Jump to content
Cold?
Local
Radar
Snow?

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


Recommended Posts

Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk

    Agreed, would be useful to see the actual values. There might be good reasons, pertaining to the fact that this is still in its development stage without a paper on it published so far, why they aren't released, but if it is just a presentational choice I'd politely suggest that they change it to include actual daily values alongside forecast values.

     

    Absolutely agree LomondSnowstorm.

     

    Also, there's been a lot of points raised on here about the forecast element of the daily Index calculation. Whilst there are no doubt a number of areas where this could be improved, I personally enjoy the debate and model analysis around where the Index is heading. I view it as no different to looking at the "Snow & Ice in the Nth Hem" thread, where you can look at the actual and speculate about what the models indicate for the rest of the month. There would be little posting activity in most threads if we just waited until the "actual" had happened!! This thread has generated a huge amount of interest in what is often a month without too much interest in it as we wait for winter proper - just look at the fact we are on Page 29 in less than 3 weeks.

     

    So it's a thanks to Riccardo and team for creating this thread and letting us share in their trial output. I'm hoping that after the team have published their OPI paper for peer review and made any adjustments accordingly, the publication of the daily OPI during October becomes an annual feature that we can continue to follow and enjoy as part of the build up to winter.

    • Like 7
    Link to post
    Share on other sites
    Spotted a post you think may be an issue? Please help the team by reporting it.
    • Replies 1.5k
    • Created
    • Last Reply

    Top Posters In This Topic

    Top Posters In This Topic

    Popular Posts

    As ever, a great summary of how things stand from Ed and I think for the last 19, or pretty much 20 days now we have all been waiting for this point in the month and beyond. It's been rather 'fun' wat

    The discussion of the OPI index trend is understandably causing a lot of interest and (cautious) excitement amongst members after Riccardo's very interesting opening post that started this thread. The

    The monitoring page of the “October pattern index†(OPI) is presented. The OPI index  represents a analytic synthesis of the October hemispheric pattern at 500 hPa, and shows from  previous studi

    Posted Images

    Posted
  • Location: st albans
  • Location: st albans

    looking at the extended ecm ens beyond day 10 shows that the positive anomolys will become even more apparent across the arctic,asia and n america. not particularly strong but no sign of any low anomolys taking hold to drag the OPI much higher than where current modelling has it.

     

    a far cry from the situation last year but not that unusual for the end of october.  looks like a sub 2.0 OPI is well within reach (depending upon the vortex axis beyond the reliable timeframe) and possibly sub 2.5.  will then depend on riccardo's team and their analysis of the data etc. they may decide that nw europe does not look favoured to receive notable cold over the winter as a whole. remember - we are but a a pimple upon the surface of the NH !!

    • Like 5
    Link to post
    Share on other sites

    looking at the extended ecm ens beyond day 10 shows that the positive anomolys will become even more apparent across the arctic,asia and n america. not particularly strong but no sign of any low anomolys taking hold to drag the OPI much higher than where current modelling has it.

     

    a far cry from the situation last year but not that unusual for the end of october.  looks like a sub 2.0 OPI is well within reach (depending upon the vortex axis beyond the reliable timeframe) and possibly sub 2.5.  will then depend on riccardo's team and their analysis of the data etc. they may decide that nw europe does not look favoured to receive notable cold over the winter as a whole. remember - we are but a a pimple upon the surface of the NH !!

     

     

    in my opinion, very unlikely that Western Europe is not affected by cold waves if the IPO index is below -1.5 for example. Since 1976, every time the index was below -1.5, the Western Europe had enjoyed a winter with several wave of severe frost including France, Germany and Britain . I do not see why this scheme would stop our current era. Another thing, El Nino is also unfavorable to the waves of gel in the eastern and central United States. Europe would be more favored by cold repeating especially the Central part of Europe

    • Like 4
    Link to post
    Share on other sites
    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

    looking at the extended ecm ens beyond day 10 shows that the positive anomolys will become even more apparent across the arctic,asia and n america. not particularly strong but no sign of any low anomolys taking hold to drag the OPI much higher than where current modelling has it.

     

    a far cry from the situation last year but not that unusual for the end of october.  looks like a sub 2.0 OPI is well within reach (depending upon the vortex axis beyond the reliable timeframe) and possibly sub 2.5.  will then depend on riccardo's team and their analysis of the data etc. they may decide that nw europe does not look favoured to receive notable cold over the winter as a whole. remember - we are but a a pimple upon the surface of the NH !!

     

    Whilst the highlighted is very true, Nick, the European map is appended with a geopotential height anomaly scale to correspond with positive or negative score. A southerly tracking jet stream is indicated - diffluent blocking perhaps?

     

    Of course, the whole of the W. European coast could have a large negative GPH, as it did last winter. I would prefer to see other countries shaded as well.

    • Like 3
    Link to post
    Share on other sites
    Posted
  • Location: Manchester
  • Location: Manchester

    No update from the 0z so they must be skipping it again. However, like bluearmy already mentioned, things are looking good for the next 10 days so maybe yesterday's gfs was too keen to remove those Arctic heights.

    Link to post
    Share on other sites
    Posted
  • Location: st albans
  • Location: st albans

    Whilst the highlighted is very true, Nick, the European map is appended with a geopotential height anomaly scale to correspond with positive or negative score. A southerly tracking jet stream is indicated - diffluent blocking perhaps?

     

    Of course, the whole of the W. European coast could have a large negative GPH, as it did last winter. I would prefer to see other countries shaded as well.

     

    i am playing devils advocate somewhat ......

     

    note the gfs ops struggling over asia re heights and slp, run to run within 7 days!

    Link to post
    Share on other sites
    Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

    WOW, look at the 6z!!!!!,   a massive area of +ve heights ripping clean through the pole.

    Link to post
    Share on other sites
    Posted
  • Location: Manchester
  • Location: Manchester

    Awesome 6Z GFS, the AO index is expected to drop again  :blink2:

    Yes, good to see and a significant difference with the 0z. Watch at 120 hours how much further north the East Scandi-Russian high is and some energy of the Atlantic low cuts under it rathen than push it southeast like the 0z did.

    Link to post
    Share on other sites
    Posted
  • Location: Siston, Bristol 70m ASL
  • Location: Siston, Bristol 70m ASL

    12Z has more blocking than the 6Z so I am thinking the next OPI update could be lower again, I am feeling very happy about this outcome.

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: st albans
  • Location: st albans

    Not surprisingly, weather bell also don't agree with the GCM's. joe made a blog on his site a couple of days ago to illustrate their view of the upcoming winter. The preferred analogue being HLB with a greeny block and the circle of low heights running below and into Europe. -AO and - NAO.

    Mucks - my query relates to the disposing of gfs runs wrt to the OPI generated. do they just look for a lack of continuity in respect of previous gfs runs or gefs or ECM/ECM ens? it can't be just the OPI generated being too large a swing from the previous run as we saw big divergence last October being recorded on three occasions.

    Edited by bluearmy
    • Like 5
    Link to post
    Share on other sites
    Posted
  • Location: Penkridge
  • Weather Preferences: Virgins
  • Location: Penkridge

    Well its still displaying the data from the 06z, maybe the 12z has been binned.

    Anything showing up on the ensemble?

    Link to post
    Share on other sites
    Posted
  • Location: Portrush. (NI) UK
  • Location: Portrush. (NI) UK

    Below is a quote from Riccardo on 23rd October 2013:

    As said, the correlation betwwen SAI and winter AO is "only" a derivative correlation. In fact snow cover shedule and location change in function of the october pattern, that is correlated with winter AO (for this reason the SCE is not correlated, because it doesn't reflect the features of october pattern).For these reason in some particular season, like 2005-2006, the correlation SAI-winter AO is less good: in this season the october patter was very good, but its particular configuration wasn't positive for snow cover advance (SAI).

    To conclude it is important to remark that there is a STRONG correspondence between the october pattern (when the NEW winter VP is being born) and the winter pattern (when the VP ITSELF is "adult") and that the correlation between snow cover-winter AO is only a derivative correlation. I think that this discovery can be useful in order to improve the GCM (climatic global model).

    However the resaerch will traslate into english and after will be issued, so that all you can read. Moreover I tell you that currently the OPI is abaut +1/+1.5, so the winter will be probably a AO++ winter.

    ************************************************

    Final OPI was +1.65 the second highest in satellite era to +1.7 in 1992.

    1992 was a positive AO but 2013 remained slightly negative through DJF at 1000mb, (first 10 days Feb 2014 was slightly positive) but the effects on Winter 2013/14 in Western Europe ie UK weather pattern underwent the effects of what a positive AO would be wet,mild and windy.

    The 2013/14 PV's strength and position was always going to have this effect, deep down we all knew this.

    So the OPI decoupled from AO but the outcome for us was in a round about way correct.

    Is that a failure? In regards to predicting AO 2013/14 yes. If you accepted final OPI figure you could have been prepared for low pressure rolling in continuously and as a result for Western Europe it was correct.

    So if the OPI for Oct 2014 results in a -2.5 to -3.5 we would be expecting cold incursions and a Arctic air battle with Atlantic several times this winter. If OPI is this negative then some could justifiably say we should expect one period of Mid latitude blocking in months of DJF for OPI to verify.

    I don't know exact methodology being used I'm making an estimate. I'm aware a forecast will follow from the team so other factors will be in play, but I stand intrigued with how it pans out.

    Edited by KyleHenry
    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Dulwich Hill, Sydney, Australia
  • Weather Preferences: Hot and dry or cold and snowy, but please not mild and rainy!
  • Location: Dulwich Hill, Sydney, Australia

    -3.04 on the 0z so still strong negative.

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Yatton, South of Bristol
  • Location: Yatton, South of Bristol

    As said, the correlation betwwen SAI and winter AO is "only" a derivative correlation. In fact snow cover shedule and location change in function of the october pattern, that is correlated with winter AO (for this reason the SCE is not correlated, because it doesn't reflect the features of october pattern).For these reason in some particular season, like 2005-2006, the correlation SAI-winter AO is less good: in this season the october patter was very good, but its particular configuration wasn't positive for snow cover advance (SAI).

    To conclude it is important to remark that there is a STRONG correspondence between the october pattern (when the NEW winter VP is being born) and the winter pattern (when the VP ITSELF is "adult") and that the correlation between snow cover-winter AO is only a derivative correlation. I think that this discovery can be useful in order to improve the GCM (climatic global model).

    However the resaerch will traslate into english and after will be issued, so that all you can read. Moreover I tell you that currently the OPI is abaut +1/+1.5, so the winter will be probably a AO++ winter.

    Quote from Riccardo Oct 2013.

    Final OPI was +1.65 the second highest in satellite era to +1.7 in 1992.

    1992 was a positive AO but 2013 remained slightly negative through DJF at 1000mb, but the effects on Winter in Western Europe ie UK suffered through the effects of what a positive AO would be wet,mild and windy.

    The 2013/14 PV's strength and position was always going to have this effect, deep down we all knew this.

    So the OPI decoupled from AO but the outcome for us was correct.

    Is that a failure? In regards to predicting AO 2013/14 yes. If you accepted final OPI figure you could have been prepared for low pressure rolling in continuously and as a result for Western Europe it was correct.

    So if the OPI for Oct 2014 results in a -2.5 to -3.5 we would be expecting cold incursions and a Arctic air battle with Atlantic several times this winter. If OPI is this negative then some could justifiably say we should expect one period of Mid latitude blocking in months of DJF for OPI to verify.

    I don't know exact methodology being used I'm making an estimate. I'm aware a forecast will follow from the team so other factors will be in play, but I stand intrigued with how it pans out.

    That highlighted paragraph makes no sense regarding the current OPI? Have you messed up your copy and paste or are referring to another year. This years OPI hasn't gone positive yet so not sure how you come to that conclusion.

    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: Portrush. (NI) UK
  • Location: Portrush. (NI) UK

    That highlighted paragraph makes no sense regarding the current OPI? Have you messed up your copy and paste or are referring to another year. This years OPI hasn't gone positive yet so not sure how you come to that conclusion.

    Just below highlight is quote from Riccardo October 2013.

    Link to post
    Share on other sites
    Posted
  • Location: Yatton, South of Bristol
  • Location: Yatton, South of Bristol

    Just below highlight is quote from Riccardo October 2013.

    That's what I thought. So how have you come to a positive OPI output for October? Quote your post 'Moreover I tell you that currently the OPI is abaut +1/+1.5, so the winter will be probably a AO++ winter."

    • Like 1
    Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now
    ×
    ×
    • Create New...