Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Weather / Turbulence
General None Reported / Taken
Weather
160 nm east of waypoint DUSAC over the Eastern Pacific we experienced a quick moment of severe turbulence which caused the aircraft to bank as much as 45 deg. Altitude FL370. Mach .80. Wind 260 @ 110. VMC on top. Layer 4;000 feet or more below us. LNAV/VNAV on. Autopilot on. Seat belt sign on due to continuous light chop.Aircraft slowly began to roll (similar to a mountain wave event) which got our attention. Seconds later aircraft began to bank right excessively and rapidly. Autopilot and Autothrottle were disengaged and a recovery to straight and level flight was achieved. Recovery was smooth and forceful but not abrupt. Bank angle may have reached as much as 45 deg right. Airspeed remained within limits. Descent was arrested manually before -300 feet. No significant sink rate. Engine instruments normal. No ECIAS or STATUS messages.After autopilot reengaged and flight seemed normal; FO called FAs to make sure both they and pax were okay. No reported injuries. A few minutes later I made a passenger announcement. No one seemed to care. It just felt like turbulence to them. There were two aircraft below us at 360 and 350 about 10-20 miles ahead. There was another aircraft (likely a 737-800) 2;000 feet above us but far enough ahead to be out of TCAS range. In my professional opinion (25+ years) this was not a wake turbulence event. A blind announcement was made on guard. As air was again relatively smooth; returned to Mach .80 speed and continued flight with no further incidences. Normal landing in HNL. No apparent damage on walk-around.I think this was a case of wrong place at wrong time. According to WX charts; we were likely in the vicinity of the crossing of a 120 kt. jet stream at both FL340 and FL410.
B757 Captain reported experiencing an uncommanded 45 degree bank angle at FL370 that the reporter felt was related to jet stream activity.