We have seen in the last six years probably the greatest example of two contrasting winter months in the UK, notably December 2010 for being so cold and December for being so exceptionally mild. The infographics that I have put together for the two months, are due in no small part to the wonderful anomaly charts that I download from the UKMO, overlaid with the climate anomalies and graphs that I produce from the monthly regional gridded data that they also make available. So I say a big thank you to them, as we approach the end to another fascinating year of weather across the UK, and don’t believe it when someone says that I have an axe to grind with the Met Office, occasionally I think they are just a wonderful organisation.
I was right when I said at the end of November that December looked likely to carry on the anticyclonic theme. I made the recent anticyclonic spell that we have just come through 13 days long-lasting from the 23rd of November to the 5th of December to be exact. That’s according to the objective LWT analysis from the UEA. I don’t have a function to look at long spells of anything, so this post is more a reminder to myself to take a look and see how exceptional or not this recent spell of almost two weeks has been. By the way, don’t forget that the objective LWT types are based on the 1200 UTC analysis and not the 0000 UTC one.
Yesterday was (provisionally) the second warmest 7th of December since the CET daily series commenced in 1879, the mean temperature of 13.8°C was +5.8°C above the long-term average, and was only pipped by the 7th of December of 2015 into second place. It was an exceptionally mild day across the whole country, in fact it seemed to me that the mildest areas seemed to lie outwith the CET area.
At 1800 UTC the air temperature was 15.8°C and the mean wind speed was 29 knots with gust to 44 knots at RAF Lossiemouth, Morayshire. The cold front that is crossing Northern Scotland at the moment is producing some sharp troughing and a tightening gradient, with strong to gale force winds right across the North of Scotland this evening.
Just a quick look at the 24 hour temperature differences at the SYNOP stations across the British Isles between 09Z today (Wednesday 7 December 2016) and 09Z yesterday (Tuesday 6 December 2016) revealed that Altnaharra, Sutherland was a full 18°C warmer. The temperature at Altnaharra yesterday at 09Z was -4.4°C but today it was +13.6°C at the same time. I’m sure if you extend the period a little this could possibly exceed 22°C in 30 hours, but that would be a little too dramatic.
Strictly, the diurnal temperature range is the variation between a high temperature and a low temperature that occur on the same day.
An interesting news item on the BBC news today about last year’s floods being the ‘most extreme on record’. Unfortunately due to the reluctance of the Met Office to digitize rainfall records that existed before 1910, we are stuck with hearing the phrase “since records began in 1910” yet again. They don’t seem to qualm at the cost of a new supercomputer every three years (£97 million), or in a new building to house it (£20 million), but extending the climate record back before 1910 with data that they already have is obviously seen as very low priority.
If you notice the ‘experts’ have had to make do with the three months November to January to find something that they could claim was a record, because if they had looked at winters in the 1910 data series from the Met Office, they would have found that 2013-14 was in fact a lot wetter. I’m sure their values are correct, but it does smack to me as a bit of cherry picking the data to get ‘most extreme on record‘ in the title of their report – at this point I should add that I should know because I do it all the time – but that would be completely untrue! Here is my list of the wettest winters since 1910 in the UK.
The graph below is for all winters since 1910 in the UK and as you can see the simple linear trend indicates that winters in the last 106 years are around 30 mm wetter than the were in 1910.
The Met Office do maintain another long-term rainfall series ‘England Wales Precipitation’ [EWP], which although is made up of only monthly data and for one specific region, does have the advantage that it extends way back to 1766. In that series the winter of 2015-16 slips a little bit further down the rankings of wettest winter. The table below shows just how wet the winter of 2013-14 was, and that 2015-16 could only manage 8th place.
And here are all the winters since 1766 in the EWP series:
It’s always difficult to assess rainfall amounts across the whole ‘UK’ for an entire month or season, especially for such prolonged periods of orographic rainfall that there were during December 2015 in the Lake District, and a composite gridded value for the whole UK becomes almost meaningless. All I know is that the high ground in the west and north of the British Isles see an awful lot of rainfall every year, and that’s never changed very much, well at least since records began that is!
I must admit that the variable period that the report covers – November through to January – did throw me a little bit, because none of the applications that I have written to display data from either the EWP or UKP series, allow me to produce stats for a 3 month period that isn’t seasonal, but never fear I will redouble my efforts and try to rectify that when I get a minute.
The recent demise in the Arctic sea ice extent reminds me of a story that went around about the death of Mark Twain, which he refuted by saying “The reports of my death are greatly exaggerated”. It didn’t look good in September and October as the graph of the sea ice extent showed how slow the Arctic was creating new sea ice. So I decided to look at the figures from the NSIDC in a bit of a new way. The graph above shows daily anomalies, that is the value on the day, divided by the 1988-2016 long-term average [LTA] for that day of the year, multiplied by a 100 to get a percentage. The graph as you can see had two distinct dips, one in early September just after that early minimum when the anomaly was around 65% of the LTA. The sea ice bounced back very quickly from that minimum and before the end of October was above 76% of the LTA. Those gains were quickly lost though, and by the middle of October the values had dropped to less than 68%. But interestingly, in fits and starts, the sea ice extent has bounced back and is now above the 85% mark. If you look back at summer 2012 just before the summer minimum things were a lot worst than in September with the LTA less than 55% of the LTA for a few days. Here’s a bit more of a close-up of the last few months.
This method of graphing daily anomalies is very sensitive to any daily changes in the sea ice extent, and I think it’s one of the best ways of keeping an eye on sea ice extent levels both in the Arctic, and the Antarctic, and talking of the Antarctic, here are the latest daily anomalies south of the equator.
The above graph shows very nicely the rise and fall of Antarctic sea ice in recent years. If you remember up until early 2015 Antarctic sea ice had gained a lot of new sea ice. In fact the 2014 season set a new maximum extent of over 20 million square kilometres, but since then things have been going down hill, and since early October of 2016 the sea ice anomalies have been tumbling. At the moment (3 December 2016) the anomaly stands at 84% of the LTA for that day, not a record low by any means, but certainly this season’s melt looks very aggressive, and these daily anomalies are the lowest since early 2011.
Sea ice extent is certainly in crisis, in both the Arctic and the Antarctic, but at least in the Arctic the season seems to be finally getting itself into gear a little.
The media seemed to have now picked up on this autumn’s shenanigans going on in the Arctic, a little bit late, but never mind.
- John Hammond has done a short bit of video for BBC news about it.
- And the good old Met Office, not to be outdone, an expert there blogged about the unusually warm Arctic.
Here is a list of recent articles that I’ve written on the subject, and I think it’s fairly evident that I have a bit of a thing for sea ice.
- Tropical Arctic (27 Nov)
- Polar sea ice entering unchartered waters (19 Nov)
- Sluggish ice growth in the Arctic – you bet! (3 Nov)
- Older sea ice disappearing video (29 Oct)
- Latest sea ice figures (28 Oct)
- Latest Arctic sea ice extents look dire (10 Oct)
- Fourth shortest melt season in Arctic (25 Sep)
- Second lowest Arctic sea ice minimum (Sep 16)
- Polar sea ice extremes (Sep 9)
So you can see when I add a comment to the Met Office blog, and 10 days later it’s still sat there “awaiting moderation”, I do get a bit irked. I’m not sure what’s particularly wrong with it, there are no swear words or personal insults, just a few comments about the slightly arrogant tone of the piece, and how slow off the mark they’ve been (in my opinion). So here is what I said and you can be the judge, because after 10 days I think they binned them – so much for democracy!