A321
Flight Crew Air Transport Pilot (ATP)
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Returned To Clearance
Weather
During our preflight crew briefing; I had advised the crew of the expected turbulence on the flight plan; the maximum listed was a '1.' We were west of GLD and had started deviating for weather. I had instructed the cabin crew to go to moderate turbulence procedures. The ATC report from aircraft ahead of us was for continuous light occasional moderate turbulence. We had nothing other than green displayed on the radar in the immediate vicinity of the aircraft. We were more than halfway through the area of weather when the green area on the radar began to expand. The other colored areas remained the same size. We were in a left turn to take us further away from the storm area abeam GLD; when without warning; we hit an area of heavy moderate almost severe turbulence. The autopilot disengaged and the aircraft was push upward about 900 FT. The VNE and VLE bars closed in on each other. We attempted to keep the aircraft in a level pitch attitude. The First Officer notified ATC we were unable to maintain altitude due to turbulence. The turbulence lasted for about twenty (20) seconds. At the end of the turbulence we gently descended back to FL330. We called the cabin to check on possible injuries. The A Flight Attendant stated that one of the other crewmembers had spilt coffee but there were no injuries known at the time. I had the crew remain seated. When I was confident that we were clear of the turbulence area I had the cabin crew get up and check on the passengers. The A Flight Attendant reported no injuries. No other aircraft before or after us reported turbulence of this nature.
A321 Captain describes an encounter with unexpected moderate to severe turbulence at FL330 causing the aircraft to climb 900 FT before returning to assigned altitude.