Jump to content
Sign in to follow this  
Riccardo

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

Recommended Posts

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

 

You mean -2.0  :D

Share this post


Link to post
Share on other sites

You mean -2.0 :D

Phew...... Winter could have been over with one small typo!

Edited by Fingers

Share this post


Link to post
Share on other sites

Monthly AO index:

 

Jan    Feb    Mar    Apr    May    Jun    Jul    Aug    Sep    Oct    Nov    Dec 
1950 -0.060  0.627 -0.008  0.555  0.072  0.539 -0.802 -0.851  0.358 -0.379 -0.515 -1.928
1951 -0.085 -0.400 -1.934 -0.776 -0.863 -0.918  0.090 -0.377 -0.818 -0.213 -0.069  1.987
1952  0.368 -1.747 -1.859  0.539 -0.774 -0.441  0.383 -0.030 -0.383 -0.437 -1.891 -1.827
1953 -1.036 -0.249  1.068 -1.256 -0.562  0.023  0.333  0.085  0.662 -0.194  0.354  0.575
1954 -0.148 -0.181  0.476  0.512 -1.656 -0.268  0.341 -0.122  0.301  0.513 -0.328  0.553
1955 -1.163 -1.542 -1.568  0.194  0.242 -0.266  0.332  0.760  0.357  0.099 -1.342 -0.444
1956 -1.204 -2.029  0.470 -0.868  1.391  0.280 -0.215 -0.652 -0.202  1.139 -0.066  0.001
1957  2.062 -1.513 -2.013  0.238 -0.966 -0.760 -0.646  0.097 -0.956  0.903 -1.380  0.828
1958 -1.438 -2.228 -2.522 -0.360 -0.336 -1.149 -0.684 -0.755 -0.012  0.770 -0.011 -1.687
1959 -2.013  2.544  1.432  0.119 -0.341 -0.033  0.105 -0.745 -0.281 -0.249 -1.411 -0.042
1960 -2.484 -2.212 -1.625 -0.297 -0.857  0.055 -0.619 -1.008 -0.382 -1.187 -0.553 -0.343
1961 -1.506  0.621  0.341 -0.237  0.157  0.837 -0.108  0.013  0.815  0.203 -0.010 -1.668
1962  1.645 -0.358 -2.848  1.169  0.068  0.287 -0.927  0.152 -0.056 -0.016 -1.112 -0.711
1963 -3.311 -1.721  0.724 -0.348  0.771 -0.585 -0.303 -0.625  0.083  1.069 -0.419 -1.178
1964  0.385 -0.575 -0.558  0.663  1.174  0.142  0.734 -1.207 -0.227  0.342 -0.344 -0.246
1965 -1.046 -2.084 -0.905  0.568 -0.153  0.038 -0.510 -0.255 -0.698  0.394 -1.341  0.163
1966 -3.232 -1.438 -0.911 -1.837  1.124  0.408  0.011 -0.945  0.011 -1.077  0.111 -1.401
1967 -0.576  1.180  1.967  1.700  0.127  0.647  0.259 -0.293  0.133  1.299  0.334 -0.347
1968 -0.409 -2.154  1.741  0.328 -0.241  0.420 -0.836 -0.671 -1.009 -1.013 -2.183 -0.783
1969 -2.967 -3.114 -1.582  0.438 -0.720 -0.348  0.410 -0.782 -0.083  0.098  0.326 -1.856
1970 -2.412 -1.325 -2.084  0.302  0.531  0.875  0.139 -0.263  0.030  0.098  0.378 -0.399
1971 -0.163 -0.922 -1.091 -0.583  0.679 -0.668 -0.578  0.818  0.153  1.185  0.419  0.824
1972  0.166 -0.195 -0.141  1.007  0.140 -0.049 -0.553 -0.082 -0.920  0.392 -0.380  1.238
1973  1.232  0.786  0.537 -1.126  0.073  0.531  0.270  0.313  0.114  0.337  0.002 -0.181
1974  0.232 -0.489 -0.746  0.309 -0.507 -0.048  0.390 -0.533 -0.136 -1.024 -0.435  0.556
1975  1.595  0.194  0.151  0.409 -0.614 -0.323  0.345  0.130  1.278  0.138  0.619  1.290
1976  0.034  1.656  0.587  0.440  0.060  0.328 -0.325  0.559 -0.743 -0.804 -0.087 -2.074
1977 -3.767 -2.010  0.344  1.329  0.104 -0.226 -0.492 -1.412  0.586 -0.009  0.605 -0.240
1978 -0.347 -3.014  0.502 -0.967  0.059  0.635 -0.604 -0.354 -0.099  0.895  2.470 -0.980
1979 -2.233 -0.697 -0.814 -1.157 -0.250  0.933  0.039 -0.684 -0.046 -1.243  0.475  1.295
1980 -2.066 -0.934 -1.433 -0.419 -1.155  0.721 -0.622 -0.185  0.313 -0.521 -1.361 -0.057
1981 -0.116 -0.332 -1.645  0.430  0.180 -0.438  0.561 -0.244 -1.040 -1.167 -0.188 -1.216
1982 -0.883  0.974  1.074  1.454 -0.209 -1.180  0.005  0.362  0.558 -0.211  0.661  0.967
1983  1.359 -1.806 -0.567 -0.738 -0.441  0.313  0.131  1.098  0.167  1.369 -0.688  0.186
1984  0.905 -0.303 -2.386 -0.284  0.479  0.007  0.019  0.466 -0.413 -0.270 -0.966  0.446
1985 -2.806 -1.440  0.551  0.652 -0.432 -0.347 -0.390 -0.001  0.114  1.035 -1.218 -1.948
1986 -0.568 -2.904  1.931  0.103  0.367  0.535 -0.008 -0.826 -0.023  1.425  0.926  0.060
1987 -1.148 -1.473 -1.746  0.387  0.325 -0.710 -0.466 -0.836  0.287 -0.080 -0.536 -0.534
1988  0.265 -1.066 -0.197 -0.561 -0.846  0.061 -0.143  0.255  1.039  0.032 -0.035  1.679
1989  3.106  3.279  1.530 -0.250  0.889  0.345  0.866  0.551  0.703  0.991  0.034 -0.644
1990  1.001  3.402  2.990  1.879  0.943  0.304 -0.296 -0.180 -0.210  0.660  0.521  1.277
1991  0.723 -0.876 -0.527  0.530  0.486 -0.115 -0.188  0.797 -0.112 -0.252  0.285  1.613
1992  0.550  1.122  0.984 -0.521  1.341 -0.302  0.191  0.535 -0.640 -0.366  0.717  1.627
1993  3.495  0.184  0.764 -0.435 -1.607 -0.520 -0.511 -0.393 -0.361 -0.565  1.002 -0.104
1994 -0.288 -0.862  1.881  0.225 -0.115  1.606  0.351  0.828 -0.084  0.174  1.779  0.894
1995 -0.154  1.429  0.393 -0.963 -0.891 -0.112 -0.217  0.544 -0.549  0.075 -0.723 -2.127
1996 -1.200  0.163 -1.483 -1.525 -0.226  0.497  0.715  0.125 -1.140  0.183  0.136 -1.721
1997 -0.457  1.889  1.091  0.324 -0.961 -0.815 -0.431  0.121  0.195 -0.700 -0.661 -0.071
1998 -2.081 -0.183 -0.254 -0.038  0.429 -0.711 -0.212  0.650 -1.050  0.294 -1.449  1.353
1999  0.110  0.482 -1.492  0.284  0.226  0.707 -0.002 -0.672  0.059 -0.006  0.611  1.043
2000  1.270  1.076 -0.451 -0.279  0.969  0.586 -0.649  0.144  0.395  0.317 -1.581 -2.354
2001 -0.959 -0.622 -1.687  0.906  0.452 -0.015 -0.031  0.521 -0.707  0.707  0.819 -1.322
2002  1.381  1.304  0.902  0.748  0.401  0.573  0.328 -0.229 -0.043 -1.489 -1.425 -1.592
2003 -0.472  0.128  0.933 -0.178  1.017 -0.102  0.075 -0.280  0.467 -0.670  0.642  0.265
2004 -1.686 -1.528  0.318 -0.409 -0.094 -0.236 -0.201 -0.720  0.855 -0.515  0.678  1.230
2005  0.356 -1.271 -1.348 -0.046 -0.763 -0.383 -0.030  0.026  0.802  0.030  0.228 -2.104
2006 -0.170 -0.156 -1.604  0.138  0.156  1.071  0.103 -0.265  0.606 -1.029  0.521  2.282
2007  2.034 -1.307  1.182  0.544  0.894 -0.555 -0.397 -0.034  0.179  0.383 -0.519  0.821
2008  0.819  0.938  0.586 -0.455 -1.205 -0.090 -0.480 -0.080 -0.327  1.676  0.092  0.648
2009  0.800 -0.672  0.121  0.973  1.194 -1.351 -1.356 -0.054  0.875 -1.540  0.459 -3.413
2010 -2.587 -4.266 -0.432 -0.275 -0.919 -0.013  0.435 -0.117 -0.865 -0.467 -0.376 -2.631
2011 -1.683  1.575  1.424  2.275 -0.035 -0.858 -0.472 -1.063  0.665  0.800  1.459  2.221
2012 -0.220 -0.036  1.037 -0.035  0.168 -0.672  0.168  0.014  0.772 -1.514 -0.111 -1.749
2013 -0.610 -1.007 -3.185  0.322  0.494  0.549 -0.011  0.154 -0.461  0.263  2.029  1.475
2014 -0.969  0.044  1.206  0.972  0.464 -0.507 -0.489 -0.372  0.102
 

Share this post


Link to post
Share on other sites

Daily figures up to and including 11/10 @ 18z: -1.2, -0.8, -0.3, -0.2, -2.2, -2.1, -3.42, -3.57, -3.85, -1.13, -2.0,

Mean at -1.89

Clem

Share this post


Link to post
Share on other sites

It struck me this evening that Super Typhoon Vongfong may be having an impact on the Nth Hemisphere profile forecast for the next 10 days and therefore included in the OPI model calculation. This is just an observation and may be nothing to do with yesterday's swing in the Index value, but if nothing else it's very interesting how a typhoon battering Japan seems to end up dragging the PV along in its' wake. I've marked up a few charts showing this:

 

Vongyong enters the arena on 12th Oct: post-20040-0-51508000-1413056124_thumb.j By the 15th engages with cold uppers  post-20040-0-18967000-1413056193_thumb.j

 

By the 16th an active influence on the Nth Hemisphere cold pool and arguably already impacting the axis of the PV  post-20040-0-56339300-1413056322_thumb.j

 

By the 19th it appears to me that Vongfong is saying to the PV "follow me".... post-20040-0-34469000-1413056467_thumb.j 

 

So interesting in my view, with GFS suggesting from these forecast charts that Vongfong will have an impact on the axis of the PV over the 10 day forecast period, which is included in the OPI calculation.

Share this post


Link to post
Share on other sites

Just spend a good 45 minutes reading through the posts in this thread, thoroughly interesting subject and one to sure keep updated with over the coming weeks  :good:

Share this post


Link to post
Share on other sites

How exactly is the ODI index calculated? I'm guessing it's similar to how the AO index is arrived at only with regard to contrasting 500mb anomalies.

Share this post


Link to post
Share on other sites

looking at the polar profile over the next 10 days shows a current situation where there is one small defined vortex just east of the pole to one where we have several chunks split around the arctic. that is still promising but it drags the OPI up as the more area of the arctic with a negative gpt anomoly, the higher the opi reading. there seems little appetite to build a decent singular vortex in the week 2 ens modelling so i doubt very much that we are going to see a positive final OPI. whether we can stay below 1.0 seems to be the main question for me.  thus far in october, we have seen virtually no low thicknesses (in context) the american side of the pole. that will change over the next week as a vortex segment becomes established week 2 ne canada/nw of greenland. eventually, we seem likely to end up with a potential vortex axis siberia across to ne canada (not great) but note 'potential'. the arctic high has done its job thus far and the fi op ecm would seem to show that it might be capable of keeping the developing lobes of vortex split which will keep the OPI that bit lower.

Share this post


Link to post
Share on other sites

Putting aside the way the OPI is or isn't calculated, the relationship with the AO later on is surely as simple as the vortex being allowed or not being allowed to form 'properly' during October. Obviously the vortex will do so as Autumn gathers pace no matter what, that's unavoidable, but the more fragmented and disorganised it is at this critical stage of its formaton, the less of an early foothold it will gain and thus the less influence it will have in terms of dominating and dictating the succeeding winter.

 

If the car race starts in, say, Mid-November and the PV was an entrant, he would rather have a car in top working order for the race than one with a misfiring engine and a poor steering. Most of us on the other hand will of course be hoping he qualifies last and splutters off the line with the exhaust hanging off. Yes some of the problems may well be fixed in pitstops later on but the car will likely always be more susceptible.

 

Of course even this doesn't guarantee a cold spell for us but it improves the chances ten fold when compared to a self-fuelling raging vortex sat around Greenland steering in the Atlantic weather to our shores unabated!

Edited by s4lancia

Share this post


Link to post
Share on other sites

 we seem likely to end up with a potential vortex axis siberia across to ne canada (not great) 

 

This would actually be calculated as a low axis angle and would lower the OPI

Edited by Interitus

Share this post


Link to post
Share on other sites

This would actually be calculated as a low axis angle and would lower the OPI

Thus is where I get lost . I would have thought that a vortex on its usual long term standard axis of Siberia across to ne Canada would not be conducive to one which is struggling to become established??

Share this post


Link to post
Share on other sites

 

After today's 06Z : -0.64

 

Not good to see it rise but I guess the 6z was a more mobile run compared to yesterday's. The ECM also looks more mobile than yesterday so not a good trend today.

Share this post


Link to post
Share on other sites

At this time last year (12th October), we'd seen 3 negative days and 9 positive days, compared to 12 negative days this year. To come last year were 19 positive days and no negative days.

 

Just in case people were wanting comparisons.

Share this post


Link to post
Share on other sites

At this time last year (12th October), we'd seen 3 negative days and 9 positive days, compared to 12 negative days this year. To come last year were 19 positive days and no negative days.

 

Just in case people were wanting comparisons.

That's useful to know and compare. I guess we need to be as far away from last year's outcome as possible so any rise is a worry.

Share this post


Link to post
Share on other sites

I have a funny feeling the value will stay negative but slowly creep up towards 0 at day 15 then it will stay positive and rise steadily until the end of October.  

Heard it here first. 

Share this post


Link to post
Share on other sites

This was copied and posted on an Italian weather forum on 28th October, so pretty much the final article.

 

OPI002.png

Share this post


Link to post
Share on other sites

This was copied and posted on an Italian weather forum on 28th October, so pretty much the final article.

 

OPI002.png

Thanks. Those 3 days with a negative value look really weird!

Share this post


Link to post
Share on other sites

Thanks. Those 3 days with a negative value look really weird!

 

Yes, looking at the archives of the GFS H500 anomalies for last October, it is not immediately obvious.

 

The runs are here if anybody is interested in looking at them.

 

http://www.meteociel.fr/modeles/gfse_cartes.php?jour=1&mois=10&annee=2013&heure=12&archive=1&mode=12&ech=6&carte=1

Share this post


Link to post
Share on other sites
yes it is highly strange. Riccardo should probably know why? 

 

But it is true that the days (thus the 5, 7 and 10 October 2013), there was no evidence of a negative OPI cards medium and long term

 

Returning to the present, the IPO index is negative and this is the most important. There was no day is spent in the positive. The average of 1 to October 15 will be negative and no doubt this is a very positive :)

Share this post


Link to post
Share on other sites

Thus is where I get lost . I would have thought that a vortex on its usual long term standard axis of Siberia across to ne Canada would not be conducive to one which is struggling to become established??

 

Regarding axis angle this is their explanation from their analysis of 1984/5 - http://daltonsminima.altervista.org/2013/10/26/opi-reanalisi-1984-85/

Google translation -

As we explained in the study, the increase in capacity of the waves intrusive (and thus their ability to Bilobar / split the VP) does not grow in a linear fashion, but it becomes very dominant only for very low inclinations of the vortex (when in fact it located next to be orthogonal to the imaginary line joining between the two major oceans). In these conditions, for reasons related to the continuity of mass, the wave manages to be much more effective in interrupting the circulation westerly and easterly moment to introduce large quantities within the normal westerly circulation of the VP.

 
About these topics, we talk about 84 that provides a very useful case study to learn some good concepts, related precisely to the question "axis" of the VP.....
 
.......October 1976 was characterized by the anomaly on the positive pole, and the axis was in fact much less inclined than 84 (one of the least inclined of the series).
 
To conclude, therefore, 1984 is a unique case, but very well framed from October because:
 
a) the strong anomaly on the pole (areas on Mar Kara / mar Siberia) which characterizes all the years in which the vortex is very bilobed / split;
 
b) high tilt axis. As has been stated several times, principally for reasons related to the continuity of mass, the waves are able to be highly intrusive and therefore able to split the vortex generally when they are centered on the two oceans (axis slightly inclined); 84 did not.
 
So using NCEP/NCAR reanalysis, 1976 low axis inclination -
post-2779-0-63097000-1413123262_thumb.pn
 
1984 high axis angle
post-2779-0-04995900-1413123309_thumb.pn
 
Some further observations -
 
the "factor ε value" = (Asia + America - Arctic) / 10
 
φ angle = 34.37 - Angle
Some exponential or perhaps trigonometrical function transforms this to the Φ(φ) value, not sure exactly but easy to approximate. Then as already established this is added to the Îµ value for the final result.
Now need to work out where and how the measurements are made, might not be able to recreate exactly but there should be enough to recreate something similar to test with historical data.

Share this post


Link to post
Share on other sites

 

yes it is highly strange. Riccardo should probably know why? 
 
But it is true that the days (thus the 5, 7 and 10 October 2013), there was no evidence of a negative OPI cards medium and long term
 
Returning to the present, the IPO index is negative and this is the most important. There was no day is spent in the positive. The average of 1 to October 15 will be negative and no doubt this is a very positive :)

 

 

At a guess, until the average establishes itself the axis angle will be very sensitive to changes in pressure pattern, far more so than the changes in GPH and it is also the larger contributor to the overall value.

Share this post


Link to post
Share on other sites

Seems that each passing day takes us towards the idea that this thread should perhaps be locked for the next ten days in order to sustain the sanity of those opening it!

Share this post


Link to post
Share on other sites

Maybe if it was based on the ECM ensemble mean instead of GFS op runs,things might be a bit smoother,although

that would probably rob us of the sub -3 OPI goodness!

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  

×
×
  • Create New...