B737-800
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Situational Awareness
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Regained Aircraft Control
Airspace Structure; Weather
At 32000 ft. just north of PUB the aircraft experienced Moderate to Severe turbulence. About 10 minutes before the incident the aircraft was in continuous light chop due to cloud tops. Seatbelt sign was on and PA was made by Pilot Monitoring and Pilot Flying reduced thrust to Mach .76. Pilot Monitoring contacted ATC for rides above; at about that time the airspeed began to show a decreasing trend and the Pilot Flying added power to adjust; airspeed continued to decrease and the Pilot Flying added even more power. At about that time the turbulence started and the right wing dropped and aircraft bank angles showed in excess of 50 degrees kicking off autopilot. Airspeed loss was an excess of 30-40 kts. whereby Pilot Flying applied max power. Barber poles came together however no overspeed or stall warning occurred. The aircraft lost at least 500 ft. during upset recovery with no excessive force to the aircraft. After recovery Pilot Monitoring requested an immediate climb due to Moderate to Severe turbulence up to 36000 ft. and was given 33000 ft. ATC gave us a frequency change and got an immediate climb to 36000 ft.; with no further incident.  During upset recovery aircraft lost at least 500 ft. This is an approximate guess by the pilots since the loss of airspeed and power at firewall along with excessive bank angles were in the primary scan. ATC gave an immediate climb clearance and crew complied. No further action was taken. Keep seat belt sign on when crossing know turbulent areas like over the Rockies; even when weather radar; and ATC aren't reporting anything. Keep the Flight Attendant's informed and always give those important PA's to passengers 'when seated to keep those seatbelts securely fastened in case we hit any unexpected turbulence'. Because it really does happen!
B737 First Officer reported unexpected moderate to severe turbulence caused a temporary loss of control.