AO/NAO could be heading to deepest November level since 2010, Arriving 5 weeks earlier than thought

Written by on November 17, 2018 in Rest of Europe, United Kingdom & Ireland with 0 Comments

There’s no getting away from this. I didn’t see it coming this early. We’re potentially looking at the deepest negative AO/NAO for November since 2010 and this is rather ominous for so early.

Low solar could be triggering this early blocking and could be an indicator of the level of winter ahead. A 2009-10 repeat is on the table but I still have my hesitations on the detail. Length of cold spells and timing.

I never doubted that this type of blocking wouldn’t occur this winter but nowhere near as early. In fact I was expecting this around Christmas or indeed after the New Year.

A wet mid and late autumn can suggest cold later. We saw this during the previous solar min and certainly this front end cold pattern certainly doesn’t appear to be driven by the ‘polar vortex’ or strat warming but in low solar years, weakened, displaced or even collapsed PV’s are more likely which makes me think if we get the kind of blocking the models are suggesting now, then there’s room for some very pronounced, PV driven blocking as the winter matures.

So, a colder pattern is developing thanks to building heights over the pole, AK and Greenland/Scandinavia. There are several questions around the next couple of weeks. How cold, how long etc?

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

This cold spell isn’t extreme by the looks of it this week or next but let’s keep an eye on what this may be showing us for later.

This return to seasonal or slightly below average is coming of a spell of ridiculous warmth.

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