The local weather station reported fair weather (few cloud), 20km visibility, calm winds
Looking at a couple of those photos, the background away from the crash scene appears foggy, so I suspect 20km is incorrect.
A middle-age man who survived the crash told China Central Television there was bad turbulence as the plane descended, then several big jolts that caused the luggage to come crashing from the overhead bins.
Environmental turbulence would be very unlikely considering the foggy conditions.