A319
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 34; Flight Crew Type 3531
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Regained Aircraft Control; Flight Crew Requested ATC Assistance / Clarification
Weather
During a smooth ride at cruise altitude of FL360; we experienced an increase of performance of +10 kts due to mountain wave.  Upon reaching up for the MCP to reduce selected speed; the turbulence and severe wave hit; causing a nearly instant and simultaneous loss of 500 feet; 30 degree rolls in either direction; and loss of 30 knots. This seemingly lasted 10-20 seconds and was accompanied by jostling bumps that made us light in our seats and shook the cabin.  I disconnected the autopilot and attempted to regain control of the aircraft as the Captain coordinated a lower altitude with ATC as well as monitored my performance and communicated with flight attendants.  The turbulence turned to smooth air at about FL350 in the descent.
A319 First Officer reported encountering severe turbulence and mountain wave at FL360 that resulted in loss of control; including loss of 500 feet in altitude and rolls of 30 degrees in both directions.