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Riccardo

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

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Using BFTV's list of  the OPI values,here is a composite anomaly of October's when the OPI was around the -1 mark which is where it currently stands (before the 00z update),and also a composite anomaly for the first week of October this year...

 

 this Oct.so far..

 

 

...and now a composite of the winters following October's when the OPI index was around -1...

 

 

 

:)

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models always very interesting this morning with a VP placed towards the Urals and still ubiquitous high pressure on the central Arctic. The IPO index is expected to remain negative well

 

Recmnh2401.gif

 

gfsnh-0-240.png?0

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The most pertinent point yet.

 

After having a discussion on twitter last night I went back and looked at the previious OPI scores. And to me it looks like that the scores are the daily values ( go back and look at the daily scores) rather than the cumulative score with the addition of the average T+240 GFS score factored in. So the OPI indicated is the score today (yesterday now -1.13 ) rather than the cumulative score that perhaps Riccardo had led us to believe ( - this could be lost in translation).

 

However, all is not lost as I suspect that the next 10 days we will be near an average score. After that we may get a more positive daily OPI value as the AAM is set to rise and this will lead to a more pronounced polar jet stream. Perhaps not a bad thing to temper winter expectations at this point..... but I am likely to suggest a negative AO winter, unless there is a significant change in pre-winter conditions for the worse in the next 6 weeks.

 

how do you derive a daily score ed?  there are three different opi's issued each day following each gfs run? surely it has to be a consolidated running figure ??  there are things here which dont seem to make any sense. perhaps we should be extremely cautious and try to ignore the OPI until we get to the 20th ??  riccardo has already stated that the number will solidify as the month enters its second half. i guess we had a situation yesterday where the forecast ten days was still greater than the existing 9 days of the month. 

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how do you derive a daily score ed?  there are three different opi's issued each day following each gfs run? surely it has to be a consolidated running figure ??  there are things here which dont seem to make any sense. perhaps we should be extremely cautious and try to ignore the OPI until we get to the 20th ??  riccardo has already stated that the number will solidify as the month enters its second half. i guess we had a situation yesterday where the forecast ten days was still greater than the existing 9 days of the month. 

Had just been thinking about it again this morning, Nick - with a clearer head I may add. And I agree with you either this daily chart

 

post-4523-0-92755200-1413017223_thumb.pn

 

is showing the figure for each day, or it shows the figure for the cumulative amount up to that point which encorporates the projected 10 day as well.

 

If it is the latter, then we don't actually know the daily values and do not have an idea what the OPI is up to date, only what it will be in ten days time if the GFS forecast verifies.

 

I think it will be wise to be cautious until we actually know.

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Also, I thought it was supposed to automatically update after the GFS run. The 00z finished a while ago. Unless he means it automatically updates after data is fed in? So many questions!

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Had just been thinking about it again this morning, Nick - with a clearer head I may add. And I agree with you either this daily chart

attachicon.gifImage.png

is showing the figure for each day, or it shows the figure for the cumulative amount up to that point which encorporates the projected 10 day as well.

If it is the latter, then we don't actually know the daily values and do not have an idea what the OPI is up to date, only what it will be in ten days time if the GFS forecast verifies.

I think it will be wise to be cautious until we actually know.

It must be the figure for day 10 of the gfs run which is most recent (either in ten days time or the 31st oct if that is sooner). Clearly, low res operational modelling is poor re verification so the fact that we don't see wild swings from day to day should give us some comfort in the number. Once we pass the middle of the month, we have more actual data than forecast data so the number should slowly become less variable. As we are only a third of the way through the month, we are still liable to big swings. Today's numbers will be interesting, following on from the figure for the 20th October which we saw yesterday evening. Edited by bluearmy

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Also, I thought it was supposed to automatically update after the GFS run. The 00z finished a while ago. Unless he means it automatically updates after data is fed in? So many questions!

 

I was just going to say, I don't think I've ever seen an update based on the 0Z. Sometimes its the 06Z, sometimes the 12Z and sometimes like yesterday it updates twice in the same day with both the 06Z and 12Z...It's a little confusing.

Edited by radiohead

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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)

 

 

.....is showing the figure for each day, or it shows the figure for the cumulative amount up to that point which encorporates the projected 10 day as well.

 

...I think it will be wise to be cautious until we actually know.

 

Agreed gentlemen. But also, another clue as to what the daily figure represents can be gleaned from the "Calculation Parameters" box just below the headline Index at the top of the OPI webpage. It clearly states the date of the GFS run the calculation is based on, and it clearly states the "OPI Calculate at..(date)" which is 10 days out from the current run. Hence my take that it is a running Index based on actual charts to date plus 10 forecast charts.

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Had just been thinking about it again this morning, Nick - with a clearer head I may add. And I agree with you either this daily chart

 

attachicon.gifImage.png

 

is showing the figure for each day, or it shows the figure for the cumulative amount up to that point which encorporates the projected 10 day as well.

 

If it is the latter, then we don't actually know the daily values and do not have an idea what the OPI is up to date, only what it will be in ten days time if the GFS forecast verifies.

 

I think it will be wise to be cautious until we actually know.

I am sure it would be that Ed, going by his original explanation.

As we know FI modelling will  often show wild swings from one run to the next.How often do we see changes in the polar 500hPa pattern at even closer range?

Surely this will reflect on the  OPI projection of the PV profile?

 

With only 11 days recorded  and 10 days forecasted then there's plenty of time for movement on this yet.

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Also, I thought it was supposed to automatically update after the GFS run. The 00z finished a while ago. Unless he means it automatically updates after data is fed in? So many questions!

 

It has not been updated after every one of the stated runs -more like once a day.

 

I'm of the opinion that the shift yesterday is to do with the change to negative 500mb anomalies north of us - the composite from cloud shows well the to date heights over Scandinavia. That was due to continue until the runs of yesterday; no longer the axis across the pole as before.

 

day 10 H500 anomaly.

 

gfsnh-12-240_ktd7.png

Edited by Gael_Force
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So the long and short of it is that we don't actually know what the OPI is up to day 10 of the month.

 

But we do know the projected figure up to day 20.

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Do we not share the 10 days to get an average. And at the end of the month we share it with 31. (I'm probably being thick lol)

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So the long and short of it is that we don't actually know what the OPI is up to day 10 of the month.

 

But we do know the projected figure up to day 20.

That's how i see it.

The current figure is merely a forecasted index because we do not have the full 31days of historical data.

As you say 10 days actual(to yesterday)+10 days forecast =20 days leaving still 11 days with no imput,either historical or forecasted.

As i suggested above there's plenty of wiggle room either way before the final OPI is ascertained. 

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Do we not share the 10 days to get an average. And at the end of the month we share it with 31. (I'm probably being thick lol)

That can't be right mark or we couldn't have a wild swing, day to day.

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I'm at times way out of my depth with this thread. But would it not be a better indicator of what MIGHT happen if the data was the actual value on any day, plotted, so that it could be seen what was happening over the period with data? Using a predicted or partial predicted value leaves it open to even more doubt. Why? Because you will be using a forecasted value to try and forecast what the predicted value might mean in terms of using it to then suggest what the winter MIGHT be like. Too many forecast bits in there, get some actual data and then try and use that as a predictor. The data for 31 October is surely the only one with any real use with it being the value, I would imagine the average value of the OPI over the 31 days. There is some merit in seeing how that has changed over the month but not as some seem to be using it with the forecast values being used.

just my take on it-shoot it down by all means.

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and to quote from the first post

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.
 
So it is fine and part of the model thread up and down for coldies to watch it change each day but the only time you can use it constructively is after the data, actual data that is, has been received, then to work out what the OPI ACTUAL shows.
The work suggests that it can then be used as a tool to help TRY and predict what the AO will be. Remember even then that the AO can be -ve and the UK area can still not get a cold snowy winter. I think the work being done on this is great and MAY lead to another link in the puzzle of trying to predict the winter season but it is just that ONE of the tools to use. Like most things in meteorology everything is linked, the clever bit is knowing what weight to give to each link. Very interesting though but I would urge some folk to think a bit before shooting so to speak. It is in its infancy and as I posted a day or two ago it has YET to be peer reviewed those working on it may well agree with at least some of my post regarding caution. I note that Steve, Lorenzo and chio all suggest to a degree some caution. It is not the answer to winter on its own, be it good or bad, depending on ones wish for the type of weather preferred over the winter months. Fun of course to speculate but don't get too hung up with it is my advice.
Edited by johnholmes
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Am I being really thick?  probably yes!!   but these swings can happen from day to day surely, look how much the shape of the vortex changes every 6 hour flick on the GFS runs, that figure in big letters is the daily figure, as long as the bar graph continues to be in the significant negative territory, then the end result will be good surely, its only time to start worrying when we go into positive territory for any length of time.

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Very interesting thread.with some great input.

If i understand correctly how this works, then the actual final value of the OPI will not be available until the 31st. As of now we only have 11 days of data plus 10 forecast days out of 31. Therefore we can't consider the daily OPI figure as a prediction of the final value until the 21st when we then have 31 days worth of actual and predicted data. From that point, it becomes a forecast with a 10 day (increasingly more accurate)countdown to the actual OPI

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It has updated based on the 06z : -1.67

 

I guess the good thing compared to last October's OPI is that the value was going up and down like a yo-yo in the first third of the month while this year it is consistently negative. Let's hope it continues. 

 

Karyo

Edited by karyo
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If i understand correctly how this works, then the actual final value of the OPI will not be available until the 31st. As of now we only have 11 days of data plus 10 forecast days out of 31. Therefore we can't consider the daily OPI figure as a prediction of the final value until the 21st when we then have 31 days worth of actual and predicted data. From that point, it becomes a forecast with a 10 day (increasingly more accurate)countdown to the actual OPI

 

That's how I see it too bobbydog. Well summed up!

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The daily value updating @ -1.67 perhaps cements the concerns that there is a contradiction in terms of whats been said by the author ( in terms of rolling average + Forecast 10 day index = the total average for the month being presented at the top of the OPI link on the page.

 

It would appear that as some of us have 'guessed' the OPI at the top of the page is just 1 day forecast ( or without checking the previous days actual)

 

Whilst we dont have the definitive end of month result, those of you with a little nowse can continue to calculate the rolling average by review the daily scores & dividing it by the amount of days to get the Mean.

I think I calculated 1.87 last night at day 10 so

18.7 + 1.67 / 11 = 1.85-

 

So to be fair not a bad position at all. 

 

In terms of going forward, the big anomalies have eased off with perhaps a little more forward momentum in the jet, however we are still presenting a negative index all the way through with the general anomalies all be it weaker still generally in the same place.

 

The key landing zone, as I presented way back at the start the key is to get the end of the month figure south of -1.5 for & as it stands that seems a fair assessment based on what the models show & what the rolling average currently sits at.

 

Forecast estimate for the cone of OPI at day 11 looks to be -1 to -2 for end of month. With the final 10 days still to be fixed apon on the model front......

 

best regards

Steve

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and to quote from the first post

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.
 
So it is fine and part of the model thread up and down for coldies to watch it change each day but the only time you can use it constructively is after the data, actual data that is, has been received, then to work out what the OPI ACTUAL shows.
The work suggests that it can then be used as a tool to help TRY and predict what the AO will be. Remember even then that the AO can be -ve and the UK area can still not get a cold snowy winter. I think the work being done on this is great and MAY lead to another link in the puzzle of trying to predict the winter season but it is just that ONE of the tools to use. Like most things in meteorology everything is linked, the clever bit is knowing what weight to give to each link. Very interesting though but I would urge some folk to think a bit before shooting so to speak. It is in its infancy and as I posted a day or two ago it has YET to be peer reviewed those working on it may well agree with at least some of my post regarding caution. I note that Steve, Lorenzo and chio all suggest to a degree some caution. It is not the answer to winter on its own, be it good or bad, depending on ones wish for the type of weather preferred over the winter months. Fun of course to speculate but don't get too hung up with it is my advice.

 

Think everyone realises that JOHN, don't think anyone is pinning their winter (mild or cold) on this new model. This is interesting and ads to the debate, you seem more hung up on it than anyone else :)

Edited by MPG
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I certainly wouldn't want to overstate its significance at such an early stage of its development but as IF's post shows it appears to be an incredibly good predictor of the winter CET. Going back to the Scottish mean temperature data there are 45 winter months following a positive or neutral OPI, and just 7 were below average (4 of those were Decembers) and only one winter as a whole out of the 15 was below average, that being 90/91, so if that correlation does continue to be borne out then it is actually quite important that we get a negative value, ideally sub -1, registered. A negative OPI certainly doesn't guarantee a cold winter either (although a very negative one almost certainly *should*) but the negative QBO and weakly positive borderline El Nino mean that we've got at least a fighting chance of vortex disruption. 

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Updated on the 12z and is now at -2.0. I thought it updated on every run apart from the 18z?

(That's better!!!) 😃😃

Edited by Fingers

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Updated on the 12z and is now at 2.0. I thought it updated on every run apart from the 18z?

 

 

All data are from the GFS 00Z, 6Z and 12Z. The 18Z GFS is not taken into account

Edited by neige57

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