General aviation pilot reported inadvertently entering a thunderstorm while in contact with ATC and experienced severe turbulence and precipitation. The pilot turned the aircraft around and exited the adverse weather. There were no injuries or aircraft damage.

Narrative

While flying from ZZZ to TYS; Jax Center rerouted me to NRAVN Intersection then to CABLO to navigate through a line of thunderstorms. This was the suggested route by one of the Jax Center controllers. Other aircraft that were higher than us were making it through; despite another hole we were trying to go through that closed up North of TERES Intersection. We were at FL280 and once entering IMC we encountered an updraft the climbed us to 28;125 MSL then instantly a downdraft descended us to 26;975 MSL over the course of approximately one minute. Once I encountered the updraft and downdraft we also encountered severe turbulence and I immediately made a 180 turn Southbound to heading 180 while trying to maintain altitude at the time of FL270. The controller at Jax Center was extremely busy and controlling the airplane was my number one priority. Once established on a 180 heading and having leveled out at FL270; I was waiting for an opportunity to key the mic and let the controller know what I encountered. However; before I could do that the controller asked me what I was doing and what I had encountered. I explained to him that I had just experienced an updraft; downdraft; severe turbulence; and severe precipitation and needed to get out of the situation. He told me to fly heading 180; and gave me a block altitude from FL270 to FL280 upon my request. I climbed back up to FL280 on a 180 heading and quickly exited the IMC. Once stable again in VMC conditions; the controller asked if we had any aircraft damage or injuries which I responded 'negative' to both. He then asked our intentions and I said I would like to fly heading 270 and make a North turn over Pensacola; FL to then head NE to East of Montgomery; AL and then a turn to the North to Knoxville. He granted this permission and did a great job assisting us. The rest of the flight was uneventful. But I wanted to report this given the bust in altitude and heading due to severe turbulence and precipitation. Given the weather briefing I received I expected the thunderstorms to start dissipating upon my arrival to the Panhandle of Florida but instead they intensified. To prevent the problem next time I will be much more cautious of flying in the vicinity of thunderstorms and definitively find a better course than in the vicinity of thunderstorms despite other aircraft ahead of me making it through.