real inhibiting factor was the sprawling nature of the storm itself. Without a well-organized core, storms take longer to respond to favorable conditions. None-the-less, Dolly began to slowly strengthen as is took aim at the Texas-Mexico border.

The Tropical Rainfall Measuring Mission satellite (also known as TRMM) has been in service for over 10 years now and continues to provide valuable images and information on tropical cyclones around the Tropics using a combination of passive microwave and active radar sensors, including the first precipitation radar in space. These unique images were captured by TRMM at 12:44 UTC (7:44 am CDT) 22 July 2008 while Dolly was in the western Gulf of Mexico. The first image shows the horizontal pattern of rain intensity within the storm. Rain rates in the center swath are based on the TRMM Precipitation Radar (PR), and those in the outer swath on the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM reveals that Dolly has a rather large wavy eye with most of the moderate to heavy rain (green and red areas, respectively) wrapping around the southern side of the storm.

The second image was collected at the same time and shows a 3D perspective of the storm via the TRMM PR. The eye is clearly visible by the deep center (in blue), which is completely surrounded by a ring of moderately high precipitation areas (green). A few somewhat taller towers are visible in red within the eastern eyewall. At the time of these images, Dolly was a moderate tropical storm with maximum sustained winds reported at 55 knots (63 mph) by NHC. Dolly is expected to continue off to the west-northwest and make landfall in the vicinity of Brownsville, TX as a minimal hurricane before turning more westward over central northern Mexico.

TRMM is a joint mission between NASA and the Japanese space agency JAXA.