January CET

[Nick L]

That will take a hit the next 2 days, especially with the negative double figures expected tonight in the CET zone.

[Stratos Ferric]

That will take a hit the next 2 days, especially with the negative double figures expected tonight in the CET zone.

The CET minimum will be nowhere near that low, and I'd be fairly surprised if -10C was widespread tonight at all - that day off school seems to have gone to your head a bit; it depends where and if the snowcover has persisted, whether skies clear (slightly more likely given the subtle change in airmass today), and whether the wind drops. I suspect that generally -5 will be cloer to the mark; still cold.

At the moment I'd say it is unlikely to be colder than the 1st half of winter 1996/7.

It would require a 1st half of January of around -1.0°C (I'm sure someone can be more exact). I can see Jan 1-10 coming in around -0.5°C and then possibly milder for the following 5 days.

Anyway, it makes a (pleasant) surprise that the coldest part of the country in the next week will be the central southern and far south east of England.

Just checking other notable cold spells. For the benefit of those worried about the potentially arbitrary nature of these things, I've used a daily mean at or below 4C as the mark. I make our current sequence ten days to yesterday, with as many as four or five more at least still looking likely to follow.

Long sequences in the not too distant past include:

15 days (J-F 2006)

20 days (J-F 1996)

22 days (D-J 96-97)

30 days (J-F 1991)

36 days (J-F 1986)

Interestingly 1979 managed no very long sustained cold, indicative of frequent pattern changes that winter, though each mild interlude amounted to one day only, and even then they only just crept above 4C. Between Dec 30th - Feb 28th that year there were just four none cold days out of 61.

1963 is in a class all of its own: there were 73 consecutive cold days using the 4C bar.

[Nick L]

The CET minimum will be nowhere near that low, and I'd be fairly surprised if -10C was widespread tonight at all - that day off school seems to have gone to your head a bit; it depends where and if the snowcover has persisted, whether skies clear (slightly more likely given the subtle change in airmass today), and whether the wind drops. I suspect that generally -5 will be cloer to the mark; still cold.

Just checking other notable cold spells. For the benefit of those worried about the potentially arbitrary nature of these things, I've used a daily mean at or below 4C as the mark. I make our current sequence ten days to yesterday, with as many as four or five more at least still looking likely to follow.

Long sequences in the not too distant past include:

15 days (J-F 2006)

20 days (J-F 1996)

22 days (D-J 96-97)

30 days (J-F 1991)

36 days (J-F 1986)

Interestingly 1979 managed no very long sustained cold, indicative of frequent pattern changes that winter, though each mild interlude amounted to one day only, and even then they only just crept above 4C. Between Dec 30th - Feb 28th that year there were just four none cold days out of 61.

1963 is in a class all of its own: there were 73 consecutive cold days using the 4C bar.

Well I am only quoting what the BBC said, "-7c to -10c" possible in the area where CET readings are taken, -10c is negative double figures. You might have misunderstood my post.

Edited January 5, 2009 by nick2702

[Stratos Ferric]

Well I am only quoting what the BBC said, "-7c to -10c" possible in the area where CET readings are taken, -10c is negative double figures. You might have misunderstood my post.

I think it's fair to say that I know what double figures are. As I said, -10C is unlikely, which put another way is "possible", just that I wouldn't give very short odds on it as a general outcome. Still a bit of cloud about, and still a fair breeze giving a bit of mixing. Even with general snowcover -10C would be a low outcome from this set up. As I said, -5 to -7C I'd think generally. None of the CET locations is a particularly cold locale and they certainly aren't representative of the 'favoured' cold spots in England / Wales, nor should they be.

[Nick L]

I think it's fair to say that I know what double figures are. As I said, -10C is unlikely, which put another way is "possible", just that I wouldn't give very short odds on it as a general outcome. Still a bit of cloud about, and still a fair breeze giving a bit of mixing. Even with general snowcover -10C would be a low outcome from this set up. As I said, -5 to -7C I'd think generally. None of the CET locations is a particularly cold locale and they certainly aren't representative of the 'favoured' cold spots in England / Wales, nor should they be.

But what I am saying is that it will be a very cold night across most of the country, so surely that would help peg the CET down for tomorrow?

[Stratos Ferric]

But what I am saying is that it will be a very cold night across most of the country, so surely that would help peg the CET down for tomorrow?

Don't disagree with that at all, though things are on the move slowly now. On other recent days with temps as low as tonight's we've struggled to get above freezing, tomorrow looks like getting above 0C fairly widely. The running mean may reach its nadir in the next 24 hours. Not sure I buy the current projections from GFS for overnight minima at the end of the week.

[Optimus Prime]

Philip Eden starts us of, as from the 4th at -0.4c.

Mean Max 2.0c (-4.4c)

Mean Min -2.8c (-4.8c)

[Supercell]

Could anyone inform me which stations are used for the CET ?

I would have thought my local Church lawford site might just be on the boundary.

[cheeky_monkey]

But what I am saying is that it will be a very cold night across most of the country, so surely that would help peg the CET down for tomorrow?

what exactly do we gain from keeping the cet down?

[Supercell]

what exactly do we gain from keeping the cet down?

We get to prove that global warming and the associated even larger teapot are mythical terms. :winky:

[Nick H]

None of the CET locations is a particularly cold locale

I think it's fair to say that Pershore is a notable frost hollow, lying in the Vale of Evesham.

As to the others, Rothamsted, near me, is at the foot of the Chilterns but not a frost pocket. Stonyhurst, on the Lancashire Plain, is I imagine too high up (if such a thing is possible) and certainly too flat to record very low temperatures.

Edited January 5, 2009 by Nick H

[7andY]

I think it's fair to say that Pershore is a notable frost hollow, lying in the Vale of Evesham.

As to the others, Rothamsted, near me, is at the foot of the Chilterns but not a frost pocket. Stonyhurst, on the Lancashire Plain, is I imagine too high up (if such a thing is possible) and certainly too flat to record very low temperatures.

Last time I looked, the Vale of Evesham was flat and wide - that's why it's called a Vale and not a Valley!!

If Pershore is in a frost hollow, then so are places like York, Gloucester, London, Peterborough, Newport (Wales) etc etc - they're all in wide flat river valleys... :winky:

7&Y

[cheeky_monkey]

We get to prove that global warming and the associated even larger teapot are mythical terms. :winky:

wouldnt it be poetic justice if we got 3 winter months with below average cets....but had less snow than the previous 2 winters???

[Stratos Ferric]

I think it's fair to say that Pershore is a notable frost hollow, lying in the Vale of Evesham.

As to the others, Rothamsted, near me, is at the foot of the Chilterns but not a frost pocket. Stonyhurst, on the Lancashire Plain, is I imagine too high up (if such a thing is possible) and certainly too flat to record very low temperatures.

I grant you that Pershore lies low in the Vale, but does it really lie in a frost hollow in the way that the stations at, say, Rickmansworth, Eskdalemuir, or Redhill do?

Stonyhurst sits comfortably above the Ribble valley.

Could anyone inform me which stations are used for the CET ?

I would have thought my local Church lawford site might just be on the boundary.

You have to remember that strictly speaking the CET is indicative of nothing specific that bears comparison with individual locations. I'm not sure we can meaingfully talk about a boundary of the CET zone, as there are locations within the boundary of the line between these sites (and the original intent which was, if I remember rightly, something like the triangle between London, Bristol and Manchester) for which the CET is a poor surrogate (e.g. Leek and Buxton), just as there are sites outside it for which it might be a reasonable proxy (e.g. the various RAF stations up the A1). At the end of the day it's an average of three sites, with some additional sites used to correct and level anomalies.

Edited January 5, 2009 by Stratos Ferric

[Snowyowl9]

Tomorrows maxes look very low,may be nearer the mark for here and not low ground.

http://91.121.93.17/pics/Rtavn3017.png

[Stratos Ferric]

Last time I looked, the Vale of Evesham was flat and wide - that's why it's called a Vale and not a Valley!!

If Pershore is in a frost hollow, then so are places like York, Gloucester, London, Peterborough, Newport (Wales) etc etc - they're all in wide flat river valleys... :winky:

7&Y

The generally recognised locations tend to have a specific microclimate triggered in particular conditions (almost invariably calm, clear weather) and enhanced by peculiarities or irregularities in the location of the measuring station which serve to exacerbate the impact upon still, clear air. Ricky is located near a railway embankment, which effectively dams cold air coming from higher ground above; I vaguely recall that Redhill has a similar geography; either or both might be further enhanced by sandy soils. The well known Scottish sites are all in narrow and fairly deep glens.

[Nick H]

I grant you that Pershore lies low in the Vale, but does it really lie in a frost hollow in the way that the stations at, say, Rickmansworth, Eskdalemuir, or Redhill do?

I must confess I've never been to Pershore but it certainly seems to record some very low temps (e.g. -8°C a couple of nights ago).

The Redhill frost hollow is caused by the M23 motorway embankment, as well as sandy soils, and is actually in South Nutfield and is not particuarly close to the town of Redhill itself. I know that because I used to live in South Nutfield - fortunately I managed to escape just as Edwina Currie moved in.

Perhaps flatness is not necessarily as important as I thought it was: Topcliffe, and the Vale of York generally, seem to record low temps given the right set up.

Edited January 5, 2009 by Nick H

[Stratos Ferric]

I must confess I've never been to Pershore but it certainly seems to record some very low temps (e.g. -8°C a couple of nights ago).

The Redhill frost hollow is caused by the M23 motorway embankment, as well as sandy soils, and is actually in South Nutfield and is not particuarly close to the town of Redhill itself. I know that because I used to live in South Nutfield - fortunately I managed to escape just as Edwina Currie moved in.

Perhaps flatness is not necessarily as important as I thought it was: Topcliffe, and the Vale of York generally, seem to record low temps given the right set up.

Vale of York tends to stay cold when there's persistent fog, but apart from that the farther reaches of the A1 RAF stations don't tend to register anything exceptional.

[TEITS]

Whilst Pershore is being mentioned on this thread I shall let you know that as of 7am the temps in Pershore are -9C.

Widespread -5C to -7C with -9C being recorded in a few locations and even -10C in Farnborough.

[Polar Continental]

Whilst Pershore is being mentioned on this thread I shall let you know that as of 7am the temps in Pershore are -9C.

Widespread -5C to -7C with -9C being recorded in a few locations and even -10C in Farnborough.

Yes this cold spell has really dug in now, -5.2 here, and still falling, my mean so far this month is -1c.

Paul

[Roger J Smith]

This will make Rich laugh wherever he is, it is -1 C at Calgary Alberta, milder than about 80% of the stations in England at the moment.

But that is considered a warm spell in Alberta.

[Nick H]

Whilst Pershore is being mentioned on this thread I shall let you know that as of 7am the temps in Pershore are -9C.

Widespread -5C to -7C with -9C being recorded in a few locations and even -10C in Farnborough.

-10°C at Pershore now.

Manchester troughed at -7°C and Luton at -6°C. If these are assumed to be reasonable proxies for Stonyhurst and Rothamsted respectively that would give a CET minimum of -7.6°C.

At 8am it would appear there was an air frost at every recording station in England.

Edited January 6, 2009 by Nick H

[Great Plum]

I must confess I've never been to Pershore but it certainly seems to record some very low temps (e.g. -8°C a couple of nights ago).

The Redhill frost hollow is caused by the M23 motorway embankment, as well as sandy soils, and is actually in South Nutfield and is not particuarly close to the town of Redhill itself. I know that because I used to live in South Nutfield - fortunately I managed to escape just as Edwina Currie moved in.

Perhaps flatness is not necessarily as important as I thought it was: Topcliffe, and the Vale of York generally, seem to record low temps given the right set up.

I believe the Redhll station used to be located at the aerodrome which is, as you say in South Nutifeld... However, (conspiracy theory here!), as it recorded these low temperatures, it was closed a year or too back and now Charlwood (at the end of Gatwick's runway!!!) is used...

The low temps here in Reigate and Redhill I think come because we are in the hollow of the south scarp of the chalk North Downs and the sandstone hills just south...

[Stu_London]

Slight rise on Hadley to the 5th

CET 01/01/09-05/01/09 -0.2C

Goes to show that with such a low starting point, it needs to be really cold for falls to occur, although the 6th should see a fall.

[reef]

Slight rise on Hadley to the 5th

CET 01/01/09-05/01/09 -0.2C

Goes to show that with such a low starting point, it needs to be really cold for falls to occur, although the 6th should see a fall.

It will fall some way tomorrow, as Hadley have today's minima down as -5.6C. I do think after today we're going to havew trouble sustaining any daily means of below freezing though. That weak front passing through tonight will increase cloud amounts, which along with slightly higher maxima, could well stop night temperatures falling very low.