Evolution of software systems is almost a natural process. Evolution can occur at different levels of abstraction of software. Evolution at the architectural level, being the highest level of solution, can often times be the most critical to the success and survival of the pertaining software system. Metrics for software architectural evolvability will help determine the extent to which the architectural evolution can take place. In this paper we propose a framework called the POMSAE, Process-Oriented Metrics for Software Architecture Evolvability, that will help not only to intuitively develop architectural evolvability metrics but also to trace the metrics back to the evolvability requirements. This will then help analyze the reasons for the strengths/weaknesses in the metrics. POMSAE is partially validated by demonstrating its application to two practical telecom systems.