The answer comes from one of our Dallas contractors during a recent coating installation on the roof of a major department store.
The roof substrate was modified bitumen. The coating was NovaTuff RC-100 with full fabric embedded.
The installer stood on the roof during the application of the first coat and fabric and took the following photos. The two temperature readings were about 5 feet apart within a minute of each other. The differential in this situation was over 60 degrees F.