Sense and Nonsense in Radar QPE

Over a number of years a terminology and a number of concepts that were used originally as a first step in formulating a problem became broadly accepted and acquired an established status not compatible with their lack of precision. One such concept is “stratiform” precipitation as opposed to “convective” precipitation. The characteristics of precipitation from these two ill-defined categories are supposed to be well differentiated and it is broadly believed that distinct Z-R relationships for the two will lead to an improvement in radar QPE. However, microphysics in stratiform precipitation falling from an anvil of a convective cell and in stratiform precipitation resulting from a large scale uplifting should be expected to be quite different. The two do not deserve to go under the same name of “stratiform” unless we do not pretend to give a quantifying meaning to the term. Some examples, given in Figures 1a, 1b, and 1c illustrate this.