B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Situational Awareness
Deviation - Speed All Types; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Weather / Turbulence
Flight Crew Diverted
Human Factors; Weather
Upon arrival on the SID; weather around the airport began to rapidly deteriorate. Thunderstorms quickly developed in all quadrants during final phase of the arrival. Multiple deviations and vectoring from Approach eventually put us on a direct course just outside the FAF for The RNAV/GPS Runway XX. The LNAV transition was a 90 degree intercept to the final approach course. Aircraft was in IMC; moderate rain and light to moderate turbulence; level at 2;000 feet AGL and fully configured with flaps 30 degrees.During our flight to the fix we watched a storm develop over the field and start to rapidly intensify. Just prior to our turn to final we noticed via TCAS that the preceding aircraft started a go-around. We queried Approach about the preceding aircraft and were told he went around. At that point we advised Center that we were unable to turn onto approach assuming some kind of wind shear encounter by the preceding aircraft. As the intensity of the effects of the storm intensified I elected to go-around; straight ahead. I directed flaps 15; gear up; and then pushed TOGA (Takeoff Go-Around). As the power came up; [the] aircraft started to accelerate and we encountered a flaps 15 over speed by 5 to 10 kts. FO (First Officer) immediately continued flap retraction to 5 degrees and I started a climb to slow the acceleration as the flaps continued up. As we climbed through 2;300 feet; Approach directed us to descend back to 2;000 feet and turn immediately to the southeast away from the weather and the airport. After aircraft was cleaned up and level at 2;000 feet; we advised Approach we were going to divert due to weather and the ability to have Maintenance inspect the flaps.Experience has shown me that the most awkward and difficult go-arounds are from level flight when not on any published missed approach procedure. The feeling of the need to press the TOGA switches is a hard habit to break especially in the midst of other distractions such as extreme weather and thunderstorms in close proximity to the ground. If I had merely called for flaps 15 gear up and then used the MCP (Mode Control Panel) to slowly increase the airspeed and clean the aircraft up; the altitude deviation and flap over speed could have both been avoided. Consider adding some training on this type of go around to get some muscle memory on this type of procedure. We always train missed approaches while descending on the final approach course at minimums and following the published procedure.
B737-800 pilot flying reported over speeding during go-around due to weather.