January 2021 C.E.T. and EWP forecast contests

[damianslaw]

Thanks for the stats for first 10 days of Jan since 2010, I was thinking the outlook bears a resemblance CET wise to 2009, that was indeed a cold start to Jan, and I doubt we will be below 0 degrees on the 10th, but likely to be substantively below the norm, probably not much above 1 degrees, so a notably cold start to Jan, coldest since 2010 on the cards.

Another start to Jan that was cold was 1997, first 10 days, it became much milder from the 11th on.

 

 

[Roger J Smith]

I looked for any cases where January had a first ten days below 1.0, rose above 1.5 at any point thereafter, and finished below 1.0. 

There were none. The closest cases I could find managed these weaker efforts in the same direction.

(weaker cases, 2 of 3 elements reaching at least 1.0 mid-month)

1784 ______-0.7 ___________ 0.6 16th __________-0.6

1833 ______ 0.9 ___________ 1.5 17-20th _______ 1.2

1895 ______ 0.0 ___________ 1.0 23rd __________ 0.2

1945 ______ 1.7 ___________ 2.2 18th __________ 0.4

with higher numbers 1947 had the profile I was searching:

1947 _______ 2.5 __________ 4.5 18th __________ 2.2

Moral of the story seems to be, cold at first, milder mid-month, usually leads to no better than a mediocre finish. 1833 came close to meeting the criteria although it was quite a gentle transition more like steady-state modified cold. I think 1945 comes closest to being what we would likely want to see, if in fact there is mid-month warming. The 1784 warming at mid-month was fairly restrained, the highest daily value was 6.6 (16th) and that was the third consecutive day above 3.0, the only such days in the whole month. If we're lucky this will be the template for 2020, and the cold was most severe Feb 11-12 before the cold spell finally ended. 

1895 led into a very cold February, the milder part of January was from 16th to 20th, in the 3-4 C range.

 

Edited January 4, 2021 by Roger J Smith

[Summer Sun]

1.0c to the 3rd

2.4c below the 61 to 90 average
3.4c below the 81 to 10 average

___________________________

Current high this month 1.0c on the 3rd
Current low this month 0.5c on the 1st & 2nd

Edited January 4, 2021 by Summer Sun

[Summer Sun]

1.5c to the 4th

1.9c below the 61 to 90 average
2.9c below the 81 to 10 average

___________________________

Current high this month 1.5c on the 4th
Current low this month 0.5c on the 1st & 2nd

[BornFromTheVoid]

Here's the January CET projection (with 5 day GFS forecast) and probability distribution

 

At the moment, we have >80% chance of finishing between 2.0C and 5.0C

The chances of finishing:
Close to average (3.9 to 4.9C) is 20.6%
Above average (>4.9C) is 4.8%
Below average (<3.9C) is 74.6%

The above are all before corrections.

[Duncan McAlister]

Is there a complete table available of the new 1991-2020 CET averages for each month?

[feb1991blizzard]

I had reservations when i lowered my guess but didn't want to end up a mile out, my 2.4 now though will definitely bust on the low side.

[Frigid]

This Jan could be colder than 2013 with the right setup especially at the latter stage of the month. CET currently at 1.5, will probably be under 1 at day 10 and make a gradual increase after. My prediction of 2.9 seems reasonable, for now..

 

[I remember Atlantic 252]

As predicted in my CET guess, it wouldn't be a normal Jan, still could be too high with 4.6, but likely right with one of driest, at 35mm

February will not be zonal either

[damianslaw]

Trending milder as we move past 10 Jan, but the next few days will be cold, so not expecting much of a rise until then. Lots of uncertainties where we go thereafter, how long any milder incursion will be, will it be particularly mild, or quite cold still with anticyclonic conditions leading to cold nights. Its going to be an interesting January, most interesting since 2013.

[The PIT]

Sunny Sheffield at 1.5C -3.1C below average, Rainfall 5.6mm 6.9%

[Summer Sun]

1.7c to the 5th

1.8c below the 61 to 90 average
2.7c below the 81 to 10 average

___________________________

Current high this month 1.7c on the 5th
Current low this month 0.5c on the 1st & 2nd

[damianslaw]

Does anyone have the CET mean since 28 December?, with the cold spell expected to relent come Sunday, that will have been a fortnight of preety cold conditions, and I'd like to compare the running mean for 28 December to 10 January. Suspect it will be our coldest since late Feb 2018 - early March 2018 and probably beats anything else since March 2013. 

[Relativistic]

Assuming that 1st-10th January averages 1C then this gives a mean of 0.8C for the period 28th December to 10th January. The coldest 14-day period 2018 had to offer was 1.2C from 21st February to 6th March (the 5th and 6th of March pulled this figure up, both at 5.9C). The coldest such period in 2013 was 12th-25th January, whose mean was -0.4C.

[Roger J Smith]

First report on EWP this month, 8 mm so far (7 mm to 4th, est 1 mm since then to start of GFS 18z run today) then only about 10 mm on average shown for next ten days, charts for days 11-16 appear to give a further 10 mm then (to late 22nd). That's a total of only 28 mm with nine days left in the month. 

For the CET, the current output suggests that once it turns slightly milder after about 10th, it still won't get all that mild with an average CET in the milder spell around 4.5 C, then another cold spell is predicted, so the blend looks like 2.5 C on average to around the 22nd. 

[Frigid]

7 minutes ago, Roger J Smith said:

First report on EWP this month, 8 mm so far (7 mm to 4th, est 1 mm since then to start of GFS 18z run today) then only about 10 mm on average shown for next ten days, charts for days 11-16 appear to give a further 10 mm then (to late 22nd). That's a total of only 28 mm with nine days left in the month. 

For the CET, the current output suggests that once it turns slightly milder after about 10th, it still won't get all that mild with an average CET in the milder spell around 4.5 C, then another cold spell is predicted, so the blend looks like 2.5 C on average to around the 22nd. 

the mild spell next week has rly been watered down over the past day or so. Was expecting maxes of 9-10 but looking about average here. CET wise, im expecting a significant drop in the next 2-3 days

[damianslaw]

4 hours ago, Relativistic said:

Assuming that 1st-10th January averages 1C then this gives a mean of 0.8C for the period 28th December to 10th January. The coldest 14-day period 2018 had to offer was 1.2C from 21st February to 6th March (the 5th and 6th of March pulled this figure up, both at 5.9C). The coldest such period in 2013 was 12th-25th January, whose mean was -0.4C.

Thanks for these stats, so a good chance could see our coldest 14 day spell since Jan 2013, not bad going! I thought we may have had a colder 14 day spell in March 13 but I guess there were a few milder days by then in the mix.

In terms of rainfall we could be looking at a very dry month for the NW. Last cold dry Jan was probably way way back in 2001. 

[Roger J Smith]

On 05/01/2021 at 07:08, Duncan McAlister said:

Is there a complete table available of the new 1991-2020 CET averages for each month?

Nothing official yet as far as I know, but here are the values that I worked out from the daily averages (I derived similar results from an average of the 30 monthly CET values in the interval). I give these results in two decimals, you can see which ones are going to be close to a rounding (up or down) boundary, various different methods can lead to slight differences of about .01 or maybe .02, so the values that end with a 4, 5 or 6 could go either way. 

Jan _ 4.66 _ should end up 4.7 but they may calculate just low enough to stay 4.6. 

Feb _ 4.90 _ this one seems safe to say will be 4.9

Mar _ 6.74 _ rounds to 6.7, but if they call it 6.8 would not be that surprised.

Apr _ 8.95 _ just don't know which way they go on this one, to all decimals it's 8.95033' _ that rounds to 9.0, but so close.

May _11.90 _ this one will be 11.9 for sure. 

June _14.70 _ this one also looks certain (14.7).

July _ 16.79 _ seems set at 16.8

Aug _ 16.51 _ seems set at 16.5

Sep _ 14.19 _ call this one 14.2

Oct _ 10.91 _ 10.9

Nov _ 7.41 _ 7.4

Dec _ 4.96 _ seems more likely to be 5.0 than 4.9 but not entirely sure.

year _ 10.236 _ 10.2 although as I mentioned elsewhere, 19 of 30 were 10.3 or higher. It was 2010 that kept the average from soaring.

[The PIT]

Unchanged all road still at 1.5C and -3.1C below average.

[Duncan McAlister]

2 hours ago, Roger J Smith said:

Nothing official yet as far as I know, but here are the values that I worked out from the daily averages (I derived similar results from an average of the 30 monthly CET values in the interval). I give these results in two decimals, you can see which ones are going to be close to a rounding (up or down) boundary, various different methods can lead to slight differences of about .01 or maybe .02, so the values that end with a 4, 5 or 6 could go either way. 

Jan _ 4.66 _ should end up 4.7 but they may calculate just low enough to stay 4.6. 

Feb _ 4.90 _ this one seems safe to say will be 4.9

Mar _ 6.74 _ rounds to 6.7, but if they call it 6.8 would not be that surprised.

Apr _ 8.95 _ just don't know which way they go on this one, to all decimals it's 8.95033' _ that rounds to 9.0, but so close.

May _11.90 _ this one will be 11.9 for sure. 

June _14.70 _ this one also looks certain (14.7).

July _ 16.79 _ seems set at 16.8

Aug _ 16.51 _ seems set at 16.5

Sep _ 14.19 _ call this one 14.2

Oct _ 10.91 _ 10.9

Nov _ 7.41 _ 7.4

Dec _ 4.96 _ seems more likely to be 5.0 than 4.9 but not entirely sure.

year _ 10.236 _ 10.2 although as I mentioned elsewhere, 19 of 30 were 10.3 or higher. It was 2010 that kept the average from soaring.

This deserves a big thank you!

[Summer Sun]

1.7c to the 6th

1.8c below the 61 to 90 average
2.8c below the 81 to 10 average

___________________________

Current high this month 1.7c on the 5th & 6th
Current low this month 0.5c on the 1st & 2nd

[damianslaw]

Should be a drop in the next couple of days, maxima today were widely in the 1-3 degree range, and same likely tomorrow and sub zero mins. Then a rise likely Sunday onwards but perhaps not an especially steep one at least initially.

May end up with a CET tracker same shape as December, a cold first 10 days, then a climb and a drop at the end, but hoping the rise isn't especially steep and that the drop starts earlier. 

Thinking about low CET values, was March 2013 last time we had a month below 3 degrees? That's our benchmark for this month.

Edited January 7, 2021 by damianslaw

[Roger J Smith]

Feb 2018 was 2.9 C. 

[damianslaw]

11 minutes ago, Roger J Smith said:

Feb 2018 was 2.9 C. 

Oh just scraped in then. Would be nice to see a sub 3 degree month this winter at least. Not had many such months in last 10 years, think only Feb 2013, Mar 2013 and Feb 2018, very poor showing!

[Don]

2 minutes ago, damianslaw said:

Oh just scraped in then. Would be nice to see a sub 3 degree month this winter at least. Not had many such months in last 10 years, think only Feb 2013, Mar 2013 and Feb 2018, very poor showing!

Feb 13 had a CET of 3.2C, followed by a colder March with a CET of 2.7C.