[OCTOBER PATTERN INDEX (OPI) MONITORING WINTER SEASON 2014-2015]

We are only half way through December, still over two weeks left, so your statement is too early, come back in 16 DAYS!

15 days later and the original statement stands. It wasnt too early to make the statement as there was already strong support for it out to at least 10 days i.e. 26th. Therefore not enough time to change the outcome.

[OCTOBER PATTERN INDEX (OPI) MONITORING WINTER SEASON 2014-2015]

So I think we can chalk December off as a CET that will end up at least normal and probably around +5 or more. The AO will out turn on average above normal as will the NAO.  Therefore I suggest the OPI has not worked for December. 1-0 to the Met Office long range this time around. An embarrassment for the likes of Piers Corbyn at WeatherAction and James Madden at Exacta snomageddon forecasts.

 

However, the OPI from what I can tell only suggests at least 2/3 super negative AO months in a winter given the near record -ve value this year. So there is still time for it to claim some success. 

[OCTOBER PATTERN INDEX (OPI) MONITORING WINTER SEASON 2014-2015]

I get the feeling that actually you maybe a year out with your analyses.

I know it is standard practice in tables when you see a season that overlaps a year and they just use a single year, say winter 1992, the 1992 actually refers to the January and not the December so it's not 1992-93 but 1991-92.

I don't know if that is the case with these analogues but what makes me wondering is that wasn't it the OPI in the October of 1976 and not 1977 that was less that -1?

Edit: looking at it further you looked at December 2013 but the OPI for October 2013 was over +1, the October of 2012 was below -1.

Having said that -AO and even -NAO is not be all end all. It is possible like January 1969 that the UK could still be mild despite those values being negative.

March 1957, the warmest March on record for the CET, had a negative AO and NAO

Agree totally about your negative AO and NAO comments. A -ve AO and NAO forecast should be used as a warning of potential for cold, but it can not be used as accurate forecasting tool which is also why I seriously question how the correlation stats of the OPI are generated.

[OCTOBER PATTERN INDEX (OPI) MONITORING WINTER SEASON 2014-2015]

Hi pbweather,

 

You seem to missing the overall point of the analogue. The years shown are for the winter period running from December to February not just December!!! Also as the winter period runs through from one year to the next, the analogue takes the year that Febuary ends in. For example, 2010 was in fact the winter of 2009/10 and 1977 was indeed 76/77 and so on.

 

As for the results, if you go back through the years in the analogue you will find that all the winters had at least 2 out of the 3 winter months, with below average temperatures and at least 1 month with well below average. 

 

Capture.PNGCapture1.PNGCapture2.PNG

 

 

 

Regards,

Stu.

Apologies for the year confusion but some archives work on the year of the first month of winter e.g EarthSat. Using my running 10 year Dec CET 4.3 and 30 year Dec CET 4.8, then even if you use the previous years only 1976 and 2009 are below normal and the average of all years is close to normal. 2, 5.2, 6.2, 3.1, 4.8.  Factor in sunspots and 1976 and 2009 were bang in the middle of very low sunspot periods which is almost certainly a factor as well so then these Dec CETs are probably not cold at all. Once you get a normal or warmer than normal Dec then getting a strongly cold winter becomes increasingly difficult because you need at least one month to cancel out Dec anomalies and this is why there is not a very clear stats relationship between -ve AO and -ve NAO winters. Similar story with all the other teleconnections as well.

[OCTOBER PATTERN INDEX (OPI) MONITORING WINTER SEASON 2014-2015]

Hi guys,

 

I've took all the sub -1 OPI years coupled with an easterly QBO and produced a 500 mb height anomaly plot for the winter period. The results speak for themselves!!!

Do the results speak for themselves?  Blocking and -ve AO signals do not necessarily translate to cold everywhere. Look at the CET in these OPI analog years. Dec 1977 = 6.3, Dec 1985= 6.1, Dec 1987 = 5.6, Dec 2013 = 6.3  so all of these are very warm Decembers with only Dec 2010 seeing extreme cold. I would argue that Dec 2010 was in a period of exceptionally low sunspots and other drivers all lined up to bring the perfect storm of cold.  So although the graphic shows anomalous pressure heights over the polar region and a southerly displaced storm track over the N Atlantic I would argue that statistically from those years the risk is warm not cold for December in the UK and probably W parts of Europe.  The rest of winter is another matter, but just wanted point out that all the hype about -ve AO winters is not all it seems.