To the airline pilots around here (A4s in particular), what do you do if you have rapid decompression while over top a huge, severe thunderstorm cell? Seems like you'd have no choice but to take your chances in the storm. How long is the crew's O2 supply good for? Passengers only have about 10 minutes, if I remember correctly (though I think that was an FAA-mandated figure, don't know what the French regs are).
IIRC the Checlist, it's O2 masks on; crew comm establish; seat belt sign on; announce to cabin, "emergency descent" etc.
The crew immediately dons the masks. In the smaller Airbus, minimum O2 pressure is enough for both crew-members for "two hours at 10,000 ft."
Normally, if a thunderstorm is severe, it usually tops above cruise altitude, so you wouldn't normally find yourself "above one." You would have given it a wide berth. And if accidently in one, with or without radar, a 180 would be logical for the decompression descent.
BWTFDIK That's what black boxes and experts are for.