Hurricane force winds on top of Cairngorm this morning, where the winds is meaning 77 knots (113 mph) and gusting to 98 knots (120 mph) at 10 UTC, that’s close to category two hurricane strength, and that’s a ten-minute and not a two-minute mean. The wind has been slowly backing over the last couple of days, and with the air temperature currently at -3.7°C that means a wicked wind chill equivalent of -17.2° for any poor sod who’s daft enough to be up there at the moment.
Lovely morning down here in the southwest, but the wind is adding a bit of a bite to it even so, with a-5.6°C wind chill at nearby Dunkeswell at 10 UTC (fig 1). The SC sheet that’s lying across northern England and Wales seems to be aligned with the lighter winds down the axis of the ridge (fig 2).
There’s talk of a SSW event later in the month, which may explain why the GFS model has been in a total quandary for a while now, with little consistency from run to run beyond T+120.
The wind chill is certainly making it feel very cold further north, but it’s certainly much milder across southern counties (fig 1).
Any morning cloud that’s been affecting some southern areas has now dissolved away, and it’s a wonderful afternoon across the bulk of the country. It’s still possible to see the extent of the snow over the mountains of Scotland through the thickening frontal cloud (fig 1).
The easterly wind is blowing fresh or strong across southern areas though (fig 2).
This has meant that wind chill has been sub-zero in the more exposed places (fig 3), but not excessively low because of the clear skies and widespread sunshine (fig 4).
A large range of wind chill values across the country (JAG) as you would expect today, from -17°C on top of Cairngorm behind the cold front, to 11°C at Benson in Oxfordshire still in the warm air at 11 UTC. I can already see that the BBC weather presenters have dusted down ‘the feels like’ graphics in their presentations.
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)).