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Riccardo

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

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What are the chances of the opi going positive into November though strengthing the polar vortex.?

Erm, well the OPI measurement stops on October 31st?, so unless we have an NPI, i dont think it matters.

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What are the chances of the opi going positive into November though strengthing the polar vortex.?

 

Its called the OCTOBER pattern index Doylem.

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Erm, well the OPI measurement stops on October 31st?, so unless we have an NPI, i dont think it matters.

ok new to all this. But surely this is all very experimental. And we could still end up with a strong pv forming. With us seeing similar winter to last year. Or am I wide of the mark on this one.

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Quick question, given the +ve OPI last year and the low DJF AO could you say this is more of a likely guide to our weather than that say of North America where despite that OPI value of 1.6 they had record cold?

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ok new to all this. But surely this is all very experimental. And we could still end up with a strong pv forming. With us seeing similar winter to last year. Or am I wide of the mark on this one.

It is still experimental, however the correlation is between October pattern and winter AO index. Its silent as to what happens in November as far as I know.  If it is right then I expect we should see a weak PV or at least one that breaks up under s SSW at some point.

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guys the point of the OPI is to measure the Strength & Angle of the PV relative to the norm.

 

If we get a negative index its already indicating the PV is weak & incoherent....

s


Quick question, given the +ve OPI last year and the low DJF AO could you say this is more of a likely guide to our weather than that say of North America where despite that OPI value of 1.6 they had record cold?

 

last year the AO was positive especially front loaded inc November,

 

the record Cold was concentrated in the NE of the US, but didn't penetrate 'that' far south. for that pattern you don't especially need a -AO index.

 

S

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ok new to all this. But surely this is all very experimental. And we could still end up with a strong pv forming. With us seeing similar winter to last year. Or am I wide of the mark on this one.

 

so is almost everyone else, and it is as yet untried to any real extent. No one has peer reviewed the ideas postulated but some of the data does look compelling at the moment.

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Threads like this are brilliant, cheers Riccardo, Chiono, Steve, LS, BFTV and more, brilliant input, and all of a sudden October is as exciting as Christmas!

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guys the point of the OPI is to measure the Strength & Angle of the PV relative to the norm.

 

If we get a negative index its already indicating the PV is weak & incoherent....

s

 

last year the AO was positive especially front loaded inc November,

 

the record Cold was concentrated in the NE of the US, but didn't penetrate 'that' far south. for that pattern you don't especially need a -AO index.

 

S

Hi Steve , to be fair it wasn't only northeast USA that got battered , the were various extremely cold outbreaks pushing further south , it got into Central regions at times .I remember it clearly . With the news reports saying the vortex had dropped into Central parts. But obviously they have different variables to us and the fact they had such a stubborn ridge in the pacific meant low pressure naturally dropped further east into the states . A good article hear http://en.m.wikipedia.org/wiki/2013–14_North_American_cold_wave

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Can you please rename this thread

The 'october porn influence'

The excitement,and the trying really hard NOT to get excited,yet! is so apparent in the posts!

Sorry for the non technical post,I am just enjoying this thread.

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Hi Steve , to be fair it wasn't only northeast USA that got battered , the were various extremely cold outbreaks pushing further south , it got into Central regions at times .I remember it clearly . With the news reports saying the vortex had dropped into Central parts. But obviously they have different variables to us and the fact they had such a stubborn ridge in the pacific meant low pressure naturally dropped further east into the states . A good article hear http://en.m.wikipedia.org/wiki/2013–14_North_American_cold_wave

Correct me if I'm wrong but wasn't last years OPI forecast  for last winter pretty much mixed for the NH?

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Been watching and trying to get the basics for nearly 5 years now but they still elude me. How is it last years, and seemingly any year, with a tight PF and I guess +OPI still results in a large 500 hpa anomaly off the NW USA enabling them to avoid the zonal problems that drive us all mad in UKs winter?

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because a + OPI is a + AO Oscillation same as the - OPI is a negative -AO

 

Last year the eastern pacific ended up with a HUGE mid level block- which is DIFFERENT to high level blocking......

 

attachicon.gifWinter 2013.png

 

Because the AO was positive there was no blocking to slow the jet down across the atlantic = Steamroller.

 

You CAN have the SAME synoptics over the states with more of an -AO pattern & a different result for the UK-

 

here:

 

attachicon.gifWinter 77.png

 

Notice the wedge of high pressure over Greenland & the Negative AO- but same cold vortex in NE US....

 

Another example-

 

A CHUNK of vortex in the NE US but the UKs best winter with a -AO & -NAO

attachicon.gifWinter 63.png

 

 

Don't look at the cold in America & think its game over, look at the distribution of the blocking between 65 & 90N & how many chunks the vortex is split into....

 

S

 

Yes, trough in Eastern USA can = ridge in Atlantic up towards GL and trough to S or E of us, all depends on how amplified the Eastern USA trough is.

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In no way want to be "difficult" but it seems in every case the states manage a trough more or less E of central I guess it's just more typical than a trough east of us

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Well big Joe bastardi called a neg ao winter in his twitter feed lol.

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I presume that the index will have its components and their weighting chosen after regression analysis in order to produce the best fit to historical winter data.  The crunch is therefore the robustness of the correlation going forward.

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Well that’s a third of October under our belt and it being the 10th of the month, today could also be considered a small milestone along the way as the OPI calculation will consist of the same number of “actual†days (i.e. 10) as the number of forecast days. From here on in the Index will increasingly contain more “actuals†than forecasts. Here's a simple table I've knocked together showing this:

post-20040-0-44356800-1412944350_thumb.p

So today’s calculation takes GFS’s forecast out to 20th Oct and it’s very encouraging to see the 06z Nth Hemisphere forecast for the 20th still showing high pressure dominant across the Pole. And today’s ECM/GFS H500 8 – 10 Day Height Anomalies remains supportive. 

 

GFS for 20th Oct:  post-20040-0-16856400-1412943990_thumb.p  ECM/GFS 8-10 Day Hgt Anomalies:  post-20040-0-52557200-1412944039_thumb.g

 

We continue to look in great shape for the OPI to remain well south of any positive value!!

 

 

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Good afternoon -

Todays index is -3.91 which is great news.

The positives apart from the actual value is the fact that the forecast value at day 10 is stabilizing, now whilst some of this is due to an increase in recorded actual data, the variable is still the GFS 10 day forecast.

To go fron 3.85 to 3.91 24 hours later shows the model volatilty in minimal & therefor presents a vote of confidence for the next 10 days....

If at the 15th we are still north of 3.75 we are looking at a very strong negative month in the same order of 2009......

S

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