Advance notice
As usual the predictions for November and December will be via PM to me to avoid any tactical predictions in the competition and to keep things as interesting as possible right up to the end of the year. So this is the last month in 2013 for predictions directly into the thread.
September retrospective
Overall a very average month when compared to the 1971-2000 mean. A warm start followed by a very cool middle part of the month but a mild finish. Not as cold as September 2012 but the fourth year out of the last seven where the CET has been less than 14C in September.
Looking ahead to October
Probably starting relatively mild but this may not last for very long.
Please place your October CET predictions in this thread. The deadline for entries with no penalty is 23:59 on 30 September. Late entries will be accepted up to 23:59 on 2 October but are subject to a penalty of 0.2C per day for the purposes of the annual competition.
October historic data summary
Here is the usual rundown of historic data for previous years.
2012 saw one of the coolest October's for a while with a CET of just 9.7C. Only 3 times has the CET failed to reach 10C since 1993. You have to go back to 1993 and 1992 for the last really cold Octobers with 8.5C and 7.8C respectively. 2011 saw a very warm October with 12.6C. The CET has exceeded 13C three times since 2000.
Long run averages:
1971-2000: 10.4C
1981-2010: 10.7C
1988-2012: 10.8C
Here is a chart of the October CET since 1961 with a 10 year moving average
Here are some details of what the models and forecasters generally are saying at the moment.
GEFS (850 and 2m temps)
http://www.wetterzentrale.de/pics/MT8_London_ens.png
http://www.wetterzentrale.de/pics/MT2_London_ens.png
http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png
http://www.wetterzentrale.de/pics/MT2_Manchester_ens.png
An above average start. 850's gradually tail off towards average but 2m temps only fall slightly.
ECM (De Bilt) maximum and minimum temps
http://www.knmi.nl/exp/pluim/kansverwachtingen_staafdiagram.php?run=12&type=tn
http://www.knmi.nl/exp/pluim/kansverwachtingen_staafdiagram.php?run=12&type=tx
Staying on the mild side throughout the first 10 days although also a sign of a slight cool down towards the end.
Weatheronline
http://www.weatheronline.co.uk/cgi-app/reports?MENU=Month-ahead
Out of date but suggests a reasonably mild first half of the month.
Terry Scholey
http://www.gavsweathervids.com/terryscholey.html
A generally mild first half of the month although could be some cool nights.
Netweather
http://cdn.nwstatic.co.uk/images/lrf/aug2013/xocttemp.png.pagespeed.ic.g5nFqo5FJm.png
Out of date as such but the forecast issued end of August suggested October would be cooler than average
Exacta
http://www.exactaweather.com/UK_Long_Range_Forecast.html
A warm start but turning progressively cooler and cold by the end of the month with the risk of snow even at lower levels.
WeatherOutlook
http://www.theweatheroutlook.com/twoforecasts/17-to-30-day-outlook.aspx?region=6
Again a warm start but also signs that it could turn very cold by the end of the month
Met office
http://www.metoffice.gov.uk/publicsector/contingency-planners
Contingency planners forecast not yet available
http://www.metoffice.gov.uk/public/weather/forecast/city-of-london#?tab=regionalForecast
30 day forecast - a warm start but then fairly average
Pattern matching (just for fun)
My analysis of years with similar temperature profiles to 2013 for the summer and September suggests there is little likelihood of a cold October overall. The matching years tend to be warmer than average as a whole with a central range of around 10.7C to 11.7C. The coldest matching years since 1900 were 1935 with 9.5C and 1953 with 9.7C.
My summary
Taking all the available data and analysis into account it is clear that the first week of the month is likely to be above average. Beyond that there is some uncertainty as to whether things return to normal or stay somewhat on the mild side. There are signs of a possible significant cool down as we move into the final third of the month possibly with a very cold end to the month. If this happens it could have a big impact on the overall CET. The lack of an active tropical season in the Atlantic should help prevent too many spanners in the works which can sometimes make predicting at this time of the year very difficult.
At this point I am leaning towards a close to average month with a preference for something slightly on the milder side of average. A warm start offset in part by a cool end to the month. If we do get a very cold end to the month then overall slightly below average would be more likely.
Edited by moderator
06 November 2013 21:23:00
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