January CET

[godber]

if todays ecm output was to verify,then my guess of 3.8c would possibly be a tad high?

[TonyH]

The way the models are lately anything between 4 and 6.5c possible.

[Roger J Smith]

Since there is some chance of a much colder second half, and the change to colder is starting already (could be reversed briefly), here's a look at the CET daily data through a filter I just ran comparing 1-12 with 13-31 Jan and looking for the largest falls in CET. These are all the cases where the CET ended more than 2.0 C deg lower by month's end.

YEAR ... CET 1-12 ... CET 13-31 ... CET 1-31 ... reduction

_______________________________________________

1810 ......... 6.6 ................. -0.6 ................ 2.2 ............ 4.4

1855 ......... 6.4 ................. -0.1 ................ 2.4 ............ 4.0

1950 ......... 8.0 .................. 1.8 ................ 4.2 ............ 3.8

1881 ......... 1.7 ................. -3.5 ............... -1.5 ............ 3.2

1776 ......... 1.5 ..................-3.5 ............... -1.6 ............ 3.1

1917 ......... 4.6 ................. -0.3 ................ 1.6 ............ 3.0

1933 ......... 5.2 ................. 0.3 .................. 2.2 ........... 3.0

1992 ......... 6.7 ................. 1.7 ................. 3.7 ............ 3.0

1873 ......... 7.9 .................. 3.5 ................ 5.2 ............. 2.7

1880 ......... 3.6 ................. -0.8 ................ 0.9 ............. 2.7

1803 ......... 4.2 .................. 0.3 ................ 1.8 ............. 2.4

1902 ......... 7.1 .................. 3.2 ................ 4.7 ............. 2.4

1905 ......... 5.9 .................. 2.3 ................ 3.6 ............. 2.3

1808 ......... 4.8 .................. 1.2 ................ 2.6 ............. 2.2

1813 ......... 4.1 .................. 0.6 ................ 1.9 ............. 2.2

1996 ......... 6.5 .................. 3.0 ................ 4.3 ............. 2.2

1909 ......... 5.6 .................. 2.2 ................ 3.5 ............. 2.1

1952 ......... 4.8 .................. 1.4 ................ 2.7 ............. 2.1

1950 had the greatest first half to second half fall, if we take 1st to 16th as first half, these values were 7.7 and 0.5, for a difference of 7.2 and a fall of 3.5.

If you were looking for 1991 here, it didn't quite make the list, the change to colder was more notable after the 18th.

[damianslaw]

Since there is some chance of a much colder second half, and the change to colder is starting already (could be reversed briefly), here's a look at the CET daily data through a filter I just ran comparing 1-12 with 13-31 Jan and looking for the largest falls in CET. These are all the cases where the CET ended more than 2.0 C deg lower by month's end.

YEAR ... CET 1-12 ... CET 13-31 ... CET 1-31 ... reduction

_______________________________________________

1810 ......... 6.6 ................. -0.6 ................ 2.2 ............ 4.4

1855 ......... 6.4 ................. -0.1 ................ 2.4 ............ 4.0

1950 ......... 8.0 .................. 1.8 ................ 4.2 ............ 3.8

1881 ......... 1.7 ................. -3.5 ............... -1.5 ............ 3.2

1776 ......... 1.5 ..................-3.5 ............... -1.6 ............ 3.1

1917 ......... 4.6 ................. -0.3 ................ 1.6 ............ 3.0

1933 ......... 5.2 ................. 0.3 .................. 2.2 ........... 3.0

1992 ......... 6.7 ................. 1.7 ................. 3.7 ............ 3.0

1873 ......... 7.9 .................. 3.5 ................ 5.2 ............. 2.7

1880 ......... 3.6 ................. -0.8 ................ 0.9 ............. 2.7

1803 ......... 4.2 .................. 0.3 ................ 1.8 ............. 2.4

1902 ......... 7.1 .................. 3.2 ................ 4.7 ............. 2.4

1905 ......... 5.9 .................. 2.3 ................ 3.6 ............. 2.3

1808 ......... 4.8 .................. 1.2 ................ 2.6 ............. 2.2

1813 ......... 4.1 .................. 0.6 ................ 1.9 ............. 2.2

1996 ......... 6.5 .................. 3.0 ................ 4.3 ............. 2.2

1909 ......... 5.6 .................. 2.2 ................ 3.5 ............. 2.1

1952 ......... 4.8 .................. 1.4 ................ 2.7 ............. 2.1

1950 had the greatest first half to second half fall, if we take 1st to 16th as first half, these values were 7.7 and 0.5, for a difference of 7.2 and a fall of 3.5.

If you were looking for 1991 here, it didn't quite make the list, the change to colder was more notable after the 18th.

Jan 1991 was an interesting case of a CET value becoming progressively lower as the month wore on. It was a cooling month in every sense of the word and as we know led into a very cold first 2 weeks or so in February.

Its a brave man who bets on the final CET for this month at this stage - I still believe firmly the second half of the month will be apprecaibly colder than the first half, but by what degree who knows, but I'll be surprised if we end up with a CET value any higher than 6 degrees. Something in the range of 4 - 6 degrees most likely at this stage, yes a very wide margin but there is far too much uncertainty at this stage to be more definate.

I doubt we will see anything below 4 degrees - this would require some major serious cold starting this weekend, and this is obviously not going to happen, but a very cold last 10 days is still very plausible enabling a value close to 4 degrees to still be within reach - just about.

February is certainly looking like being the coldest month of this winter - and probably by some margin..

[reef]

Hadley is 7.9C to the 12th.

Just to record a CET of 6.0C at the end of the month the remaining days need to average 4.8C. 2.2C is required in the final 19 days to reach the 1981-2010 average.

It would be a brave person to bet against anything but an above average finish right now.

[Scorcher]

The month is panning out just the way I expected it to- an exceptionally mild first half followed by what I believe will be an average second half overall. The 2nd half is probably going to end up being much sunnier than the first.

[BornFromTheVoid]

7.6C to the 13th

http://www.metoffice.gov.uk/hadobs/hadcet/cet_info_mean.html

Yesterday was 3.7C. Minimum today is -3.2C while maxima were around 5C, so a drop to 7.1C is likely tomorrow.

After that, the 12z GFS has the CET at

6.7C to the 15th (1.9)

6.4C to the 16th (1.4)

6.2C to the 17th (2.4)

6.2C to the 18th (6.0)

6.4C to the 19th (10.1)

6.3C to the 20th (5.8]

6.4C to the 21st (8.3)

[The PIT]

While people vainly hope cast for prolonged cold on the model thread it seems we're sleep walking into a very mild Jan. Yup temps should fall back the next few days before rebounding again. We could end up looking at a really mild month.

[summer blizzard]

]

7.6C to the 13th

http://www.metoffice..._info_mean.html

Yesterday was 3.7C. Minimum today is -3.2C while maxima were around 5C, so a drop to 7.1C is likely tomorrow.

After that, the 12z GFS has the CET at

6.7C to the 15th (1.9)

6.4C to the 16th (1.4)

6.2C to the 17th (2.4)

6.2C to the 18th (6.0)

6.4C to the 19th (10.1)

6.3C to the 20th (5.8]

6.4C to the 21st (8.3)

ECWMF disagrees from the 19th onward.

Will end up above average though.

[damianslaw]

7.6C to the 13th

http://www.metoffice..._info_mean.html

Yesterday was 3.7C. Minimum today is -3.2C while maxima were around 5C, so a drop to 7.1C is likely tomorrow.

After that, the 12z GFS has the CET at

6.7C to the 15th (1.9)

6.4C to the 16th (1.4)

6.2C to the 17th (2.4)

6.2C to the 18th (6.0)

6.4C to the 19th (10.1)

6.3C to the 20th (5.8]

6.4C to the 21st (8.3)

Very much doubt GFS will be right - those temp forecasts appear to be too high, end of next week we should be in the 5's. Look how quickly the CET can fall in conditions as we have now, a drop of 0.5 degrees, if we had three or four similiar days with similiar CET values we will easily be down into the 5's.

It will be an above average January but not exceptionally so.

[reef]

A half a degree drop today on Hadley, which is now 7.1C to the 14th.

[The PIT]

Double figure temps later this week for a few days should counter the cold weekend somewhat. After that I wouldn't be surprised seeing more average to slightly below average be the dominating feature. Guess we may end up around 6C

[leicsnow]

What would we need for the remaining days of January to reach the 1971-2000 average of 4.2? According to the netweather tracker the CET is currently 6.85.

http://www.netweather.tv/index.cgi?action=cet;sess=

[Scorcher]

Very much doubt GFS will be right - those temp forecasts appear to be too high, end of next week we should be in the 5's. Look how quickly the CET can fall in conditions as we have now, a drop of 0.5 degrees, if we had three or four similiar days with similiar CET values we will easily be down into the 5's.

I disagree, the cold isn't going to be prolonged enough for that I don't think. It's not going to drop 0.5C every time- it's only dropped that much because we are at such a high point at the moment. Last night wasn't even as cold as many expected, we barely even managed a frost here in the end.

[kev238]

I predict a cet in the mid 5s to around 6 at this stage

No clear signal for anything especially cold in any timeframe after a couple more frosty days. Indeed falls should stabilize from Wednesday onwards.

If the cet remains around 6ish we will have had two mild to very mild winter months in the cet region..

[leicsnow]

I disagree, the cold isn't going to be prolonged enough for that I don't think. It's not going to drop 0.5C every time- it's only dropped that much because we are at such a high point at the moment. Last night wasn't even as cold as many expected, we barely even managed a frost here in the end.

I agree. Also, as the month goes on it will become harder and harder for the CET to change.

If the cet remains around 6ish we will have had two mild to very mild winter months in the cet region..

And will also mean the winter will likely to come out as mild overall in the end, regardless of what happens in February.

[damianslaw]

I agree. Also, as the month goes on it will become harder and harder for the CET to change.

And will also mean the winter will likely to come out as mild overall in the end, regardless of what happens in February.

The CET is on a downward path, I very much doubt once the current colder spell is finished we will see a return of sustained CET values of 7 - 7.5 degrees through until the months end. Yes Wednesday and Thursday will probably deliver such values, but the trend is colder thereafter and I see no signal for a raging westerly/southwesterly airstream during the last week of the month. I do believe a good finishing bet is around 5 - 5.5 degrees, with 6 degrees probably the upper limit, certainly a mild CET but not one of the mildest.

Your right in saying the winter will go down overall as a mild one despite what happens in February - even a record cold feb can't cancel out a mild December and January, but a cold feb will prevent the winter as going down as a particularly mild one in the main and a particularly severe feb would probably mean it goes down as quite a good one. - if the cold extended well into March even more so (even though March is classed as spring, many people classed the second half of last nov as belonging to winter).

[leicsnow]

The CET is on a downward path, I very much doubt once the current colder spell is finished we will see a return of sustained CET values of 7 - 7.5 degrees through until the months end. Yes Wednesday and Thursday will probably deliver such values, but the trend is colder thereafter and I see no signal for a raging westerly/southwesterly airstream during the last week of the month. I do believe a good finishing bet is around 5 - 5.5 degrees, with 6 degrees probably the upper limit, certainly a mild CET but not one of the mildest.

Your right in saying the winter will go down overall as a mild one despite what happens in February - even a record cold feb can't cancel out a mild December and January, but a cold feb will prevent the winter as going down as a particularly mild one in the main and a particularly severe feb would probably mean it goes down as quite a good one. - if the cold extended well into March even more so (even though March is classed as spring, many people classed the second half of last nov as belonging to winter).

I personally wouldn't class the second half of November as winter. If anything I'd count the first half as March as winter and the first half of December as Autumn! I think people forget just how exceptional the end of November 2010 was, and the start of December for that matter (it's not as unusual later in the month).

[summer blizzard]

The CET is on a downward path, I very much doubt once the current colder spell is finished we will see a return of sustained CET values of 7 - 7.5 degrees through until the months end. Yes Wednesday and Thursday will probably deliver such values, but the trend is colder thereafter and I see no signal for a raging westerly/southwesterly airstream during the last week of the month. I do believe a good finishing bet is around 5 - 5.5 degrees, with 6 degrees probably the upper limit, certainly a mild CET but not one of the mildest.

Your right in saying the winter will go down overall as a mild one despite what happens in February - even a record cold feb can't cancel out a mild December and January, but a cold feb will prevent the winter as going down as a particularly mild one in the main and a particularly severe feb would probably mean it goes down as quite a good one. - if the cold extended well into March even more so (even though March is classed as spring, many people classed the second half of last nov as belonging to winter).

Not true.

December was 1.4C above the 1981-2010 average, so if January was 6C and 1.6C above the average then a Feb CET of 1.4C would put winter bang on average, 1.4C is still about 3C warmer than the coldest on record, February 1947.

[Optimus Prime]

The remaining 16 days of this month 'only' needs to average 2.0c for the month to finish bang on average at 4.4c (assuming the first half comes in at 6.8c)

1.0 = 3.9c

0.0 = 3.4c

-1.0c = 2.9c

Below average is still just about in the realsms of possibity. We haven't had a really cold second half to January since 1985 I believe.

3.4c is a distinct possibility going by some of the output tonight.

[reef]

Hadley is 6.7C to the 15th. Yesterday was 1.5C.

2.2C is required in the final 16 days for the 1981-2010 average of 4.4C

[The PIT]

Unless you've been on the booze 3.4c is as about likely as you winning the Lottery. Too many mild days thrown into the mix.

[Roger J Smith]

Only if the models are right (speaking of the booze)

[damianslaw]

The remaining 16 days of this month 'only' needs to average 2.0c for the month to finish bang on average at 4.4c (assuming the first half comes in at 6.8c)

1.0 = 3.9c

0.0 = 3.4c

-1.0c = 2.9c

Below average is still just about in the realsms of possibity. We haven't had a really cold second half to January since 1985 I believe.

3.4c is a distinct possibility going by some of the output tonight.

Yes we haven't seen a notably cold second half to January for a long time. Apart from Jan 91, 96 and to a lesser extent 01 and 86, all Januaries since 1985 have seen either short lived cold spells, or more often preety average/mild or very mild conditions reign supreme during the second half of the month. I don't mention 1987 as the cold spell occured during the mid month period - starting on the 9th and ending on the 20th. We saw a long run of mild second halves to Jan between 2002 - 2008, 2009 delivered more average conditions along with 2010 - though it turned cold at the months end, last year saw some colder weather from high pressure a bit like we have now but it was relatively short lived and the month ended on a very mild note - so its nearly 10 years since any notably chilly conditions occured during the second half of the month and 2001 wasn't that cold, so we then have to go back to 1996 for a notably cold snowy spell in the second half of the month - 16 years ago!!!!. All rather dissapointing it has to be said as I always think of the second half of Jan as deep mid winter when the greatest potential for severe cold occurs. Still hopeful the end of the month will deliver notably wintry conditions, with Scotland always prone to wintry blasts before then these perhaps extending into n england from time to time - such as this weekend.

Edited January 16, 2012 by damianslaw

[Styx]

So lets see, if January comes in at +1.0 above average it will be the 5th consecutive month to do so! Anyone able to say whether this has happened before?

A big raspberry to all the global warming conspiracists out there.