Medium Large Transport
Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 2500
Deviation - Altitude Excursion From Assigned Altitude; Flight Deck / Cabin / Aircraft Event Illness / Injury; Inflight Event / Encounter Weather / Turbulence
Weather
We departed DCA just after some thunderstorms had passed through the area. After around 20 minutes we leveled off at our cruising ALT of 320. The Captain (CA) was the pilot flying and I was the pilot monitoring. Around 5 minutes after we leveled off we encountered severe turbulence. At the time we were in an overcast layer with weather radar on. I was not showing any Weather (WX) on my MFD but ATC alerted us of weather 12 miles ahead; I remember the CA immediately scaling down his radar to a closer range and we saw what ATC was talking about and I immediately told ATC we would be deviating left to avoid the WX and they approved. In the turn I believe we just clipped the edge of the cell and encountered what we described as severe turbulence for about 10-15 seconds until we cleared the WX. Either the auto pilot shut off on its own or the CA took control of the airplane during this event but regardless I believe we got off on our altitude about 300 feet maybe more while flying through the turbulence even though ATC never questioned us about it. After exiting the turbulence we made sure to check and see if we had anyone injured. Lucky no passengers were injured. Unfortunately one of our Flight Attendants (FA) hurt his knee but said that we could continue with no issue to him and he could perform his duties; so we continued on to with no further incident and we had medical personnel meet the FA at the gate per his request to be checked out.If I would have had my Radar tilt down more at a smaller range I might have seen the precipitation and deviated a little earlier from the WX. Or if ATC had alerted us sooner of the WX we could have avoided it.
Air Carrier First Officer reported severe turbulence at FL320 after level off west of DCA.