A synoptic meteorologist is a person who can diagnose a weather pattern on the basis of known principles. He or she then can extrapolate the evolution of the weather pattern based upon known principles and intuition. The term "known principles" includes forecast models based upon the solution of the primitive equations, as discussed in ERTH 260 (Metr 201).
A weather technician can interpret weather patterns that appear on conventional charts, often times on the basis of "rules of thumb". However, unless a meteorologist provides value added to those charts or the weather technician obtains that training, the technician will be unable to distinguish patterns that are conceivable from those that are not.