Jump to content
Cold?
Local
Radar
Snow?

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


Recommended Posts

Posted
  • Location: Stoke Gifford, Bristol
  • Location: Stoke Gifford, Bristol

    When i read it last night i thought it bore similarities to Roger Smith's prelim forecast from the other week.

    Some cold, poss snowy spells with milder rain events in between.

     

    This is based on Europe mainly, yes? So we're (UK) probably on the edge i guess, which could mean some interesting 'battleground' events

    • Like 1
    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: Bude
  • Weather Preferences: Extreme weather...heavy snow and heat waves
  • Location: Bude

    Does anyone have a link to the OPI team's UK/Europe forecast for last year? I know they got the US forecast spot on, but how did they do with Europe? Giving that the OPI last year was very positive, you'd have thought they would have got it spot on and forecast a predominantly zonal winter for the uk

    Link to post
    Share on other sites
    Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

    So the OPI team are not expecting a very cold winter but they do suggest frequent colder periods are possible with widespread snow over Europe

     

    After last 'winter' thats certainly an improvement if it was to make it to us of course

     

    :)

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Just a quick one, sort of a reference for the coming weeks and months but full November update of the EC Seasonal model is now out and it continues the theme from the last few months and seeing it is now November, essentially the EC Seasonal model is predicting a mild, wet and unsettled winter period with a text-book +NAO and +AO pattern across the Atlantic and polar region. Pressure is higher to the south and south-west of the UK and lower to the north and north-west with a broad W or SW'ly type with temps circa +0.5C to +1.5C above average.

     

    The EUROSIP Seasonal model which takes into account the UKMO, NCEP, Meteo-France and ECMWF seasonal data will be out around the 15th, but I don't expect this to be much different as they have both been showing the same thing for some time now. In essence it looks a fascinating winter for a number of reasons and without question it is definitely a case of "seasonal models v signs and signals" this winter. Clearly there will be one outcome. My money is for the signs and signals to come to fruition this year and for the seasonal models to be wrong, but that being said they can't be ignored and won't be ignored at the UKMO I can tell you.

     

    Regards, Matt.

     

    fascinating that Matt and thanks. As you say one will be right, or will it?  Perhaps some kind of in between is possible with both 'sides' able to claim their version is more correct. What puzzles me is how the two sets can be so different. Surely Met and EC input things like SAI etc, not sure of course about anything else.

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

    Just a quick one, sort of a reference for the coming weeks and months but full November update of the EC Seasonal model is now out and it continues the theme from the last few months and seeing it is now November, essentially the EC Seasonal model is predicting a mild, wet and unsettled winter period with a text-book +NAO and +AO pattern across the Atlantic and polar region. Pressure is higher to the south and south-west of the UK and lower to the north and north-west with a broad W or SW'ly type with temps circa +0.5C to +1.5C above average.

     

    The EUROSIP Seasonal model which takes into account the UKMO, NCEP, Meteo-France and ECMWF seasonal data will be out around the 15th, but I don't expect this to be much different as they have both been showing the same thing for some time now. In essence it looks a fascinating winter for a number of reasons and without question it is definitely a case of "seasonal models v signs and signals" this winter. Clearly there will be one outcome. My money is for the signs and signals to come to fruition this year and for the seasonal models to be wrong, but that being said they can't be ignored and won't be ignored at the UKMO I can tell you.

     

    Regards, Matt.

     

    The EUROSIP seems to have been updated on the NOAA NMME page.

     

    0tOqibX.png

     

     

    • International MME: The EuroSIP (European Seasonal-to-Interannual Prediction) project is presently a collaboration of ECMWF, MeteoFrance, UKMet Office, and NCEP. Raw data from IMME is not available. IMME is not currently included in NMME, but is provided on the NMME webpage for informative purposes. More information on EuroSIP.

     

    http://www.cpc.ncep.noaa.gov/products/NMME/iMMEindex.shtml

    • Like 3
    Link to post
    Share on other sites
    Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.

    So the OPI team are not expecting a very cold winter but they do suggest frequent colder periods are possible with widespread snow over Europe

     

    After last 'winter' thats certainly an improvement if it was to make it to us of course

     

    :)

     

    Yes, given the expectations promoted by the OPI, I think the chances of at least one bitter spell complete with a lot of widespread heavy snow within a short timeframe must be on the cards. We had the extreme of some thirty-six depressions one and the after, hitting our shores last season, so this time around we can probably expect some other type of extreme at the opposite end. Perhaps we'll strike it lucky with a piece of PV lobe distributed over the UK on at least one occasion this Winter. Overall, I must say I'm expecting a mixed one to say the least. A blend of all the current LRFs is what I'm expecting, but truth knows, no-one can truly tell what will happen. Many a factor in the coldie's favour this year unlike last and more akin to the most exciting charts of years gone by.

    Edited by gottolovethisweather
    Link to post
    Share on other sites
    Posted
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast
  • Weather Preferences: Severe Storms and Snow
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast

    So the OPI team are not expecting a very cold winter but they do suggest frequent colder periods are possible with widespread snow over Europe

     

    After last 'winter' thats certainly an improvement if it was to make it to us of course

     

    :)

     

     

    Just one blast of winter snow can paralyse the country, let alone a very cold winter. What does a cold winter actually mean anyway? Cold for a week, months?

    Link to post
    Share on other sites
    Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL

    Just one blast of winter snow can paralyse the country, let alone a very cold winter. What does a cold winter actually mean anyway? Cold for a week, months?

     

     

    I'd define it as below average CET across DJF, but I suppose it can be a subjective measure.

     

    Even if the OPI/SAI prove to be a better predictor (fingers crossed!), then I still think the MetO are correct in ignoring them for the moment. These are nascent metrics and need many more years of robust correlation before they can be used professionally. 

     

    I bet the pros are as interested as we are and discuss these things privately, though. :)

    Edited by Yarmy
    • Like 3
    Link to post
    Share on other sites
    Posted
  • Location: E Lancs, 900ft asl
  • Weather Preferences: Snow, blizzards, cold, thunderstorms, frosts, fog, general extreme weather
  • Location: E Lancs, 900ft asl

    fascinating that Matt and thanks. As you say one will be right, or will it?  Perhaps some kind of in between is possible with both 'sides' able to claim their version is more correct. What puzzles me is how the two sets can be so different. Surely Met and EC input things like SAI etc, not sure of course about anything else.

     

    Hi John,

     

    Yes, I guess there is that option which wouldn't be the end of the world if you're after cold and snow, especially compared with last year. If two winter months are generally average to mild but one is particularly cold and snowy I don't think there could be too many complaints. To an extent I wouldn't want something 'down the middle' as there would then be an equal argument for both, overall, being correct. What is quite surprising is the vast difference between the seasonal models and that of the signs and signals which help us to come to the conclusion that a -AO pattern, for example, is likely/possible. As I mentioned to have a 2m temp anom of up to +1.5C would be quite noteworthy and to me that, overall, would signal that most of the winter would need to be on the milder side of average rather than colder.

     

    No sitting on the fence for me this year, I can't divulge too much of my own thoughts as I have a winter forecast that I need to produce and provide for clients, but I've said it enough on twitter for it not to be a secret and over the space of Dec to Feb and especially if you include March as well, even though not a winter month of course, I'm expecting a winter completely different to last year and a strat vortex that, at some point, wil get ripped apart and a result have a big impact on the troposphere further down the line and it could well be the middle and back end of the winter that provides those 'winter goodies' for those who want it.

     

    Cheers,

     

    Matt.

    • Like 3
    Link to post
    Share on other sites
    Posted
  • Location: Mile Oak, 3 miles West of Brighton UK, 130 Meters above sea level
  • Weather Preferences: Anything Extreme
  • Location: Mile Oak, 3 miles West of Brighton UK, 130 Meters above sea level

    The EUROSIP seems to have been updated on the NOAA NMME page.

     

    0tOqibX.png

     

     

    http://www.cpc.ncep.noaa.gov/products/NMME/iMMEindex.shtml

     

    Those charts look  like the SST anomaly charts 

     

    Especially with the blue ''cold'' pool of water  in the Mid North Atlantic, I think too much weight has been put on that and the LR Models will fall flat on their faces this winter

     

    sst_anom.gif

    • Like 8
    Link to post
    Share on other sites
    Posted
  • Location: leicester
  • Location: leicester

    Those charts look  like the SST anomaly charts 

     

    Especially with the blue ''cold'' pool of water  in the Mid North Atlantic, I think too much weight has been put on that and the LR Models will fall flat on their faces this winter

     

    sst_anom.gif

    is that the classic tripole set up that brings about a negative nao in the winter?
    Link to post
    Share on other sites
    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

    I think we have been seeing variations of this pattern in recent winters where the jet tracks southerly but it depends on the progression into Europe and the tilt/shape of the low as to what weather we get. My hunch is that the OPI forecast, using the analogue years, is a little too extreme. By that, I mean, the inclusion of 62/63 skews too much to cold overall.

     

    When I looked at their Z500 composite, I immediately thought of Feb/March 2013.....

     

    oDFuFqZ.gif

     

    .....a little tweaking of orientation would make a good fit as long as we assume the latitude variabilty of the lows approach.

    • Like 5
    Link to post
    Share on other sites
    Posted
  • Location: Chorley, Lancashire
  • Location: Chorley, Lancashire

    Hi guys,

     

    I've took all the sub -1 OPI years coupled with an easterly QBO and produced a 500 mb height anomaly plot for the winter period. The results speak for themselves!!!

    post-10097-0-90256000-1415787467_thumb.p

    Edited by iamstuart
    • Like 5
    Link to post
    Share on other sites
    Posted
  • Location: The Netherlands
  • Location: The Netherlands

    Anyone interested in a weblog update from Judah Cohen?

     

    Visit 

    http://www.aer.com/science-research/climate-weather/arctic-oscillation

    With Arctic Oscillation Anylysis and forecasts, from the near term to a longer term (30 days) forecast.

     

    A discussion about the SAI and its implications for the winter season 2014-2015. 

     

    Judah anticipates a sudden stratospheric warming within the next two months and a prospensity for a negative AO.

     
    • Like 2
    Link to post
    Share on other sites
    • 2 weeks later...

    Hi guys,

     

    I've took all the sub -1 OPI years coupled with an easterly QBO and produced a 500 mb height anomaly plot for the winter period. The results speak for themselves!!!

    Do the results speak for themselves?  Blocking and -ve AO signals do not necessarily translate to cold everywhere. Look at the CET in these OPI analog years. Dec 1977 = 6.3, Dec 1985= 6.1, Dec 1987 = 5.6, Dec 2013 = 6.3  so all of these are very warm Decembers with only Dec 2010 seeing extreme cold. I would argue that Dec 2010 was in a period of exceptionally low sunspots and other drivers all lined up to bring the perfect storm of cold.  So although the graphic shows anomalous pressure heights over the polar region and a southerly displaced storm track over the N Atlantic I would argue that statistically from those years the risk is warm not cold for December in the UK and probably W parts of Europe.  The rest of winter is another matter, but just wanted point out that all the hype about -ve AO winters is not all it seems.

    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: Irlam
  • Location: Irlam

    Do the results speak for themselves? Blocking and -ve AO signals do not necessarily translate to cold everywhere. Look at the CET in these OPI analog years. Dec 1977 = 6.3, Dec 1985= 6.1, Dec 1987 = 5.6, Dec 2013 = 6.3 so all of these are very warm Decembers with only Dec 2010 seeing extreme cold. I would argue that Dec 2010 was in a period of exceptionally low sunspots and other drivers all lined up to bring the perfect storm of cold. So although the graphic shows anomalous pressure heights over the polar region and a southerly displaced storm track over the N Atlantic I would argue that statistically from those years the risk is warm not cold for December in the UK and probably W parts of Europe. The rest of winter is another matter, but just wanted point out that all the hype about -ve AO winters is not all it seems.

    I get the feeling that actually you maybe a year out with your analyses.

    I know it is standard practice in tables when you see a season that overlaps a year and they just use a single year, say winter 1992, the 1992 actually refers to the January and not the December so it's not 1992-93 but 1991-92.

    I don't know if that is the case with these analogues but what makes me wondering is that wasn't it the OPI in the October of 1976 and not 1977 that was less that -1?

    Edit: looking at it further you looked at December 2013 but the OPI for October 2013 was over +1, the October of 2012 was below -1.

    Having said that -AO and even -NAO is not be all end all. It is possible like January 1969 that the UK could still be mild despite those values being negative.

    March 1957, the warmest March on record for the CET, had a negative AO and NAO

    Edited by Weather-history
    • Like 6
    Link to post
    Share on other sites
    Posted
  • Location: Exile from Argyll
  • Location: Exile from Argyll

    Do the results speak for themselves?  Blocking and -ve AO signals do not necessarily translate to cold everywhere. Look at the CET in these OPI analog years. Dec 1977 = 6.3, Dec 1985= 6.1, Dec 1987 = 5.6, Dec 2013 = 6.3  so all of these are very warm Decembers with only Dec 2010 seeing extreme cold. I would argue that Dec 2010 was in a period of exceptionally low sunspots and other drivers all lined up to bring the perfect storm of cold.  So although the graphic shows anomalous pressure heights over the polar region and a southerly displaced storm track over the N Atlantic I would argue that statistically from those years the risk is warm not cold for December in the UK and probably W parts of Europe.  The rest of winter is another matter, but just wanted point out that all the hype about -ve AO winters is not all it seems.

     

    I see it is your first post - a warm welcome.

     

    The OPI is a measure of October whereas the composites are dated for the last month of the following winter. You are right about it not being a good fit with December CET - it does not purport to be - I guess that is why the UK has no shading.

     

    An overall negative AO is often the product of stratosphere warming - in most cases these don't get going till January. It is a forecast for an Arctic state, whether the UK or Europe benefit from any cold outbreak is merely a sideshow.

    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: Ireland
  • Location: Ireland

    I get the feeling that actually you maybe a year out with your analyses.

    I know it is standard practice in tables when you see a season that overlaps a year and they just use single a year, say winter 1992, the 1992 actually refers to the January and not the December so it's not 1992-93 but 1991-92.

    I don't know if that is the case with these analogues but what makes me wondering is that wasn't it the OPI in the October of 1976 and not 1977 that was less that -1?

    Edit: looking at it further you looked at December 2013 but the OPI for October 2013 was over +1, the October of 2012 was below -1.

    Having said that -AO and even -NAO is not be all end all. It is possible like January 1969 that the UK could still be mild despite those values being negative.

    March 1957, the warmest March on record for the CET, had a negative AO and NAO

     

    That is indeed the case with the those NCEP analogues. 1977 refers to the winter of 76/77.

    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: Chorley, Lancashire
  • Location: Chorley, Lancashire

    Do the results speak for themselves?  Blocking and -ve AO signals do not necessarily translate to cold everywhere. Look at the CET in these OPI analog years. Dec 1977 = 6.3, Dec 1985= 6.1, Dec 1987 = 5.6, Dec 2013 = 6.3  so all of these are very warm Decembers with only Dec 2010 seeing extreme cold. I would argue that Dec 2010 was in a period of exceptionally low sunspots and other drivers all lined up to bring the perfect storm of cold.  So although the graphic shows anomalous pressure heights over the polar region and a southerly displaced storm track over the N Atlantic I would argue that statistically from those years the risk is warm not cold for December in the UK and probably W parts of Europe.  The rest of winter is another matter, but just wanted point out that all the hype about -ve AO winters is not all it seems.

     

    Hi pbweather,

     

    You seem to missing the overall point of the analogue. The years shown are for the winter period running from December to February not just December!!! Also as the winter period runs through from one year to the next, the analogue takes the year that Febuary ends in. For example, 2010 was in fact the winter of 2009/10 and 1977 was indeed 76/77 and so on.

     

    As for the results, if you go back through the years in the analogue you will find that all the winters had at least 2 out of the 3 winter months, with below average temperatures and at least 1 month with well below average. 

     

    post-10097-0-73143500-1416958253_thumb.ppost-10097-0-30858100-1416958277_thumb.ppost-10097-0-05407500-1416958298_thumb.p

     

     

     

    Regards,

    Stu.

    Edited by iamstuart
    Link to post
    Share on other sites

    Hi pbweather,

     

    You seem to missing the overall point of the analogue. The years shown are for the winter period running from December to February not just December!!! Also as the winter period runs through from one year to the next, the analogue takes the year that Febuary ends in. For example, 2010 was in fact the winter of 2009/10 and 1977 was indeed 76/77 and so on.

     

    As for the results, if you go back through the years in the analogue you will find that all the winters had at least 2 out of the 3 winter months, with below average temperatures and at least 1 month with well below average. 

     

    attachicon.gifCapture.PNGattachicon.gifCapture1.PNGattachicon.gifCapture2.PNG

     

     

     

    Regards,

    Stu.

    Apologies for the year confusion but some archives work on the year of the first month of winter e.g EarthSat. Using my running 10 year Dec CET 4.3 and 30 year Dec CET 4.8, then even if you use the previous years only 1976 and 2009 are below normal and the average of all years is close to normal. 2, 5.2, 6.2, 3.1, 4.8.  Factor in sunspots and 1976 and 2009 were bang in the middle of very low sunspot periods which is almost certainly a factor as well so then these Dec CETs are probably not cold at all. Once you get a normal or warmer than normal Dec then getting a strongly cold winter becomes increasingly difficult because you need at least one month to cancel out Dec anomalies and this is why there is not a very clear stats relationship between -ve AO and -ve NAO winters. Similar story with all the other teleconnections as well.

    • Like 1
    Link to post
    Share on other sites

    I get the feeling that actually you maybe a year out with your analyses.

    I know it is standard practice in tables when you see a season that overlaps a year and they just use a single year, say winter 1992, the 1992 actually refers to the January and not the December so it's not 1992-93 but 1991-92.

    I don't know if that is the case with these analogues but what makes me wondering is that wasn't it the OPI in the October of 1976 and not 1977 that was less that -1?

    Edit: looking at it further you looked at December 2013 but the OPI for October 2013 was over +1, the October of 2012 was below -1.

    Having said that -AO and even -NAO is not be all end all. It is possible like January 1969 that the UK could still be mild despite those values being negative.

    March 1957, the warmest March on record for the CET, had a negative AO and NAO

    Agree totally about your negative AO and NAO comments. A -ve AO and NAO forecast should be used as a warning of potential for cold, but it can not be used as accurate forecasting tool which is also why I seriously question how the correlation stats of the OPI are generated.

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

    Apologies for the year confusion but some archives work on the year of the first month of winter e.g EarthSat. Using my running 10 year Dec CET 4.3 and 30 year Dec CET 4.8, then even if you use the previous years only 1976 and 2009 are below normal and the average of all years is close to normal. 2, 5.2, 6.2, 3.1, 4.8.  Factor in sunspots and 1976 and 2009 were bang in the middle of very low sunspot periods which is almost certainly a factor as well so then these Dec CETs are probably not cold at all. Once you get a normal or warmer than normal Dec then getting a strongly cold winter becomes increasingly difficult because you need at least one month to cancel out Dec anomalies and this is why there is not a very clear stats relationship between -ve AO and -ve NAO winters. Similar story with all the other teleconnections as well.

     

    Other analogue years include 1984/85 and 1986/87, I think 2012/2013 also.

     

    Yes all these winters didn't produce cold Decembers, but January 1985 and 1987 were jolly cold with fairly cold February's thereafter. Jan and Feb 2013 saw much northern blocking as well - though didn't produce exceptional cold. Interestingly the three years above produced cold Marches..

     

    A pivotal time will be late December to see whether the theory of negative OPI correlating with a cold winter occurs. Late December is always a crucial time for spotting trends for the rest of the winter as a whole. I remember 2012 seeing signs of blocking to our NE developing in early Jan despite the very mild wet conditions we were in - compared to 2011 and 2013 where we had the same type of weather but no signal for a pattern change.

    • Like 3
    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
    • Election weather- Still chilly with showers to dodge on May 6th

      Voting takes place on May 6th across Britain with Scottish and Welsh parliamentary elections, Mayoral and local councils including for London Mayor. If you've not postal voted, what's the weather for Thursday? Read more here

      Jo Farrow
      Jo Farrow
      Latest weather updates from Netweather

      UK Storm and Severe Convective Forecast

      UK Severe Convective & Storm Forecast - Issued 2021-05-05 09:08:00 Valid: 05/05/2021 0600 - 06/05/2021 0600 THUNDERSTORM WATCH - WEDS 5TH MAY 2021 Click here for the full forecast

      Nick F
      Nick F
      Latest weather updates from Netweather

      Unseasonably cool & showery theme continues, wet & windy but milder this weekend

      Chilly with sunshine & showers by day for the rest of the week, where skies clear at night a frost is likely too. Turning wet & windy over the weekend, but at least it will be a little warmer. Read the full update here

      Netweather forecasts
      Netweather forecasts
      Latest weather updates from Netweather
    • Recently Browsing   0 members

      No registered users viewing this page.

    ×
    ×
    • Create New...