That goes back to what I mentioned yesterday-pattern recognition. There are times when that happens, meaning a 10-14 day stretch of overall mild weather followed by a stretch of 10-14 days of cool/cold weather. And there can be patterns withing a pattern. For example it is stormy when it is mild but not stormy when it is cool/cold...and vice versa.
Ask chess players about pattern recognition in chess and they will tell you that it is vitally important to being a good chess player. Understanding patterns helps to "unlock" chess positions. The same applies in weather but far too many fallback on the models rather than being able to recognize patterns.