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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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#1
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After being reminded about this a couple of weeks ago I decided to have a look at the stats back to 1806 and see what the results are.
If there is a run of cold days (3.3C or less) around mid-month the chance of an average to colder than average January and February is 94% and 74% respectively. The chance of an average to colder than average March is 96%. Also notable is that the chance of a severe spell in January (4C colder than normal) is 30%. The full blog post can be found here. http://wp.me/p2VSmb-wO |
#2
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On Wednesday, December 10, 2014 1:53:07 PM UTC, Scott W wrote:
After being reminded about this a couple of weeks ago I decided to have a look at the stats back to 1806 and see what the results are. If there is a run of cold days (3.3C or less) around mid-month the chance of an average to colder than average January and February is 94% and 74% respectively. The chance of an average to colder than average March is 96%. Also notable is that the chance of a severe spell in January (4C colder than normal) is 30%. The full blog post can be found here. http://wp.me/p2VSmb-wO ========= Interesting as far as it goes - but what temperature is this? CET? Or one location's maximum temperature? Or 24-hour average? In any case it looks like being slightly milder just after mid month. If the measure is maximum temperature I don't at see that below 3 or 4 deg C for most. It makes a kind of sense because mid Dec-Jan regimes are often linked, so a cold block, for example, in mid December would more often than not also be January's characteristic. Stephen. |
#3
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On Wednesday, 10 December 2014 14:24:10 UTC, Stephen Davenport wrote:
It makes a kind of sense because mid Dec-Jan regimes are often linked, so a cold block, for example, in mid December would more often than not also be January's characteristic. This is what I was thinking. Cold air in the UK in December, especially prolonged cold suggest it's come from the East which in itself implies that the "East" has cooled down quickly and provide a source of cold and I'd imagine that a colder East with an existing high pressure/cold pool might be prone to more stagnation during the remainder of the winter. Richard |
#4
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Richard Dixon wrote:
On Wednesday, 10 December 2014 14:24:10 UTC, Stephen Davenport wrote: It makes a kind of sense because mid Dec-Jan regimes are often linked, so a cold block, for example, in mid December would more often than not also be January's characteristic. This is what I was thinking. Cold air in the UK in December, especially prolonged cold suggest it's come from the East which in itself implies that the "East" has cooled down quickly and provide a source of cold and I'd imagine that a colder East with an existing high pressure/cold pool might be prone to more stagnation during the remainder of the winter. Richard One that perhaps supports your argument in a negative way is Dec 1981 to Feb 1982. Dec 81 was extremely cold in the SE. At Chalfont St Giles the mean daily max was only 2.8 and there were 6 days with the max below zero. There were 23 days with snow lying at 0900. It would easily have triggered Colin Finch's rule yet Jan/Feb 82 were rather mild overall, apart from the 2nd week in January which was cold with a major snowstorm on the 8th. The cold in Dec 81 was not the result of in incursion of easterly air. If I recall correctly it resulted mostly from northerly plunges behind lows tracking SE across the country. It was a very cyclonic month, not what you would initially think would produce severe cold in December. There was therefore no pre-existing block to persist into Jan/Feb. -- Norman Lynagh Tideswell, Derbyshire 303m a.s.l. http://peakdistrictweather.org |
#5
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Daily Tmax at Greenwich
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#6
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On Wednesday, December 10, 2014 3:14:27 PM UTC, Scott W wrote:
Daily Tmax at Greenwich ===== Thanks. |
#7
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In message ,
Scott W writes After being reminded about this a couple of weeks ago I decided to have a look at the stats back to 1806 and see what the results are. If there is a run of cold days (3.3C or less) around mid-month the chance of an average to colder than average January and February is 94% and 74% respectively. The chance of an average to colder than average March is 96%. Also notable is that the chance of a severe spell in January (4C colder than normal) is 30%. The full blog post can be found here. http://wp.me/p2VSmb-wO Those are remarkably high percentages. The biggest surprise is that it should be such a strong pointer for as far ahead as March, and - oddly - stronger than for February. -- I'm not paid to implement the recognition of irony. (Taken, with the author's permission, from a LiveJournal post) |
#8
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On 10/12/2014 15:14, Scott W wrote:
Daily Tmax at Greenwich Thanks Scott, interesting stuff. I think you just have to take it on face value and not get to hung up on detail. Not convinced of a pre Christmas cold snap atm. -- Keith (Southend) "Weather Home & Abroad" http://www.southendweather.net Twitter:@LawnscienceEssx |
#9
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On Wed, 10 Dec 2014 17:09:18 -0000, John Hall
wrote: In message , Scott W writes After being reminded about this a couple of weeks ago I decided to have a look at the stats back to 1806 and see what the results are. If there is a run of cold days (3.3C or less) around mid-month the chance of an average to colder than average January and February is 94% and 74% respectively. The chance of an average to colder than average March is 96%. Also notable is that the chance of a severe spell in January (4C colder than normal) is 30%. The full blog post can be found here. http://wp.me/p2VSmb-wO Those are remarkably high percentages. The biggest surprise is that it should be such a strong pointer for as far ahead as March, and - oddly - stronger than for February. If it's cold in December, reckon mostly likely we're in for a long winter. (sucks on straw) -- Bah, and indeed, Humbug |
#10
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Scott. I am not sure how you have arrived at those figures. Using the values
on the link you gave, and taking my own average monthly mean temp for the periods 1882 to 1990 as an approximation, I find that for the years you list, the Dec cold spells were followed by: Normal (anom +1 to -1) Jan 38%, Feb 24%, Mar 34% Cold (anom colder than -1) 48%, Feb 34%, Mar 32% Mild (anom warmer than +1) 14%, Feb 42%, Mar 34% So the 38 minus rule in Dec was followed by an average or warmer Jan in 52%, Feb in 66% and Mar in 68%. I can see no useful peredictave value in that. -- Bernard Burton Wokingham Berkshire. Weather data and satellite images at: http://www.woksat.info/wwp.html "Scott W" wrote in message ... After being reminded about this a couple of weeks ago I decided to have a look at the stats back to 1806 and see what the results are. If there is a run of cold days (3.3C or less) around mid-month the chance of an average to colder than average January and February is 94% and 74% respectively. The chance of an average to colder than average March is 96%. Also notable is that the chance of a severe spell in January (4C colder than normal) is 30%. The full blog post can be found here. http://wp.me/p2VSmb-wO --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
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