Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Flight Deck / Cabin / Aircraft Event Illness / Injury; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Fuel Issue
Air Traffic Control Issued New Clearance; Flight Crew Diverted; General Physical Injury / Incapacitation
Weather; Human Factors
The flight was fairly uneventful for the first hour. Once we crossed into United States airspace and began talking with Center; the plan took a drastic change. ATC assigned us a reroute. I immediately started to send a message advising Dispatch of the reroute. But before I finished typing the request; ATC changed the route [again; resulting in a large deviation from planned route]. It is also notable that this was the point where I started to utilize the fuel management functions in the FMS to constantly monitor and check our progress; the remaining fuel and the fuel needed to go to [destination] and various alternates; etc. On the other hand; I wanted to keep the Dispatchers in the loop as they are usually better able to assess the weather status looking at the radar and flight path. I showed the FO (First Officer) how to use the FMS to check fuel needs to and from present position or from point to point. We were checking the fuel needs constantly for the remainder of the flight.The response I received from the Dispatcher was 'we always file ZZZ as an alternate for that flight and we cannot change it; because it's an international flight.' I called Dispatch and spoke to the Dispatcher directly. The latter refused any chance of an alternate other [those already listed] and told me to go ahead and divert to ZZZ. The proposed diversion struck me as suboptimal; but I decided in favor of it based on a 1500-lbs fuel reserve and the assumption that the Dispatcher was closely watching the flight path and radar and could see more of the weather than I could. In retrospect; I believe he was not remotely aware of the situation as he had ignored my requests for support for the previous hour. Perhaps he also was task-saturated. But he still should have realized that with every minute that ATC was pushing us northeast of [destination]; we were getting farther and farther from ZZZ as a logical alternate.After what seemed like 20 minutes of trying to get in touch with a busy Center; I asked for a diversion to ZZZ. The Controller tried to get me to continue toward [destination] but could not be sure that it would stay open. So I said 'send me to ZZZ.' I was given a direct vector; followed shortly after by a clearance to deviate as necessary. Up to that point; the flight had been in smooth air and almost entirely under VMC. Moments later we entered IMC. Shortly afterward; the Controller mentioned that we were authorized to deviate if needed. I saw on radar a few specs of red at 12 o'clock. They didn't appear to be nearly as menacing as they turned out to be. I chose deviation to the right and advised ATC.We began to experience continuous light turbulence that was quickly growing more intense. I switched to the PA and said 'flight attendants; please be seated.' Seconds later; the airplane began to buffet violently as we entered heavy rain. The autopilot disengaged and we lost about 500 feet in altitude. I assumed manual control of the aircraft and got the autopilot turned back on. As we returned to FL350; ATC asked us to verify that we were level at FL350. I reported the severe turbulence and ATC asked if everyone was OK. I called the flight attendants and was informed that FA 2 had hit her head (causing me concern of possible concussion); knee and hip.  At least one other passenger also reported being injured. The turbulence had subsided as quickly as it had begun; and the air was smooth for the remainder of the flight.We were about 35 minutes from ZZZ and ATC asked me several questions. I asked for a phone number and told ATC I would answer their questions when we were safely on the ground. ATC asked if I wanted an arrival or just direct. I opted for direct and began setting up the cockpit for the longest runway.We joined the localizer about 15 miles from the runway. At around 5 mile final on the ILS and still in IMC; we received a Fuel Low caution message that came on and off several times until finally remaining on.I informed the Tower that we had emergency fuel remaining as we were flying the last few miles of the ILS. We got the runway in sight at less than 1;000 feet. There was about 1;000 lbs of fuel left when we touched down -- not enough to do a go-around.Once we landed; we asked for progressive taxi instructions to a suitable gate. After we reached the gate; it took almost 20 more minutes until we had a ground crew to marshal us into the gate. A sizable group of paramedics and law enforcement personnel had gathered on the jet bridge. They removed the injured occupants first before the rest of the passengers were deplaned and sent to Customs. I cleared Customs and then returned to the plane to finish the maintenance write-up for severe turbulence. After completing the write-up; I ran the shutdown checklist and left the aircraft with about 500 lbs of fuel indicated on the EICAS. Two things could have prevented the severe turbulence encounter in my opinion. 1. The Dispatcher could have and should have taken my requests for information and alternative options into consideration and acted accordingly at the first indication that things were not going as filed or anticipated.2. I operated on the assumption that the Dispatcher had full access and the capacity to use better weather information than I had available on the aircraft. In hindsight; I could have exercised PIC authority and diverted to an airport closer and on the side of the weather system that I was already on. In the future; I will consider use of Captain's authority and if so; use it sooner.What went well was that I had the FO do all of the flying with the exception of assuming manual control after the turbulence hit. This allowed me manage the rest of the situation and stay focused on handling the abnormal procedures.
CRJ-900 Captain reported a Flight Attendant and passenger were injured due to severe turbulence during a weather diversion.