Regional Jet 900 (CRJ900)
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Returned To Clearance; Flight Crew Regained Aircraft Control
Human Factors; Weather
We were at FL350 in cruise between ZZZ and ZZZ1. ATC had given us left and right deviations and ZZZ1 when able. The radar was not painting much at the time but we were trying to deviate around what we saw on the radar. At the time everything was obscured and we were in the clouds. We did pop out just a little before the front and could make our way around a couple of the darker areas but it was not possible to get around all of it. As we crossed the front we started to get some shear in the winds that caused the airspeed to start to go up and down quite a bit. The autopilot then kicked off so my FO (First Officer) took manual control and the airspeed and altitude varied a lot as he flew the aircraft. The turbulence only got to a moderate level at most of the time but the downdrafts and updrafts made it difficult to keep any specific altitude or airspeed. Soon we hit a downdraft that was much worse than the rest and we were unable to maintain altitude even in climb power. I took control of the aircraft and told him to tell ATC we were descending because we were unable to maintain altitude at the time. We ended up descending about 1;000 feet and were able to level off at FL340 once we were through it. At the time I was just worried about keeping airspeed and not stalling the aircraft. Once we were clear ATC cleared us down to FL330 and we continued on to ZZZ2. At the time of the initial shear we were talking and did not detect the variations in airspeed that were the telling signs of the shear coming. At the time I did not declare an emergency but looking back at it I would now because we were unable to maintain altitude at the time.
While enroute we were navigating around some weather that was obscured. We were communicating with ATC about the best route to take around the weather. We were not painting much if any precipitation at all angles on the radar. We were on left and right deviations and ZZZ when able. Just after passing the ZZZ1 VOR at FL350. We started to experience some light turbulence which continued to worsen. I turned on continuous ignition and continued to maneuver around the weather the best we could. The VSI (Vertical Speed Indicator) started a small trend of 120 FPM down. Our altitude quickly started to dip 300-400 feet as we encountered an unexpected large downdraft that kicked the autopilot off. The VSI showed 2;000 FPM descent. I continued to hand fly the aircraft but we were unable to maintain airspeed and altitude and began a descent down to FL340. We advised ATC that we were unable to maintain altitude because of the downdraft and that we would be leveling at FL340. ATC then gave us a descent to FL330. We continued down to FL 330 and leveled there. We exited the obscured weather and continued to ZZZ2. Limited visual and pictorial view of the weather as we deviated around it. Access to current weather information through the iPad such as tops reports.
CRJ-900 flight crew reported windshear in cruise resulting in a momentary loss of aircraft control and excursion from assigned altitude.