The National Hurricane Center (NHC) announced the formation of tropical storm Emily on 1 August 2011 at 2330 UTC (7:30 PM AST). The TRMM satellite flew over the storm a short time later on 2 August 2011 at 0137 UTC (9:37 PM AST). A rainfall analysis from TRMM's Microwave (TMI) and Precipitation Radar (PR) data is shown above. This analysis shows that relatively little rainfall was occurring near the storm's approximate center that is indicated by a red tropical storm symbol. Moderate rainfall was revealed in a large feeder band on the eastern side of the storm. Emily is predicted to move

The TRMM satellite showed that tropical storm Eugene was very well organized with heavy thunderstorms located south of a forming eyewall on 1 August 2011 at 1350 UTC. Eugene is expected to move to the northwest and stay off the Mexican coast as have all eastern Pacific tropical cyclones except Beatriz so far this year.

MUIFA was a super typhoon with wind speeds of 140 kts (~161 mph) on 30 August but wind speeds had dropped to about 110 kts (~127 mph) when it was seen by the TRMM satellite on 1 August 2011 at 1320 UTC. This TRMM orbit revealed that MUIFA had a double eyewall indicating that the typhoon was undergoing eyewall replacement with a larger eyewall shown forming farther out from a smaller inner eyewall. Muifa is expected to still be a powerful typhoon on 4 August 2011 as it passes directly over the Japanese island of Okinawa.

On 1 August 2011 at 0056 UTC the TRMM satellite traveled above an area of low pressure east of the Lesser Antilles that the National Hurricane Center (NHC) has assigned a high probability (90%) of becoming an Atlantic tropical cyclone within the next few days. TRMM's Precipitation Radar (PR) saw a few tall convective thunderstorm towers within this area (see below image).

The TRMM satellite again viewed tropical storm DON on 29 July 2011 at 1322 UTC (7:22 AM CDT). A rainfall analysis from TRMM's Microwave Imager (TMI) was overlaid on a sunlit combination visible/infrared image from TRMM's Visible and Infrared Scanner (VIRS) instrument. Below is an animation that fades between the sunlit visible/infrared image and the PR/TMI rainfall analysis.