Tropical depression Three was showing much better organization with more heavy rainfall when the TRMM satellite saw it again on 7 July 2011 at 1636 UTC. Data from TRMM's Microwave Imager (TMI) showed that heavy rainfall was present in a large area over the center of the intensifying depression and in a feeder band to the west of the center. There were also a few showers shown along the Mexican coast to the northwest of the storm.

The TRMM satellite passed over an area of low pressure in the eastern Pacific Ocean south of Mexico on 7 July 2011 at 0234 UTC. The National Hurricane Center (NHC) in Miami, Florida upgraded this area of low pressure to a tropical depression at 1500 UTC ( 08:00 AM PDT) making it the third tropical depression in the eastern Pacific this hurricane season. Conditions are expected to be favorable for the depression to become a tropical storm within the next couple days. The rainfall analysis from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data was overlaid on an infrared image from

Arlene formed into a tropical storm on the evening of 28 June 2011 in the Bay of Campeche in the southwestern Gulf of Mexico from an area of low pressure that had formed the day before just west of the Yucatan Peninsula. Arlene did not have time to fully develop and came ashore as a strong tropical storm two days later on the morning of 30 June near Cabo Rojo along Mexico's east coast with sustained winds reported at 65 mph. Although wind damage from the storm was relatively minor, Arlene brings the threat of heavy rains and flash flooding to the region as it continues to move inland. The

The National Hurricane Center (NHC) named Tropical Storm Arlene the first tropical storm of the 2011 Atlantic hurricane season on 29 June 2011 at 0000 UTC (7 PM CDT). The TRMM satellite had a good look at Arlene when it passed above on 29 June 2011 at 0502 UTC (0:02 AM CDT). At that time Arlene's winds were estimated to be about 34 knots (~39 mph) indicating that it was barely a tropical storm. TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data were used in the analysis on the upper left and show that Arlene was getting better organized and contained scattered heavy thunderstorms