For analogue #11 of Autumn 2018, we're going to be looking at ENSO neutral Autumns that were preceded by La Niña Winters as 2017-18 was a weak La Niña season. When the NOAA 20th century reanalysis v2c generator begins to work again, we'll be looking at weak El Niño, moderate El Niño Autumns as well as El Niño Autumns that were preceded by a La Niña Winter. We need to cover all possibilities!
The 500mb height anomaly reanalysis for Autumn overall suggests an anticyclonic signal with the centre of above average heights anchored just to the west indicating the potential of some northwesterly or even northerly incursions at times during the season. Temperatures don't look like a big deviation with this setup.
The Septembers overall look anticyclonic for most away from the north of the UK and some parts of the west of Ireland. Fairly warm signal.
The Octobers look fairly cool with northwesterlies being the dominant influence but also unsettled.
The Novembers look very dry but maybe not all that mild as like the Autumn reanalysis overall shows, the above average heights are anchored rather out to the west. We're on the periphery of a northerly blast on that chart.
So a very quiet Autumn for the most part this analogue signals though October is more unsettled. Kind of an odd one out with most of the analogues we've looked at when October seems to be the anticyclonic one.