Hi Craig,

This, it turns out, is a very complicated question. I did a quick survey of some of the published literature on the relationship between ARs and the PNA, and the results are somewhat conflicting. Some say a negative PNA is related to more ARs, others that a positive PNA is. Another suggested that the PNA provides a lower-frequency modulation of the MOJ influence. Also, the strength, frequency, and location of ARs vary a lot. So my response would be that this is still a very active area of study! However, most of the studies concluded that, between ENSO, MJO, PNA, etc., there are a lot of complex interactions governing AR characteristics.