A321
Flight Crew Air Transport Pilot (ATP)
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Returned To Clearance
Weather
We were at FL350 and 20-25 miles east of Tulsa. We had been mostly smooth but with some mountain wave activity. All of a sudden; we experienced severe turbulence that disconnected the auto pilot and increased our altitude by 500 feet. The flight envelope went from approximately 35 Kts spread to less than 10-15 Kts. Aircraft oversped by 10-15 Kts for a duration of 3-5 seconds; the aircraft attitude was controllable but not the altitude. We reported the encounter to ATC and told them about our altitude excursion. ATC thanked us for the report and asked us to descend back to FL350 when possible. After this episode; there was some intermittent moderate turbulence and were still getting mountain wave. We decided to descend to FL330 and the situation improved. Seconds after regaining aircraft control; I communicated with the purser and asked if there were any injuries to the crew or passengers. She said that there wasn't any because everyone was seated at the time. Prior to the event; I had made several announcements to the passengers stressing the importance of staying seated with seatbelts fastened. I was asked to do this by the purser also because the passengers were not abiding by it. Luckily; after my last announcement; they were all seated at the time of the turbulence encounter.I communicated with our dispatcher and after several ACARs messages back and forth; and consulting with my manuals; I determined that the encounter with the turbulence would be considered 'severe'. I made the appropriate entry in the aircraft maintenance log. Appears that it was caused by a frontal boundary. Either categorizable as wind shear or Clear Air Turbulence.
A321 Captain reported encountering severe turbulence in the vicinity of TUL VOR at FL350.