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.