Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 80; Flight Crew Total 13500; Flight Crew Type 2500
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Returned To Clearance
Weather
Cruising at 40;000 feet we were in between tops of cells estimated at 41;000 feet.  Distance between cells 20 miles estimated.  Nothing of a return on radar to speak of.  Got a little light turbulence when we received a very hard; severe shot of turbulence.  The Autopilot kicked off; the plane rolled approx 35 degrees and a sudden loss of altitude of approx 500 feet to 39;500 feet.  I was the pilot flying; got control of the plane and was back at altitude in less than 30 seconds.  ATC inquired as to what was going on; we explained and were instructed to 'maintain 400'.  We did; no problem; and continued the flight.  Nothing more was said and this was a case of turbulence I have not experienced in over 15 years.
A Challenger 300 Captain reported encountering severe turbulence in cruise flight at FL400 that resulted in a 35 degree roll and a 500 foot altitude excursion.