Fawbush-Miller Method for Determining Maximum Hail Size
Having now determined that hail is likely to be observed in thunderstorms later in the day, we now proceed to try and estimate the maximum hail size. There are several empirically derived, hail-size forecast algorithms; we will focus on one here. The Fawbush-Miller method (Miller 1972) is a tried and true method that has been used by Air Force forecasters since the 1950s.
Procedure:In this procedure, the temperature difference A-B serves as a substitute for lower cloud buoyancy and hence, vertical velocity. The difference C-B serves as a substitute for cloud depth below the -5°C level.
The second nomogram provides a modification to the maximum hail size forecast to account for higher wet-bulb zero levels that are typically observed with summertime thunderstorms over the southeast U.S.