The anticyclonic theme thats been so common through much of October and November this year, is set to run into at least the first few days of December. The three main NWP models all have an anticyclone across the country aligned NW to SW. This kind of setup can mean fog and frost in December, but it’s all cloud dependent, and if today is anything to go by, there may be a good amount of it.
Here’s a chart of temperature anomalies that I’ve calculated from the NCEP reanalysis data for the first 24 days of November 2016 for the Arctic region. And again, it’s showing massive positive temperature anomalies across the board, it’s no wonder that the sea ice is struggling to increase in extent this Autumn in the Arctic. Below is a bar chart of temperature anomalies for the grid point at 77°30’N and 15° E (close to Ny-Ålesund on the Island of Jan Mayen), and as you can see they have been generally between +5°C and +10°C for much of the time since September 2016. Obviously there is a lot of warm air finding its way into the Arctic from further south, but I think the anomalies may be even larger around Jan Mayen because this winters sea ice has been so slow to form (see bottom image), and temperatures over open water (even though the sea surface temperature is close to zero) are obviously going to be much warmer than they would be over frozen sea ice.
The boys down at Exeter have really outdone themselves today with the 06Z analysis – a triple warm sector – I kid you not, three distinct warm sectors, embedded one within the other, between Iceland and Norway.
There is no doubt that warmer air aloft – above 4000 feet at least – has spread down from the northwest over northern Scotland since midnight, take a look at this thermograph of hourly temperatures from the AWS on Cairngorm [1237 M].
At least the low cloud cleared from all but parts of Yorkshire today, so yesterday’s forecast was correct after all. We have had seen some thick cirrus (from the frontal system over central France) to the south for most of the day in Devon, but I notice that’s now finally starting to edge away this afternoon.
The Greenwich Lightvessel Automatic to give it’s full title, is anchored in the middle of the English Channel at latitude 50°24″ N and longitude 0°, and that’s why it got it’s name – something I hadn’t realised until I came to write this article. The ship currently on this station is solar powered, as you can see from the above picture, and was built in 1946 for Trinity House, and has been in active service at various stations since 1947 as Lightvessel No. 5 – good old Wikipedia! I think I am right in saying that it must have been manned for many years until it was finally automated, some lightship men have probably spent a whole lifetime of service on vessels like this one.
This week has been a real roller coaster ride for Lightvessel No 5 in the channel, first the hurricane force southwesterly that storm Angus generated on Sunday morning, and then a complete flip, as an almost straight anticyclonic easterly set in from Wednesday, with gale or near gale force east northeasterly winds for over 36 hours. This week is nothing exceptional though, and I’m sure that there have been periods when it exceeded these strengths and for much longer. But at least now I know just a little more about the Lightvessel No. 5 with the callsign 62305 as it appears in the SYNOP reports. Here is a plotted grid of observations from the automatic weather station:
And here’s my pseudo anemograph for the Greenwich light vessel since Sunday:-
When I added this graphic I noticed that the winds slumped at main synoptic hours (00,06,12 & 18). The raw SYNOP data reveals that the AWS for 62305 reports in knots as it should do, but occasionally at main synoptic hours it reports in metres per second [MPS]. I had forgotten to check the wind units in my code and failed to make the conversion from MPS to knots. It’s very odd though, and it may well be worth reporting to the Met Office, but in all truth I think it’s probably a conversion problem at OGIMET (the wesite that I get my SYNOP data) who convert data in BufR format to SYNOPs. If not, you’ll know the next time that you listen to the shipping forecast why the wind in the channel seems a bit on the light side!
The 1 in the fifth character position of the time group in the raw SYNOP code indicates that wind speeds are in MPS rather than 4, which indicates knots. I’ve fixed the code in my application and here’s the correct version of the anemograph for the Greenwich Lightvessel with all wind speeds in knots!
Just for the more curious amongst you – here is a graph of wave heights from the Lightvessel for the same period:-
Today’s persistent low cloud over parts of England and Wales – a mix of stratus and stratocumulus – has been a little more persistent than the BBC weather presenters would have us believe – and ultimately what the Met Office NWP model forecast. Despite TV weather presenters Carol Kirkwood, Darren Bett and Chris Fawkes all promising how the low cloud would readily break up over England and Wales, it’s been stubbornly persistent, although there have been some breaks along the south coast and in the far southwest.
Meanwhile, yet again for the bulk of Scotland (apart from the far north), Northern Ireland, Northwest England and the West of Wales it’s been another beautiful day with gorgeous blue skies and another sharp frost tonight.
The BBC are forecasting more or less clear skies across England and Wales for tomorrow – let’s hope they get that right. Apparently the model is forecasting a cloudy weekend, but the way it’s performing at the moment I wouldn’t bank on it!
Here is a plotted chart of the minimum overnight [18-06] temperature anomalies from this morning’s 0600 UTC SYNOP reports. An amazing contrast between the anticyclonic north and the windy south, with minimum anomalies ranging from as low as -11°C in the Highlands of Scotland, to +5°C along the coast of southeast England.
A very interesting news article from Pallab Ghosh on the BBC News this afternoon for anyone interested in the global climate and sea ice. It appears that Antarctic sea ice extents are very similar to what they were a hundred years ago, according to a report that used log books from the early expeditions to the continent.
I would link directly to the article on the BBC news website, but for some reason although the BBC provide a link to allow sharing with other social media apps, strangely they don’t for WordPress.
The minimum temperature last night [18-06] dipped to -8.5°C (16.7°F) at Tulloch Bridge, Inverness-shire, meanwhile temperatures at many places across the south didn’t fall any lower than 10°C, that’s because there’s a fresh to strong E’NE blowing across areas south of 53°N, and a full gale blowing down the English Channel – in the opposite direction to which it was blowing on Sunday and Monday just for a change. I just wonder if there’s some kind of theme already starting to play out for the weather over the coming winter months here?
Alex Beresford – the ITV Weather presenter – says that it will be breezy over Cornwall today, well spotted Alex.
Scotland is once again the place to be at the moment, at least if it’s glorious late Autumn weather and views of snow-capped mountains that you’re after, thanks to high pressure that’s reestablishing itself over the north of the country. As well as snow on the highlands, snow is also clearly visible on the southern uplands and the mountains of the Lake District. Here are the visible satellite images of the UK for the last seven days, and if you take a close look you’ll see that the snow-capped mountains of Scotland have been visible for 6 out of 7 of those days.
Of course clear days by day spell cold nights and nights have been quite cold. I’m not privy to the hourly Braemar temperatures which the Met Office keep under lock and key but here is the thermograph for the last 10 days or so from Aboyne just down the road and a little bit warmer.