Hail/No Hail Nomogram
This figure plots the occurrence of hail versus no hail for 70 thunderstorm cases in the Midwest U.S. The horizontal position of each point shows the height of the freezing level. Hail is more likely to occur if the freezing level is relatively low. Thus, a position further to the right favors hail.
The vertical position of each point shows the cloud depth ratio, which is the ratio of the depth of the cloud above freezing to the depth of the cloud below freezing. A deep cloud layer that is below freezing will maximize the potential for hail formation and growth. Thus, a lower position favors hail.
Overall, positions in the lower-right corner indicate hail is likely, while positions in the upper-left indicate hail is unlikely.
The method outlined above considers the CCL (cloud base), the freezing level, and the equilibrium level (cloud top).
Procedure: