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

[Mucka]

The 18z certainly has a good deal more blocking at higher latitudes and that is reflected through the ensembles as well, including this strange beast.

 

 

Hopefully we will get sub -2 tomorrow in the 00z.

[bluearmy]

The 00z gem very blocked throughout. The 00z gfs less so and at day 6, gfs and Ukmo look closer than gem. Fwiw, GEM is a decent tool in the arctic but I think it isn't progressive enough at the moment. definitely a shift for gpt anomalys to be less marked in the 5/7 day period as the op modelling has ticked down. ignoring where the models are in the 8/10 day period, that mid range variance is bound to lift the OPI wrt the modelled element as we saw in yesterday's 12z. By the end of the gefs, those members looking like they are building a compact vortex are still well outnumbered.

It's possible we won't get an update wrt the 00z, looking at some of the anomalys at day 6.

[Timmytour]

I think of the PV like a plum tree....is it going to bear a lot of fruit or not this year.  Only in this analogy "bearing fruit" is the opposite of what we'd normally think of as "bearing fruit"!

So the tree can much look the same come as any other year come late March....but some years it will bear a lot of fruit and some years it will hardly bear any.

I see the OPI as a means of an early measure of what the year will be like. A negative return indicates that, whatever the tree looks like, the blossom is not of a quality that will result in a good crop.....or the PV hasn't got the inherent strength required to keep itself compact throughout the winter and will be vulnerable to attacks from time to time.
 

[Paul_1978]

There's been 48 years of OPI recording, and in 8 of them, the OPI has been sub -1 (of course only one year, 2009, was sub -2)

 

OPI (Winter CET anomaly)

2009:  -3.15 (-2.1c)

1985:  -1.9 (-1.6c)

1984:  -1.8 (-1.8c)

1978:  -1.8 (-2.9c)

1976:  -1.75 (-1.2c)

2012:  -1.65 (-0.7c)

1986:  -1.3 (-1.0c)

1982:  -1.1 (-0.2c)

 

See, don't get too scared folks! Hell, even 1981-82, 1995-96 and 2010-11 are missing from here, night!

Was 1976/77 a good winter anyone? It's not one that gets talked about often - all the others crop up from time to time but never 76/77.

[Timmytour]

Was 1976/77 a good winter anyone? It's not one that gets talked about often - all the others crop up from time to time but never 76/77.

December is in the top 15% of coldest winters since 1700......January is in the top third.

I think it was a cold winter without being all that spectacular in terms of snow

[Weather-history]

Was 1976/77 a good winter anyone? It's not one that gets talked about often - all the others crop up from time to time but never 76/77.

December 1976 is seldom talked about despite being colder than December 1995 but there were some decent snowfalls during first half of January 1977

[karyo]

Not a good 0z GFS or UKMO for that matter but at least the ECM is much better with at least some high pressure over the Arctic till the end of the month.

[Interitus]

Amusing how this has become a version of the model thread with 'predict the OPI', and even more so when most interpretations don't seem to take into account how the OPI is calculated.

However, there may be more to Arctic heights than meets the eye.

Over the 38 years of the OPI data, the October AO correlation with winter AO is a weak positive 0.279 and 65.8% of winters have the same AO sign as October (compared to ~50% by chance).

But looking at the October 500mb geopotential anomaly over only the north pole from NCAR/NCEP plots though shows that a positive anomaly followed by a negative winter AO and vice versa is correct 73.7% of the time with a correlation of 0.387.

Now the figures aren't up to what is claimed for the OPI but shows they might have stumbled on something.

One more thing particularly piqued my interest, in creating some sort of index to compare the north pole geopotential to the winter AO, the anomaly was negated and divided by 100 and notably the result was identical to the OPI for 1980, 1993 and 1994.

Admittedly this is from BFTVs figures but then it was also very close on a couple of others.

Edited October 21, 2014 by Interitus

[karyo]

-2.52 based on the 6z which is a relief.

Edited October 21, 2014 by karyo

[Radiating Dendrite]

-2.52 based on the 6z which is a relief.

 

Another encouraging update.

 

I think people need to all relax a little - we aint going to end up at +1.6 like last year and there are many other drivers too.

 

Last winter was as bad as it could get for cold here (not a single snowflake) so anything will be an improvement on that.

[shaky]

Quite an increase on yesterday's 12z!!!we are pretty much there now to be confident of a negative opi!!!!my guess is we shall end up somewhere between sub-1.5 or -2!!

[MPG]

Quite an increase on yesterday's 12z!!!we are pretty much there now to be confident of a negative opi!!!!my guess is we shall end up somewhere between sub-1.5 or -2!!

Just wait until next year when the OPI is well in the positive, imagine all the 'winters over' comments. But........those comments will only appear if this years winter is something to talk about regarding cold.......due to a possible negative OPI this Oct.

Edited October 21, 2014 by MPG

[Ali1977]

There is a little pattern on the OPI charts, an decrease from a low point ( -1.86 to -2.52 ) has always been followed by another decrease...Eg, tonights update may go lower.....

I know it doesn't work like that in reality, but so far this month that is the pattern.

[radiohead]

Looking at the years we have OPI numbers for, it's remarkable that with the single exception of 90/91, there has never been a +OPI followed by a cold winter.

[karyo]

Just wait until next year when the OPI is well in the positive, imagine all the 'winters over' comments. But........those comments will only appear if this years winter is something to talk about regarding cold.......due to a possible negative OPI this Oct.

At least then we can forget about the winter and focus on other hobbies. I've spent so many hours last year looking at the models and the stratosphere hoping for the appearance of a decent cold spell that never came.

[MPG]

At least then we can forget about the winter and focus on other hobbies. I've spent so many hours last year looking at the models and the stratosphere hoping for the appearance of a decent cold spell that never came.

I know exactly what you mean

[feb1991blizzard]

Looking at the years we have OPI numbers for, it's remarkable that with the single exception of 90/91, there has never been a +OPI followed by a cold winter.

 

And to add to that, the most potent cold spell of that winter was actually a +NAO signal, one of those quirks of fate, a really thin shaped scandi high.

[Gael_Force]

Looking at the years we have OPI numbers for, it's remarkable that with the single exception of 90/91, there has never been a +OPI followed by a cold winter.

 

Perhaps you are being UK specific. October 2011 was weakly positive yet winter saw record breaking cold all over mainland Europe. As others have said in this thread,  where you are geographically, can alter perspective to a great extent.

 

http://en.wikipedia.org/wiki/Early_2012_European_cold_wave

[neige57]

Perhaps you are being UK specific. October 2011 was weakly positive yet winter saw record breaking cold all over mainland Europe. As others have said in this thread,  where you are geographically, can alter perspective to a great extent.

 

http://en.wikipedia.org/wiki/Early_2012_European_cold_wave

 

except that in December 2011 and January 2012 was very soft on Europe. The cold snap in February 2012 was a stroke of luck, thank you Russian anticyclone. And case studies from February 2012 was explained by Riccardo. The cold snap was expected three months in advance

[Continental Arctic Front]

There is a little pattern on the OPI charts, an decrease from a low point ( -1.86 to -2.52 ) has always been followed by another decrease...Eg, tonights update may go lower.....

I know it doesn't work like that in reality, but so far this month that is the pattern.

i'm looking at the 12z right now, and based on this run i see more blocking then the 06z on +96hr, so you can be right. i'm also glad to see that the OPI has dropped again in the 06z. The change of ending below -1.5 is realistic i think

[Ali1977]

Pressure already much higher over the NH at T108 on the 12z gfs....

[Gael_Force]

except that in December 2011 and January 2012 was very soft on Europe. The cold snap in February 2012 was a stroke of luck, thank you Russian anticyclone. And case studies from February 2012 was explained by Riccardo. The cold snap was expected three months in advance

 

Hi Neige, - did they have a forum discussion board for that year? First I saw on here was last year but maybe locally a topic for longer. I see you use the term soft for the mildness,  you are both knowledgeable and very protective of the theory - are you one of the team involved in the research?

[shaky]

Crazy change on the gfs 12z and pretty early on in the run aswell!!much stronger blocking across the arctic!!looking good again for a drop in the opi!!

[neige57]

Hi Neige, - did they have a forum discussion board for that year? First I saw on here was last year but maybe locally a topic for longer. I see you use the term soft for the mildness,  you are both knowledgeable and very protective of the theory - are you one of the team involved in the research?

 

 

negative but I would have loved to work on 

[karyo]

Yes, very good 12z, especially early on!