January CET

[AderynCoch]

Never mind 3C, I'd be surprised to see this month reach 2C given the expectation that it will turn cold again after a very short mild interlude (which may not even be that mild).

In fact, we need only 2.3C for the rest of the month to finish below 1C - and that's definitely on.

[reef]

Hadley is now -1.0C to the 13th. Yesterday came in at just 0.5C, the same as the day before.

http://hadobs.metoffice.com/hadcet/cet_mean_est_2010

Another below freezing minima at -0.4C, but maxima are starting to rise now. 4.1C is required to hit 2.0C provisionally.

[Weather-history]

11th December-13th January CET: 0.5C

[damianslaw]

11th December-13th January CET: 0.5C

Have we just missed out on recording a 30 day sub-zero mean CET then? i.e. what was the 11th dec-10th jan CET figure?

[paul tall]

The 17th - 15th might be interesting.

[osmposm]

The 17th - 15th might be interesting.

Indeed. 17th - 13th provisionally works out at -0.1 (rounded from 0.093). The 14th & 15th will surely push that above zero (they only need to average +1.3), but January's daily figures may perhaps be adjusted down later.

Also of interest is that we finally managed to achieve one (the second) of the three measures I arbitrarily suggested in November as representing significant cold, and did it twice - once in December & already again in January, both of which have had a week with the mean continuously below zero:

"For the daily figures since 1772:

the current and continuing run of 22 winters without a single day whose mean was -5.0 or below has never happened before;

the current and continuing run of 18 winters without a week where every day's mean was zero or below has never happened before;

the current and continuing run of 13 winters without a 3-day period where every day's mean was -2.0 or below has never happened before."

On the current figures, however, the other two measures (three straight days at -2.0 or below, and/or a single day at -5.0** or below) are still eluding us - confirming the impression that in south (very different in Scotland) the cold has been unusually persistent, but not at all severe.

Let's hope that this winter may still hold one or both of them in store.

(**or -4.0 for that matter)

Edited January 15, 2010 by osmposm

[osmposm]

Have we just missed out on recording a 30 day sub-zero mean CET then? i.e. what was the 11th dec-10th jan CET figure?

11th Dec-10th Jan was +0.5 (rounded from 0.494). That's 31 days, though, not 30.

For 30 days, 11th Dec-9th Jan was also +0.5 (rounded from 0.530); 12th Dec-10th Jan was +0.4 (rounded from 0.407).

So a bit more than "just missed out". 17th Dec-15th Jan will be much closer - perhaps +0.1, or even zero (rounded down).

[West is Best]

Looking at the model outputs I'd say it may be touch and go for us to get 2C below the average. There's obviously a mild trend for the third quarter of the month so it all depends on the final quarter as to which way this will go.

[Snowly does it]

Also of interest is that we finally managed to achieve one (the second) of the three measures I arbitrarily suggested in November as representing significant cold, and did it twice - once in December & already again in January, both of which have had a week with the mean continuously below zero:

"For the daily figures since 1772:

the current and continuing run of 22 winters without a single day whose mean was -5.0 or below has never happened before;

the current and continuing run of 18 winters without a week where every day's mean was zero or below has never happened before;

the current and continuing run of 13 winters without a 3-day period where every day's mean was -2.0 or below has never happened before."

On the current figures, however, the other two measures (three straight days at -2.0 or below, and/or a single day at -5.0** or below) are still eluding us - confirming the impression that in south (very different in Scotland) the cold has been unusually persistent, but not at all severe.

Let's hope that this winter may still hold one or both of them in store.

(**or -4.0 for that matter)

One or both of these reaiming criteria may well fall once the adjusted figures are released at month end - certainly Manley has one of those very cold days around or just colder than -5.0, and 4 out of 5 days were below -2.0, with the middle day being -1.7 and therefore well witin scope of being adjusted to meet criteria.

[Thundery wintry showers]

(**or -4.0 for that matter)

I think 28 December 1995 managed -4.7, so that would make it 14 winters since the last sub -4C CET day. Still 22 since the last -5C CET day though, pending downward corrections to the data.

[reef]

We could well get that -4.0C day and three consecutive days with an average of -2.0C or below when the adjustments come in at the end of the month. The fact its even a possibility shows what a potent spell it was.

Hadley has come in at 1.4C yesterday, taking us to a mean of -0.8C to the 14th. 4.3C now required to hit 2.0C at the end of the month provisionally.

[Weather-history]

We are strictly speaking in the second half of the meteorological winter now (1st Dec-14th Jan: 45 days; 15th Jan - 28th Feb: 45 days)

1st Dec - 14th Jan CET: 1.9C (2.4C below the 1961-90 average)

Edited January 15, 2010 by Mr_Data

[Optimus Prime]

Equally the 15th January - 28th February could come in 2.4c above normal. Looking at the charts, it's not something I would dismiss at all.

Edited January 15, 2010 by Optimus Prime

[Paul Sherman]

Equally the 15th January - 31st February could come in 2.4c above normal. Looking at the charts, it's not something I would dismiss at all.

I'd be amazed if that ever happened tbh :o

[osmposm]

One or both of these reaiming criteria may well fall once the adjusted figures are released at month end - certainly Manley has one of those very cold days around or just colder than -5.0, and 4 out of 5 days were below -2.0, with the middle day being -1.7 and therefore well witin scope of being adjusted to meet criteria.

We could well get that -4.0C day and three consecutive days with an average of -2.0C or below when the adjustments come in at the end of the month. The fact its even a possibility shows what a potent spell it was.

Hadley has come in at 1.4C yesterday, taking us to a mean of -0.8C to the 14th. 4.3C now required to hit 2.0C at the end of the month provisionally.

Indeed - I have a feeling the three days at or below -2.0 may be cracked. Less optimistic about the -5.0 - the provisional Hadley figure for the 7th is -3.9....that would be a big adjustment, though -4.0 is quite likely.

[chionomaniac]

Currently -12.2C at Sennybridge and -10.7C at Pershore. Today is going to be extremely cold on tomorrows update.

Indeed - I have a feeling the three days at or below -2.0 may be cracked. Less optimistic about the -5.0 - the provisional Hadley figure for the 7th is -3.9....that would be a big adjustment, though -4.0 is quite likely.

I was really surprised when the 7th came in at -3'9ºC and with both the minima (-7.5ºC) and maxima(-0.2ºC) recorded. The min and max temperatures being recorded in the CET zones by members on the day seemed a lot lower than Hadley has provisionally come out with. I was also checking the hourly met office updates for the CET sites on the 7th and I can't remember one of them getting that high! Perhaps there will be some downward correction here.

[Optimus Prime]

Yeah that's true. Philip Edens Manley had it down at -11.8c with a maximum of -1.8c.

[stewfox]

Indeed. 17th - 13th provisionally works out at -0.1 (rounded from 0.093). The 14th & 15th will surely push that above zero (they only need to average +1.3), but January's daily figures may perhaps be adjusted down later.

Also of interest is that we finally managed to achieve one (the second) of the three measures I arbitrarily suggested in November as representing significant cold, and did it twice - once in December & already again in January, both of which have had a week with the mean continuously below zero:

"For the daily figures since 1772:

the current and continuing run of 22 winters without a single day whose mean was -5.0 or below has never happened before;

the current and continuing run of 18 winters without a week where every day's mean was zero or below has never happened before;

the current and continuing run of 13 winters without a 3-day period where every day's mean was -2.0 or below has never happened before."

On the current figures, however, the other two measures (three straight days at -2.0 or below, and/or a single day at -5.0** or below) are still eluding us - confirming the impression that in south (very different in Scotland) the cold has been unusually persistent, but not at all severe.

Let's hope that this winter may still hold one or both of them in store.

(**or -4.0 for that matter)

Where are you getting your data from ?

There were at least 3 days of max -2 and mins greater then -10c in a row inside the CET zone. I assume you mean the MAX was -2 or below rather then a mean of -2 or below ?

Its probably the poor phraseology e.g 'single day' is referring to the max during the day etc

Edited January 15, 2010 by stewfox

[Roger J Smith]

There was quite a turnaround in the 12z GFS, it brings in sharper cold later than a few runs previously, and keeps it around to month's end. I'm not too confident on that part but any three-day return to cold will pretty much lock in a 2 to 3 CET as the worst outcome for cold lovers. That sort of spell would pretty much cancel out the three mildest days ahead giving only ten days any real leverage on the outcome from a presumed 0.0 about end of tomorrow.

By the way, my original postulate is close to being right on the money (absent presumed correction), the CET predictions offered originally will essentially need to be doubled in each case to give the second half outcome required (if by second half we mean 17th-31st). This applies to negatives as well, to get -3.0 from a first half 0.0 you need -6.0.

And good luck with that.

Meanwhile, I'm placing the over/under at 2.3 given the mix of model outputs available, 1.5 to 3.0 the most likely landing zone, 1.0 to 3.5 still in play. I have factored in a likely -0.3 correction in these formulations.

[osmposm]

Where are you getting your data from ?

There were at least 3 days of max -2 and mins greater then -10c in a row inside the CET zone. I assume you mean the MAX was -2 or below rather then a mean of -2 or below ?

Its probably the poor phraseology e.g 'single day' is referring to the max during the day etc

I don't understand what you mean, Stew. I am sorry you think my phraseology is "poor", I will try and make myself clearer (though I'm not sure anyone else is having a problem with it).

I am referring to the Hadley (Met Office) published daily CET means (halfway beween min & max averaged over the three representative stations used). The confirmed daily data (up to the end of 2009) comes from here: http://hadobs.metoffice.com/hadcet/cetdl1772on.dat . The unconfirmed provisional data for January so far comes from here: http://hadobs.metoffice.com/hadcet/cet_mean_est_2010 .

What I am looking at (or for) is a single day with a CET mean value of -5 degrees or below; and three successive days with a CET mean value of -2 degrees or below. The third measure - seven successive days with a CET mean value of zero degrees or below - has, as I've said, already been achieved this winter twice.

Edited January 15, 2010 by osmposm

[Thundery wintry showers]

4.3C now required to hit 2.0C at the end of the month provisionally.

Judging by the current outlook from the ECM and the teleconnections I think that's probably about what we're going to get. It looks like being near or a little below average for the coming week (daily CET outturns between 2 and 5C likely) and then the westerlies are looking likely to make it through into the last third of January- with teleconnections hinting at cool zonality or possibly even a cold northerly type following the initial zonal spell. I don't think there's much likelihood of it being much milder than 4.3 over the second half of January.

[damianslaw]

Judging by the current outlook from the ECM and the teleconnections I think that's probably about what we're going to get. It looks like being near or a little below average for the coming week (daily CET outturns between 2 and 5C likely) and then the westerlies are looking likely to make it through into the last third of January- with teleconnections hinting at cool zonality or possibly even a cold northerly type following the initial zonal spell. I don't think there's much likelihood of it being much milder than 4.3 over the second half of January.

Yes there are some strong signals that after a week or so of near average temps, starting Sunday (tomorrow looks below average), we will see renewed northern blocking and I wouldn't be surprised to see January end with a potent arctic blast courtesy of strong heights over Greenland which would help keep the CET from going any higher than 3, my guess is a finishing mark of 1.5-2 degrees.

[bluearmy]

kev, today we're half way through winter. any stats on where the current winter CET sits historically or is there no split jan data easily available

[Stratos Ferric]

Latest projection from Stratosdale herewith.

Sub 2C now looks unlikely, but not yet out of the question. Coldest month of the christmas pudding would require a major shift in projection, but coldest January is probably still better than evens, probably around 70-30 I'd say. Certainly sub 3C though.

[The PIT]

Going to be interesting too see if this is going to be a return to a split month. One part cold and one part mild. Although I don't think we'll get the mild bit just average. I suspect GFS may have the temps a bit on the low side but neither can I see a heatwave either.