Jump to content
Snow?
Local
Radar
Cold?
IGNORED

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


Riccardo

Recommended Posts

Posted
  • Location: Irlam
  • Location: Irlam

My mistake: I was taking the astronomical winter (a by product of other research I am doing) insofar as NDJ being the months with the shortest days and least solar insolation.

 

I thought the astronomical winter is from the winter solstice to the spring equinox?

  • Like 4
Link to comment
Share on other sites

Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

That is true in the definitional sense, astronomical winter is the season from the winter solstice to the spring equinox. Their dates can vary slightly. But the previous poster was probably thinking more of the radiation budget that is created by the axial tilt, or some modified version of that function based on feedback from changing albedo etc. By that definition, a sort of astronomical winter is the quarter of the year with the lowest radiation balance, likely to be negative at latitudes north of about 45 deg N. I think you get a fairly good sense of when that is from looking at the daily means and observing that about 10 Dec to 10 Mar forms the coldest 91 days of the year, give or take a day or two (long-term averages).

 

How did winter get to be defined as that period of time, 21 Dec to 21 Mar or thereabouts? Why did our ancestors not hit upon our climatological winter concept of the three months Dec to Feb? I think the answer to that lies in the fact that the medieval year did not start on 1 January but some time around the end of March. Will look into this further and see if there is anything in the literature to explain this. I don't think that back then there was necessarily a belief that winter must be the coldest quarter of the year, perhaps it had more of a religious significance as a season between Christmas and Easter. Of course it was roughly speaking the coldest part of the year but maybe it was just as important to divide the year then into four religious quarters. Spring would be Easter to Pentecost, summer would be the less rigorous portion of the church year ending with Michaelmas and then autumn would be the gradual approach to Advent. Whether that was a formal decision or just the way the medieval world turned, I have to wonder if our seasons were not always as weather-related as they are in our modern estimations.  

  • Like 8
Link to comment
Share on other sites

Posted
  • Location: Solihull, West Midlands. - 131 m asl
  • Weather Preferences: Sun, Snow and Storms
  • Location: Solihull, West Midlands. - 131 m asl

 

Since I have insomnia I thought I would write a pointless and unscientific post about the OPI statistics provided in the excellent chart in snowking's post.

Now all of this is somewhat tongue in cheek, especially since the sample size is far too small to be statistically significant but it is kind of fun playing with data so bare with me.

By the way when I set out on this little task I had absolutely no idea what the results might be.

 

There are 38 years OPI values listed but of those

63% (24) returned a negative value

and only 37% (14) a positive value.

This may suggest the OPI formula is more likely to produce a negative value than a positive one. (Or it may not)

 

Also the average negative value is somewhat higher than the average positive value;  -0.97 against 0.76

If the neutral value were considered to be 0 the mean average OPI bias per year would be -0.33

 

If we took this absurd premise as reality and add 0.33 to all the OPI values we end up with 18 positive values and 20 negative values.

 

If we then use <-0.6 negative and >0.6 positive as definitive values we get 9 negative OPI years and 11 positive and 18 neutral.

 

Of the 9 negative years all 9 had below average CET (100%)

Of the 11 positive years 10 of a possible 11 had an above average CET. (91%)

Of the 18 neutral years there were 9 above average CET (50%) and 9 below average CET (50%)

 

Now that's correlation baby! :crazy:

 

Lies, damn lies and statistics.  :hi:

LOL You don't work in East Anglia do you?

Seriuosly though a good piece of statistical juggling.

Just shows what a good piece of retrofitting the researchers put into the exercise.

The really remarkable fact is that it fits the CET so well, when it is designed as a Northern European tool!

MIA

Edited by Midlands Ice Age
Link to comment
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

Winter was traditionally  winter solstice (21st of Dec) as it was relatively easily observable even in pre-historic times and is reasonably close to the coldest period (10th of Dec to 10th of March) as Roger says above. There is no real reason other than convinience we should define winter as a fixed set of calendar months.

  • Like 1
Link to comment
Share on other sites

Posted
  • Location: Ireland
  • Location: Ireland

Have the OPI team mentioned when they intend to release their thoughts on the upcoming winter? I think last year they released a report on Nov 7th.

Edited by radiohead
  • Like 1
Link to comment
Share on other sites

Posted
  • Location: Ripon , North Yorkshire 41m/135ft ASL
  • Weather Preferences: heat and cold, storms and blizzards...zonal a no no
  • Location: Ripon , North Yorkshire 41m/135ft ASL

According to Gavin Partridge

 

1/2 OPI news; I've spoken with the lovely Riccardo Valente today. OPI forecast should be made public within the week.

  • Like 9
Link to comment
Share on other sites

Posted
  • Location: Boar's Hill, Oxon
  • Weather Preferences: Interesting weather
  • Location: Boar's Hill, Oxon

I suppose the problem is we get used to calling the solstice "midwinter" and it really is at the start, not mid.

  • Like 1
Link to comment
Share on other sites

Posted
  • Location: Rochester, Kent
  • Location: Rochester, Kent

What is median?

(I actually know what it is, but i can't understand its usefulness here and perhaps you mean something different)

 

 

Mean, Mode, and Median are all measures of central tendency. The median is always useful since it less affected by outliers, whilst the mean can be really affected by outliers.

Link to comment
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

Mean, Mode, and Median are all measures of central tendency. The median is always useful since it less affected by outliers, whilst the mean can be really affected by outliers.

 

Yes but what median are you using? Based on the daily CET or Monthly?

 

ie is your median just the average CET of the middle of the three months?

Link to comment
Share on other sites

Posted
  • Location: Rochester, Kent
  • Location: Rochester, Kent

Yes but what median are you using? Based on the daily CET or Monthly?

 

ie is your median just the average CET of the middle of the three months?

 

Effectively, it's the middle value of the three winter months.

Link to comment
Share on other sites

Posted
  • Location: Nr Chelmsford, Essex
  • Weather Preferences: Hurricanes, Thunderstorms and blizzards please!
  • Location: Nr Chelmsford, Essex

 

Of the 11 positive years 10 of a possible 11 had an above average CET. (91%)
Of the 18 neutral years there were 9 above average CET (50%) and 9 below average CET (50%)
 
Now that's correlation baby! :crazy:
 
Lies, damn lies and statistics.  :hi:

 

 

A bit late, but I have to say brilliant work sir - and that correlation is scary!!!!

Link to comment
Share on other sites

Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

Have the OPI team mentioned when they intend to release their thoughts on the upcoming winter? I think last year they released a report on Nov 7th.

 

I asked Guido and he replied,

The forecast will be released next Monday on their website and available to all in Italian, French and English.

Edited by Mucka
  • Like 3
Link to comment
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

Could the OPI be proved within a month from now ? The signs are appearing now. :cold:

In the strictest sense, it will never be proved, but if the correlation is still 90% in 100 years time, we will have increased confidence. :-)

Edited by Yarmy
  • Like 6
Link to comment
Share on other sites

Posted
  • Location: Banbury
  • Location: Banbury

Await Monday report very tentatively. Will be intriguing

 

Won't mean anything though...............will it?? Even if the value has people jumping through hoops there are so many other factors to complete the complicated UK jigsaw

  • Like 4
Link to comment
Share on other sites

Posted
  • Location: Oyne Aberdeenshire 120m asl
  • Weather Preferences: SNAW
  • Location: Oyne Aberdeenshire 120m asl

Well today is the day that we have been waiting for....my nerves are even kicking in. the wife just asked whats the big deal?? i do wonder how long it will take for the police to discover she is under the patio..lol...

 

But in all seriousness its going to a very big forecast, if its a forecast that us coldies want to see then i expect this place to go into total meltdown and then we will get the toys and prams the very second the models dont do what the OPI says they should but thats something that will never change..but as ever the buzz word will be patience...lets thinks back to 2012 that failed ECM and all the winters over posts back then the winter/spring that followed you would think we would all learn...

 

But then also if the OPI team forecast is not what we want to hear it does not mean winter is over on 10/11/14..

  • Like 4
Link to comment
Share on other sites

Posted
  • Location: York
  • Weather Preferences: Long warm summer evenings. Cold frosty sunny winter days.
  • Location: York

Well according to the OPI website the forecast will be available tommorow not today!!!

Link to comment
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

do you guys really need to wait....

 

The OPI being the figure it should be ~ middle 2's neg then theres plenty of analogue data available.....

 

S

 

It's their forecast I'm awaiting rather than the number. The height anomalies over central Europe looked promising, but we'll see. 

  • Like 3
Link to comment
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
  • UK Storm and Severe Convective Forecast

    UK Severe Convective & Storm Forecast - Issued 2024-03-29 07:13:16 Valid: 29/03/2024 0600 - 30/03/2024 0600 THUNDERSTORM WATCH - FRI 29 MARCH 2024 Click here for the full forecast

    Nick F
    Nick F
    Latest weather updates from Netweather

    Difficult travel conditions as the Easter break begins

    Low Nelson is throwing wind and rain at the UK before it impacts mainland Spain at Easter. Wild condtions in the English Channel, and more rain and lightning here on Thursday. Read the full update here

    Netweather forecasts
    Netweather forecasts
    Latest weather updates from Netweather

    UK Storm and Severe Convective Forecast

    UK Severe Convective & Storm Forecast - Issued 2024-03-28 09:16:06 Valid: 28/03/2024 0800 - 29/03/2024 0600 SEVERE THUNDERSTORM WATCH - THURS 28 MARCH 2024 Click here for the full forecast

    Nick F
    Nick F
    Latest weather updates from Netweather
×
×
  • Create New...