Hi Mohammad,

That is an excellent question that I just don't have a great answer for. Strength forecasts this far in advance are difficult. And given just how rare it is for a third consecutive winter to have a La Nina, we just don't have a lot of historical context to go back on. 
Once we get through the spring predictability barrier and into the northern hemisphere summer, I imagine we'll start feeling more confident to start discussing strength levels if the forecast continues to favor a la nina during the upcoming winter.