Air carrier flight crew reported encountering turbulence and updrafts which resulted in a high bank angle with altitude deviation.
Synopsis
Air carrier flight crew reported encountering turbulence and updrafts which resulted in a high bank angle with altitude deviation.
Narrative
We had deviated around the southern end of a line of thunderstorms then made the turn in the general direction of Chicago. We were then paralleling the storm by about 40 miles. It was a bit of a choppy ride so we requested a right deviation to get some more distance between us and the line of storms in hopes of a better ride. We were about 60 miles east of the line now and encountered what I would classify as moderate turbulence with a very strong updraft to it. Vertical speed increased to over 2000 FPM and aircraft banked 20-25 degrees right and the autopilot disconnected. Captain was Pilot Flying and took controls and leveled the wings and stopped it from climbing. I notified ATC as we were about 500 ft. above our assigned altitude at this point. ATC informed us we had traffic at FL340 below and kept querying us to see if we were out of it yet. I informed him we were still in it. Captain was maintaining the attitude while we were riding out the drafts. Lasted about 45 seconds to a minute and then ride improved. We were +500 -0 on our assigned altitude throughout the event.
Second reporter narrative
At FL350 on a radar vector; we experienced altitude deviation from frontal boundary passage. Aircraft rolled 15 to 20 degrees autopilot kicked off. While recovering aircraft; we climbed to 35;500 ft. and advised ATC asked for a farther right vector. This event lasted approximately two minutes. Advised our Dispatcher after.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.