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Riccardo

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

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Ah right. Well, if anyone wants to use the one I made, go ahead.

 

Year: OPI

1976:  -1.75
1977:  -0.95
1978:  -1.8
1979:  -0.5
1980:  -0.05
1981:  -0.4
1982:  -1.1
1983:  -0.3
1984:  -1.8
1985:  -1.9
1986:  -1.3
1987:  -0.45
1988:  1.45
1989:  0.25
1990:  0.55
1991:  1.1
1992:  1.75
1993:  -0.15
1994:  0.7
1995:  -0.65
1996:  -0.75
1997:  -0.75
1998:  0.1
1999:  -0.2
2000:  -0.75
2001:  0.45
2002:  -0.9
2003:  -0.7
2004:  0.3
2005:  -0.7
2006:  0.85
2007:  0.75
2008:  0.25
2009:  -3.15
2010:  -0.85
2011:  0.65
2012:  -1.65
2013:  1.6

 

 

 

 

I did a quick bit of playing around with the data for the mean Scotland winter temperature (and my own 'fudged' OPI dataset) and found an R2 value of 0.52 between the OPI and Scottish winter temperatures generally, improving to 0.58 when stripping out v. strong ENSO years (magnitude greater than or equal to 1.5) and 0.65 when also considering only -ve QBO winters. Incredibly, the OPI actually correlates more strongly to the Scotland Temperature Series than the winter NAO, which has Rvalues of 0.48, 0.48 and 0.51 respectively, though I reckon that's possibly just a statistical quirk given the small sample size. Nonetheless, the OPI certainly does have the potential to be a gamechanger as far as winter forecasting goes.

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Ah right. Well, if anyone wants to use the one I made, go ahead.

 

Year: OPI

1976:  -1.75

1977:  -0.95

1978:  -1.8

1979:  -0.5

1980:  -0.05

1981:  -0.4

1982:  -1.1

1983:  -0.3

1984:  -1.8

1985:  -1.9

1986:  -1.3

1987:  -0.45

1988:  1.45

1989:  0.25

1990:  0.55

1991:  1.1

1992:  1.75

1993:  -0.15

1994:  0.7

1995:  -0.65

1996:  -0.75

1997:  -0.75

1998:  0.1

1999:  -0.2

2000:  -0.75

2001:  0.45

2002:  -0.9

2003:  -0.7

2004:  0.3

2005:  -0.7

2006:  0.85

2007:  0.75

2008:  0.25

2009:  -3.15

2010:  -0.85

2011:  0.65

2012:  -1.65

2013:  1.6

2013 was certainly a shocker!

1991 was also positive but still had a very cold spell which goes to show that a positive value is not complete doom and gloom.

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2013 was certainly a shocker!

1991 was also positive but still had a very cold spell which goes to show that a positive value is not complete doom and gloom.

Wouldn't that be October 1991?

1991-92 wasn't a brilliant winter.

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Ah right. Well, if anyone wants to use the one I made, go ahead.

 

Year: OPI

1976:  -1.75
1977:  -0.95
1978:  -1.8
1979:  -0.5
1980:  -0.05
1981:  -0.4
1982:  -1.1
1983:  -0.3
1984:  -1.8
1985:  -1.9
1986:  -1.3
1987:  -0.45
1988:  1.45
1989:  0.25
1990:  0.55
1991:  1.1
1992:  1.75
1993:  -0.15
1994:  0.7
1995:  -0.65
1996:  -0.75
1997:  -0.75
1998:  0.1
1999:  -0.2
2000:  -0.75
2001:  0.45
2002:  -0.9
2003:  -0.7
2004:  0.3
2005:  -0.7
2006:  0.85
2007:  0.75
2008:  0.25
2009:  -3.15
2010:  -0.85
2011:  0.65
2012:  -1.65
2013:  1.6

 

 

 

Thanks

 

I had fun checking the results of the AO according to the OPI index and no real surprise, I board found only four errors on 38 years tested, it is the winter 1982/1983, 1983/1984, 1998/1999 and 1999/2000. So I board not taken as reference trismestre December / January / February, but only in December / January because these are the two months that the OPI index may be the most important. In the end, it's amazing to see how the numbers are very close between the AO and the IPO index, it works wonderfully

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Ah right. Well, if anyone wants to use the one I made, go ahead.

 

 

 

 

Hopefully we can steer clear of the 1992 OPI ...

 

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Wouldn't that be October 1991?

1991-92 wasn't a brilliant winter.

 

1990/1991 Winter is a cold but mainly thanks to February winter. January was unusually mild in Europe with a positive AO and December 1990 was cold that first half, very soft in the second half and especially at Christmas with a compact VP. Finally, the AO was 1.0, OPI index was 0.6 (rounded 0.55) is very close

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I forgot 2013/2014 winter that is failing because the AO was of 0.3 on average in December / January when the IPO index was 1.6. Despite this, the VP was as expected very compact in the first part of winter which was well planned final anyway

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1990/1991 Winter is a cold but mainly thanks to February winter. January was unusually mild in Europe with a positive AO and December 1990 was cold that first half, very soft in the second half and especially at Christmas with a compact VP. Finally, the AO was 1.0, OPI index was 0.6 (rounded 0.55) is very close

 

Winter 1990/91 was a preety blocked one overall, however, average overall temp wise. The second of half of January was quite cold with high pressure and plenty of frosts. It was only the latter part of Dec/early Jan and end of Feb that was particularly mild.

 

I'll leave others to comment in this thread, but it is notable years with very negative OPI's such as 1978, 1984, 1985 and 2009 all produced at least one lengthy 4 week cold spell in the following winter (Jan 1979, Jan 1985, Feb 1986, Mid Dec 09 - Mid Jan 10), with much northern blocking., and indeed overall our four coldest winters of the last 40 years. Years with strong positive OPI's such as 1988, 1992 and 2013 saw very little cold weather during the following winter, mid-late Dec 92 was cold thanks to high pressure overhead and in 1988/89 and 2013/2014 produced two of our mildest winters of the last 40 years, with 1992/93 ranking quite high in the mild stakes as well - this must be more than just a significant coincidence?

 

1976 and 2012 the two years with the next highest OPI level, also produced a lengthy cold spell in Dec 1976 and March 2013.

Edited by damianslaw

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Its mad to see all the yrs being negative from 76-87 for example ,then the next 5 yrs all postive during that milder phase of winters during the late 80s/early 90s. Surely not coincidence

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Its mad to see all the yrs being negative from 76-87 for example ,then the next 5 yrs all postive during that milder phase of winters during the late 80s/early 90s. Surely not coincidence

 

And to add to that 84,85,86 all come in at sub -1 and just for good measure 88 comes in the massive +ve territory!!

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Still marvelling at this. Putting aside what a -OPI means (or doesn't mean) for the uk weather wise and the undoubted tight correlation to the DJF AO, what stands out like a massive glaring sore thumb to me is that a high positive OPI value equals an organised vortex early on, equals little or no chance of HLB, equals game over for winter as a whole in terms of cold. 1989, 1993, 2014, THE 3 most Atlantic driven winters of the past 40 years and the 3 highest OPI values by a relative mile.

This could indeed be the gamechanger for seasonal forecasting (obviously with other indexes etc factored in each year). As others have said though the data set is still too small for certainties just yet but exciting stuff nevertheless

Edited by s4lancia

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Just a footnote to my post above, I had forgotten about 1983, this was a very Atlantic driven winter as well I think and I see '82 OPI is pretty strongly negative. Not got all the data sets to hand but would be interesting to see what, if anything, was different during this winter.

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Just a footnote to my post above, I had forgotten about 1983, this was a very Atlantic driven winter as well I think and I see '82 OPI is pretty strongly negative. Not got all the data sets to hand but would be interesting to see what, if anything, was different during this winter.

El Nino Grande. (The largest El Nino of the 20th Century up to that point in fact)

Edited by Yarmy

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Just a footnote to my post above, I had forgotten about 1983, this was a very Atlantic driven winter as well I think and I see '82 OPI is pretty strongly negative. Not got all the data sets to hand but would be interesting to see what, if anything, was different during this winter.

 

February '83 was cold at 1.7c. Otherwise, west QBO, strong Nina and active solar cycle are not ideal for cold to our shores.

 

Just to add, for anyone wanting to look at the different parameters.

 

ENSO state.

 

WRfWDsV.jpg

 

QBO phase and January SSN available from the Berlin site.

 

http://www.geo.fu-berlin.de/met/ag/strat/produkte/northpole/index.html

Edited by Gael_Force

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Thanks

 

I had fun checking the results of the AO according to the OPI index and no real surprise, I board found only four errors on 38 years tested, it is the winter 1982/1983, 1983/1984, 1998/1999 and 1999/2000. So I board not taken as reference trismestre December / January / February, but only in December / January because these are the two months that the OPI index may be the most important. In the end, it's amazing to see how the numbers are very close between the AO and the IPO index, it works wonderfully

 

While I don't want to spoil anyone's fun nor would I suggest that the OPI should be ignored, you should keep in mind its been calibrated based on the historical set that it matches to 90% correlation. Given this a high correlation is to be expected. Thus far we have had one actual test of the model (last year) which it did well. It is highly likely that 90% correlation won't be maintained in the future given we are predicting 2-4 months ahead, but if it can get even a 70-80% correlation going forward it will be a massive step forward in long range forecasting. At the moment its a very interesting but nearly untested method. It should be watched and taken notice of but its going to be some years till you can reasonably say with confidence "it works wonderfully". 

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Also,people comparing years that are pos opi values with snowfall etc,myself i would be inclined to look for a more prolonged cold pattern with hlb and see what other factors are in favour.Also the same with a mild pattern in a neg opi.Loads of parts to a massive jigsaw.Great thread though!

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If we can get above average temperatures in the stratosphere, combined with a strong negative OPI, then we will be in a very good position indeed. We will surely be able to say with almost certainty, that this Winter will be colder than last. It's going to be a very interesting month of developments :cold::bomb::drinks:

Edited by Barry95

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Lol and nobody even mentioned the neg values of 2009 and 2010 the most negative out of them all.

I wonder what 63 would have been and 1947.

09/10 was incredible for the block over Greenland and if I'm correct the was some incredible nao and ao negative values.

And there are similarities with this coming season.

All eyes on the vortex and El Niño and OPI been very quiet to in the Atlantic for hurricaines and in 09/10 hurricane season most were more from Pacific as is this year so far.

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Whilst acknowledging there is more to Riccardo's OPI model than a simplistic look at Northern Hemisphere patterns, a look at today’s NWP model output gives reasons to be cautiously optimistic that the current negative index won’t be suffering a major reversal in the near term.

 

Today’s GFS N. Hemisphere H500 output shows the PV still disorganised with plenty of high pressure where it might normally be expected to rule the roost at this time of year.

post-20040-0-46110400-1412776335_thumb.p

 

And bearing in mind the OPI calculation today will be using GFS forecasts out to the 18th Oct, looking at the H500 chart for that date shows high pressure stretching right across the pole, from the Aleutians over to the Euro high, with the PV pushed into Siberia. This scenario is supported by ECM H500 chart for the 18th Oct, and today’s ECM/GFS Mean H500 8 – 10 day Anomaly chart adds weight.

 

GFS post-20040-0-52856500-1412776550_thumb.p  ECM post-20040-0-38354400-1412776561_thumb.p 8-10 day anomaly post-20040-0-20436200-1412776573_thumb.g

 

According to GFS it’s not until around the 22nd of October that the PV finally muscles the high pressure residing over the pole out of the way. By then we would have 22 days actual and 9 days forecast to month end.
 

A long way to go, but reasons to be cheerful!

 

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Lol and nobody even mentioned the neg values of 2009 and 2010 the most negative out of them all.

I wonder what 63 would have been and 1947.

09/10 was incredible for the block over Greenland and if I'm correct the was some incredible nao and ao negative values.

And there are similarities with this coming season.

All eyes on the vortex and El Niño and OPI been very quiet to in the Atlantic for hurricaines and in 09/10 hurricane season most were more from Pacific as is this year so far.

 

Plenty of mention 2009 in previous pages - Steve mentions the analogue, several times.

 

I plotted the October '62 500mb anomaly - it certainly doesn't have the Aleutian/cross pole positive anomaly that the other very negative OPI years show. Perhaps I'm missing some important element to get the whole picture.

 

compday.Y3kwhTTQYm.gif

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