The tornado effect occurs due to an incorrect turntable alignment.
Often the cause of this is the surface on which the scanner and turntable are placed, as it might be too dark or highly reflective (a difficult surface to scan). If this is the case the initial sweep will not work correctly and will place the laser at an incorrect angle.
A quick fix is to place a sheet of white paper underneath the turntable, covering the area between the scanner and turntable - please watch the video below.
Secondly be careful to not accidentally push the scanner when you tap the scan button on the screen, this will move the scanner out of alignment.
Note: At the time of writing, the models created do not export as one complete stitched model but as individually aligned scans.