Rob K

Say what? http://www.wzkarten.de/pics/Rtavn1622.png - from 12Z as I post, -10C over the whole of mainland UK! In high-res: http://www.wzkarten.de/pics/Rmgfs1622.gif -12s over many areas. Will change as the 18Z rolls out though, but hopefully not much! More snow around on the 18Z run... http://www.wzkarten.de/pics/Rtavn784.png

ECM out to 144 hours on Meteociel: http://www.meteociel.fr/modeles/ecmwf.php Scandy high, easterly flow a little slacker than the 00Z run, but very cold air (510dam touching east coast)

OK well I'm quite happy to be wrong in that case!

I have to disagree about the UKMO 00Z - it's a much worse run than we've seen recently. It shows no sign of the all-important linkup to Scandinavia, so no long-fetch easterly. It's a sinker, pure and simple. Compare UKMO: http://www.wzkarten.de/pics/Rukm1441.gif to ECM: http://www.wzkarten.de/pics/Recm1441.gif and look at the pressure over Scandinavia. Or scroll through the evolution here: http://www.meteociel.fr/modeles/ukmo2.php?carte=1021&ech=84 Worrying development, but only one model - let's hope it disappears on the 12Z!

Presumably standing in for figures above 9, so they fit in to a single space? so A = 10, B = 11, C = 12 and so on?

This is off topic for this thread but you are totally wrong there. Currently there are warnings for Heavy Snow for the following areas: Early Warning: Blaenau Gwent Caerphilly Merthyr Tydfil Monmouthshire Powys Rhondda Cynon Taff Torfaen Herefordshire Shropshire And advisories for: The whole of the rest of Wales, plus Derby Derbyshire Leicester Leicestershire Northants Nottingham Notts Rutland Bedfordshire Luton S Yorks W Yorks Blackburn Blackpool CHeshire Gtr Manchester Halton Lancs Merseyside Warrington Staffs Stoke Telford W Midlands Warwickshire Worcs Shropshire Bucks Oxfordshire Milton Keynes Bath & NE Somerset Bristol Gloucestershire N Somerset S Gloucestershire

And at the other end of the country, some impressively low readings in Hampshire at 11pm, with -8C at Middle Wallop, -5C at Farnborough... and an unofficail -9C at Stratfield Mortimer up in Berkshire by 9pm. Here in Yateley it's -5C too and the 7-8cm of snow cover has frozen rock solid.

I think there's some cloud moving in up there, which could start pushing the temperature up again. Not ideal still calm clear conditions tonight it seems.

Tulloch Bridge -15.6ºC at 5pm. It was -11.4ºC at midday

Bump... I see Topcliffe reached -13.3C at 7am, and may have gone lower between obs. -13.1C at 9am.

The GFS minima aren't really suggesting 1981-style cold. Back then there were -20s and even -25s in central England. The lowest the GFS has gone for in England has been about -14C I think. A few days ago there was a rogue -21 over Scotland following this weekend's northerly.

That 12Z GFS run is pretty remarkable. If I am correct, the gridpoint temperature for the far north of Scotland is at zero or below for EVERY SINGLE CHART from T+6 hours right out to T+384 hours, day and night. I don't think that has ever happened before....

Yes - that fax chart is remarkable not really for the temperatures or weather it will produce as for the synoptics - a perfect semicircle of high pressure centres across the top with lows trapped below. Flip it upside down and you'd have a more usual winter chart!

And as I posted on the previous page, -11.9C at Chesham on January 7 this year. I recorded -10.5C in northeast Hampshire. There was no snow cover at the time.

For people that are discounting these double-digit negative minima... remember we saw minima below -10C in southern England in January 2009 (at my local station, Farnborough, for one), and that was with no snow cover! I think the lowest recorded in that spell was -11.9C at Chesham, Bucks.

Apologies. But those charts were being posted a few days ago with people misreading the scale and claiming sub -15C uppers were on the way!

Yes agreed, I posted a few days ago about people being unable to read a simple colour key on these charts! BTW there has been a lot of nonsense spouted about the 850s being "downgraded". The GFS ensemble mean has NEVER shown -15C uppers over the UK. The coldest mean for London has been -9C, and that is still what is shown around the 19th. The upper air temps have been very consistent.

Well, for those that think the ECM is infallible, let's have a look at what its 168hr chart looked like... 168hrs ago (well, 174 actually) Erm... look much like the current analysis chart to you, because it sure doesn't to me!

Well although all the real cold is in "FI", what is important is that the progression to a situation that will likely deliver that cold has now been firmed up and is shown at about 96 hours, which is pretty well within reliable range. (Touch wood!) By 96 hours, high pressure is starting to ridge northwards starting the process of moving up to Greenland/Iceland or thereabouts (exact position subject to change).

No, he was wrong. Look at the scale. From the right: red means 10 to 15C Dark orange means 5 to 10C Light orange means 0 to 5C Yellow means -5 to 0C Light blue means -10 to -5C Next blue means -15 to -10C and so on until dark blue means -25 to -20C So the coldest air on the above chart is over Scotland and is between -5C and -10C (likely fairly close to -5C as it is close to the boundary with the yellow). The yellow air over England is between 0 and -5C. The -5C isotherm closely follows the Scottish border, and also just clips East Anglia. This can be confirmed by comparing with Meteociel: http://www.meteociel.fr/modeles/ecmwf/run/ECM0-168.GIF?08-0 That has -4C and -6C isotherms, not -5C, but the -6C covers NE Scotland only.

Farnborough in Hampshire has recorded some of the coldest night-time temperatures in the UK over the past few days with several minima of -8C or below (-10C last night). Here are a couple of pics from a rather cold Sunday bike ride... Basingstoke Canal alongside Farnborough airfield. The swans had kept a little area free of ice, and there's also a heron there although rather hard to spot!: The ice was pretty difficult to smash but I had to find out how thick it was... 4 inches, thicker in places: And up on the heath there were some big puddles that were frozen solid enough to play around on with my bike... :blush:

A low of -6C here in NE Hampshire and a very white frost. Farnborough a few miles away got down to -9C according to WeatherOnline. Those who were scoffing at the GFS temperature forecasts might have to be eating their words!