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

[karyo]

06z -3.37!

Could it be stabilising for the rest of the month? I certainly hope so.

[neige57]

Strange, the angle values are exactly the same as the 0z

 

Not at all surprisingly, the situation of 6Z GFS has not changed at all compared to this morning. Things have changed very little.

The value of the OPI index this morning was -3.36

[Interitus]

Not at all surprisingly, the situation of 6Z GFS has not changed at all compared to this morning. Things have changed very little.

The value of the OPI index this morning was -3.36

 

Well the angle is reported to the hundredth of a unit - assume they're degrees - to be identical as they are is a surprising result by chance.

[Blessed Weather]

I've used the NOAA NCEP website to generate the 16 day mean 500mb geopotential heights anomaly for 1st Oct to 16th October. In many aspects it resembles the composite heights anomaly for the top ten most negative OPI years and (hopefully!) shows how the Nth Hemisphere heights profile so far this October has helped give us the current negative OPI.

 

1st - 16th Oct mean 500mb heights anomaly:  

 

Composite for top ten negative OPI years: 

Edited October 17, 2014 by Blessed Weather

[Allseasons-Si]

What a fantastic post Tamara,very informative

[Mucka]

I doubt the OPI (As I understand the way it is calculated) will be great for the 12z but it looks like it off on one big time so I wouldn't put much stock in it,

It is the perpetual GFS failing of not dealing with any ridge or block to the East at all well - it will always try to send all the energy over the top and flatten the pattern.

Doesn't mean it is 100% wrong in this case but it is a known failing and it is not supported by the UKMO which historically deals with such set ups better,

 

Sorry, I am being a little over enthusiastic here I know. 

Edited October 17, 2014 by Mucka

[Captain Shortwave]

Well if the GEM is right then the tropospheric vortex looks pretty trashed by the end of the month.

[neige57]

I doubt the OPI (As I understand the way it is calculated) will be great for the 12z but it looks like it off on one big time so I wouldn't put much stock in it,

It is the perpetual GFS failing of not dealing with any ridge or block to the East at all well - it will always try to send all the energy over the top and flatten the pattern.

Doesn't mean it is 100% wrong in this case but it is a known failing and it is not supported by the UKMO which historically deals with such set ups better,

 

Sorry, I am being a little over enthusiastic here I know. 

 

 

it is a little worse in the short term but it is much better in the medium and long term so it will no doubt many negative

[LomondSnowstorm]

12Z GFS looks ok to me as far as the OPI goes, probably not quite as negative as the other two runs today as the Arctic heights do get shunted off the pole a bit but overall the vortex does not look in very good shape at all (which is very good news for us).

Edited October 17, 2014 by LomondSnowstorm

[Mucka]

Well if the GEM is right then the tropospheric vortex looks pretty trashed by the end of the month.

 

 

Yeah the result of the Scandi ridge being undercut, UKMO similar ideas but the GFS quite different in this respect. Well actually it sends some low pressure under but deals with the split energy very differently.

 

it is a little worse in the short term but it is much better in the medium and long term so it will no doubt many negative

 

Oh I'm sure it will be negative but my thinking was it would be less so than previous runs recently but that it didn't matter because this run has little support overall with the other models looking better.

I'm sort of testing my own understanding of what to look for as well.

Edited October 17, 2014 by Mucka

[bluearmy]

Well if the GEM is right then the tropospheric vortex looks pretty trashed by the end of the month.

 

 

i suspect that gem op will look a little isolated among its ens wrt the -AO value it derives !

[karyo]

The 12z gfs looks fine to me! Much better than the 0z ECM for sure.

[Mucka]

The 12z gfs looks fine to me! Much better than the 0z ECM for sure.

 

It is the worse of the 12z output for me though not terrible by any means. ECM 12z run is tasty day 10 chart

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014101712/ECH1-240.GIF?17-0

[feb1991blizzard]

It is the worse of the 12z output for me though not terrible by any means. ECM 12z run is tasty day 10 chart

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014101712/ECH1-240.GIF?17-0

 

Its an absolute ripper and not just for OPI purposes either!!!

 

[bluearmy]

It is the worse of the 12z output for me though not terrible by any means. ECM 12z run is tasty day 10 chart

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014101712/ECH1-240.GIF?17-0

And so far away from yesterday's 12z op that comparisons are useless.

[karyo]

It is the worse of the 12z output for me though not terrible by any means. ECM 12z run is tasty day 10 chart

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014101712/ECH1-240.GIF?17-0

The 12z ECM is an improvement throughout the run compared to its 0z output! 

 

As for the OPI it is stuck in the 6z figure.

[Yarmy]

The GFS actually verifies better at day 10 than the ECM:

 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/dieoff/cordieoff_HGT_P500_G2NHX.png

 

Although they both trail the...um...PRHW14 

[snowking]

The GFS actually verifies better at day 10 than the ECM:

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/dieoff/cordieoff_HGT_P500_G2NHX.png

Although they both trail the...um...PRHW14

Pure speculation, I wonder if perhaps that is the parallel GFS for the upcoming upgrade

SK

Edit: thinking about it, yes it will be - that was the codename used for the upgrade

Edited October 17, 2014 by snowking

[bobbydog]

seems to be a lot of scepticism about the OPI and Riccardo's motives for posting on here. i would have thought the ideal place to get a new forecasting theory 'out there' would be on weather forums. plenty of opportunity for independent review and evaluation before 'throwing himself to the wolves' so why not?

anyway, Cohen is an interested party and his theory of the Snow Advance Index has proven correlations to the AO. the OPI has yet to be proven but it does show undeniable similarities to the SAI.

understandably, we are all trying to get our heads around how it works but to be fair, he didnt just knock out the idea during an ad break in the x-factor! if it was that easy, someone on this forum would have done it by now!

however it works, the thing we have learned is that the nearer the end of october, the more accurate it becomes. by the 21st, we have the full month covered by actual and forecast data. from that point there will (should) be little deviation in the figures until we reach final value on the 31st.

now, going back to the similarities between the OPI and the SAI, we are well ahead on snow cover at this point, in all the right places.

 

 

 

the large snow anomaly is where we want it-

 

 

...and plenty more forecast- http://www.weather-forecast.com/maps/Russia?symbols=none&type=prec

 

even if we try to ignore the OPI, its making us look at the stratospheric and tropospheric profiles for the PV and its formation at this time of year, which we can (apparently) see is struggling to form. in future years we will take more notice of these details in october and maybe develop an instinct through model watching as to how the PV might be affected for better or worse during winter.

 

anyway, as far as i can see, things are looking promising up to now and if all goes according to plan, this winter could end up being colder than my ex-wife.....

 

 

[Blessed Weather]

seems to be a lot of scepticism about the OPI and Riccardo's motives for posting on here. i would have thought the ideal place to get a new forecasting theory 'out there' would be on weather forums. plenty of opportunity for independent review and evaluation before 'throwing himself to the wolves' so why not?

 

...even if we try to ignore the OPI, its making us look at the stratospheric and tropospheric profiles for the PV and its formation at this time of year, which we can (apparently) see is struggling to form. in future years we will take more notice of these details in october and maybe develop an instinct through model watching as to how the PV might be affected for better or worse during winter.

 

 

Good post bobbydog!

 

Moving on to some other posts tonight about ECM, at face value the model seems to be really struggling with the Nth Hemisphere profile at the moment. If you take the furthest ECM output available on the 27th Oct (which is also the outer day of the 10 forecast that will be incorporated in today's OPI calculation) and then compare it with the GFS and GEM output, you can see the ECM is out on its own with height placements, and as Captain Shortwave noted in the model thread, the high pressure over the UK "looks very overdone". Of course, at this stage we don't know who will actually be the closest on the day. But I guess we should be happy all 3 models still have heights near the Pole disrupting the vortex.

 

ECM 27th Oct:   GEM:   GFS:

[bluearmy]

The ECM ens mean at day 10 is generally the best verifying output we see at that range. Just checking the mean and anomalys from the 06z gfs op and 12z ECM ens mean at T240 shows a reasonably decent correlation.

[Mapantz]

It was a good post until you said 'and if all goes according to plan, this winter could end up being colder than.. '

As I pointed out earlier, a +1.64 for the end of October for the states, final Winter figure was +0.18. So it's first year in use for there, was a failure.

What I do see, is that OPI is good at predicting a pattern, the weather on the other hand.. A different kettle of fish!

My point is, too many people are figuring we're in for a cold one this Winter if we finish with a -ve OPI. I'm sure the cold lovers in the states must have been depressed at seeing +1.64 at the end of October last year, then look what happened? lol

Edited October 17, 2014 by Mapantz

[bluearmy]

It was a good post until you said 'and if all goes according to plan, this winter could end up being colder than.. '

As I pointed out earlier, a +1.64 for the end of October for the states, final Winter figure was +0.18. So it's first year in use for there, was a failure.

What I do see, is that OPI is good at predicting a pattern, the weather on the other hand.. A different kettle of fish!

My point is, too many people are figuring we're in for a cold one this Winter if we finish with a -ve OPI. I'm sure the cold lovers in the states must have been depressed at seeing +1.64 at the end of October last year, then look what happened? lol

If you read Riccardo's prediction for the States winter (issued 7/11/13 based I presume on the OPI), it was pretty accurate. It's clearly not just A=B=C so once we have the actual 31/10 OPI, we have to wait for Riccardo and his team to issue their guidance for the upcoming winter.

See post 424 on this thread for detailed prose.

Edited October 17, 2014 by bluearmy

[Yarmy]

It was a good post until you said 'and if all goes according to plan, this winter could end up being colder than.. '

As I pointed out earlier, a +1.64 for the end of October for the states, final Winter figure was +0.18. So it's first year in use for there, was a failure.

What I do see, is that OPI is good at predicting a pattern, the weather on the other hand.. A different kettle of fish!

My point is, too many people are figuring we're in for a cold one this Winter if we finish with a -ve OPI. I'm sure the cold lovers in the states must have been depressed at seeing +1.64 at the end of October last year, then look what happened? lol

The final figure was for the averaged AO, which has the square root of nothing to do with the United States. I've no idea whether the OPI will turn out to be a useful metric long term, but its only purpose is to predict the AO. It doesn't claim to predict the weather in the mid-latitudes. But we've been through this already?

[SMU]

It was a good post until you said 'and if all goes according to plan, this winter could end up being colder than.. '

As I pointed out earlier, a +1.64 for the end of October for the states, final Winter figure was +0.18. So it's first year in use for there, was a failure.

What I do see, is that OPI is good at predicting a pattern, the weather on the other hand.. A different kettle of fish!

My point is, too many people are figuring we're in for a cold one this Winter if we finish with a -ve OPI. I'm sure the cold lovers in the states must have been depressed at seeing +1.64 at the end of October last year, then look what happened? lol

 

Why do you keep referring to the united states in relation to the -AO, they don't need it.

We are the ones that need it as we don't have the expanse of cold on tap like them......

 

After 17 days of analysis ( & possible over analysis) the only real thing left to determine is where the cut off point is where we would decide the index becomes negative or positive.

Just because the metric might be -0.37 for a month doesn't mean that the AO is then significantly -AO for the winter.

 

The cut off should be related to where there is significant change in weather at a certain point in the numbers.  Whilst the sample size is small I would suggest at this point for the UK the influence seems to be more significant on Opis North or south of 1.5 + or -1.5.

Once you get to these values the metric is beginning to indicate that the month & subsequent vortex alignment is at a very positive ( or negative) end of the average. Suggesting that across 70 N in positive years over 1.5 the weather will be VERY westerly, & in sub -1.5 years the Weather will be very stagnant & blocked- either very cold or very warm depending on your location.

As we are ticking through October with a value now that's dropped to around 2.2- the inference is that we are seeing a very disjointed polar jet with large wavelengths & cold air reaching further south earlier than Normal.

 

The SAI & the OPI measures are NOT cause they are measures of effects & are essentially retrospectively highlighting the jet-with both measures highlighting the NET weakeness in the jet.

 

The 500MB Charts also give us some clues which I will add in the model thread as well.

 

regards

S

Edited October 17, 2014 by Steve Murr