SomeLikeItHot

ECM London 0Z Ensembles are interesting. While the Op is below the mean its pretty much in the middle of the main cluster from day 8 comprising probably 2/3 to 3/4 of the ensemble members, with the mean pulled higher by a minority of very much higher runs. So looking good for something cold, at least for a bit, although still with a risk of a very different and much warmer outcome. (That path with the min of -10 and day time of below -5 on the 11th is interesting!).

I disagree they are similar. In the UKMO the low on the US east coast is split into a small fragment going north and a larger bit further south, this is what was happenning in the earlier GFS and ECM runs, which produced the amazing synotipcs later. GEM and others this morning went the one big low route and did something similar to the GFS 12Z

Personally I think your summaries are excellent and balanced view of what the main NWP models are saying. Some may like to go beyond the models and try and argue to why we should prefer diferent soluions and that's good also, but on days when I am too busy to trawl through a range of models I always refer to them to get and idea of what is happenning. Would be disappointed to see them go.

6.5 to the 27th -0.3 anomaly (61-90) -0.9 anomaly (81-10) Min today of 6.1 and max likely around 10 should see stay on 6.5 tomorrow. Met office forecasts for 5 days 28th 6.6 (8.1) 29th 6.6 (7.7) 30th 6.6 (7.3) +0.1 (61-90) -0.5 (81-10) Again a higher Max than I had estimated (10.9 vs 9.5) and a slight increase in forecast temps puts it at 6.6 + 0.1 above average. A chance the month will end at rather than below average.

The ensemble mean often doesn't really tell the full story so while useful shouldn't be taken as most likely outcome unless they are clustered around the mean. You really need to look at individual members and how they are splitting. A poor ensemble mean can result from 50% great and 50% rotten split particularly if there is a spread in timing. The mean is a poor measure if there is a bi-modal split. Its like standing with one foot in a bucket of ice and another in a bucket of boiling water. You don't have warm feet despite what the average foot temperature may be. Looking at last nights ECM London ensembles shows that probably 2/3 of ensemble members go for some cold shot, 1/3 don't go for any cold, of those that go for cold about half to a third keep it for at least 4 days, while the others end it more quickly. That is probably the best way of looking at the chances of something. (My estimates are rough).

-0.9 anomaly (81-10) Min today of 2.7 and max likely around 9.5 should see stay on 6.5 tomorrow. Met office forecasts for 5 days 27th 6.5 (6.1) 28th 6.5 (7.7) 29th 6.5 (7.3) 30th 6.5 (5.5) 0.0 (61-90) -0.6 (81-10) So that seems like the last of the falls, and a slightly warmer correction nudges it to average at the end of the month (and yesterday’s max was a bit higher than I thought). Still likely to end up below average after corrections.

Based on the above calculations this looks to be the people with some realistic chance. Bold is where I think the most likely result is, but MarkN, and March Blizzard being slightly better placed due to owning 6.2 also. 6.6 ... BARRY, BARRY95 ... ... ... ... ... ... ---- mean of 1961-1990 ----6.5 ... ISOLATED FROST, DUNCAN McALISTER ... ... ... ... ---- mean of 1901-2000 ----6.4 ... CREWECOLD6.3 ... MARK N, MARCH BLIZZARD6.2 ...6.1 ... ... ... ... ... ... ... ---- mean of all years 1659-2012 ----6.0 ... SIMSHADY, SNOWM4N 5.9 ... SCEPTICAL INQUIRER, BOBD29 ... ... ---- mean of 1801-1900 ----

6.6 to the 25th -0.3 anomaly (61-90) -0.8 anomaly (81-10) Min today of -0.2 and max likely around 6.5 should see it fall to 6.4. Met office forecasts for 5 days gives 26th 6.4 (3.3) 27th 6.4 (6.3) 28th 6.5 (7.9) 29th 6.5 (7.3) 30th 6.4 (4.5) -0.1 (61-90) -0.7 (81-10) So again a couple of warmer days at the end of month looks like it will stop it falling more than slightly below 61-90 average before corrections. After corrections anything 6.0-6.5 seems possible.

Or it could be the GFS pushing towards the climate mean, which hurts it in the short term but assists it in the longer term. Either way the verification of both at that range is really poor.

Yes, correct figures are here. http://www.metoffice.gov.uk/hadobs/hadcet/cet_info_mean2010.html If this December ends up below 2013 would have had more below average months than 2010. (presuming November finished below that is!)

6.7 to the 24th -0.3 anomaly (61-90) -0.8 anomaly (81-10)Min today of 2.3 and max likely around 6.0 should see it fall to 6.6.Met office forecasts for 5 days and GFS 0Z ensemble mean after that give25th 6.6 (4.2)26th 6.4 (3.3)27th 6.4 (5.5)28th 6.4 (7.2)29th 6.4 (7.0)30th 6.4 (5.0) -0.2 (61-90) -0.7 (81-10)With a couple of warmer days at the end of month looks likely we will finish just slightly below 61-90 average before corrections. After corrections anything 5.9-6.5 seems possible.

-0.6 anomaly (81-10) Min today of 2.2 and max likely around 7.0 should see it fall to 7.0. Met office forecasts for 5 days and GFS 0Z ensemble mean after that give 22nd 7.0 (4.6) 23rd 6.8 (3.3) 24th 6.7 (3.9) 25th 6.6 (4.2) -0.3 (61-90) -0.8 (81-10) 26th 6.5 (4.2 ) 27th 6.5 (7.8 ) 28th 6.5 (6.8 ) 29th 6.5 (6.0) 30th 6.5 (5.5) -0.1 (61-90) -0.6 (81-10) So warm up, or at least fail to cool down over the last few days of the month see the value head more towards the 61-90 average. Most likely post corrections it will still be below but its looking closer than it did a few days ago.

-0.6 anomaly (81-10) Min today of 3.6 and max likely around 8.0 should see remain on 7.1. Met office forecasts for 5 days and GFS 0Z ensemble mean after that give 21st 7.1 (5.9) 22nd 7.0 (4.3) 23rd 6.8 (2.8 ) 24th 6.6 (3.8 ) 25th 6.5 (3.9) -0.4 (61-90) -0.9 (81-10) 26th 6.3 (2.8 ) 27th 6.3 (5.0) 28th 6.3 (5.0) 29th 6.3 (5.5) 30th 6.2 (4.0) -0.4 (61-90) -1.0 (81-10) So a bit warmer again today as the last 4-5 days go from below to near average days. Seems the likely range is 5.8-6.8 before corrections.

7.3 to the 19th +0.1 anomaly (61-90) -0.4 anomaly (81-10) Min today of -0.5 (first negative since April) and max likely around 7.5 should see it fall to 7.1. Met office forecasts for 5 days and GFS 0Z ensemble mean after that give 20th 7.1 (3.5) 21st 7.0 (5.1) 22nd 6.9 (4.2) 23rd 6.8 (3.6) 24th 6.6 (3.0) 25th 6.5 (3.0) -0.4 (61-90) -1.0 (81-10) 26th 6.3 (2.5) 27th 6.2 (2.8 ) 28th 6.1 (2.5) 29th 6.0 (2.8 ) 30th 5.9 (2.8 ) -0.7 (61-90) -1.3 (81-10) So while the next few days are now slightly warmer than they were a few days ago, the GFS ensembles are now saying frosty mornings at the end of month which is pushing that part down.

-0.4 below 81-10 average. Min today of 1.8 and max likely around 9.0 should see it remain 7.5. Met office forecasts for 5 days and GFS 6Z ensemble mean after that give 19th 7.3 (3.3) 20th 7.1 (3.5 ) 21st 7.0 (4.6) 22nd 6.9 (4.2) 23rd 6.7 (3.8 ) 24th 6.5 (2.5) 25th 6.4 (2.5) -0.5 (61-90) -1.0 (81-10) … 30th 5.9 -0.7 (61-90) -1.3 (81-10) Slightly colder in the longer term (in November that is). I missed the 0Z ensembles today and have used the 6Z instead.

No where in the further outlook do they say it will return to average. Nor do they even say near average. They said "nearer to average" ie warmer than the previous period when they forecast wintry showers in the SE and Cold in the NW (ie a cold period). Also not to forget that "average" in December is colder than average in November.

Its worth noting that as much as I like ensemble models, that at this longer range they do tend towards the normal the further out you go. Eg check the Met office update from 16th of Feb this year (First post in the Met office 16 to 30 day outlook Forum). Its states regarding March this year "towards the middle of March temperatures may recover close to the seasonal norm.". If anything today's update is more pesimistic about that chances then it was then today states "there are signs of a slight recovery nearer to normal by the middle of December." So not trying to come down on the met but you've got to read it in the context of increasing uncertainty always pulling us towards normal. Edit: Pessimistic is with regard cold being good. From Gavin's point of view I should have said optimistic!

7.5 to the 17th +0.02 anomaly (61-90) -0.5 anomaly (81-10) Min today of 1.8 and max likely around 9.0 should see it remain 7.5. Met office forecasts for 5 days and GFS 0Z ensemble mean after that give 18th 7.5 (8.1) +0.2 (61-90) -0.4 (81-10) 19th 7.3 (3.25) 20th 7.1 (3.8 ) 21st 7.0 (5.0) 22nd 6.9 (4.6) 23rd 6.8 (3.5) 24th 6.6 (4.0) 25th 6.5 (4.0) -0.4 (61-90) -0.9 (81-10) … 30th 6.1 -0.5 (61-90) -1.40 (81-10) So warmer than it was prior to the weekend, due mostly to this coming week not being quite as cold as previously. Longer term the slightly below average trend continues. A below average (61-90) month is looking the most likely outcome, with a below 81-10 average month almost certain.

If they weren't right before when they were suggesting a more blocked pattern, why would they be more right now? Personally I think that beyond 2 weeks we are pretty clueless about what may happen, and even then we only get the most basic hints of the pattern.

The 6.5 we would reach on the 22nd (should it occur) will be -0.5 below the 61-90 rolling mean.

Thanks, Was going to dig this out myself. At this point it looks like we are some chance of a top 10 drop, and very likely for a top 20

7.6 to the 14th -0.0 anomaly (61-90) -0.6 anomaly (81-10)Min today of 1.8 and max likely around 9.5 should see a fall to 7.5.Met office forecasts for 5 days and GFS 0Z ensemble mean after that give15th 7.5 (5.65)16th 7.5 (6.6)17th 7.5 (7.8 )18th 7.5 (7.7) +0.2 (61-90) -0.5 (81-10)19th 7.3 (3.6)20th 6.9 (0.5)21st 6.7 (1.5)22nd 6.5 (2.3)23rd 6.4 (3.5)24th 6.2 (3.8 )25th 6.1 (3.5) -0.8 (61-90) -1.3 (81-10)…30th 5.7 -0.8 (61-90) -1.4 (81-10)

The ECM ensemble mean at 240 hours looks pretty good for ongoing cold.

ECM at 192 rapid reload? For a moment at 168 I was thinking it was getting worse.

GFS ensemble mean seems to be convinced of a developing Greenland high