Tornadoes can be classified into the following distinct formation groups:
Type I – in association with supercells;
Type II – in association with quasi-linear convective systems; and
Type III – localized convective and shear vortices. These comprise: Landspouts, Waterspouts and Cold-air funnels.
The text enclosed in grey-shaded boxes, like this example, comprises Annex I to the Technical Regulations (WMO-No. 49) and has the legal status of standard practices and procedures.