Ok FE Hoppy, maybe the changes in OAT are a bit too much and it's OAT that I'm talking about, remember the lines on the altitude capability paper charts? ISA + 20, ISA + 15, etc??, ... Well they do influence your envelope, and a change in temperature when you are pushing your aircraft to secure a flight level or whatever other reason can have an impact on your performance, the point I'm trying to make if this change becomes large enough along with even moderate turbulence it will get you in some very tight situations.
Weather in that part of the world can be very violent and nasty, perhaps the worst next to the north american midwest. Now large changes in temperature did ocurr and happened to the B747 flight, and the satellite picture picture was similar showing a very active ITCZ.