Air France Flt 358 vs. thunderstorms

I've read several reports online re the Air France crash at Toronto
that there were thunderstorms in the vicinity (one account said "right
over the airport") If so I'm curious why the captain didn't divert or
hold away from the storm until it passed (fuel status?). If there was a
storm nearby that could have caused massive wind shear and been the
reason for the jet going off the runway(?) It'll probably take
Transport Canada a while to investigate, but I wonder what consequences
this may have for the crew.