Date: 201812
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: IMC
Aircraft: B757-200
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Second reporter function: First Officer; Pilot Flying
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Regained Aircraft Control; Flight Crew Took Evasive Action
Contributing factors: Weather
Primary problem: Weather

Narrative: While at cruise in IMC received turbulence report on ACARS along our route of flight. Seated passengers and FAs (Flight Attendants). In IMC; utilizing weather radar for thunderstorm cell avoidance; remained 40 miles west of line of 3 cells. Captain on 80 mile scale; FO (First Officer) on 20 mile scale. Red cell popped-up immediately ahead; FO initiated turn to avoid; encountered possible rapidly building cell underneath us. Airspeed excursions +/- 40 KIAS; autopilot tripped-off; FO allowed aircraft to descend while attempting to keep wings level and avoid high/low speed stall and remain within aircraft structural limits. As PM (Pilot Monitoring) I notified ATC of our altitude excursion due to severe weather penetration. ATC immediately cleared us to FL 370. Leveled at FL370 after regaining airspeed control. Sustained lightning strike on tail and horizontal stab. Ozone reported in cabin and flight deck. No injuries to passengers or crew as they were all strapped-in due to previous PA. Dispatch and maintenance notified. Inspection revealed lightning strike damage previously stated. Accepted altitude loss to prevent aircraft damage.


Second narrative: While in cruise flight at FL380 we were actively trying to avoid thunderstorms that were rapidly moving towards our course. I had my radar on a closer in 20 mile scale and the Captain had his further out scanning for storms. Within a very short timeframe I noticed a cell essentially ahead of us change from green to yellow; to red in rapid succession. I asked the Captain to ask ATC for a turn. That was granted and we started turning but the turn was not enough and we flew right into a rapidly building TCU/CB. The Captain had previous had the FA's (Flight Attendants) sit based on earlier ACARS turbulence reports. I did my best to stay level at FL380 but the autopilot disengaged and we rapidly but not violently descended to approximately 37;200 feet. We had rapid Airspeed fluctuations of +/- 40 KIAS. I let the airplane descend as I first brought the power to idle to prevent an overspeed. I also did not want to load the airplane up and stress it with positive G's. I recognized a descending situation with rapidly increasing Aispeed so I based my reactions on trying to stabilize the Aircraft based on what I learned.We continued to have moderate turbulence for a number of minutes and we climbed back up to FL380 and notified ATC of the altitude loss and why it happened.We smelled ozone and observed flashed and thought a lightning strike was possible.After the situation was stabilized and in conversation with Center the controller said that at the same time we had our altitude excursion he noticed extreme precipitation form in that area literally at almost the same time.Upon further examination in ZZZ a lightning strike was confirmed on the left elevator and the tail.


Synopsis: B757 flight crew and company dispatcher reported thunderstorms along the route resulted in turbulence with large airspeed/altitude variations and a lightning strike.