Abstract
Surface parameters at the location of over 5000 tornadoes from January 1968 through 15 June 1974 were computed objectively at the National Severe Storms Forecast Center. This set of conditions 0–3 h prior to tornado occurrence provides a large sample and was used to determine a variety of tornado related averages. The mean conditions associated with tornadoes include: temperature 74°F, dew point 62°F, sea level pressure 1007 mb, and wind 175° at 7 kt. Significant seasonal and geographical variations from these averages were noted and illustrated.
