Do severe winters follow anticyclonic Octobers?

north-atlantic-surface-analysis-ukmo-1-oct-2016-31-oct-2016

October 2016 has been the third most anticyclonic October since 1871. Not a lot of people know that. Here’s a table of the monthly analysis ranked on highest anticyclonicity using the Objective Lamb Weather Type [LWT] data series maintained by the Climate Research Unit at the University of East Anglia.

2016-11-03_14343

And here’s a more detailed breakdown of the daily LWT values for October 2016.

lamb-weather-types-for-31-oct-2016-1-oct-2016

The more eagled eyed amongst you may have noticed that I have highlighted October 1946, 1962 & 1978  in the first table in green. These of course are October’s that preceded the most severe winters since the second World War, namely 1946/47, 1962/63 and 1978/79. In fact the more I look at the list the more severe winters I see, for example 1879/80, 1887/88 and 1985/86 and the bitter cold spell in the January of that winter. Having said that 2007 was the joint 2nd most anticyclonic October and the following winter was super mild, so forget all that twaddle!

October temperatures

I can’t understand why the BBC weather presenters can’t be bothered to use temperature anomaly charts like the one below. I admit it would have been even better if I had contoured the results and colour fill them, but alas that’s beyond me at present. The beauty of an anomaly chart is that they are simple to understand and in a situation like today’s easy to visualise. Perhaps it will all change when Meteo Group take over the contract, one can but hope, because I’ve heard so many explanations about how cold it feels in the last week. Carol Kirkwood this morning for example said that although today would be colder that tomorrow, because there would be more wind tomorrow, tomorrow would feel much colder than today even though it would be warmer. I know all about wind chill, but the public must be pretty bewildered when they hear that, and are then presented with a chart of minimum temperature in towns and cities and then another one of rural temperatures. Why not simplify matters and just report the extreme minimum temperature in the region like they did in the good old days of magnetic numbers? They don’t seem to mind doing that with extreme maximum temperatures all through summer, so why not for extreme minimum? You’ve probably heard me going on about this in previous years, and it usually starts in early autumn so I apologise!

air-temperature-anomaly-at-12-utc-on-monday-10-october-2016

Having said that the Indian summer continues in Northwest Scotland and here in the Southwest of England with another gorgeous day, and at the moment the temperature in mid-Devon is 16.6°C. But even if it’s a little on the cold side at the moment it isn’t quite a cold as it was on the 10th of October 2013.

synops-0600-utc-on-thu-10-oct-2013

And these are the 1200 UTC anomalies anomalies for that day.

air-temperature-anomaly-at-12-utc-on-thursday-10-october-2013

 

The cold October of 1881

I get the distinct feeling that October 2016 is going to be an unusual month as far as weather is concerned in the British Isles. The reason I say this is down to the early intense Scandinavian anticyclone that initially formed on the 3rd of the month, and the first substantial block we’ve had in the circulation pattern across the British Isles for some considerable time. As usual I always call on the aid of the central England temperature [CET] series to help me out , and this time is no different. Here’s a table of the coldest October’s in the CET series. You’ll notice that I’ve highlighted 1881, I did this because 1881 was the best match that I could find to the start of this October in the Objective Lamb weather type [LWT] series. The October of 1881 was the eleventh coldest since 1659 in the monthly CET series, with a percentile of 4 (i.e. one of the top 4% coldest) and a mean temperature of 7.06°C, which was -3.45°C below the 1961-1990 long-term average.

warmest-october-cet

This is a graph of all Octobers since 1659. There has been a slow warming over the centuries in October’s, with many more warm than cold since the World War II. As as you can see the last notably cold one was in 1992.

october-mean-cet-anomaly

Below is a more detailed look at the CET of Autumn 1881 and the one thing that striked me about it how quickly a long period of cold can suddenly give way to a long period of mild, before flipping back to cold again.

daily-cet-autumn-1881

The month of October across the British Isles was very anticyclonic in nature. It started in a very similar way to October 2016 with a large anticyclone over Norway, which eventually gave way by the 10th to allow a low pressure system to run and intensify from Iceland and into the Norwegian sea and into the Baltic before filling and being replaced by a transient high pressure cell on the 16th. The high migrated to Scandinavia and before you know it the 19th of October looked a lot like the first day of the month again. That high remained for the rest of the month, it retrogressed NW’ward from the 20th to allow low pressure to take up residency across the SW of the British Isles and produce another spell of E’lys from the 19th to the 30th of the month.  The low over the SW gradually filled as high pressure built from the north from the 25th, and by the end of the month an anticyclone sat over the country.

lamb-weather-types-for-1-oct-1881-31-oct-1881

Here are the 0000 UTC weather charts for October. Please note that the LWT table uses 1200 UTC data so they are not perfectly in synch.

I would have included a graph of  rainfall for October 1881 but the daily totals only go back as far as 1931, and the regional monthly totals only go back to 1910 so they’re of no use, so we are left with the total from the monthly England Wales [EWP] rainfall series of 82 mm, which was 94% of average. It’s surprisingly difficult to glean much information about past weather across the country, and 1881 is just a little too early to be included in the daily and monthly weather reports of the Met Office.

In Conclusion

Well what was all that in aid of? Well it’s been almost 25 years since we experienced a really cold October, and I suppose I’m still vaguely looking to find some kind of analog between the October of 1881 and 2016. I know I’m totally delusional, but what the hell.