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Riccardo

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

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The better the 12z, the bigger fall you're setting yourself up for- it's all a trap!

But seriously, it does look like another sub -2.5 run, just hoping for the next 10 days it can hold steady around here. Landing range between -1.5 and -2.5 I'd say.

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The UKMO is much more mobile and pushes the Arctic high away pretty quickly! It is similar to its 0z output so maybe it is slow at picking the new signal. Let's see what the ECM says later.

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The UKMO is much more mobile and pushes the Arctic high away pretty quickly! It is similar to its 0z output so maybe it is slow at picking the new signal. Let's see what the ECM says later.

pretty strong Greenland high though to maybe balance things out? Edited by shaky

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Todays OPI of -2.52 continues to cement the thoughts on where the landing zone is going to be.

 

Heres a nice statistic & very simple.

 

If we have 4 more days after today at -2 which looks likely-

 

This takes us out to the 25th,

 

After that even if the last 6 days averaged Only Neutral we would deliver -1.65.

 

Nearly there folks....

 

S

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pretty strong Greenland high though to maybe balance things out?

It looks like a surface high to me.

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GEM has backed off its cut off arctic hgh and subsequent high anomolys spread across the arctic. now finds an aluetian ridge and general nw canadian/alaskan blocking in contrast with its earlier run. at least gfs is showing a modicom of consistency though tbh, no model currently covering itself in glory with its arctic modelling post day 6 at the moment.

 

cant really see any way that a sub -1.5 OPI cannot be returned, though whether it could get below -2 remains in the balance.

 

thereafter, we await riccardo's teams analysis.

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Todays OPI of -2.52 continues to cement the thoughts on where the landing zone is going to be.

 

Heres a nice statistic & very simple.

 

If we have 4 more days after today at -2 which looks likely-

 

This takes us out to the 25th,

 

After that even if the last 6 days averaged Only Neutral we would deliver -1.65.

 

Nearly there folks....

 

S

 

So it will be a super duper -AO then? :yahoo:

 

get ready folks...a repeat of winter 2009/10 looks likely :bomb:

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Maybe, I would like to see an OPI of -2 for the month to be able to forecast at least 1 month with a SUPER -AO ( -2 index )

S

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So it will be a super duper -AO then? :yahoo:

 

get ready folks...a repeat of winter 2009/10 looks likely :bomb:

 

That is if the correlation between a negative OPI and a higher chance of a weak polar vortex/mean -AO pattern during winter holds true of course...

 

Either way, it will certainly make watching this winter unfold even more interesting/heart palpitation inducing and it will be a good test for the model.

Edited by Chris K
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I hope these OPI stats turn out right for a cold winter in the UK, otherwise the Samaritans will be busy in a few months time.

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I hope these OPI stats turn out right for a cold winter in the UK, otherwise the Samaritans will be busy in a few months time.

I've held back up to now, but i'm genuinely starting to get a little excited.... Let hope it delivers the goods tongue.gif

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2.19   looking very good

 

If it was 2.19 I'd be crying right now

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If it was 2.19 I'd be crying right now

whoops  forgot this -  

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I feel a bit disappointed by that, however it's still sub -2 which is good. If the OPI theory is correct anyway!!!!

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get ready folks...a repeat of winter 2009/10 looks unlikely :bomb:

 

Fixed that for you. :wink:

Edited by The Eagle
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Fixed that for you. :wink:

 

Thanks.

 

get ready folks...a repeat of winter 2009/10 looks unlikely, because were getting 1962/63 repeat.

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I can't help feeling we would not be in the current position with the OPI if it were not for us being in an Easterly QBO phase.

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I can't help feeling we would not be in the current position with the OPI if it were not for us being in an Easterly QBO phase.

Indeed...but an Easterly QBO is no guarantee of a colder winter either.

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Another angle on this ... one thought in my mind has been that, though the PV has taken time to get its act together, it hasn't been far off at any point and now as the end of October approaches all the PV cards might fall into line, at least if some recent model runs are to be believed:

 

ECH1-192.GIF?21-0

 

... also, some others on here have wondered if the state of the atmosphere at the end of October is more important than at the beginning - after all, why should the OPI limit itself to being a straight average across the 31 days of October?

 

So I dug out the NH charts for the end of October for some of the recent "super negative" OPI years:

 

archivesnh-2012-10-31-0-0.png

archivesnh-2009-10-31-0-0.png

archivesnh-1984-10-31-0-0.png

archivesnh-1976-10-31-0-0.png

So all of the previous years had a far more scattered PV come the end of October, I'd sure you'd agree from the above - and therefore I suggest the daily OPI readings at the end of these months were still contributing to the overly negative OPI score - whereas with this year, the OPI might be holding on based on "gains" from earlier in the month (though of course the chart for 29th October 2014 is merely a forecast that could be wrong).

 

Something to think about if this year's AO does not match up to previous years with -1.5 OPIs or less.

Edited by rjbw
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Having viewed the 12z output it appears that the GFS is the most promising in terms of blocking! The ECM unfortunately sides more with the UKMO and sinks the Arctic high quite quickly. We just need this sinking process to slow down as much as possible! Quite a frustrating evening for me...

 

Karyo

Edited by karyo

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Another angle on this ... one thought in my mind has been that, though the PV has taken time to get its act together, it hasn't been far off at any point and now as the end of October approaches all the PV cards might fall into line, at least if some recent model runs are to be believed:

 

 

 

... also, some others on here have wondered if the state of the atmosphere at the end of October is more important than at the beginning - after all, why should the OPI limit itself to being a straight average across the 31 days of October?

 

So I dug out the NH charts for the end of October for some of the recent "super negative" OPI years:

 

 

 

 

So all of the previous years had a far more scattered PV come the end of October, I'd sure you'd agree from the above - and therefore I suggest the daily OPI readings at the end of these months were still contributing to the overly negative OPI score - whereas with this year, the OPI might be holding on based on "gains" from earlier in the month (though of course the chart for 29th October 2014 is merely a forecast that could be wrong).

 

Something to think about if this year's AO does not match up to previous years with -1.5 OPIs or less.

 

I've deleted the charts in your post for economy of space.

 

As far as I understand, the pattern needs to be looked at in terms of geopotential height anomalies - these charts do not show that and as far as I can see not available in archived data. Probably can do it in reanalysis if important.

 

What the anomalies of the month to date show, is that it will take very negative poleward heights to make inroads on what we have already 'banked'.

 

89uqx1P.gif

Edited by Nouska
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I wouldn't say there's that much in it rbjw - 76 in particular was significantly more organised and in a much worse position than our current one.

While heights over the Arctic are maybe a bit lower generally than some of those other charts it still doesn't look particularly organised. Also worth remembering Interitus' comments on this too - the -ve value this time actually comes from the angle bit of the equation rather than just the heights.

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