There is no doubt that a change of type will occur in the next week or two because of the SSW that started late last week. The next problem is where the actual block will be positioned and orientated. The two main available NWP models at T+240 have different views on that matter at the present time. The ECMWF has the block centred over the southern North Sea at the 500 hPa level and aligned northeast-southwest (fig 1), whilst the GFS has it centred over NE Greenland, and ridging more or less north-south across Iceland towards western Ireland (fig 2).
The exact position of where any block sits at the 500 hPa level, will make a big difference at the surface, because it dictates the surface flow and the source of the coldest air. As you can see the ECMWF at T+240 has higher than average 850 hPa temperatures across the UK in a strong SE’ly flow, and the coldest air over SE Europe and the Balkans (fig 3).
Meanwhile the GFS model has the coldest air at 850 hPa over Scandinavia with the UK in a much colder regime and the flow more easterly and not as strong (fig 4).
Here’s what the experts are saying down at the Met Office about the medium term (fig 5).
The Global Forecast System has been nominated for a Hugo award for its latest model run for the UK (fig 1)! The Hugo Awards are a set of literary prizes that are given annually for the best work of science fiction or fantasy. This is the first time that a piece of software has ever been nominated, but the trilogy of T+288, T+312, & T+336 forecast charts do meet the essential criteria for any nomination, in that they are both science and fiction.
Despite this tongue in cheek humour, and as a snow lover, I would love something like this to happen, and perhaps now that the polar vortex is split we will finally see a change in type that means something like is possible and not just science fiction.
“More showers, occasionally they’ll be of sleet, one or two of hail”
I don’t think David Braine is having a particularly good week. Last nights forecast caught him out down on the Lizard, there were more showers as he rightly forecast, but they were rather more in the way of snow than sleet, with Culdrose ending the night with a 5 cm covering of snow that led to a rash of road traffic accidents in the area (fig 2). As far as I know there were no weather warnings out either for this event, but that’s impossible to verify because the Met Office refuse to maintain an archive.
Meanwhile there was 15 cm of snow over the French Capital late yesterday.
The heavy snowfalls of the last couple of days over western Russia and central Asia have put our overnight warning for of just 1 to 3 centimetres into perspective. The above chart are the reported snowfall depths at 06 UTC this morning overlaid with contoured MSLP (fig 1). As you can see from the inset table one of the observing stations close to Moscow (WMO #27612 Dolgoprudny) is reporting 53 cm of level snow (~21″). Dolgoprudny,I’m reliably informed by Wikipedia, lies 20 km north of the city of Moscow.
Russia has a terrific SYNOP observing network, but they only report a snow depth once a day, and for some strange reason, probably to do with time zones, eastern Russia report it at 03 UTC, and western Russia stations at 06 UTC. Without some kind of bespoke SYNOP snowfall application that scans all observations for the latest reported snow depth in all observation for a selected day (now there’s an idea), I can’t extend the chart any further eastward.
I see that it’s snowing again across parts of Scotland this morning. It was only 10 days or so ago that Tulloch Bridge had 15″ of snow lying, just to see it all washed away, but it’s back again now, and they have a fresh cover of 4 cm (fig 1). The source of the cold air is once again from the west, and in these days of climate change I wonder if it’s time to adjust the old children’s nursery rhyme to reflect which wind direction we are now more likely to get snow from?
The cold air that’s currently affecting the North of Africa at the moment, is certainly producing some intense convection over the seas that’s resulted in this water-spout just off the coast of Tenerife yesterday. The video is courtesy of Twitter.
Up at Izaña on Tenerife at 2,390 metres (7,841 feet) above sea level, winter has the Observatory (fig 1) in its grips at the moment (fig 3).
Here are the observations from the last 24 hours from the Izaña observatory (fig 4).
And here are the temperatures for the last month at Izaña (fig 5).
So it’s no wonder that there was heavy snow in Ouarzazate, Morocco for the first time in 30 years on Sunday (28th January 2018). Thanks to Facebook for this particular video clip.
It certainly seems that there’s a lot greater chance of seeing some snow in North Africa than there is here in mid-Devon. It’s now over eight years since we have seen any snow lying here – what a place to retire to for a professed snow lover!
The sunshine totals for the first 22 days of January 2018 reveal that it’s been a depressingly dull month so far, especially over mainland Europe. Top of the shop at the moment is Cork with 50.6 hours of sunshine, but it looks like another dull month over Snowdonia.