mistrals are a product of low pressure moving into the bay of biscay.
untill about the end of the month atlantic weather
remains quite stable and predictable,making the prediction of mistrals fairly accurate.
however after about the 15 nov with the onset of winter the weather at that lattitude speeds up with fast moving low pressure systems and associated trough's reaching further south making accurate prediction more difficult in the gulf de lion.
high cirrus will indicate a change within 12-24 hours, generally clear weather with mares tails indicate an impending mistral within 2-5 hours