Regarding the steep climb of the aircraft prior to the accident, I can imagine a couple of causes and keep in mind these are not mutually exclusive.
1. What is the barometric pressure variance at a fixed altitude above sea level in this sort of storm? A drop in air pressure (perhaps by an updraft) might artificially increase the apparent climb. Has this been factored in?
2. Strong convection-induced issues?
3. Erroneous instruments?
4. Software bugs (thinking of the MH124 b777 uncommanded climb).
I strongly suspect the fdr will be needed to resolve these questions.