Cool weather

Posted: December 29, 2014 by tchannon in Analysis, Surfacestation, weather

Been away for a variety of reasons, has been a horrible few weeks including frenetic work on software workarounds. Several personal matters were far worse. Lets hope that is the end of it, more stuff keeps on dumping on me.

The weather is a tad chilly in England, went down to -6.8C at Katesbridge Northern Ireland last night (27th into 28th) [UPDATE] and what happened next? See comments and link to another blog article with data, went off the bottom of plot shown here –Tim][UPDATE 2, -8.8C ]


It might drop further tonight, flat anti-cyclone calm over the UK, unusually clear skies but there is still humidity to freeze out.

We had a remarkable day today in southern England, clear sunny all day with flat calm, just right to look at insolation and radiation balance.

Benson, south Oxfordshire tends to be the coldest weather station in the south of England, up to midnight [UPDATE: some cloud was arriving warmied slightly –Tim]


During the sunny day here an IR reading on the sky zenith read < -40C, at 20 hours it read -42C, concrete paving -2C and roof of my car -12C. A shaded thermometer near the house -1.8C

Humidity will keep air temperature up.

Chilbolton yesterday shows the clear conditions


As you can see close to the winter solstice there isn’t much insolation. Temperature is falling noisy as presumably frost sparkles out.


I’ve computed the radiation balance where assuming this is correct is around negative 40 Watts sqm. (various details not mentioned about errors in quick plots etc., all I can do quickly)

The estimate of a universal fudge factor to do with clear air insolation is wrong in this case, low by about 10%. This an ongoing work, early days. Next month the official data should be available so I could do some checking. (archive is updated monthly)

Post by Tim

  1. Graeme No.3 says:

    Not a good start to the new year; work and personal problems and a madman loose. I hope all of these clear up quickly for you, so you can have a happy new year.

  2. colliemum says:

    Here’s hoping that after this ‘annus horribilis’, things will look up for you in 2015, Tim!

    Thanks for your excellent work.

  3. Richard111 says:

    Just checked Milford Haven weather

    Temperature is -3.4C and humidity 95.6% not exactly normal for here.
    Took a screen dump for posterity.

  4. Joe Public says:

    Thanks for your interesting posts, Tim. I’ve learnt a lot from them.

    Hope you have a good 2015.

  5. Season’s greetings Rog, it’s a bit frosty here in North Bristol so won’t go out on the bicycle but gardening instead

  6. tallbloke says:

    Hi Adrian, and seasons greets to you too. Gardening is off my agenda at the moment but it is beautiful outside.

  7. […] blog article is an addition to this one at Tallbloke’s, and providing the […]

  8. tchannon says:

    Another cloudless day today if less blue so there is humidity up there.

    I’ll trip a data capture.

    And it was… site 99014, Katesbridge, bottomed at -8.6C, official published at 23hrs tonight will be slightly lower. This is an excellent exponential cooling plot.

    Next up surprisingly was Hurn Airport at -7.1C
    This is good because it is a synoptic station WMO 03862 and we get the other weather parameters to Met Office allow out.

    Followed by Benson, WMO 3658 at -6.9C which I had expected to fall further but nicely the reason is in the data, some clouds appeared, was coldest at Zulu.

    I’ll make the data available.
    Done as a post on my own blog, Link here.

  9. tchannon says:

    I mentioned some troubles with software. For the word some read fatal.

    WordPress tend to meddle with things, in this case mixing up HTTP and HTTPS which tripped basic communication problems where it had worked for years. This locked me out of writing offline posts, no comms and there are no alternative tools which work here.

    It also broke a critical software suite, blog backup, there is none supplied, why I wrote one, somewhat complicated. Fixing this was an imperative.

    Unfortunately the only viable way out was not available, openSSL is in such a mess I can’t compile it, been trying off and on for years. There are alternatives, none compatible enough. Longer term I hope that the openBSD succeed, have forked openSSL (not their code, is dire mess) and are creating libressl. To their credit they are trying to create a portable version as well for usage away from BSD. (openBSD is superbly done, very correct, but not very practical for ordinary desktop use, such as no official binary updates for user land)

    Took me a week or so to figure out and test workarounds. Offline written posts are up on this and my own blog. Backups are to use a wince word, normative according to the log files.

    Now I have to try and get my brain back to what I was trying to do.

    Humour never comes across well in writing, I’m in a way as much amused as hacked off over life playing it’s trick, rarely are fair.

    Oddity, yesterday I nearly posted on the bad weather in the Mediterranean, focusing as much on the pressure driven winds and storms caused by land mass funneling. This was _before_ the various marine disasters; based on looking at GCM output. Been meaning to write a post on the notorious Etesian northern winds. Misral and others merit mention.

  10. tchannon says:

    Met Office figures for yesterday

    UK extremesParameter Location Value
    Highest maximum temperature Harris Quidnish 9.1 °C
    Lowest maximum temperature Threave -0.7 °C
    Lowest minimum temperature Katesbridge -8.8 °C
    Highest rainfall Emley Moor 5.4 mm
    Sunniest Camborne 7.2 hours

    Issued at: 2303 on Mon 29 Dec 2014

  11. tchannon says:

    Not as cold last night, probably from increased water content as air masses move.

    Coldest was Benson, -7.2C at dawn.

    Boscombe Down at -7.1C

    Farnborough at -6.8C which is a good one to find given I have recently posted on the Farnborough site

    Wisley is close to Farnborough yet there is a clear sign of somewhat different conditions at what is a poor meteorological site where there is poor exposure: Farn. is open, Wisley is enclosed. Maybe something important can be learnt.

  12. tchannon says:

    UK extremes Parameter Location Value
    Highest maximum temperature Achnagart 10.6 °C
    Lowest maximum temperature Cranwell 2.0 °C
    Lowest minimum temperature Benson -7.5 °C
    Highest rainfall Lusa 5.0 mm
    Sunniest Bude 7.0 hours

    Issued at: 2303 on Tue 30 Dec 2014

  13. tchannon says:

    Perishing cold here just after midnight, -3.4C for a poorly exposed remote but when I checked Benson, quite close by it is much warmer.

    On looking at data, Farnborough -5.7C and partly cloudy
    Hurn -5.6C
    Northolt -4.7C, London outskirts

    Looking at IR satellite and then forecast progression I expect it will warm here during the late night, coldest will probably be east of here.

    End of cold snap with normal January to follow.

  14. tchannon says:

    Dead on and a gift if anything can be made of it.

    Weather is changing, actually light cloud here but still sunny.

    Farnborough coldest -6.1C
    Charlwood -6.0C (nearly mentioned before)
    Northolt -5.9C

    Lots of details worthy of looking, oddities about cooling details. These sites are known well enough to link features.

    Heathrow does not figure (-3.5C) but the Stevenson screens are 8.08km apart, both synoptic stations which ought to be similar. Neither are estimated as WMO class 1, Farnborough is yet even there a hot collar will exist.
    I’ll hazard a guess at wind run on why Heathrow did not fall flat calm but given so much infrastructure too close, who knows. Northolt is hardly clean.

    I expect sloping ground is involved to a degree. (Heathrow though is flat, neither fly at night, little road traffic at this time of year)

    The critical factor on this kind of cooling is flat calm, wind is dominant. This is my point, why I am doing this. These are passive screens so they probably fail well before flat calm, nevertheless direct radiation is demonstrated as a very weak factor in temperature control.

    I expect temperature inversions were present, no data nor would radiosonde say much since low altitude is not their forte. Chilbolton might reveal more from other instruments. Does it matter?

    Can draw a line for now, move on to other things, maybe mull over what can be done for a future article. Suggestions welcome. Ask if you want data. (I’ll add the official extreme data when it arrives)

  15. tchannon says:

    UK extremesParameter Location Value
    Highest maximum temperature Kinlochewe 12.4 °C
    Lowest maximum temperature Fylingdales 3.9 °C
    Lowest minimum temperature South Farnborough -6.7 °C
    Highest rainfall Achnagart 29.2 mm
    Sunniest Wittering 5.8 hours

    Issued at: 2303 on Wed 31 Dec 2014

    (Farnborough is qualified South because there is more than one station, the other is for flying purposes, a compare would be interesting)

  16. tchannon says:

    Another cold night

    UK extremes Parameter Location Value
    Highest maximum temperature Isles of Scilly 11.0 °C
    Lowest maximum temperature Marham 0.4 °C
    Lowest minimum temperature Topcliffe -7.3 °C
    Highest rainfall Lerwick 7.0 mm
    Sunniest Waddington 6.4 hours

    Issued at: 2303 on Sun 04 Jan 2015

    Not forecast here as a frost last night. Murky first thing, went outside and found a hard frost glazing things, ice right through. Called winter.

  17. tchannon says:

    Met Office forecast out into February

    Met Office forecast for period day16to30 issued at 2015-01-04T16:00:00

    Forecast for All regions (shared forecast) day16to30, from 2015-01-19 16hrs (Mon) to 2015-02-02 16hrs (Mon)
    UK Outlook for Monday 19 Jan 2015 to Monday 2 Feb 2015:
    The most likely scenario is for conditions through the latter part of January onwards into early February to remain unsettled and often windy with periods of milder but dull and wet weather, interspersed by brief clearer but colder and showery spells with frosty nights.
    Towards the end of this period drier and more settled conditions may start to become a little more dominant across southern Britain.

    Met Office forecast for period day6to15 issued at 2015-01-04T16:00:00

    Forecast for All regions (shared forecast) day6to15, from 2015-01-09 16hrs (Fri) to 2015-01-18 16hrs (Sun)
    UK Outlook for Friday 9 Jan 2015 to Sunday 18 Jan 2015:
    On Friday, cloud and rain, heavy at times, will spread quickly eastwards across the UK, rain heaviest and most persistent in the west.
    Clearer, showery conditions follow later and into Saturday, showers most frequent in the north and west, wintry over northern hills.
    Brisk winds across the UK Friday will be strong in many areas, with severe gales and possible storm force winds in the far northwest early Friday.
    Temperatures will be above average in the rain, slightly below normal under clear skies.
    Thereafter, the weather will alternate between unsettled conditions with spells of rain, and colder, clearer, more showery interludes.
    Often windy, even inland, with risk of severe gales in exposed areas.
    Temperatures will vary, often above average in unsettled spells, and generally below normal under clearer, brighter conditions.