Not incredibly cold as far as wind chill goes today across the country, generally in the range of 1 to 4°C using the JAG/TI formula, except of course if you find yourself on top of a mountain such as in the Cairngorms, where the wind chill is as low as -15°C at the moment.
This is the wind chill for around the British Isles for 09 UTC this Sunday morning (fig 1). It’s still predominantly cloudy over most places apart from the northwest of Scotland, and the SC layer in the west is showing a good wave effect to it (fig 2).
I wonder if the Helm wind is blowing today? I certainly wouldn’t fancy my chances on top of Cross Fell this morning (fig 3), but no doubt there will be some people up there nevertheless.
The milder air that’s forecast to warm things up during the coming week is already showing it’s hand over the south of France (fig 4).
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.
Another great visible satellite image again this morning (img 1), which clearly shows the extent of the low stratus cloud sheet across the south and east of the country. The Pennines and Snowdonia are acting as a natural barrier to it, so many places in the North Wales and the Northwest of England are clear of it, and I notice that in the lee of Dartmoor there are some strung out gaps as well. Drier air is now starting to stream off France, and it won’t be long, I should imagine, before this clearance makes it across the Channel to southern counties of England.
Today’s windchill across the country is pretty high, or should that be pretty low? Whatever it’s pretty raw out there today, and typically the JAG values on lower ground are coming in at between -3°C and -7°C, but as low as -12°C on any higher ground (figs 1 & 2).
There’s an intense high sat over Ottawa on the 06 UTC chart this morning of around 1044 hPa. You usually associate light winds with anticyclonic weather, but not this morning on Mount Washington just to the southeast of the centre in New Hampshire, the wind from the observatory was meaning 62 knots (77 mph) at 06 UTC, with an air temperature of -24.4°C, and a resultant wind chill of -47°C (-52.6°F (JAG)).
The Bora is a cold, dry gusty north or northeasterly downslope wind that affects (according to Roger Barry in Mountain Weather and Climate) the eastern shore of the Adriatic from Trieste in the north of Italy southward down the eastern shore of the Adriatic for about 500 km. It’s the big brother to the Helm wind of Cross Fell in this country, and this morning it’s going at it hammer and tongues. There is an interesting Wikipedia article about it that gives a lot more information. Here’s the 09 UTC plotted chart (fig 1) for this morning for the Adriatic area.
Here is the latest gust analysis for the area (fig 2).
Observations are only three hourly for most of the places that I can see, but here is a plot grid of observations from Dubrovnik (fig 3) to give you a favour of the weather there, and the Bora does look to be a very gusty wind just as Roger Barry described it. Temperatures at Dubrovnik have been falling all the while, and the wind chill in the 12 UTC observation today was around -12.2°C with the wind gusting to 70 knots and a temperature of -2.3°C.
Mind you it’s even wilder on the other side of the Adriatic at Termoli in Italy (fig 4), the wind there is meaning 43 knots from 350° at 12 UTC (strangely they don’t report any gusts) and the air temperature is only 1.4°C. I suppose there has to be strong convection going on over the sea with those temperatures, but possibly that the air is so dry that it’s limited. I don’t know if this wind is known as a Bora down the eastern Adriatic coast Italy , but it’s still a severe gale whatever you call it.
I’m rambling a bit now, but I notice that the SST in the central Adriatic is around 15°C (fig 5), and well above average at the moment, this cold spell might readjust that over the next few days or so.
Figure 6 is a visible satellite image that shows the convection that’s streaming southwestward from the Adriatic across eastern Italy.
In this chart of SFERIC activity (fig 7) there are some isolated thunderstorms over the high ground of southeast Italy, but many more further south in the Mediterranean especially off the coast of Greece, where there is deeper instability. I would conclude by including a weather radar, but surprisingly in the 21st century the ones that I can find are absolutely dreadful.