The Recent Cold Spell Compared To Other Cold Spells

[Terminal Moraine]

With all the interest concerning the recent cold spell I thought it would be interesting to look back through my records and see how it compared with other cold spells since I set up my current station in 1977.

For the purposes of this discussion a cold spell is defined as a period of at least 7 days when the maximum temp' does not exceed 2.9c but one of the days can have a max' of between 3.0 and 4.4c. So, by this method if a period of 6 consecutive days with maximum temp's of 2.9c or less is then followed by two days with a max' between 3.0c and 4.4c, the 6 days following the second of these two must also have a max' temp' of 2.9c or less for the cold spell to continue.

This definition is taken almost directly from Brazell's 'London Weather' and seemed as good a yardstick as any.

The recent cold spell here has lasted 15 days, beginning on the 26th of Dec' and ending on Jan' 10th, this is the longest cold spell since Dec' 20th 1996-Jan' 10th 1997, a spell of 22 days.

The mean max' temp' during the current spell was 0.8c and the mean temp' was -0.6c. There have been 3 spells since 2000 colder than this but all were shorter, lasting 8 or 9 days; these were Jan' 3rd-11th 2003, Dec' 28th 2001-Jan' 4th 2002 and Jan14th-21st 2001.

Since 1977 there have been a total of 39 cold spells, the longest of these were 40 days in 1986 and 37 days in 1979, the current cold spell has been exceeded in length on 12 occasions.

Taking mean maximum temperature there have been 18 colder spells and by mean temperature there have been 24 colder spells, an indication that, at this site at least, the mean minimum in the recent spell has been higher than in previous cold spells.

Overall then a decent cold spell falling into the mid-range of cold spells occurring during the last 30 years but with a tendency to higher minima, probably due to a lack of very cold air at depth and/or increased cloud cover.

Comments from other stations welcome.

[johnholmes]

very interesting TM, and as usual from you very precise.

For here its the coldest, using the mean as a yardstick since December, I think the 28th (I only started routine observations on 1 January 1997) to about 10 January 1997.

The mean temperature over the 15 day period from 27 December 2008 to 10 January 2009 was 1.1C, for the 15 days.

The 1996-97 I cannot give data for December as I was not collecting it, but the first 11 days of January the mean was 1.0C.

In terms of maximum the average this last time was 3.1C compared to 2.6 in 96-97, and the minimum was -0.8C compared to -0.6C in 96-97.

Maybe TM, this corroborates your view about deeper cold air as I've seen you mention on a number of times about inversions with highs over the country. Here, either will give low values.

The major difference of course here and with you was that 1996-97 saw a good snowfall,10-15 cm of snow on N Y Eve here which lasted, at more than half cover, until the morning of 6th.

Edited January 11, 2009 by johnholmes

[Stratos Ferric]

...

For the purposes of this discussion a cold spell is defined as a period of at least 7 days when the maximum temp' does not exceed 2.9c but one of the days can have a max' of between 3.0 and 4.4c. ...

Comments from other stations welcome.

TM, you might want to clarify: isn't that a non-sequitur? Either seven days don't exceed 2.9C, or one of the seven does. Or should the first 'max' be 'daily mean'?

Maybe I'm missing something...

Good stats by the way.

Edited January 11, 2009 by Stratos Ferric

[Snowyowl9]

That means it was a 13 day cold spell with 2.9c or below here beginning from december 26th to January 7th...

4c on the 8th just 1 day above 2.9c so it was 15 days next day was 1.6c.

Mean max here was 0.9c

Mean min was -3.0c

1996 started from the 28th to January 10th,the 27th was over 2.9c if I would be using newer more accurate readings.

But it also started before that on the 19th to 26th so another week 23 days cold spell,just 1 day less cold.

Much more snow cover during that cold spell with 2inches on the 31st, then 3 to 4 inches during early January.

As this one only gave a covering.

Edited January 11, 2009 by Snowyowl9

[Terminal Moraine]

TM, you might want to clarify: isn't that a non-sequitur? Either seven days don't exceed 2.9C, or one of the seven does. Or should the first 'max' be 'daily mean'?

Maybe I'm missing something...

Good stats by the way.

I must admit, S.F, when I first saw the written criteria many years ago the same thought crossed my mind. I have quoted the description directly but perhaps it could be better, although perhaps more clumsily, defined as, 'A period of at least 7 days, one of which may have a maximum temp' between 3.0c and 4.4c provided the other 6 have a maximum of 2.9c or less'.

The basic tenor of the defining criteria is that no day will exceed 4.4c and for every day that has a maximum of between 3.0 and 4.4c there must be 6 others within a consecutive 7 day period which do not exceed 2.9c.

[johnholmes]

it sounds almost like some of the gobbledgook that a one time boss of London Weather Centre used to delight in.

Quite amusing watching even senior staff acratching their heads wondering just what the latest Staff Instruction actually meant!

[MAF]

the Met Office view on the recent cold snap is a good read

Background

The British Isles has experienced almost a fortnight of freezing conditions. Temperatures as low as -9 °C have been fairly common throughout southern areas of the UK, with temperatures struggling to rise above freezing in some places.

The lengthy spell of cold weather has been caused by an area of high pressure which has stayed close to the UK over the past few weeks, bringing cold air across the UK from Europe.

This spell of cold weather is now forecast to end, as milder and more unsettled conditions push across the UK through the weekend, with strong winds in the North.

Impacts

The cold spell caused significant problems in many areas of the country. The Government's bill for Cold Weather Payments is expected to rise to more than £100 million, with Londoners becoming eligible for the payment for the first time since the scheme was introduced a decade ago.

South East Coast Ambulance Service manned its GOLD control for a period, and many A&E departments reported being busier than normal, with cases of flu and broken bones raising admissions.

On the roads, icy conditions led to numerous closures and a significant increase in accidents. Motoring organisations reported a 100% increase in the number of call-outs they received.

The continuous cold conditions caused lakes and rivers to freeze in areas such as the Lake District, Hertfordshire and Essex. Boats were frozen in their moorings on the Monmouthshire and Brecon canal in Pontypool.

The sea froze along a part of the south coast at Poole, and Padstow Harbour was partially frozen. Even the fountain in Trafalgar Square was frozen.

Weather data

Parts of southern England have experienced some of their lowest temperatures since 1991, with south-east and central England recording an average minimum temperature of -8.1 °C and south-west England and South Wales recording an average minimum temperature of -8.0 °C.

Throughout the last fortnight, night-time temperatures have consistently fallen to lows of -8 to -10 °C. The coldest temperature recorded during the period was -12.3 °C during the night of 6-7 January, at Buntingford in Hertfordshire.

[TEITS]

Excellent if we look at the max/mins temps and the length of the cold spell.

However the cold spell was poor for snowfall and nothing special from a synoptic point of view.

[Rob]

in general cold wise this has been an amazing cold snap, but snowfall wise its not been great, weve still got a lot of winter to go yet so we cant complain just yet

[Snowyowl9]

I make this the coldest longest spell since 1996/97.

[Great Plum]

Around here, we have had some amazing frosts in the recent cold spell, the most special reserved for Friday night when a combination of freezing fog and very cold weather left some of the most amzing hoar frosts I have ever seen!

[Polar Continental]

Recent cold spell, December 26th to January 10th.

At this station, the mean maximum was 1.7c, mean minimum, -2.0c, mean, -0.1c.

Easily the coldest spell since my records began, but then they only go back to 2005.

Though Rosliston Station only 2 miles away as the crow fly’s has complete records going back to 1991, he made a comment on Metlink a couple of days ago that the period 1st-10th January averaged –0.6c making it the coldest early January period on his records.

Paul

[DR Hosking]

Recent cold spell, December 26th to January 10th.

At this station, the mean maximum was 1.7c, mean minimum, -2.0c, mean, -0.1c.

Easily the coldest spell since my records began, but then they only go back to 2005.

Though Rosliston Station only 2 miles away as the crow fly’s has complete records going back to 1991, he made a comment on Metlink a couple of days ago that the period 1st-10th January averaged –0.6c making it the coldest early January period on his records.

Paul

Dont really have any figures but the current cold spell was certainly the coldest since 1996/97, may even have been colder, although as others have said 96/97 was pretty snowy too. So far this winter ive had 3 snow events, the coldest december for a decade, the coldest start to January for over a decade and were only half way through, no complaints so far!

[Snowyowl9]

Since 1977 there have been a total of 39 cold spells, the longest of these were 40 days in 1986.

Yes thought it was 6 weeks and thats the longest with snow on the ground,1963 was the only longer spell which nearer to 3 months.

Last december`s 2007 cold spell came out as 9 days.

Recent cold spell, December 26th to January 10th.

Though Rosliston Station only 2 miles away as the crow fly’s has complete records going back to 1991, he made a comment on Metlink a couple of days ago that the period 1st-10th January averaged –0.6c making it the coldest early January period on his records.

Paul

I did record 2 colder days to January 1997 and one colder night. :lol:

This is from my other reading average

Jan 1997 these reads much lower but better to compare -7.4c

This month first 10 days is colder -7.75c to Jan 1997!!!!

Edited January 12, 2009 by Snowyowl9

[DR Hosking]

For me the thing that puts the cold spell into a very cold category is the number of days where the average temperature was below freezing, we had 7 days averaging below freezing, and another averaging just 0.1c This is unheard off in recent history, especially as 4 of the days were in a row. Also the temperature reached -10 on 2 occasions, again this hasent happened for many years. I cant ever remember seeing temperatures of -3 at midday and -6 at 5:30 pm, this happened on a couple of occasions.

[Optimus Prime]

Generally the coldest spell of weather since 1991 for minimums but maxima since 1997. Interestingly, Larkhill in Wiltshire had it's lowest january minimum tremperature since 1979 of -9.7C on the 10th, just beating 1987.

Edited January 12, 2009 by Optimus Prime

[Tucco]

Generally the coldest spell of weather since 1991 for minimums but maxima since 1997. Interestingly, Larkhill in Wiltshire had it's lowest january minimum tremperature since 1979 of -9.7C on the 10th, just beating 1987.

In the South? Only the lowest recorded min in England since Dec 2005. -13.2C in N Yorkshire.

Mark

Teesdale,Co Durham

[Terminal Moraine]

As a footnote to the data I provided originally I've had a quick scan through the records to see how the number of ice days and the amount of snowfall compares to cold spells in the past.

This spell gave 4 ice days but only 3 mornings with lying snow ( met office definition ) with a max' depth of just under 5cm.

This is comparable with the spell in January 2003 which managed 1 ice day in a 9 day spell and 3.5cm of snow which fell at the start of the cold spell and lasted until the end of it.

The cold spell from Dec' 28th 2001-Jan 4th 2002 had 3 ice days and more snow, 7cm falling on Dec' 30th and lasting until the end of the spell

The 8 day spell in January 2001 had 2 ice days but no snow until the breakdown at the end when 3.5cm fell.

Two broadly comparable with the recent spell then, apart from the length and one snowier but also shorter.

The spell in 1996-97 had 8 ice days, 4 of which were consecutive, and there was 10cm of snow on new years eve which then gave a continuous cover until the end of the spell, this definitely gave the impression of a more wintry spell than this most recent one and was longer into the bargain.

However, compared to the really cold winters the one just gone pales into insignificance. 1985 saw 10 ice days in January and another 9 in February with two 5 day spells of consecutive ice days in each.

January 1987 had 12 ice days including a consecutive spell from the 9th-19th and best of all was 1986 which had 3 ice days in January and 26 in February, including 22 consecutive days from the 2nd-23rd; this last was also accompanied by a continuous snow cover of between 22 and 32 cm in depth.

[NorthernRab]

Mean Max was approximately -4'C for about 5 days here, with minimum temperatures around -11'C. Probably the coldest 5 days in Inverness in quite a while. In saying that, only about a year ago, 15th - 23rd of Dec 07 or thereabouts was very cold also.

[Devon-Nelly]

I think we missed the worse on this spell due to it being consistantly cloudy, temps were generally around 4c by day and 1-2c by night, the coldest max and low were 0.2c and -5.1 on the 6th and 7th Jan and the highest max was 6.2c on the 30th Dec.

But it was still a good cold spell none the less though, It only reaching 0.2c in clear sunlight all day was quite remarkable for this neck of the woods.

[Michael Fishermans Friend]

Quite similar to the spell in December/January 96/97 - similar time similar duration, but that spell was more severe here in the south east with colder temps by day and more snowfall. This cold spell has come as a shock simply for it's duration (near on 2 weeks) with the coldest night temps after the new year. Here in Burnham on Crouch we experienced our first 'Ice day' since the forementioned cold spell in January 1997 with a max on Saturday of only -0.4C whilst the coldest night being -5.1C. We were relatively lucky to see any snowfall with a max depth of over 1cm (wow) on the 5th compared to nearl on 3 inches in 1997. A 'Big Freeze' maybe not but in these 'even larger teapot' times maybe so. Compared to severe cold spells/snaps such as the spells in 95/96, February 91, Jan 87 (the biggy), Feb 86, Jan/Feb 85, Dec/Jan 81/82, Winter of discontent 79, Feb 78 it simply does not compare but lets hope we might get more from round 2 or will there not be another round as per the winter of 1996/97 when after was largely mild.

[Devon-Nelly]

I think we missed the worse on this spell due to it being consistantly cloudy, temps were generally around 4c by day and 1-2c by night, the coldest max and low were 0.2c and -5.1 on the 6th and 7th Jan and the highest max was 6.2c on the 30th Dec.

But it was still a good cold spell none the less though, It only reaching 0.2c in clear sunlight all day was quite remarkable for this neck of the woods.

[johnholmes]

and best of all was 1986 which had 3 ice days in January and 26 in February, including 22 consecutive days from the 2nd-23rd; this last was also accompanied by a continuous snow cover of between 22 and 32 cm in depth.

the 'joys' of living at altitude, its easy to forget just how cold it can be even in the UK.

[stewfox]

However, compared to the really cold winters the one just gone pales into insignificance. 1985 saw 10 ice days in January and another 9 in February with two 5 day spells of consecutive ice days in each.

Small observation re how this 'cold winter'. compares to others

Its the 12th January at present so wether its 'insignificant' remains to be seen

[morfius]

Just thought i'd mention that it's silly to compare temperatures with the more snowy cold spells - we would have certainly had much lower temperatures if we had lying snow throughout the spell.