Hi Amanda,

Thanks for your question. I cannot speak for Tim, but I can offer my perspective. I would say that the jet stream is already at a point where it is more than a sub-seasonal feature - it is a permanent feature with all sorts of important subseasonal, seasonal, and decadal components. The two main ingredients for jet streams - rotation and uneven heating - are always present, and so we can always count on jet streams being around. However, there are all sorts of factors on these other timescales that modify the strength and position of the jet streams, and those factors are critical for our weather and climate predictions. 

So, these components of the jet stream not specifically tied to the seasonal cycle of solar insolation already exhibit chaotic variability that plagues our weather and climate forecasts. Whether jet stream variability becomes more or less predictable is an interesting question.