When was the last time an airliner at cruise was brought down by a thunderstorm?
2006 was the last one I remember. It was an TU-154M, on route to St. Petersburg, and cruising at 35,000 feet. The pilot diverted from his direct flight path by 20 miles to avoid a thundercell, but inadvertantly flew into a more violent storm, and the aircraft stalled and was lost. The nose rose to about 45 degrees, and IAS dropped to zero at the point of the stall.
Pulkovo Aviation Enterprise Flight 612 - Wikipedia, the free encyclopedia
Radar attenuation was identified as a contributing cause.