January CET

[damianslaw]

The peak of the upcoming mild spell looks like being the 15th Jan and this is when I expect the CET to peak this month at somewhere around the 4.5 degree mark, some very mild maxima and minima from Wednesday onwards will help to rise it significantly, there is an outside chance we may even get up to 5 degrees.

Thereafter a gradual cooldown with the CET faling a little each day with a sharp downturn from the 21st.. However, a sub 2 degree month may be too much of an ask due to the upcoming mild weather, but I feel a finishing value between 2 and 3 degrees at this stage is very plausible, with 4 degrees the absolute highest realistically we will finish at, so a below average month a very good bet I feel.

[summer blizzard]

Both GFS and ECWMF now agree that the 17th will begin the cooldown with a north westerly.

I certainly expect the CET to reach 4C though maxima will be pegged back by rain so i am hopeful of nothing spectacular.

I expect the cold to last, so i am still pleased with my 3.2C prediction.

[Kentish Man]

Hadley is on 2.9C today (Jan 1st - 8th).

Quite a lot of mild in the next 10 days in the 06z GFS so we will need a cold last third to prevent both an above average month and most peoples guesses including mine @3.7C from being too low.

Edited January 9, 2011 by Kentish Man

[DeepSnow]

I think my guess of 1.4C is way to low!! Somehow we need some sever cold to come in as soon as possible lol

Edited January 9, 2011 by DeepSnow

[damianslaw]

This January once again is proving how it is perhaps the one month of the year when you have to expect at least some mild atlantic weather of 5 days + interferring with the CET and preventing chances of a real cold CET value.

Last year, the cold half was derailed by the atlantic, preventing a notable cold CET value. 2009 we saw the same thing happen though a week earlier. We have to go back well to 1979 to see a January devoid of any lengthy atlantic mild spell, even then we saw some short lived mild atlantic spells.. The last January with no atlantic mild weather was 1963.

A flip is often switched in mid January either from cold to mild or vise versa. Conditions at the start of the month are usually very different to what they are by mid month.

In contrast December (unusually) in 2010 and February in 1986, 1991 and I will place 2010 in the same category have seen full months devoid of any lengthy mild atlantic weather (classed as 5 days +). Of the three winter months, February is and always will be our best shot of a colder than normal month with the atlantic much less likely to spoil things..

January in contrast now appears to be the least likely month. Had you asked me this back in November I would have said December but only slightly ahead of January.

[ZONE 51]

I am lifting my guess to 1.8c final.

Just for fun but to late but i had expected a very cold month...

So its now the last 2wks to watch.

[North-Easterly Blast]

This January once again is proving how it is perhaps the one month of the year when you have to expect at least some mild atlantic weather of 5 days + interferring with the CET and preventing chances of a real cold CET value.

Last year, the cold half was derailed by the atlantic, preventing a notable cold CET value. 2009 we saw the same thing happen though a week earlier. We have to go back well to 1979 to see a January devoid of any lengthy atlantic mild spell, even then we saw some short lived mild atlantic spells.. The last January with no atlantic mild weather was 1963.

A flip is often switched in mid January either from cold to mild or vise versa. Conditions at the start of the month are usually very different to what they are by mid month.

In contrast December (unusually) in 2010 and February in 1986, 1991 and I will place 2010 in the same category have seen full months devoid of any lengthy mild atlantic weather (classed as 5 days +). Of the three winter months, February is and always will be our best shot of a colder than normal month with the atlantic much less likely to spoil things..

January in contrast now appears to be the least likely month. Had you asked me this back in November I would have said December but only slightly ahead of January.

Yes, the second half of January 2010 did see the return of the Atlantic, although temps were only average and never mild; after the 11th, January 2009 was largely dominated by the Atlantic, although it was "cooler zonality" and in the last two years the zonal Atlantic spells in Jan have certainly been nothing like what we saw in the likes of mild zonality in 2007 and 2008.

You are not correct about Feb 1991, after about the 20th of that month there was a mild SW'ly spell, and the last week of that month was pretty mild. Jan 1979 was actually almost devoid of any mild Atlantic spell, although there was a brief westerly incursion from around the 7th to 10th and around mid-month, but in these cases temps hardly got above average. Jan 1985 didn't do so bad either, the only significant mild Atlantic spell was in the final three or four days.

This December was almost unprecedented in British Weather History - possibly only matched by 1890. Looking through the archives, no December in the 1900s even managed to be devoid of any mild Atlantic weather - even December 1981 saw an average / mild fairly zonal spell in the first week. Dec 1962 saw a fairly average / mild zonal spell in the middle two weeks.

The main thing about recent years is that we seem to see more zonality of the mild variety - instead of "cold zonality" where the flow is mostly polar maritime sourced, a more NW-SE track of depressions. Yes, we have at last in the last couple of years seen much more in the way of northern blocking that was more typical of the pre 1988 era, but a question still to be asked is - "Will cold zonality ever return?"

Good grief, we have just come out of one of, if not THE coldest pre-Christmas spell of weather EVER, and probably the COLDEST spell of weather for late November and early December EVER, the depth of cold we saw in late Nov / early Dec 2010 was probably more unprecedented than the 62-63 winter. I mean to say that the intense cold of 62-63 didn't start until Dec 22nd / 23rd, and to get the extreme cold like we had at the start of this winter as early in the season as late Nov / early Dec is just less heard of than a deep freeze throughout Jan & Feb as was the case in 1963. So, on top of this, why can't zonality be of the cold variety (polar maritime sourced)?

[AderynCoch]

Yes, the second half of January 2010 did see the return of the Atlantic, although temps were only average and never mild; after the 11th, January 2009 was largely dominated by the Atlantic, although it was "cooler zonality" and in the last two years the zonal Atlantic spells in Jan have certainly been nothing like what we saw in the likes of mild zonality in 2007 and 2008.

The cold start to January 2009 was somewhat "ruined" by a handful of mild CET days: 12-13th (7.5C & 7.0C) and 16-17th (both 7.1C). Apart from that, the rest of the month was quite similar to the second half of January 2010: generally nondescript but lacking in mildness and with occasional transient snowfall. In fact, January 2011 has opened in a similar manner. Not exactly a return to beasterlies, but it beats the near-endless mild zonality of January 2007 & 2008 hands down (I just hope we're not about to go back there!).

A quick remark about un-Atlantic Decembers - we can confidently assert that the very cold December of 1788 (CET: -0.3C) was also pretty much completely devoid of Atlantic air, given that it is the driest December in the England & Wales rainfall series going back to 1766 (8.9mm) and that the highest daily CET value was only 5.7C (that beats December 2010, which attained a highest daily CET value of 6.0C).

Edited January 10, 2011 by AderynCoch

[reef]

Hadley is on 3.0C to the 9th, yesterday came in at 4.0C.

Another cold night last night with the min being reported as 0.4C. Tomorrow's update should see us staying the same or increasing to 3.1C before the real warm up begins.

A mean of 5.0C is required in the remaining 22 days to reach the 1981-2010 average.

[Eugene]

Anamoly is currently -0.5C in hadley.

It's hilarious to think there are people who think its been mild the past 10 days :lol:

[summer blizzard]

Hadley is on 3.0C to the 9th, yesterday came in at 4.0C.

Another cold night last night with the min being reported as 0.4C. Tomorrow's update should see us staying the same or increasing to 3.1C before the real warm up begins.

A mean of 5.0C is required in the remaining 22 days to reach the 1981-2010 average.

Could you post the new set of monthly averages please?

Models have taken a cooler trend over the last 24 hours from the 17th onward. anybody who predicted around 3C is lookign good in my opinion.

[Weather-history]

, but a question still to be asked is - "Will cold zonality ever return?"

Wasn't the back end of November and the first half of December 2008 cold zonality?

28th November-15th December CET: 2.1C

About 60mm of rainfall.

[reef]

Could you post the new set of monthly averages please?

1981-2010 averages (1971-2000 in brackets)

JAN: 4.4C (4.2C)

FEB: 4.4C (4.2C)

MAR: 6.6C (6.3C)

APR: 8.5C (8.1C)

MAY: 11.7C (11.3C)

JUN: 14.5C (14.1C)

JUL: 16.7C (16.5C)

AUG: 16.4C (16.2C)

SEP: 14.0C (13.7C)

OCT: 10.7C (10.4C)

NOV: 7.1C (6.9C)

DEC: 4.6C (5.1C)

WIN: 4.49C (4.48C)

SPR: 8.92C (8.55C)

SUM: 15.86C (15.59C)

AUT: 10.62C (10.33C)

YEAR: 9.97C (9.74C)

Suprisingly winter is around the same, due to the milder 70s winters dropping out and the massive drop in December. Spring sees the largest rises due to a string of mild months.

[Kentish Man]

Looking at those 1981-2010 averages it is worth pointing out that there was no unusually severe January in that period (last such were Jan 1979 and Jan 1963) while we had December 2010 and February 1986 to pull down the average for both those months. Obviously we are talking tiny fractions here but you'd expect December to be rather more clearly the mildest winter month and for February to be very slightly less cold than January.

When does the new reference period come into operation?

[Kentish Man]

Hadley continues its slow climb. Now on 3.1C (Jan 1 - 10).

[Stu_London]

When does the new reference period come into operation?

Hadley will no doubt continue to use 61-90

I think a lot of other people started to use 71-00 in 2005, so I guess 2015 would be sensible.

[North-Easterly Blast]

Wasn't the back end of November and the first half of December 2008 cold zonality?

28th November-15th December CET: 2.1C

About 60mm of rainfall.

Yes, a reasonable example and possibly the only example in the last two or three years; although in that period some areas saw some snowfall at times, snow was never particularly widespread and rarely lay on the ground for more than a day except on high ground. It certainly didn't match January 1984 which gave frequent, copious and heavy snowfalls to many areas, except in the south, during the second half of that month, even though there was little in the way of northern blocking in place, and snow actually did lay on the ground for a week or more in a number of places at that time. I don't think that late Nov / early Dec 2008 saw as much snow as cold zonal setups gave in Mar 1995, Dec 1993, and further back in Jan 1978, Feb 1970, and Feb 1968 also saw a good cold zonal setup in its early part give widespread snowfalls around the 6th / 7th of that month.

Yes, we have in the last couple of years seen much more in the way of northern blocking that was relatively common in pre 1988 winters, but we have yet to see synoptics of cold zonality and good snowfalls from the type of polar maritime setups that occurred in Mar 1995, at times in Dec 1993, and further back in Jan 1978, Feb 1970, Feb 1968, and to match the holy grail of cold zonality, the second half of Jan 1984.

[Thundery wintry showers]

I don't think of late Nov/early Dec 2008 as a good example of cold zonality in the January 1984/December 1993/March 1995 sort of way, the cold was delivered primarily by a succession of northerly outbreaks (and I think the same could be said of 5-15 February 2009 which, although featuring a strong Atlantic influence, had airmasses mainly coming down from the north). The nearest approach was probably the second half of January 2009 which delivered a fair amount of snow to upland parts of the west, including SW England, though falls and accumulations of snow at low levels were very limited. I don't agree with the notion that late Nov/early Dec 2008 didn't deliver as much snow as December 1993 and March 1995- I thought the amounts and geographical distribution were quite similar to the December 1993 case in particular.

You need to remember though that the period 12-26 January 1984 was the "cold zonality" equivalent of the easterly of 11-14 January 1987- i.e. probably the most extreme case of the entire twentieth century, and most of the cold zonal weather of the past has given only short-lived snowfalls to low ground. The February 1970 instance was bolstered by a subsequent spell of northerlies around midmonth which locked in the cold air.

To be honest I would quite fancy a climate where temperatures and precipitation were inversely related all year round with a lot of cold zonality and with anticyclonic spells often being mild and sunny, but both of those have always been the exception rather than the rule in UK winters. Interestingly that sort of consistent inverse relationship does seem to hold in the east and south of the South Island of New Zealand but their equivalent of cold zonality only tends to bring snow to higher ground due to their lower latitude.

[kold weather]

The CET is going to race upwards in the next 7 days, looking very mild indeed with some days probably averaging close to 10C, probably be upto 5.5-6C by the 20th. Hints of something decently colder developing beyond then but the damage will likely be done by then and its going to require a pretty decent cold spell to end up much below average.

IMO between 4-5C looks the most likely call...

[Matty M]

The CET is going to race upwards in the next 7 days, looking very mild indeed with some days probably averaging close to 10C, probably be upto 5.5-6C by the 20th. Hints of something decently colder developing beyond then but the damage will likely be done by then and its going to require a pretty decent cold spell to end up much below average.

IMO between 4-5C looks the most likely call...

Yes, very mild for a 5 day period with 10c average days, from the 20-31st could well see the average in this period drop right back to say 1c.

I am going to say we will finish around 4.4c. Just above the 61-90 mean.

[BornFromTheVoid]

Going by the GFS 06z it looks like the CET will be at

3.3C by the 11th,

4.1C by the 13th,

4.7C to the 15th,

5.3C to the 17th.

Looks like the next week could average above 9C. Anyone know what the warmest January week on record is?

[Matty M]

Going by the GFS 06z it looks like the CET will be at

3.3C by the 11th,

4.1C by the 13th,

4.7C to the 15th,

5.3C to the 17th.

Looks like the next week could average above 9C. Anyone know what the warmest January week on record is?

5.3c to the 17th maybe 5.7 by the 19th, then a cooling trend will like see the mean dropping .1 a day until the end of the month.

[North-Easterly Blast]

Looking at those 1981-2010 averages it is worth pointing out that there was no unusually severe January in that period (last such were Jan 1979 and Jan 1963) while we had December 2010 and February 1986 to pull down the average for both those months. Obviously we are talking tiny fractions here but you'd expect December to be rather more clearly the mildest winter month and for February to be very slightly less cold than January.

When does the new reference period come into operation?

In the last 100 years, December has been the coldest winter month about 20% of the time, and the mildest winter month almost half the time. However, in the last 21 years, December has been the coldest winter month on six occasions, and it has shown significant cooling in the last 20 years, swinging the other way to the warming seen in January and February and most other months.

[damianslaw]

Suspect we will see the peak CET value for January occuring on Sunday, thereafter a slow decline becoming more marked during the latter part of the month. I am still expecting a month either very near average or a bit below.

This week does indeed look a very mild one for January, but nothing unusual, in fcat in recent January's weeks like this were quite normal, 2005, 2007, 2008 and even the mid period of 2009 saw very mild January weeks. Indeed it is a rare feat not to see at least one mild spell of weather in Jan lasting min of 5 days. Even last Jan we saw a relatively mild spell in the second half of the month.

The upcoming spell of weather reminds me a little of the infamous wet spell in Nov 2009, thank goodness we have had a dry spell of weather, otherwise plenty of severe flooding would be on the cards.

[Matty M]

I think this upcoming period has a Jan 79's appearance to it.