Regional Jet 900 (CRJ900)
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Inflight Event / Encounter Weather / Turbulence
General None Reported / Taken
Weather
Climbing out we were advised of light occasional moderate between FL250 and FL310 with good rides above FL310. We were advised as such just after climbing through 10;000 ft. FO (First Officer) then called cabin crew to sit down with seat belts fastened until advised further. The encounter started out as light. Around FL260 the conditions became more constant and moderate. Around this time pitch mode; continuous ignition and turbulence mode were selected. Climbing through FL270 the autopilot seemed out of sync with the needed corrections and airspeed deviations were becoming greater. Autopilot control inputs were becoming significant with yaw deviations such that the brick was almost completely out to the side. Around this time shaking became enough that it was becoming hard to read the displays. When conditions worsened I disconnected the autopilot (FL280) as the airspeed deviation was increasing to an unacceptable degree with general autopilot over actions. The autopilot was acting as if it was out of phase with the needed inputs. Climbing through FL310 conditions improved and the autopilot was re-engaged with turbulence mode on. We verified with the cabin crew that they and the PAX were ok. We also told them to remain seated until we gave them the all clear. During the encounter we told ATC that the conditions were more than moderate. I hesitated to call it severe until after the encounter and discussed the events with the FO. Once the severe determination was made ATC was notified; Dispatch notified; and the condition of the cabin verified to be ok. At no point was the aircraft ever out of control and the predominant conditions were moderate with some instances that may be called severe. Cabin was in good spirits upon deplaning the aircraft.
CRJ-900 Captain reported encountering severe clear air turbulence; and taking manual when the autopilot seemed unable to maintain control.