Winter in the London area this year is likely to be average overall, following the pattern of the past two winters that saw little snow.
A rather mild December, dominated by a SW’ly flow with only brief, cooler, NW’ly incursions, will be followed by a rather cold January and average February. Rainfall throughout is likely to be average or slightly above. Probabilities of this scenario are listed in the tables.
The best chance of any snow is most likely to be at the end of January, though given the generally mild pattern it is not likely to last longer than two or three days.
Much has been said about how El Niño will affect this winter. The more hysterical parts of the media tell us we will see a repeat of 2009-10, a cold winter that saw frequent snowfall. But their assertion ignores the fact that other winters following a strong El Niño have been exceptionally mild.
This autumn has shown some striking similarities with 1997, a record El Niño year, that was followed by a very mild winter in this area, the third warmest since 1797. This autumn was also similar to 1994 – another El Niño year – followed by the fourth warmest winter on record.
But just as you think the pattern is the same the El Niño this year is different in that it is an El Niño Modoki – a full-Pacific basin El Niño that differs from the one in 1997. In other words we really are in unfamiliar territory.
So before I get too bogged down in finding teleconnections with El Niño, perhaps it is wiser to go back to more traditional ways of trying to predict the coming season.
Before I trawled through the figures my initial gut reaction to this winter was that it would be mild – because of some blocking in September/October.
As well as my method of using rainfall and temperature I also considered other methods. One, of which I see mentioned very little these days, was Russian research that states that the weather pattern in the winter will be the opposite to the weather on September 17th and November 7th. This autumn September 17th was NE’ly and November 7th was SW’ly. So, of little use this year.
You can read the method 0f how I reached my conclusion here.