Cloud-free line of sight

From Glossary of Meteorology

cloud-free line of sight

(Abbreviated CFLOS.) Line of sight that is unhampered by the clouds present.

This is a military term and the data are used for determining the utility of various communications, surveillance, and weapons systems. Data express the probability that the line of sight will be unobstructed by clouds for geographic areas and climatic regions.
Compare clear line of sight.