B737 Next Generation Undifferentiated
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Became Reoriented; Flight Crew Regained Aircraft Control
Weather
While cruising at FL370; approximately 40 miles south of SAV; we experienced a severe updraft; causing the aircraft to rapidly climb to approximately 37;300 ft and then rapidly descend to approximately 36;500 ft. There was no weather displayed on our weather radar in our area of flight. The fluctuations lasted for about one minute. The rest of the flight continued as normal.
In cruise at FL370; encountered clear air turbulence. No radar echoes; must have been convective activity building below our altitude. Updraft produced rain from below; lifted aircraft 300 ft above our cruise altitude. First Officer applied upset recovery controls which required descent 600 ft below our cruise altitude. Reported the event to Jacksonville Center. No other traffic in the area; no evasive action required. Flight continued normally without further incident.
Flight crew reported encountering severe updrafts and downdrafts resulting in deviations from their assigned altitude. The flight crew recovered from the upset condition and continued the flight without issue.