We have an August frost, 0.0C mean at 3am BST

Posted: August 24, 2014 by tchannon in weather

Quick post by Tim


Katesbridge is fascinating, edge of marsh in Northern Ireland (see surfacestations, top menu), it can be very cold. Benson, south of England is down to 4C, a cool night with I suspect a touch of ground frost widely. Hopefully not enough to damage sensitive garden plants. (I have the numeric data here)

For me this is a fascinating moment, been working on an evolution of capturing and presenting UK Met Office data. First usage was literally a few minutes ago, manually grabbed the data, get get and then typed regen, it figured out what needed doing, worked.


This is part of the new work, full version is in the created PDF. Above is a bitmap export, click for larger.
Tech explanation is here, quick post on my own blog

3am data with Katesbridge is here PDF (1.2MB)

And the normal for yesterday is here  PDF (1.2MB)

Have files going back a few weeks, ask if you want a day.

Post by Tim

  1. It was even mentioned on the BBC Radio 4 weather forecast at 6.57am.

  2. colliemum says:

    Thank you for this work of love, Tim!
    It’s only fair that you unveil it on a day like this one, with a zero temp in August.
    Ironically, the BBC morning TV was just warbling about a ‘climate audit’ and that temps could rise by 6 degrees, and that just after the weather forecast where that August zero temp was mentioned. Excellent example of cognitive dissonance …

  3. Graeme No.3 says:

    In Monet’s garden in Normandy (August 18) the autumn crocus were flowering in the lawn. “A sure sign of autumn” according to the notes.
    Strange to think that a bulb can out-calculate the Met Office super computer.

  4. tchannon says:


  5. tchannon says:

    What a fantastic temperature plot, lovely frost flat on it, exponential cooling.

    Click to access uk-2014-08-24-1258.pdf

    Not got time to discuss this now.

  6. hunter says:

    Great article, going to show that of course it is all consistent with AGW theory. Not.

  7. Sparks says:

    I live near Katesbridge it is surrounded by mountains and hills, where I live it gets a bit colder than Katesbridge, we have had frost on Friday morning and it has been very cold, Ive taken some photos of the surrounding area just after last years heavy spring snowfall, it was unbelievably cold on the hills, frozen lakes and over 10ft of snow in some places, August this year has definitely been the coldest since I’ve moved here.

    I can e-mail the photos if you would like to see them.

  8. tchannon says:

    Good idea collecting information in one place sparks. Of course we are interested in photos.
    (iirc you have my email, I’ll email later need to use daylight outside for some stuff.)

    The map shows several surrounding stations, plots are in the PDF (text search should work on station number). Your explanation of a topographical reason is sound, no wind.
    I don’t consider it a frost hollow as such, slightly above the (farmed) marsh by a gentle grass down slope (see Google Street View). Senny Bridge, Wales (actually some distance from the place) is a similar site and also cool. Explanations for a few others is overgrown vegetation, no wind, poor exposure which applies to all met parameters.

    Radiative cooling and water are the dominant factors in this case. Might try computing some stuff later. The frost/dew burnoff flat cannot be seen in the hourly data, is there in high res. data, see Chilbolton works.

    Day temperature has the jagged look of water vapour limiting tempereature rise. This is a wet place not a dry desert.

  9. tchannon says:

    Some fascinating information is turning up from that natural experiment.

    For example I’ve taken three sites where similar radiative cooling occurred, normalised to Katesbridge in a conventional way but very unusually, not many people know how to do this, normalised in time. The result is surprising and also a warning message for those playing with data.

    I’ve barely scratched the surface. Any lessons or insights are I think useful.

    Question for me is whether to post results on my own blog or the Talkshop or both. The Talkshop is supposed to be about science yet technical stuff rarely goes down particularly well. New stuff however minor is still grist for the mill.

    Anyone wanting to play here is the numeric data from the night in question, CSV in a zip
    ZIP (60kB)

    Here are the Met Office extremes for the day, UK and the regions involved for the three station unification.(the plots are posted as a PDF a few messages up)

    24 hours ending 2200 on 24 Aug 2014:
    UKHighest max 0900-2100 20.1 °C Gravesend
    Lowest max 0900-2100 12.1 °C Loch Glascarnoch
    Lowest min 2100-0900 -1.9 °C Katesbridge
    Highest rainfall 2100-2100 8.0 mm Isles Of Scilly
    Sunniest 2100-2100 13.8 hours Tiree
    Last updated: 0002 on Mon 25 Aug 2014

    24 hours ending 2200 on 24 Aug 2014:
    East of EnglandHighest max 0900-2100 19.7 °C Cavendish
    Lowest max 0900-2100 16.1 °C Cromer
    Lowest min 2100-0900 2.2 °C Santon Downham
    Highest rainfall 2100-2100 5.8 mm Norwich Airport
    Sunniest 2100-2100 9.3 hours Wittering
    Last updated: 0002 on Mon 25 Aug 2014

    24 hours ending 2200 on 24 Aug 2014:
    London & South East EnglandHighest max 0900-2100 20.1 °C Gravesend
    Lowest max 0900-2100 17.2 °C Wych Cross
    Lowest min 2100-0900 2.1 °C Benson
    Highest rainfall 2100-2100 0.2 mm St James Park
    Sunniest 2100-2100 7.1 hours Odiham
    Last updated: 0002 on Mon 25 Aug 2014

  10. tchannon says:

    I got it wrong, or more correctly a decent GCM did not pan out.

    Quoting myself

    tchannon says:
    August 19, 2014 at 3:55 am

    Lets have a look at some GCM.
    Get a touch of more westerly later on, not quite as chilly but whoops, 24th (Sunday) if that comes to pass the west coast gets a heck of a blow, gales on exposed coasts, less so further east. Heavy rain across the country, frontal system into early hours Monday. Maybe, never sure that far out in time.


    Today is the 26th. The storm progressed from off US Gulf but weakened more than shown by the GCM. The winds were much weaker, and it was delayed a day. Northern France got the worst of the rain, a lot of it, 38.4mm recorded in Central London.
    Here in southern England it steadily rained for many hours.

    All the same not entirely a damp squid, oh right, it was damp.

  11. tchannon says:

    The Scots will not be outdone, Braemar goes one better in the topsy-turvy world. Exeter now the warmest in the UK. The old saying what gives takes away again.

    24 hours ending 2200 on 25 Aug 2014:
    UKHighest max 0900-2100 21.1 °C Exeter Airport
    Lowest max 0900-2100 11.7 °C Emley Moor
    Lowest min 2100-0900 -2.1 °C Braemar
    Highest rainfall 2100-2100 38.4 mm St James Park
    Sunniest 2100-2100 13.8 hours Tiree
    Last updated: 0002 on Tue 26 Aug 2014