In the previous analogue blog post for Autumn 2018, we looked at the Autumns that followed on from positive NAO Junes with a NAO index of at least 0.50. June 2018's NAO index was 1.41 which was very positive. There were a good few years in the analogue and I thought it'd be good to break the analogue down to less years; only include years that had a June NAO index of at least 1.00. That's what we're going to be looking at here in part 2 of analogue #8 for Autumn 2018.
The 500mb height anomaly reanalysis of these Autumns overall looks very mild and rather settled but perhaps some invasions from the jet stream at times as the high is centred over central Europe. Let's look at the month to month variation of these Autumns overall.
The Septembers of these Autumns look unsettled and cool to very cool perhaps. Above average heights to the southeast of Europe and over Greenland (northern blocking) with below average heights over Scandinavia, through the UK and into the Atlantic. The low over Scandinavia could suggest the possibility of northerly winds at times.
The Octobers of these Autumns look anticyclonic but the high pressure is aligned to central Europe much like the Autumn reanalysis. Low pressure is over Greenland in contrast to September. There is another ridge out in the mid-Atlantic. Overall, quite an anticyclonic signal. It would also be perhaps mild to very mild again in contrast to September.
The Novembers look exceptionally mild with a huge area of stubborn above average heights to the south of the UK. Apart from the north of Scotland, it looks very settled too. It'd be interesting to see a November as exceptionally mild and settled as this reanalysis suggests because usually when there is a very mild November, it's wet and windy such as 2015.
Overall, fairly similar signals to part 1 of analogue #8 for Autumn 2018 but better chances of settled weather in October and November. In turn, better chances for cool and unsettled weather in September.
One successful signal I have seen in the analogues is for some sort of mild and wet November but whilst this analogue suggests a very mild November, it's most certainly not wet away from the north of Scotland.
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