Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 87
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Returned To Clearance
Weather
Level at FL390 numerous reports of turbulence enroute. Thunderstorms cells developed everywhere enroute; we were above them. Captain was flying. We were in continuous light/occasional moderate when out of the blue we hit severe turbulence. The aircraft started climbing and then descending 400-500 ft. Airspeed started jumping 20 to 40 knots. We hit the overspeed pole and [then] went to low speed. Captain pushed throttles to max thrust and held pitch down to regain airspeed. We lost 800 ft; then leveled at FL382. We reported to ATC and he replied no conflict issue.This incident was weather related; we did everything we could. Also; a good thing was we held the nose down to regain the airspeed that was lost. Also communicated with ATC so he was aware.
B737 First Officer reported encountering severe turbulence at FL390 that resulted in 20-40 knot speed deviations and a loss of 800 ft of altitude.