Jump to content
Holidays
Local
Radar
Snow?
Sign in to follow this  
Riccardo

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

Recommended Posts

This index and its calculations fascinate me with such huge swings at this stage of the month, Time for another side by side comparison to have a look at what is different.

 

dmPcD8E.pngXqVPfKm.png

Edited by Gael_Force
  • Like 2

Share this post


Link to post
Share on other sites

This index and its calculations fascinate me with such huge swings at this stage of the month, Time for another side by side comparison to have a look at what is different.

 

dmPcD8E.pngdmPcD8E.png

They look pretty similar to me GF, lol.

  • Like 2

Share this post


Link to post
Share on other sites

Lol what a waste if time.(interitus)

Assumption flaw-

That the AO = OPI

The best correlation you could run is as follows-

1) all pos OPI years correlate V the following winter AO & all neg OPI years correlate to the following winter AO

That gives you the lowest correlation score as it includes months with very low neutral scores.

 

 

Since when has it been assumed that the AO = OPI?

The correlations I've shown are reproducible by anyone with the freely available data and with regards to the Taymyr peninsula the research has been subject of a published paper linked to two days ago in this thread - https://forum.netweather.tv/topic/81637-eddy-heat-flux-over-eurasian-snow-cover/

The point is that it supports a possible link between October circulation and the following winter AO which may be measured by the OPI.

But as it is unclear exactly how the OPI is calculated it cannot be independently tested. We already know that the values appear to fit the historical data well so it is correlations of the OPI and winter AO which are the waste of time.

  • Like 8

Share this post


Link to post
Share on other sites

Back to where we were this time yesterday at -2.75. Let's hope it doesn't rise on the 12z.

Share this post


Link to post
Share on other sites

-2.75! We are doing well. :-)

Edited by karyo
  • Like 1

Share this post


Link to post
Share on other sites

-2.75! We are doing well. :-)

Very little change from the 0Z. Starting to stabilize.

Edited by radiohead
  • Like 2

Share this post


Link to post
Share on other sites

Very little change from the 0Z. Starting to stabilize.

It is indeed and I am starting to get excited!

  • Like 1

Share this post


Link to post
Share on other sites

It is indeed and I am starting to get excited!

 

i'm holding back for a little month because it's still not evaluated by the prof. team. But when the blocking gets in the forecast around the end of november-dec and the OPI team aproves this OPI score then i will start to get excited (and more then usual! :))

  • Like 1

Share this post


Link to post
Share on other sites

It is indeed and I am starting to get excited!

Only 8 days of forecasting left, get that down to 5 and we are at the business end!

  • Like 4

Share this post


Link to post
Share on other sites

Only 8 days of forecasting left, get that down to 5 and we are at the business end!

I would normally be more cautious, especially if a cold spell was forecasted for the UK, but as southwesterlies are forecasted then nothing can go wrong!

  • Like 1

Share this post


Link to post
Share on other sites

My god -2.75 is excellent!!especially considering that the month is coming to a close!!!are we actually gone end up around -2.75 -2.50 :0!!!

Share this post


Link to post
Share on other sites

I have now seen Chino and Steve refer to the OPI as a hindcast. Maybe I am missing something in the meaning or something is getting lost in translation but doesn't every scientific theory uses observation and past data to formulate a theory that can hopefully make successful forecasts/predictions which will determine if it has any merit as a scientific principle?

Every theory is reverse engineered to explain the observed world and then tested for predictive accuracy isn't it?

 

Hindcast to me means that you modify your theory to fit new data when it was wrong.

Edited by Mucka

Share this post


Link to post
Share on other sites

I have now seen Chino and Steve refer to the OPI as a hindcast. Maybe I am missing something in the meaning or something is getting lost in translation but doesn't every scientific theory uses observation and past data to formulate a theory that can hopefully make successful forecasts/predictions which will determine if it has any merit as a scientific principle?

Every theory is reverse engineered to explain the observed world and then tested for predictive accuracy isn't it?

 

Hindcast to me means that you modify your theory to fit new data when it was wrong.

No, hindcast is using past data to test your mathematical theory. However, you have the benefit of the statistical data to build your theory - in fact you may have played around a number of times to modify your theory so that the backtest is improved. I very much doubt that the OPI team came out with their formula at the first time of asking. However, the true test comes in the forecast element.

 

http://en.wikipedia.org/wiki/Hindcast

Share this post


Link to post
Share on other sites

-2.39 after the 12Z. Certainly starting to look like we are getting better consistency today compared to previous days.

Edited by radiohead
  • Like 1

Share this post


Link to post
Share on other sites

No, hindcast is using past data to test your mathematical theory. However, you have the benefit of the statistical data to build your theory - in fact you may have played around a number of times to modify your theory so that the backtest is improved. I very much doubt that the OPI team came out with their formula at the first time of asking. However, the true test comes in the forecast element.

 

http://en.wikipedia.org/wiki/Hindcast

 

Hi Chino,

 

Maybe this is just semantics but what is a mathematical theory built on if not past data whether that be in statistical form or observational form?

And surely the test of the theory of the October Pattern Index is whether it can forecast future patterns not explain previous ones which would be part of the development and refinement of the theory?

Edited by Mucka
  • Like 1

Share this post


Link to post
Share on other sites

-2.39, a third consecutive drop if we compare the 12z day by day (which we should really). Just 8 more now...

 

That's not a bad finishing zone...

 

S

  • Like 1

Share this post


Link to post
Share on other sites

Has anyone managed to get a PDF of the Taymyr paper yet, everywhere I looked today it was paywalled?

Share this post


Link to post
Share on other sites

Hi Chino,

 

Maybe this is just semantics but what is a mathematical theory built on if not past data whether that be in statistical form or observational form?

And surely the test of the theory of the October Pattern Index is whether it can forecast future patterns not explain previous ones which would be part of the development and refinement of the theory?

It's a complicated problem for meteorology compared with lets say a situation where you have a simple hypothesis and test it in other scientific areas.

 

If you developed a theory that was testing the OPI for future forecast patterns the researcher would be six feet under before the theory could be properly tested, however if you build a theory around certain historic patterns and see how that's repeated then you can still build up a good picture.

 

Lets take the NAO for example in western Europe, its commonly accepted that a negative NAO is linked to colder winters but that is based on our reviewing past patterns, if we don't look back then trying to develop a theory would be almost impossible. Where exactly would we start?

 

Now of course it maybe possible that years down the line the OPI will be viewed just as the NAO is or  the AO.

  • Like 3

Share this post


Link to post
Share on other sites

judging from tonights NOAA cpc update, we may have to wait a few more days before we see a landing zone < 0.5 spread

'SIGNIFICANT UNCERTAINTY IS EVIDENT IN THE MODEL FORECASTS OVER ALASKA AND THE  NORTH PACIFIC EVEN AT RELATIVELY EARLY LEAD TIMES.' 
Edited by bluearmy
  • Like 1

Share this post


Link to post
Share on other sites

 

judging from tonights NOAA cpc update, we may have to wait a few more days before we see a landing zone < 0.5 spread

'SIGNIFICANT UNCERTAINTY IS EVIDENT IN THE MODEL FORECASTS OVER ALASKA AND THE  NORTH PACIFIC EVEN AT RELATIVELY EARLY LEAD TIMES.' 

Could this mean that there can be more blocking there than the models currently show?

Share this post


Link to post
Share on other sites

No, hindcast is using past data to test your mathematical theory. However, you have the benefit of the statistical data to build your theory - in fact you may have played around a number of times to modify your theory so that the backtest is improved.

 

This is not necessarily a mistake. If the procedure is done correctly and you succeed in a high correlation of your prediciton then nothing is wrong of course and you have done a good job. But of course the question is always if you haven't ovedone it with your model and your number of inputs is larger compared to the observation and the phenomenon you want to explain. I think you(English dudes) call it overfitting or something right?

 

And the ultimate and perhaps only test is of course the FUTURE. If your model can explain the next new "values",- in our case the next AO-, with similar correlation as the hindcasted data, then you are ok and your model really works.

Edited by Crocodile23
  • Like 3

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...