Narrative:

At cruise we were cleared to alice waypoint direct vuz. We were deviating left of course for buildups and navigating around the weather using the radar. We were IMC; while deviating; and we exited the IMC conditions and discovered a rapidly building cell was directly in front of us. We turned immediately to the right to avoid this new weather threat and we were caught in a very significant downdraft and heavy rain. Since we were in the turn; the downdraft caused us to exceed 30 degrees of bank; we got to approximately 45 degrees and we lost about 400 feet-500 feet from our assigned altitude of FL350. We quickly recovered the aircraft to level flight and exited the area of weather build ups. With the severity of the downdraft; I did not disconnect the automation for fear of exacerbating the condition we found ourselves in. We did not experience any turbulence during this event.

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Original NASA ASRS Text

Title: B737 Captain reported a 45 degree bank angle and 400-500 feet loss of altitude resulted when he encountered a thunderstorm cell at FL350.

Narrative: At cruise we were cleared to ALICE waypoint direct VUZ. We were deviating left of course for buildups and navigating around the weather using the radar. We were IMC; while deviating; and we exited the IMC conditions and discovered a rapidly building cell was directly in front of us. We turned immediately to the right to avoid this new weather threat and we were caught in a very significant downdraft and heavy rain. Since we were in the turn; the downdraft caused us to exceed 30 degrees of bank; we got to approximately 45 degrees and we lost about 400 feet-500 feet from our assigned altitude of FL350. We quickly recovered the aircraft to level flight and exited the area of weather build ups. With the severity of the downdraft; I did not disconnect the automation for fear of exacerbating the condition we found ourselves in. We did not experience any turbulence during this event.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.