The monitoring page of the “October pattern index” (OPI) is presented. The OPI index
represents a analytic synthesis of the October hemispheric pattern at 500 hPa, and shows from
previous studies quite a high correlation (r ≈ 0.9) with the winter mean Arctic Oscillation Index
(DJF AO); this implies that the lower the OPI index is in October (negative values) and the higher
will be the probability to have a weak polar vortex during the following winter. Therefore the OPI
index could be a valid support tool in the seasonal forecasting of the winter season.
The OPI index is calculated through a dedicated software modeling elaborating the 31 daily
hemispheric October at 500 hPa. This monitoring page is updated automatically with every run of
the global forecast model GFS (Global Forecast System), except the 18:00z run. The software
analyzes the previous consolidated daily charts plus 10 forecast charts as given by the GFS model.
For example on the 15th of October, the software calculates the OPI index based on the 15
consolidated daily charts (1-15 October) adding 10 forecast charts as given by the GFS model (16-
25 October). The definitive OPI index will be available only at the end of October, when the
software will be able to elaborate all the 31 daily consolidated charts of the month. During the
month the index will gradually tend to the final value starting to be reliable past the half of the
month, when the consolidated charts number will overtake the forecast charts number.
Finally, at the beginning of November, the official seasonal forecast for the winter 2014-2015
will be released based on the final OPI value and on the recent developments of this research whose
results have been discussed and analyzed so far with Prof. Judah Cohen (Director of Seasonal
Forecasting at AER) and the Italian Air Force Lt. Col. Guido Guidi.

OPI monitoring page link:

http://app.til.it/opi/

Welcome to the forum Riccardo and thanks for your informative post. I have heard of your October Pattern Index (OPI) before and know it has generated quite a lot of interest. Good luck.  

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Riccardo - it would be helpful if you could provide the raw data for the correlation, ie how many years are in the sample, and what the OPI figures for each of these years were. I ask because (a) I am interested and (b) there are some members of this forum who believe there are no winter prediction methods that have much value [not my view]

Riccardo - it would be helpful if you could provide the raw data for the correlation, ie how many years are in the sample, and what the OPI figures for each of these years were. I ask because (a) I am interested and (b) there are some members of this forum who believe there are no winter prediction methods that have much value [not my view]

I think that this graphs could help you:

 

 

Hello to everyone

 

Riccardo

Riccardo - thank you, but I would appreciate it if the actual OPI numbers for each of these years could be supplied.

Riccardo - thank you, but I would appreciate it if the actual OPI numbers for each of these years could be supplied.

I'm sorry, but we have never published the exact OPI records values  (we're going to do that with our future scientific publication). But you can get good values by those graphs.

Riccardo - do you have a rough idea when this scientific publication will become available?

Probably within the end of the next year. 

Hi Riccardo.

Is it fair to say that last year's forecast was a bit different in terms of a correlation?
The OPI was +1.64 while the AO came out around +0.2 as far as I can recall..but I could be wrong!

Joe

Hi Riccardo.

Is it fair to say that last year's forecast was a bit different in terms of a correlation?
The OPI was +1.64 while the AO came out around +0.2 as far as I can recall..but I could be wrong!

Joe

 

You're right. But last year all the forecast seasonal indexes were wrong. It was a very strange season. Moreover, as you can see on the last graphs, once every about 15 years the OPI index has been wrong.

We think that this year OPI will be good enough.

 

 

Welcome to TWO Riccardo. Fascinating post.

We will watch this with great interest.

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Welcome to Two Riccardo. Just how foolproof is this methodology and are there certain factors which can override the theory?

How's this looking?

Currently at -3.57 which as I understand it would suggest a negative AO this winter.

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I don't think people realise how significant this October is relating to this index.

If you correlate it @ 0.91 ( with the caveats that its all hindcast as opposed to forecast ) then an OPI landing Sub 3 indicates a Winter with 3 AO months sub -1.5 in index.

 

Similar to 62/63,76/77 , & more particular 2009 /10 ( remember the loss of ice is enhancing the negative anomalies through feedbacks over Eurasia leading to a weaker polar jet)

the OPI is Actual to the 8th & forecast out to the 18th, if we even get close to -3 for the 18th then we are in business.

 

This is VERY significant- especially for an Easterly QBO Winter....

S

Steve has started the cold ramping early this year!

Hope you are right mate because we havent had a decent winter since 2010/11 here.

Andy

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Steve has started the cold ramping early this year!

Hope you are right mate because we havent had a decent winter since 2010/11 here.

Andy

Now all we need, is a "Winter is over" post from Messrs A Woodcock, and we'll be in business 

Welcome to the forum Ricky 

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Must admit the OPI wasn't something I'd really heard about, but the theory does look quite compelling. 

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I don't know about others, but I would personally find it very useful if someone in the know could briefly set out the critical correlations and inferences that can be drawn from the OPI.

I've heard that a strongly negative OPI has a good correlation with a weak PV and therefore a negative AO, which in turn makes it 'easier' for conditions that favour a cold winter in the UK to set up... but this is new to me, so I probably have it entirely wrong and it's entirely possible that I'm making up all those TLAs in an effort to fit in with the other kids and it's actually an LOB scenario? :)

Thanks

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Must admit the OPI wasn't something I'd really heard about, but the theory does look quite compelling. 

I first heard of this last winter but didn't take much notice as if I recall it struggled with the pressure patterns for Western Europe, though it was spot on for the U.S. The problem I have though is the limited amount of data at hand and the fact that it's results were fairly mixed last year.

My reasoning is much more simplistic - temperatures have been above average for so long now (August excepted)- that we're due some below average months and the longer the warmth goes on, the more likely a below or well below average spell becomes. I dont care much for snow - a nice cold, dry and blocked period in December / January with plenty of crisp frosts would be lovely.

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