A B757 encountered a microburst on approach. During the escape maneuver; severe turbulence and a 30 kt airspeed drop were experienced. During the recovery a flap speed exceedance occurred as the aircraft exited the weather.

Narrative

I was pilot flying. Was aware of weather both at the time of departure; and during entire phase of flight. Had a departure maintenance delay due to inoperative CTR fuel pump. Took an hour to fix. Got routine updates in flight from Dispatcher who did an outstanding job of keeping us informed; both of the weather and PIREP of other aircraft who landed ahead of us. Had to do some minor deviations for weather on arrival. Nothing more than light to moderate precipitation on weather radar. Descended to 2900 FT MSL; per approach plate to pick up glideslope. At FAF inbound; Approach Controller advised of windshear alert. Captain and I discussed situation; light to moderate turbulence and precipitation on approach. Decided to continue approach; but reviewed windshear escape procedures as well as a departure plan due to rising terrain at departure end of runway at approximately 2500 FT MSL on glideslope with autopilot and autothrottle engaged; aircraft began to bank 25 degrees to left. Captain asked if I was doing that at the same time I disengaged autopilot. He; Captain said; 'Let's get outta here' I performed the normal go around procedure and called for flaps 20; gear up set and armed Missed Approach Altitude. At that point; we encountered the worst windshear and severe turbulence I've ever seen in my flying career since I started flying at age 13. Hard time focusing on instruments; airspeed decaying 30-40 KTS in a matter of seconds; both Captain and I pushing on yoke trying to build airspeed. When we flew through the tailwind portion of microburst and into the headwind portion; the airspeed began to build rapidly. We began with a normal go around; but turned into a windshear microburst procedure. Flaps were left at 15 degrees; and airspeed increase to 250+ KTS. We exceeded the flap limitations during a Microburst/Go Around/Severe Turbulence Escape procedure. At approximately; 1500 FT MSL; aircraft flew past microburst; we cleaned up the aircraft; and aircraft began to accelerate normally. ATC asked our intentions. I told the Captain in no way did I want to return to the severe weather. He absolutely agreed and decided on our published alternate. I felt it was a great idea. Approach and landing at our alternate was uneventful. Advised Dispatch in flight after incident that we were diverting to our departure airport. Upon landing; called Maintenance for flap limitations exceeded during windshear/severe turbulence go around.