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Will 2009/2010 Be An Historic Winter?

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I mentioned this a while back but I wonder if we had experienced a "1740"/"1940" type winter, not in terms of intensity but in terms that it suddenly came up after a period where mild had dominated. Those winters brought a shock to the system.

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Althought I have done it for a while, infact the last occasion was March 2006 but I had a "wintry" index for March, it was the same one for the winter but applied to March and April to see how "wintry" they were.

yes-no problem with that Kevin as long as anyone makes clear its March/April etc. Some of the spring months possibly November as well can come in with values greater than winter months.

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I mentioned this a while back but I wonder if we had experienced a "1740"/"1940" type winter, not in terms of intensity but in terms that it suddenly came up after a period where mild had dominated. Those winters brought a shock to the system.

The thought had crossed my mind too, Mr D. It will be a few years down the line before we know whether or not this one was the start of a trend or a 1916/17 type anomaly.

With regard to using the winter index for months outside winter, I've kept an index for both winter and summer months for the last 35 years and have always extended the index to include November and March and May and September for winter and summer respectively. As you mention this was merely to see how wintry or summery the peripheral months were in comparison to the core months of each season.

My index differs from yours so it's pointless me quoting figures but it's interesting to note that

March 1987 was more 'wintry' than all but 1 December, 8 Januaries and 7 Februaries in the last 35 years. In fact its score was very similar to February 2010.

With regard to summer, May 1989 has been bettered by only 1 June, 9 Julys and 8 Augusts in the last 35 years.

I've never extended the data to include April or October but, in view of Aprils like 1917 or even 1986 perhaps it would be worth doing. Here at least, April 1981 and 1986 would definitely score higher than January 1989 on the index.

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Ian, March is NOT winter in Met definitions. How on earth you can make a 'winter' indice using a month that does not feature and then try and compare to any other winter is beyond me.

So am I right in thinking you are going to compare Dec-March for 2009-2010 against 1946-47 December to February?

Only IF you say its your version of winter and you are comparing March along with December-February for all the years does it make any sense. Why not include April and May when its snowed or even the very isolated instance of snow on low ground in other months of spring and summer?

Jumping to conclusions? The snow index that I posted about last summer (there was a whole thread dedicated to it) covers snow events for the whole season (September to June) not just the winter quarter. The totals of 1947 and 1979 were bolstered by frequent snowfalls into early spring. The reason why I chose this measure, rather than just the winter quarter, is because many people's perceptions of "winter snowiness" focuses on the season as a whole rather than just the winter quarter- e.g. in eastern areas 1993/94 is often remembered for its snowy spell in November.

To be pedantic if we're defining "winter" as in "meteorological winter" then "winter snow events" can be argued as a misleading title but since we get a lot of posts about "winter continuing into March/April" when it ends up snowy in those months, or "winter arriving in November" when it turns snowy then, it's a question of interpretation.

Especially considering that I often pull others up for it, there is no way I would mislead by saying this "winter" was snowier than a past one by comparing Dec-Mar with Dec-Feb!

Edit: I created individual seasonal indexes for autumn and spring (and the winter quarter indexes can easily be derived from those by subtracting them from the totals) so if people do want meteorological quarters to be used then that is possible.

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Thank you for the full explanation Ian-not a problem now you have made what you are doing quite clear.

I remain of the 'old school' that winter is December to February, but provided anyone makes it clear just what they are referring to and its like for like as you describe then no problem.

The posts from Mr D and TM regarding how high up some of the 'non' winter months show in some years is quite interesting. Now I've got Kevin's' index I might try it for some of the colder and snowy months in autumn and spring for here.

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As a footnote to the above I just had a look through the Aprils of 1981 and 1986. April 1981 returned a score which made it more wintry than 18 Decembers, 10 Januaries and 11 Februaries in the last 35 years, it was comparable with January 1998.

April 1986 scored about the same as January 2000 or February 2007 but was less wintry than April 1981 as there was no lying snow and fewer very cold days.

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Actually John, you've prompted me to dig out a remarkable statistic: having calculated the respective "winter quarter" scores, they put the winter quarter of 2009/10 (53) in second place after that of 1946/47 (54). The winter of 1978/79 produced very wintry weather well into March (and to a lesser extent April and early May) which bolstered its total, and I expect it to repass this winter very shortly as a repeat of mid-March 1979 (or early to mid March 1947, which sent the 1946/47 season well ahead) is very unlikely.

Of course every snowiness index for a winter will have its downsides: I think February's contribution to this winter's total came from a large number of marginal snow events that produced accumulations for some but, for most places, didn't stick around for very long, and this index does not take into account persistence of snow cover, only the amount that accumulates and geographical distribution.

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I mentioned this a while back but I wonder if we had experienced a "1740"/"1940" type winter, not in terms of intensity but in terms that it suddenly came up after a period where mild had dominated. Those winters brought a shock to the system.

I think we may have come close to getting a 16-17 type winter this winter, funnily enough that was also estimated to be a strong El Nino so everything probably evolved in a very similar way, though the core of the cold from the looks of things in 16-17 was just a little further south then it reached this winter.

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The CET for the winter 2009-10 was 2.4C, the winter is a 90 day period except for leap years when its 91 days

It is now clear that the CET for 11th December 2009 - 10th March 2010 (also a 90 day period) is going to be colder as it is currently 2.0C

A severe winter for the CET is often described as being sub 2C, so although the official winter was above this, there is a 90 day period that is running close to the line.

Probably 2.1C

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Yes Kevin, I think however we measure winter 2009-2010 is going to be almost a bench mark for subsequent winters. Many parts of the UK, although not all, have experienced the coldest and for a good many the snowiest winter in over 30 years. As you mention along with Kold regarding the 1916-17 winter and how long after that before another similar one occurred, severe winters don't usually come along that often!

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Yes Kevin, I think however we measure winter 2009-2010 is going to be almost a bench mark for subsequent winters. Many parts of the UK, although not all, have experienced the coldest and for a good many the snowiest winter in over 30 years. As you mention along with Kold regarding the 1916-17 winter and how long after that before another similar one occurred, severe winters don't usually come along that often!

Being a cold winter lover, yes severe winters don't usually come along that often, this year has in this sense been a real treat. Perhaps we are about to enter a phase where cold or even severe winters occur in greater regularity, why not we've just gone through a period where we have seen record warm summers,time for the winters to do all the talking now I hope..

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I guess it depends where in the country you are to consider it a remarkable winter. To me the only thing that was remarkable was the absense of really mild weather. To call it severe, I would expect a fall of snow of more than 10 inches that stayed around with very little thaw for at least two weeks. That was the sort of thing we saw in 1962/3 and nearly in 1981/2 which have been the only two (what I would call) severe winters I have experienced.

Richard

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It is clear that the period 11th December 2009- 10th March 2010, a 90 day period is going to be even colder than the winter's CET (a 90 day period) probably about 2.0C or 0.4C colder. 11th December is the start date of this extended cold period.

Here is how this period compares to previous such periods up to 1772 which were colder than this. 1772 is when daily CET mean records begin.

11th Dec 1978 - 10th Mar 1979: 1.7

11th Dec 1962 - 10th Mar 1963: 0.1

11th Dec 1946 - 10th Mar 1947: 0.6

11th Dec 1941 - 10th Mar 1942: 1.7

11th Dec 1939 - 10th Mar 1940: 1.2

11th Dec 1928 - 10th Mar 1929: 1.7

11th Dec 1916 - 10th Mar 1917: 1.5

11th Dec 1894 - 10th Mar 1895: 1.1

11th Dec 1890 - 10th Mar 1891: 1.8

11th Dec 1880 - 10th Mar 1881: 2.0

11th Dec 1878 - 10th Mar 1879: 1.2

11th Dec 1854 - 10th Mar 1855: 1.8

11th Dec 1846 - 10th Mar 1847: 1.9

11th Dec 1844 - 10th Mar 1845: 1.6

11th Dec 1840 - 10th Mar 1841: 1.5

11th Dec 1837 - 10th Mar 1838: 1.7

11th Dec 1829 - 10th Mar 1830: 1.4

11th Dec 1822 - 10th Mar 1823: 1.5

11th Dec 1820 - 10th Mar 1821: 1.3

11th Dec 1813 - 10th Mar 1814: 0.1

11th Dec 1799 - 10th Mar 1800: 1.5

11th Dec 1798 - 10th Mar 1799: 1.8

11th Dec 1794 - 10th Mar 1795: 0.0

11th Dec 1784 - 10th Mar 1785: 1.3

11th Dec 1783 - 10th Mar 1784: 1.8

11th Dec 1779 - 10th Mar 1780: 1.8

11th Dec 1775 - 10th Mar 1776: 1.9

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It's very impressive that this 'winter', for want of a better term, has featured in the top 30 in the last 200 odd years. Only 7 other instances in the last 100 years too, and all this on the back of a very mild period.

Something's afoot methinks.

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11th December - 8th March currently stands at 1.94C, so a combined average for the 9th & 10th of 4.4C or lower is required to get a provisional three-month period below 2C. This is obviously still subject to official March alterations, but I can't see the next two days achieving 4.4C (minima in the CET zone shouldn't be as low as in recent days, but the maxima should be suppressed by the increased cloud cover).

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I guess it depends where in the country you are to consider it a remarkable winter. To me the only thing that was remarkable was the absense of really mild weather. To call it severe, I would expect a fall of snow of more than 10 inches that stayed around with very little thaw for at least two weeks. That was the sort of thing we saw in 1962/3 and nearly in 1981/2 which have been the only two (what I would call) severe winters I have experienced.

Richard

I tend to agree with you.

Although we use the CET as a guide for me it doesn't tell the whole story. I have known far more severe cold spells with a warmer CET. This winter might of been excellent for my region with regards to days of snow falling/lying, frosts, lack of mild days but when it comes to actual snowfalls then Feb 09 still beats this winter.

If this makes any sense I feel as though i've won a million on the Lotto before discovering I have to share this with 30 other winners i.e could of been much better. This winter has been excellent synoptically but for S England I feel we missed a great chance. Any cold pools from an E,ly were generally small in size and in January it actually turned less cold from the E,ly resulting in a thaw of lying snow. The problem at times was the blocking to our NW wasn't far E and troughing over Scandi also prevented any decent E,lys.

For me personally I would prefer a winter like 1987. This might of been mild for much of the winter but at least it consisted of a severe cold spell. For my region this was a historic winter which didn't contain any severe cold spells. The only exception was probably Dec 17/18th.

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Well it has certainly been an historic winter here as I was just adding up the snowfalls to date and they come to 35 inches over the winter. was -4c this morning and although sunny areas will thaw we still have large areas of permafrost from mid December behind woods, walls and buildings. Also some large snow patches in those same areas from the late February falls . Grass is completely brown goodness knows when it will green up, hundrds of buildings brought down by the heavy snows at New Year and wild deer now dying in their hundreds due to starvation. Even a dead deer at the farm buildings last week something I have never seen before in spite of eating a lot of turnips in my field. This is all at 100m asl and just a few hundred metres above me the fields are still snow covered.

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A notable but not historic winter from my point of view. Although the winter has been long and persistently cold, or at least chilly, it has lacked any really severe spells and there have been no, single, heavy falls of snow and no disruptive blizzards.

Yes, we have had blowing snow on occasions but nothing to compare with events like early Dec' 1990, Jan' 1987, Feb' 1991 or Feb' 1979. One or two events like this coupled with cold spells to rival those of 1982, 1985 or 1986 and this winter would have been pushed into the historic category; a 'close but no cigar' situation here.

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Guest North Sea Snow Convection

A sustained cold winter says a lot more to me than a one-off intense cold spell does. This winter has beaten the likes of 1987 and 90/91 by a long way I think.

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Winter 2009/10 was a cold winter no question and with a tweak here and there

it could so easily have been a severe winter or colder. Had the low pressure that

anchored itself off the Norwegian coast in early February moved south then a severe

winter would have almost been a certainty. Also if the track of the low from the Arctic

in December cold spell moved south instead of west again a much longer and possibly

colder spell would have ensued. Personally I think ssts played a large part here.

The winter for England and Wales was consistently rather cold or cold and I wonder

how many more in the CET index were similar and again if given a tweak here or

there would have been much colder.

There is a different category of cold CET winters where two or three prolonged very

cold perhaps severe spells have resulted in a cold CET return rather than persistent

rather cold to cold weather like we saw this winter.

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But we did have a prolonged spell of severe cold. The first third of January was the coldest since 1894.

Some people in south-eastern areas in particular are bound to compare it unfavourably with the likes of 11-14 January 1987, 14-15 February 1979 etc. but it's highly probable that by around 8 January 2010, snow covered a larger proportion of the British Isles than at any time during January 1987, and possibly mid-February 1979 as well.

The difference with this winter is that the severest conditions have affected northern areas, whereas 1947 and 1963 affected the south most heavily- 1979 probably affected both north and south in roughly equal measure.

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I do not call maximum temperatures of around 0c give or take a degree, severe cold

and yes although the cold spell in January was memorable ( 8" of snow for my area)

by Sunday the 10th the daytime temperatures had risen to about +1c or so above

freezing and there they stayed until the proper thaw on the 15th.

I would say northern blocking is very likely to continue in future winters with a return of cold,

very cold, and possibly severe cold spells likely to become fairly frequent visitors to the UK

similar in fact to some of the colder decades in the past.

Some winters you might not necessarily have a very low CET value but unlike the majority

of our recent winters they will contain some periods of widespread cold and snow.

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A sustained cold winter says a lot more to me than a one-off intense cold spell does. This winter has beaten the likes of 1987 and 90/91 by a long way I think.

Although it has beaten the likes of 1987, 91 I would still prefer one of those winters. In my location I didn't recieve any notable snowfall from fronts and the only decent snowfalls was Dec 17/18th via a stream of showers which gave 12cm of snowfall. Apart from this very little except a few heavy snow showers one evening in January.

I must admit im not a fan of cold weather unless heavy snow is around. This is mainly due to the poor insulation of my flat which also recieves very little sunlight. So at times this winter has been exciting i.e Dec 17/18th but other times its been a drag. This is why im hoping no other cold spells appear in the model output and would welcome temps in excess of 15C.

I agree CC look at the youtube forecasts of Feb 91 or even better Jan 87. A forecast predicting max temps of -5C with biting E,ly winds is what I call a severe cold spell. I remember a Anglia TV forecast in the 1980s warning people to not go outside due to windchill being below -20C. Now thats what I call severe cold!

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Although it has beaten the likes of 1987, 91 I would still prefer one of those winters. In my location I didn't recieve any notable snowfall from fronts and the only decent snowfalls was Dec 17/18th via a stream of showers which gave 12cm of snowfall. Apart from this very little except a few heavy snow showers one evening in January.

I must admit im not a fan of cold weather unless heavy snow is around. This is mainly due to the poor insulation of my flat which also recieves very little sunlight. So at times this winter has been exciting i.e Dec 17/18th but other times its been a drag. This is why im hoping no other cold spells appear in the model output and would welcome temps in excess of 15C.

I agree CC look at the youtube forecasts of Feb 91 or even better Jan 87. A forecast predicting max temps of -5C with biting E,ly winds is what I call a severe cold spell. I remember a Anglia TV forecast in the 1980s warning people to not go outside due to windchill being below -20C. Now thats what I call severe cold!

Bristol - 3 snowfalls - the night of Dec 20/21, Wednesday early morning 6th Jan and Wednesday early morning 13th Jan. Sustained cold (near or below freezing in daytime) Jan 6th to 10th.

Cold thru' Jan and Feb, but not biting cold.

2nd half of Jan and all Feb no snow, other than odd couple of hours of very wet snow that struggled to settle.

Our local BBC weather guy stated it was our coldest since 1995.

From a snow point of view nothing extraordinary in my lifetime (the 1st week of Feb 09 brought more snow, but more marginal temps).

Biggest missing 'ingredient' - blizzards with biting easterlies, and temps below freezing during any blizzard - conditions we did see in Feb 78, 78/79, 81/82, 85 and 87.

However, most of those winters prob did not have sustained 'cold' from mid-Dec thru' Feb.

IMBY summary, but fairly 'accurate' in my view.

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It's very impressive that this 'winter', for want of a better term, has featured in the top 30 in the last 200 odd years. Only 7 other instances in the last 100 years too, and all this on the back of a very mild period.

Something's afoot methinks.

It may well be...or perhaps it may not, time will tell. Here's genuinely hoping.

That is, indeed, a very impressive statistic - thanks for showing it to us, Kevin.

However, the only problem (from a statistical point-of-view) with comparing other 11th Dec-10th March periods with this one is that you are in essence "cherry-picking" one particular period that happens to be have been an unusually cold (?the coldest) one this winter.

I am not trying to nit-pick, and this is not in any way to deny the severity of those 90 days; but in order to make a true and fair comparison it would be necessary to examine the incidence of any 90/91-day period in other winters that equalled or exceeded it in severity. If you don't, you are implying that other winters should necessarily have their coldest periods also exactly coinciding with those dates.

The same problem exists, of course, with the meteorological winter, Dec-Feb - a point that has rightly been made here before. The only difference is that the Dec-Feb 90/91-day period is essentially randomly chosen as a conveniently-described, approximate coldest period of winter - random, that is, with regard to the weather of any particular year. You could well argue that something like a-third-through December to a-third-through March would be a better fit for the coldest three months of the year.......but then it needs to be decided in advance rather than because it "best fits" the situation of one particular winter. And you could also still fall foul of possible shifts in the coldest time of the year.

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