Plenty of sunshine across the southeast of the country at the moment, and for large parts of Europe. These are the hourly sunshine totals for 12-13 UTC today (fig 1), it’s a shame that Ireland, the Netherlands, Scandinavia and Iberia don’t include this hourly data in their weather reports.
I think I can say without a doubt that today has been the warmest day so far this year, at least in our part of south Devon. It’s not been particularly high, maybe just scraped a 22 or a 23°C this afternoon in the back garden, but it’s enough (fig 2). Personally speaking, this year Spring seems to have been a long time coming.
Certainly the solar radiation has been high (fig 3), and so must the UV, but unfortunately the SYNOP reports don’t include that.
Just what the Doctor ordered
Not only did the southeast get the warmest day yesterday (which is more that can be said down here in the southwest) they also got a good long spell of moderate rain, which must have come as welcome relief to the farms and gardens that have been crying out for it over the last six weeks or so. For a long time I thought that the rain gauge of the AWS in St James Park must have been faulty or perhaps full of pigeon excrement.
The estimates that I make from radar images were a little high, for example I estimated a 18-06 total for Wattisham of 21.8 mm and in reality they recorded 20.2 mm [06-06]. The coast of Kent seems to have escaped most of yesterday’s rain though.
Wattisham, as well as being the wettest place yesterday with 20.2 mm in the reported SYNOP’s (fig 3), also managed second warmest with 25.2°C (fig 4).
I still suspect that there is some kind of geothermal energy going on in close proximity to the Stevenson screen at Broadness, because yet again they were the warmest station in WMO block #03.
Despite the warmth in the southeast, I reckon the best day yesterday was in the far north or west albeit considerably fresher, Kirkwall reported 12.6 hours of sunshine, and stations in Ireland added more sunshine to their already high totals so far for May (fig 5).
I remember this particular May Day 1990 very well, because at the time I was an observer at Kinloss and was due on the night shift, taking over from John Sutherland who had been on the day shift. He told me the story of how a southerly foehn had kicked in during the early afternoon and increased the temperature by at least 10°C. All morning rotors from the strong southerly wind at 2000 feet, coupled with a sea breeze effect, had been keeping the surface wind in the north or northeast, blowing of a cold Moray Firth (fig 1), but eventually the southerly burst through and the temperatures soared from around 15°C at 12 UTC to around 27.2°C within the hour. I can’t be too precise about the exact times or magnitude in the rise of the air temperature, suffice it to say that John was not particularly happy about getting a phone call from Bracknell asking him to correct his 13 UTC observation! I think the maximum that afternoon which had been a smidgen higher at nearby Lossiemouth at 27.4°C (fig 3), will still rank as one of the warmest May Days on record in Scotland, if not the UK.
One day I’ll have to pay the archives a visit in Exeter, dig out the old obs book if they have it, and jog my memory! I only have six hourly SYNOP reports for that particular day, but here are the 12 and the 18 UTC plotted charts for posterity and for John, who was quite a character.
Exeter airport is top of the shop in the 14 UTC SYNOP reports with 12.2°C – and not “somewhere in the southeast” thank you very much Darren Bett (fig 1). My Vantage pro recorded a max of 13.2°C in a sunny spell around lunchtime here in mid-Devon, in what has been a lovely spring like day. It’s a shame it won’t last though, as I notice pressure has already start to fall ahead of another low that’s forecast to swing into the southwest of the country tomorrow (fig 2).
Figure 2 – Courtesy of OGIMET
I’ve scanned my SYNOP archives and not found a warmer February 20th 06-18 maximum since at least 1972 (fig 1) than today’s, with at least 20 stations across the UK reporting 16°C or higher. Northolt (and I believe Kew) in London came top of the shop with 18.3°C (64.9°F).
The low stratus is finally clearing across the southwest of England as drier air is entrained across the Channel from France. There’s been a lovely wave-like ripple in the low cloud running downwind of Cornwall through the Celtic Sea, and along the eastern side of the Irish through today.
It looks like that they’ll be a number of stations reporting an ice day today, judging by the mid-afternoon temperatures across some parts of Eastern England at the moment. The temperature at Wattisham for instance at 14 UTC was -2.4°C, and -1.6°C and -2.1°C at Wittering and Andrewsfield respectively, this combined with the wind speed make it a fairly penetrating black frost.
There were two meteorological bets that were focusing the minds of bookmakers such as William Hill’s and come to that most of the tabloid media this Christmas, and they were:
- Would Christmas day be the warmest on record?
- The perennial one of would it be a white Christmas?
A record mild Christmas Day?
There was no doubt that 2016 ended up as provisionally the warmest day in central England since 1878. But looking at the maximum temperatures for 06-18 UTC from the SYNOP observations it failed to beat the record set at Killerton in Devon of 15.6°C set in 1920. It certainly got close, because at Dyce Airport in Aberdeen the temperature reached 15.1°C. So close, but no cigar – CET doesn’t count – so one up the bookies.
A white Christmas?
Well you would have thought that if Christmas day had been exceptionally mild on Christmas day then a white Christmas would have been out, but no, thanks to the cold front of storm Conor temperatures fell steadily in northern Scotland during the afternoon and at 23 UTC on Christmas day, the heavy showers that followed the cond front would have almost certainly be falling as snow on ground above 200 metres, in places as far south as the Lake District and the northern Pennines. Here’s proof that it did snow inland on higher ground in Scotland courtesy of the plotted 23 UTC chart and the weather radar.
So for the vast bulk of towns and cities across the country there was no snow on Christmas day whatsoever, but for a few places such as Aviemore (228 M amsl) late on in the evening of Christmas day, did see some snow in the form of showers, and if the showers had been heavy enough they would have quickly given a covering. I did think about placing a bet, but it would have been for a place such as Tyndrum (232 M) or possibly Crianlarich (165 M) and have probably been inadmissible even if it had snowed that evening, because the location was just too small to verify without photographic evidence. So on the whole, another point to the Bookies, making it a whitewash to them if you’ll pardon the pun.
Yes, Christmas day was the warmest day in the daily CET record since 1878, but what I couldn’t fit in the headline was to say that the previous warmest occurred only last year in 2015! Of course these are still only provisional temperatures and may change at the end of the month, but as you can see the 13.2°C maximum was 0.1°C higher than 2015, and almost +6.3°C above the 1961-1990 long-term average. Christmas day 1983 still holds the record for highest mean temperature of 10.4°C by the way.
Exceptionally mild in Aberdeenshire
Here is a table of maximum temperatures [06-18] from around the country for yesterday the 25th of December 2016, and as you can see the maximum of 15.1°C at Aberdeen just pipped many other stations to the warmest place in Britain and Ireland.
That list only tells part of the story though, the following anomaly chart shows just how mild it really was in Aberdeenshire yesterday:
The maximum temperature of 15.0°C at Aboyne yesterday was in fact +10.1°C above the 1981-2010 long-term average for a 06-18 UTC maximum temperature. This must have been helped in no small way to warming of the air in the strong to west southwesterlies that were blowing down from the Cairngorms during the morning and before the cold front whizzed through at around 14 UTC. Here are the observations from Aboyne for the last couple of days, take note of the moderate snow reported at 07 UTC on Christmas Eve.
Plot grid for Aboyne
And here are the hourly temperature and dew points for Aboyne – a good morning for getting the washing done in Charlestown Road yesterday I’d wager.
And here’s evidence of the underlying reason for the extra warming yesterday on Deeside in the form of a pseudo anemograph for Cairngorm over the same time scale, a föhn wind. Yes, that’s a gust to a 148 mph at 13 UTC on the top as the cold front was passing through.
And just look what happened to the temperature up there after that. So as well as being Christmas day it was also a really very interesting day meteorologically speaking.
Here are the latest air temperatures from across the country at 13 UTC on Christmas day. It looks like last years high of 14.8°C is in serious danger of being broken. Here in the SW the sun has started to break through the SC sheet, as I thought it might, and I notice that the temperature at Exeter airport has responded quite smartly to 14.0°C in response.
Another mild Christmas day across the whole country once again this year. It’s cloudy and dry in our part of Devon at the moment, and I notice (in the visible satellite) that there’s a good deal of wave effect in the SC sheet that’s covering the country. I wonder if that hole in the SC sheet in the Celtic Sea will survive long enough to bring some sunshine to the SW this afternoon? This is a list of the mildest places for 09 UTC:
Christmas day was exceptionally mild last year , and the 14.8°C at Chivenor in Devon might take some beating, especially if it stays rather cloudy. Below is a list of 06-18 UTC maximums from Christmas 2015: