Anvil 3 : The spreading out (by strong winds) of the upper portion of the thunderstorm. It usually has a fibrous or smooth appearance. With long lasting thunderstorms, the anvil may spread 100 miles downwind
A Guide to Developing a Tornado Emergency Plan for Schools (Also includes information for Instruction of Tornado Safety) and Appendix C: General Tornado Safety, Appendix B: Glossary of Weather Terms, and Appendix C: General Tornado Safety, Tornado and Associated Severe Weather Terms, The Michigan Committee for Severe Weather Awareness), Michigan, USA 1999. http://rems.ed.gov/docs/micswa_tornado_em_plan_for _schools.pdf, (ND Emr/ Tornadoes - Amer) {938}
