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chapmanslade

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    Chapmanslade, Wiltshire 140m ASL

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  1. Indeed so - I posted last Saturday that the Met office forecaster I was speaking to said 70% chance of cold after this weekend which was in his words a very high degree of certainty at that range. That obviously leaves 30% chance of it not doing so.
  2. Well on my Met office open day visit last week they said the UKMO model is the best up to 3 days, together with ECMWF which slightly out performs it, in the UK. This latter part being bold for a reason as in other parts of the world it isn't always the case. Plus in general in the 72hrs area the spread of models is usually fairly tight so differences not massive. What was interesting was the suggestion they gave that model definition was unlikely to improve much further as 'computing power' is not really the limiting factor - data density at T0 is.
  3. Indeed so. I've just returned from a Met Office open day tour at Exeter and the topic came up there. The forecaster I spoke to was suggesting a 70% chance of cold / Easterly at the beginning of next week which he said was a very high percentage certainty at that range, whilst emphasising there is still the other 30%. He was also showing the 'London Model' 333m output but cautioned that in terms of improving model resolution the limit was quantity of input data rather than computing power. Still the current 4 day accuracy is the same as the 1 day accuracy from the early 80's.
  4. I would recommend the Met Office open days - especially to the armchair met office bashers who think the MO don't know what they are doing. Just been to the one today and it was a fascinating tour of some wonderful facilities and all of it FOC. It takes about 3 hours with a little bit of history, the brilliant MO Library, as well as a presentation by a forecaster on the process of creating a forecast. The library is open to the public but you do need to let them know if you want to visit for security reasons - that in itself is worth a visit.
  5. Here is a bit of fun to while away the convection free periods http://profhorn.meteor.wisc.edu/wxwise/thermo/h5/tstm.html
  6. Yes it was only 2C here at 08.00 this morning. Supposed to be turning to snow here at about 02.00 Wednesday and then snowing for about 4 hours. High ground should see it settle I would think, such as Salisbury Plains.
  7. It is unusual you see the op and control runs so similar but out of kilter with the ensembles - somethings brewing !
  8. Why would he be 'optimistic' - he is only providing information based on his view of where things are at present. Unlike many of the armchair forecasters on here he is paid to be accurate, as literally lives can depend on it - so suggesting it is further north when it isn't would be a quick way to lose your job as a forecaster. This storm will have a big impact on the Channel and Northern France so it is important he gets it right.
  9. Snow fields are the reason. Difficult to get much below -5C without snow but as soon as you get a good reflective layer then down it goes
  10. You will not have to wait much longer. Rapidly evolving situation as the small low over Bristol quickly traverses the south of England drawing in very cold air behind. Expect 5cm over the Mendips by later this afternoon. Overnight further risk to the south of the UK from the depression coming up the Channel. We had snow here early this morning followed by heavy rain and 6C then back to 1C or lower by 12.00. Wind will drop as the low moves through. We are literally 10 miles south of the snow here and 5C warmer - no wonder it is such a vigorous little low pressure area !
  11. ARPEGE and AROME both suggesting significant snow to have settled in CS England by early Monday morning but little south of the M4 until Sunday afternoon onwards. ICON suggesting slightly less for CS England but in the same timescale
  12. ARPEGE suggesting accumulations even in southern England later Sunday and overnight into Monday. Small scale disturbances plus a bit of height such as the Mendips and Salisbury Plain will make all the difference
  13. Model Output Discussions 12z 01/06/2017

    Ahh but the op runs show the same detail start to finish which is what a lot of people quote. Perhaps if the op runs increasingly merged into the ensemble mean with time from T0 then that would work ? Warmer in the context of my post was warmer than the run earlier in the day so therefore entirely appropriate
  14. Model Output Discussions 12z 01/06/2017

    With the greatest respect which learned meteorologist do Radio Key 103 employ ? Further to my post this morning, 12 hours later the ECM is showing a warmer more humid but still unsettled route for the coming week as alluded to by Frosty, just emphasising that the op runs mean very little post 5 days. Look at the ensemble spread on the GFS (the one we have easy access to). When the bunched lines turn into spaghetti around day 5 what follows is largely noise until it picks up on the next significant event. Whilst posting what these runs show after day 5 is factually correct it is usually a pretty futile exercise in predicting what the weather will do. A long time ago I thought it would make sense if the model charts got more and more blurred as they go forward so they just show general themes rather than detail. The fact that they show the same level of detail for 10 days time as today just encourages folks to give them equal credence.
  15. Model Output Discussions 12z 01/06/2017

    Really ! When the models were showing a deep depression over the UK for this week a couple of weeks ago and we ended up with the hottest June spell for 41 years do you really think there is much credence in what they are showing now. We all know well anything beyond 5 or 6 days on the op runs is FI so frank statements such as the above and similar from others don't demonstrate a real grasp of model watching. Yes it will be unsettled next week and cooler than of late but it isn't Armageddon, or Autumn, or the remainder of the summer written off. Arguing 'that's what the op runs show' is fair enough up to the point where you know how unreliable they are at that range.
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