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Autumn NAO & AO forecast raising some eyebrows

It's interesting to see how remarkably neutral the North Atlantic Oscillation (NAO) is forecast to be as we enter the time of year when the index becomes useful again.

That would indicate that the westerly flow across the Atlantic, and the current westerliness in the weather pattern is forecast to continue throughout September and into the middle stages of October, when the index turns more negative perhaps indicating higher pressure.

Now, I'd have some questions about the pattern below as I don't think the CFS has this one nailed down fright now. What it may be showing is what our analogues are suggesting for September which is that we see a mixed month, probably starting drier and ending wetter, before improving mid to late October.


What's of more interest to me in the Arctic Oscillation (AO) forecast. This can be taken as a measure of the strength of the prevailing westerly winds circulating the Arctic. Look at how the index stays negative right to the end of the forecast at the beginning of November.

Now, that is suggesting that higher pressure remains close to, or over the Arctic. That in turn hints the jet stream could be pushed further south into the Northern Hemisphere, which therefore hints at more mixed and westerly conditions for the UK.

It's something I'm working into my story for autumn.

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