[1] Recognition and detection issues will be treated elsewhere in this volume, by Burgess et al. (1993).

[2] It is noteworthy that the composite chart, as employed in severe weather forecasting, specifically attempts to establish the interaction between features aloft and at the surface. Thus, it is a product with a long history of addressing what Mass (1991) considers a common deficiency in synoptic analysis; namely, the failure to depict 3-dimensional relationships among features at different levels.

[3] Some of the research results have had an impact in some operational detection and warning programs, although even there, progress has been slow.

[4] For official purposes, a severe thunderstorm is defined as one which produces one or more of the following: hail > 3/4 in (2 cm) in diameter, measured winds > 50 kt (25 m s-1), "damaging" winds (involving some subjective judgment of effects required to meet the threshold), a tornado. Heavy rain, large quantities of sub-threshold hail, funnel clouds, frequent lightning, etc. are not considered to meet the official criteria (see discussion in Doswell 1985).

[5] As noted in Doswell and Burgess (1993), some atmospheric vortices are not associated with deep, moist convection. These are not considered to be tornadoes.

[6] Note that a situation we label as synoptically "evident" should not be automatically equated with an "easy" forecast. No real-world forecast situation is ever easy, except in retrospect!

[7] Since the grid is defined on a polar stereographic map projection, the grid boxes vary in size across the map by as much as about 10%. The nominal size applies only at 60 deg N latitude, where the map scale factor is unity.

[8] As is the case in accounting for currency inflation, this does not imply that there is anything special about 1955. It simply represents a base, or reference state. We could just as easily have adjusted toward a 1989 standard, with no material difference in our conclusions.