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High pressure and settled conditions 2nd week in September?
Charts that would have been very nice in July! (but will be very
welcome in 10 days time too!) http://www.wetterzentrale.de/pics/Rtavn2402.png Some nice September weather possibly on the cards, starting in the second week of Sept. Both the gfs and the ECM are in agreement. I won't take much more persuading that it is likely to happen. |
High pressure and settled conditions 2nd week in September?
On Aug 30, 9:22*am, Dawlish wrote:
Charts that would have been very nice in July! (but will be very welcome in 10 days time too!) http://www.wetterzentrale.de/pics/Rtavn2402.png Some nice September weather possibly on the cards, starting in the second week of Sept. Both the gfs and the ECM are in agreement. I won't take much more persuading that it is likely to happen. Met Office suggesting settled conditions for that week, but for the south only. I guess there's some disagreement how far north the high will get: the MetO would appear to favour a continuation of the current WSW spell, anticyclonic in the south - which would normally be absolutely fine if only it wasn't for that damned cold pool of water in the Atlantic! Nick |
High pressure and settled conditions 2nd week in September?
On Aug 30, 9:58*am, Nick wrote:
On Aug 30, 9:22*am, Dawlish wrote: Charts that would have been very nice in July! (but will be very welcome in 10 days time too!) http://www.wetterzentrale.de/pics/Rtavn2402.png Some nice September weather possibly on the cards, starting in the second week of Sept. Both the gfs and the ECM are in agreement. I won't take much more persuading that it is likely to happen. Met Office suggesting settled conditions for that week, but for the south only. I guess there's some disagreement how far north the high will get: the MetO would appear to favour a continuation of the current WSW spell, anticyclonic in the south - which would normally be absolutely fine if only it wasn't for that damned cold pool of water in the Atlantic! Nick Hi Nick, Your point about the south's weather likely to be better than the north's is a good one. The MetO's present summary shows that, but is actually is very ambiguous about next week in the south: "UK Outlook for Friday 4 Sep 2009 to Sunday 13 Sep 2009: Sunshine and showers on Friday, and perhaps longer periods of rain in the north and east. Showers ease in the south with many parts dry on Saturday, but remaining unsettled in the north. Windy at first across the UK, especially in the north, but winds ease in England and Wales during the day. **Likely to be less unsettled in the south of the UK for a time, with more in the way of drier, brighter weather but still with a chance of showers or rain, especially later in the period**. The north likely to stay unsettled with rain and strong winds at times. Temperatures below normal at first, with some cool nights expected, but recovering to around normal by the end of the period, **possibly becoming warm in the southeast**. Updated: 1256 on Sun 30 Aug 2009" Mind you, actually trying to tease out any detail from this is very difficult. This is a forecast for a 10-day inclusive period, squeezed into 120 words! Instead of doing the crossword, I reckon the forecasters have fun with the skill of precis in their tea breaks *)). Its brevity shows that it is not given any real importance and the MetO never returns to this forecast to attempt any judgement of its accuracy. They know the difficulties of forecasting at any distance above 5-7 days. There's enough consistency in the gfs and enough agreement with the ECM, for me to forecast, with 75% confidence, dry and settled conditions over the south of the UK in 10 days time, at T240. Temps will be above the September daytime average. The NW won't be faring as well and will be plagued by fronts, giving much more unsettled conditions. I reckon next week could be a good one for a short break on the south coast. Still "coulds". Nothing certain, but gamble on these forecasts and I promise you that you'll come out winning significantly more times than you lose! |
High pressure and settled conditions 2nd week in September?
On Aug 31, 9:19*am, Dawlish wrote:
On Aug 30, 9:58*am, Nick wrote: On Aug 30, 9:22*am, Dawlish wrote: Charts that would have been very nice in July! (but will be very welcome in 10 days time too!) http://www.wetterzentrale.de/pics/Rtavn2402.png Some nice September weather possibly on the cards, starting in the second week of Sept. Both the gfs and the ECM are in agreement. I won't take much more persuading that it is likely to happen. Met Office suggesting settled conditions for that week, but for the south only. I guess there's some disagreement how far north the high will get: the MetO would appear to favour a continuation of the current WSW spell, anticyclonic in the south - which would normally be absolutely fine if only it wasn't for that damned cold pool of water in the Atlantic! Nick Hi Nick, Your point about the south's weather likely to be better than the north's is a good one. The MetO's present summary shows that, but is actually is very ambiguous about next week in the south: "UK Outlook for Friday 4 Sep 2009 to Sunday 13 Sep 2009: Sunshine and showers on Friday, and perhaps longer periods of rain in the north and east. Showers ease in the south with many parts dry on Saturday, but remaining unsettled in the north. Windy at first across the UK, especially in the north, but winds ease in England and Wales during the day. **Likely to be less unsettled in the south of the UK for a time, with more in the way of drier, brighter weather but still with a chance of showers or rain, especially later in the period**. The north likely to stay unsettled with rain and strong winds at times. Temperatures below normal at first, with some cool nights expected, but recovering to around normal by the end of the period, **possibly becoming warm in the southeast**. Updated: 1256 on Sun 30 Aug 2009" Mind you, actually trying to tease out any detail from this is very difficult. This is a forecast for a 10-day inclusive period, squeezed into 120 words! Instead of doing the crossword, I reckon the forecasters have fun with the skill of precis in their tea breaks *)). Its brevity shows that it is not given any real importance and the MetO never returns to this forecast to attempt any judgement of its accuracy. They know the difficulties of forecasting at any distance above 5-7 days. There's enough consistency in the gfs and enough agreement with the ECM, for me to forecast, with 75% confidence, dry and settled conditions over the south of the UK in 10 days time, at T240. Temps will be above the September daytime average. The NW won't be faring as well and will be plagued by fronts, giving much more unsettled conditions. I reckon next week could be a good one for a short break on the south coast. Still "coulds". Nothing certain, but gamble on these forecasts and I promise you that you'll come out winning significantly more times than you lose!- Hide quoted text - - Show quoted text - 36 hours on and still looking good for a settled and warmer period of weather next week, for England, at least. Good agreement between the ECM and gfs. The MetO are coming round to the idea, but won't fully commit themselves on today's 6-15 day update. I don't really blame them. It's very easy to make mistakes forecasting at 10 days. http://www.metoffice.gov.uk/weather/...t_weather.html |
High pressure and settled conditions 2nd week in September?
On Tue, 1 Sep 2009 at 12:25:43, Dawlish wrote in
uk.sci.weather : 36 hours on and still looking good for a settled and warmer period of weather next week, for England, at least. Good agreement between the ECM and gfs. The MetO are coming round to the idea, but won't fully commit themselves on today's 6-15 day update. I don't really blame them. It's very easy to make mistakes forecasting at 10 days. http://www.metoffice.gov.uk/weather/...t_weather.html If only that set-up would wait 3 months... -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) |
High pressure and settled conditions 2nd week in September?
"Paul Hyett" wrote in message ... On Tue, 1 Sep 2009 at 12:25:43, Dawlish wrote in uk.sci.weather : 36 hours on and still looking good for a settled and warmer period of weather next week, for England, at least. Good agreement between the ECM and gfs. The MetO are coming round to the idea, but won't fully commit themselves on today's 6-15 day update. I don't really blame them. It's very easy to make mistakes forecasting at 10 days. http://www.metoffice.gov.uk/weather/...t_weather.html If only that set-up would wait 3 months... -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) Any forecast beyond 5 days needs to be taken with a huge pinch of salt at this time of year, despite any apparent consistency. Hurricanes can develop quickly and unexpectedly and have great potential for altering the strength of jets and their orientation as they become extra-tropical. Also there is at least one upper trough disruption before the forecast high pressure period and models do not handle trough disruptions well. Confidence in an anticyclone at this stage has to 50% at most I'd say. Will -- |
High pressure and settled conditions 2nd week in September?
On Sep 2, 8:25*am, "Will Hand" wrote:
"Paul Hyett" wrote in message ... On Tue, 1 Sep 2009 at 12:25:43, Dawlish wrote in uk.sci.weather : 36 hours on and still looking good for a settled and warmer period of weather next week, for England, at least. Good agreement between the ECM and gfs. The MetO are coming round to the idea, but won't fully commit themselves on today's 6-15 day update. I don't really blame them. It's very easy to make mistakes forecasting at 10 days. http://www.metoffice.gov.uk/weather/...t_weather.html If only that set-up would wait 3 months... -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) Any forecast beyond 5 days needs to be taken with a huge pinch of salt at this time of year, despite any apparent consistency. Hurricanes can develop quickly and unexpectedly and have great potential for altering the strength of jets and their orientation as they become extra-tropical. Also there is at least one upper trough disruption before the forecast high pressure period and models do not handle trough disruptions well. Confidence in an anticyclone at this stage has to 50% at most I'd say. Will -- I don't know about 5 days, but any forecast beyond a week usually needs to be taken with a huge pinch of salt at most times of the year Will - especially when it involves forecasting a change of pattern; in this case from very unsettled to very settled weather. However, I have maintained for several years that there are times when it is possible to forecast with 75% accuracy out to the far reaches of 10 days, where forecasting usually becomes guesswork. I could be wrong, of course (about 25% of the time), but I think this is one of those times where it is possible. I haven't seen anything yet to change my mind about the 10th and the MetO have certainly come around to the same way of thinking as myself, about next week and the time around the 10th in particular. "Most parts are expected to become mainly dry, bright and warm around the middle of next week" - today's 6-15 day tea-break precis! 8)) |
High pressure and settled conditions 2nd week in September?
On Wed, 2 Sep 2009 at 08:25:40, Will Hand
wrote in uk.sci.weather : If only that set-up would wait 3 months... Any forecast beyond 5 days needs to be taken with a huge pinch of salt at this time of year, despite any apparent consistency. Hurricanes can develop quickly and unexpectedly and have great potential for altering the strength of jets and their orientation as they become extra-tropical. ISTM that even the most vigorous storms bounce off high pressure cells like peas off an elephant, though... -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) |
High pressure and settled conditions 2nd week in September?
"Dawlish" wrote in message ... However, I have maintained for several years that there are times when it is possible to forecast with 75% accuracy out to the far reaches of 10 days, where forecasting usually becomes guesswork. I could be wrong, of course (about 25% of the time), but I think this is one of those times where it is possible. I haven't seen anything yet to change my mind about the 10th and the MetO have certainly come around to the same way of thinking as myself, about next week and the time around the 10th in particular. "Most parts are expected to become mainly dry, bright and warm around the middle of next week" - today's 6-15 day tea-break precis! 8)) I am intrigued by your claim of making a "forecast". Are you not simply model watching, as many of us here do, and when there is agreement at 10 days up pops your forecast. To claim the MO have come round to the same way of thinking as yourself is plainly ridiculous, when you don't actually "make" a forecast, only interpret the models. Or am I missing a skill you also have? -- Ned |
High pressure and settled conditions 2nd week in September?
In article ,
Ned writes: "Dawlish" wrote in message news:2d8c8221-e967-4149 ... However, I have maintained for several years that there are times when it is possible to forecast with 75% accuracy out to the far reaches of 10 days, where forecasting usually becomes guesswork. I could be wrong, of course (about 25% of the time), but I think this is one of those times where it is possible. I haven't seen anything yet to change my mind about the 10th and the MetO have certainly come around to the same way of thinking as myself, about next week and the time around the 10th in particular. "Most parts are expected to become mainly dry, bright and warm around the middle of next week" - today's 6-15 day tea-break precis! 8)) I am intrigued by your claim of making a "forecast". Are you not simply model watching, as many of us here do, and when there is agreement at 10 days up pops your forecast. To claim the MO have come round to the same way of thinking as yourself is plainly ridiculous, when you don't actually "make" a forecast, only interpret the models. Or am I missing a skill you also have? As far as 10 days out, are the Met Office doing anything very different from interpreting the models? I can't see what else they could be doing. Of course, they may well have access to data that Dawlish does not, notably ensembles for some models that only make their operational runs available to the general public, so that their forecasts ought to be better than his. -- John Hall "Do you have cornflakes in America?" "Well, actually, they're American." "So what brings you to Britain then if you have cornflakes already?" Bill Bryson: "Notes from a Small Island" |
High pressure and settled conditions 2nd week in September?
On Sep 2, 8:34*pm, John Hall wrote:
As far as 10 days out, are the Met Office doing anything very different from interpreting the models? I can't see what else they could be doing. -- John Hall * * - Show quoted text - Only in the sense that when Chopin sat down at the piano he was merely interpreting Chopin. Tudor Hughes, Warlingham, Surrey. |
High pressure and settled conditions 2nd week in September?
On Sep 2, 8:25*pm, "Ned" wrote:
"Dawlish" wrote in message ... However, I have maintained for several years that there are times when it is possible to forecast with 75% accuracy out to the far reaches of 10 days, where forecasting usually becomes guesswork. I could be wrong, of course (about 25% of the time), but I think this is one of those times where it is possible. I haven't seen anything yet to change my mind about the 10th and the MetO have certainly come around to the same way of thinking as myself, about next week and the time around the 10th in particular. "Most parts are expected to become mainly dry, bright and warm around the middle of next week" - today's 6-15 day tea-break precis! 8)) I am intrigued by your claim of making a "forecast". Are you not simply model watching, as many of us here do, and when there is agreement at 10 days up pops your forecast. To claim the MO have come round to the same way of thinking as yourself is plainly ridiculous, when you don't actually "make" a forecast, only interpret the models. *Or am I missing a skill you also have? -- Ned Only judge forecast accuracy by outcome percentage accuracy over time Ned. |
High pressure and settled conditions 2nd week in September?
"Dawlish" wrote in message
... I am intrigued by your claim of making a "forecast". Are you not simply model watching, as many of us here do, and when there is agreement at 10 days up pops your forecast. To claim the MO have come round to the same way of thinking as yourself is plainly ridiculous, when you don't actually "make" a forecast, only interpret the models. Or am I missing a skill you also have? Only judge forecast accuracy by outcome percentage accuracy over time Ned. But you only "forecast" once in a blue moon,on the rare occasions when models are basically in agreement at 10 days.What you seem to be suggesting is that when they agree at 10 days out, there is a 75% chance they'll be correct. What skill do you add to the forecast method beyond highlighting the agreement? -- Ned |
High pressure and settled conditions 2nd week in September?
On Sep 2, 10:54*pm, "Ned" wrote:
"Dawlish" wrote in message ... I am intrigued by your claim of making a "forecast". Are you not simply model watching, as many of us here do, and when there is agreement at 10 days up pops your forecast. To claim the MO have come round to the same way of thinking as yourself is plainly ridiculous, when you don't actually "make" a forecast, only interpret the models. Or am I missing a skill you also have? Only judge forecast accuracy by outcome percentage accuracy over time Ned. But you only "forecast" once in a blue moon,on the rare occasions when models are basically in agreement at 10 days.What you seem to be suggesting is that when they agree at 10 days out, there is a 75% chance they'll be correct. *What skill do you add to the forecast method beyond highlighting the agreement? -- Ned The MetO can't forecast with any reasonable accuracy, on a daily basis what's going to happen at 10 days. Nor can anyone else; nor can I. At present it is impossible, on a daily basis, with reasonable accuracy. Thus, when you see that 6-15 day forecast, you have no idea if it will be accurate, or how accurate the MetO thinks it is likely to be. It doesn't give you an idea of how accurate they feel it will be at 10- days plus. I wish they would and I feel it would be useful. The 6-15 dayforecast is just 120-ish words which may, or may not, be correct. There is no indication within that of how confident the forecasters are at those distances. No blame in that. It's just not possible to forecast with accuracy at that distance on a daily basis, but the MetO is under these enormous public expectations to forecast at all distances - and be correct - and the press office did it no favours by heightening those expectation with some silly soundbites to "explain" their summer forecast to the media. It fulfils the public expectation at medium ramge, but does so with a minimum of fuss and in few words in a tiny area of the site which is the 6-15 day forecast. It then ignores whatever the outcome is and never returns to it and never publishes verification figures, meaning that we have absolutely no idea whether any forecast at 10 days is accurate. That camouflages the forecasting difficulties very well and is why I joke about precis competitions in morning tea-breaks. I've developed a system where I can, on occasions (and only on occasions) forecast at 10 days, with 75%+ accuracy. Every forecast I've made with it (71) has been done in the public eye and judged by others, as well as by myself and the hrashest judge has been me; promise you. On that dataset and to that outcome accuracy, it works. The only way to apply that is to model watch at 10-days really assiduosly. I used to base it solely on consistency in gfs runs, but I've tweaked that to include a need for agreement from the ECM. That's not because I feel the gfs is the better model, it's just that the 4 runs per day, each under different peramaters renders consistency less likely, if the outcome is to be correct. Any wobbles in that and the forecast is rendered useless. I cannot forecast on a daily basis using this and the system can't be used that way. When a pattern is established; e.g. a zonal pattern, or an anticyclonic pattern, forecasting at 10 days becomes easier, but recently, I've done less forecasting at those times, being content to let the pattern run and look for a change instead. Here, I said, on 31st Aug, that I was 75+ certain there would be a change to anticyclonic weather on 10th Sept (T240 on the 31st.) and that dry and settled weather, with above average daytime temps will affect at least England. That will be a big pattern change and will be one not seen since late-June/Early July. 7 days to go now and I haven't changed my mind. I'd be happy for you to judge it at outcome. |
High pressure and settled conditions 2nd week in September?
On Sep 3, 8:11*am, Dawlish wrote:
On Sep 2, 10:54*pm, "Ned" wrote: "Dawlish" wrote in message .... I am intrigued by your claim of making a "forecast". Are you not simply model watching, as many of us here do, and when there is agreement at 10 days up pops your forecast. To claim the MO have come round to the same way of thinking as yourself is plainly ridiculous, when you don't actually "make" a forecast, only interpret the models. Or am I missing a skill you also have? Only judge forecast accuracy by outcome percentage accuracy over time Ned. But you only "forecast" once in a blue moon,on the rare occasions when models are basically in agreement at 10 days.What you seem to be suggesting is that when they agree at 10 days out, there is a 75% chance they'll be correct. *What skill do you add to the forecast method beyond highlighting the agreement? -- Ned The MetO can't forecast with any reasonable accuracy, on a daily basis what's going to happen at 10 days. Nor can anyone else; nor can I. At present it is impossible, on a daily basis, with reasonable accuracy. Thus, when you see that 6-15 day forecast, you have no idea if it will be accurate, or how accurate the MetO thinks it is likely to be. It doesn't give you an idea of how accurate they feel it will be at 10- days plus. I wish they would and I feel it would be useful. The 6-15 dayforecast is just 120-ish words which may, or may not, be correct. There is no indication within that of how confident the forecasters are at those distances. No blame in that. It's just not possible to forecast with accuracy at that distance on a daily basis, but the MetO is under these enormous public expectations to forecast at all distances - and be correct - and the press office did it no favours by heightening those expectation with some silly soundbites to "explain" their summer forecast to the media. It fulfils the public expectation at medium ramge, but does so with a minimum of fuss and in few words in a tiny area of the site which is the 6-15 day forecast. It then ignores whatever the outcome is and never returns to it and never publishes verification figures, meaning that we have absolutely no idea whether any forecast at 10 days is accurate. That camouflages the forecasting difficulties very well and is why I joke about precis competitions in morning tea-breaks. I've developed a system where I can, on occasions (and only on occasions) forecast at 10 days, with 75%+ accuracy. Every forecast I've made with it (71) has been done in the public eye and judged by others, as well as by myself and the hrashest judge has been me; promise you. On that dataset and to that outcome accuracy, it works. The only way to apply that is to model watch at 10-days really assiduosly. I used to base it solely on consistency in gfs runs, but I've tweaked that to include a need for agreement from the ECM. That's not because I feel the gfs is the better model, it's just that the 4 runs per day, each under different peramaters renders consistency less likely, if the outcome is to be correct. Any wobbles in that and the forecast is rendered useless. I cannot forecast on a daily basis using this and the system can't be used that way. When a pattern is established; e.g. a zonal pattern, or an anticyclonic pattern, forecasting at 10 days becomes easier, but recently, I've done less forecasting at those times, being content to let the pattern run and look for a change instead. Here, I said, on 31st Aug, that I was 75+ certain there would be a change to anticyclonic weather on 10th Sept (T240 on the 31st.) and that dry and settled weather, with above average daytime temps will affect at least England. That will be a big pattern change and will be one not seen since late-June/Early July. *7 days to go now and I haven't changed my mind. I'd be happy for you to judge it at outcome.- Hide quoted text - - Show quoted text - Looking very good for a period of calm, settled weather as anticyclonic influence begins to dominate the UK's weather from the middle of next week and daytime temperatures should be warm, for many. It could well hang around too and tere's plenty of consistency and model agreement, to say that in 10 days time at T240, much of the UK will still be under the influence of high pressure. I agree with the MetO that mist and fog could be an early morning problem in a few areas, but most of us will be enjoying plenty of sunshine and warm temperatures in the daytime towards mid-month. The only hiccups to the sunshine are likely to be Atlantic fronts, dying into the high pressure and introducing cloud to some areas from time to time. Some nice weather coming up. A BBQ summer in September? *)) |
High pressure and settled conditions 2nd week in September?
On Thu, 3 Sep 2009 at 23:49:42, Dawlish wrote in
uk.sci.weather : Looking very good for a period of calm, settled weather as anticyclonic influence begins to dominate the UK's weather from the middle of next week and daytime temperatures should be warm, for many. At least it shouldn't be the stifling heat of mid-summer, and the rapidly lengthening nights may get on the cool side. -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) |
High pressure and settled conditions 2nd week in September?
On Sep 4, 5:32*pm, Paul Hyett wrote:
On Thu, 3 Sep 2009 at 23:49:42, Dawlish wrote in uk.sci.weather : At least it shouldn't be the stifling heat of mid-summer, and the rapidly lengthening nights may get on the cool side. -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) True Paul. I've deliberately referred to daytime temperatures all along. The nights are likely to be fairly cool if the skies stay clear. Mind you, I'm not sure you can describe the average British summer as containing "stifling heat" very often! Maybe on occasions in an average summer and in exceptional years! *)) |
High pressure and settled conditions 2nd week in September?
"Dawlish" wrote in message ... On Sep 4, 5:32 pm, Paul Hyett wrote: On Thu, 3 Sep 2009 at 23:49:42, Dawlish wrote in uk.sci.weather : At least it shouldn't be the stifling heat of mid-summer, and the rapidly lengthening nights may get on the cool side. -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) True Paul. I've deliberately referred to daytime temperatures all along. The nights are likely to be fairly cool if the skies stay clear. Mind you, I'm not sure you can describe the average British summer as containing "stifling heat" very often! Maybe on occasions in an average summer and in exceptional years! *)) ==== Paul, I think you will find that both Paul and I consider anything higher than 25C as "stifling". Thankfully on Dartmoor such days are not common, none this year thank goodness. Will -- |
High pressure and settled conditions 2nd week in September?
In article
, Dawlish writes: On Sep 4, 5:32*pm, Paul Hyett wrote: On Thu, 3 Sep 2009 at 23:49:42, Dawlish wrote in uk.sci.weather : At least it shouldn't be the stifling heat of mid-summer, and the rapidly lengthening nights may get on the cool side. True Paul. I've deliberately referred to daytime temperatures all along. The nights are likely to be fairly cool if the skies stay clear. Mind you, I'm not sure you can describe the average British summer as containing "stifling heat" very often! Maybe on occasions in an average summer and in exceptional years! *)) It all depends on how easily you are stifled. :) Some of us find hot weather far less comfortable than do others. -- John Hall "Do you have cornflakes in America?" "Well, actually, they're American." "So what brings you to Britain then if you have cornflakes already?" Bill Bryson: "Notes from a Small Island" |
High pressure and settled conditions 2nd week in September?
Dawlish wrote:
On Sep 4, 5:32 pm, Paul Hyett wrote: On Thu, 3 Sep 2009 at 23:49:42, Dawlish wrote in uk.sci.weather : At least it shouldn't be the stifling heat of mid-summer, and the rapidly lengthening nights may get on the cool side. -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) True Paul. I've deliberately referred to daytime temperatures all along. The nights are likely to be fairly cool if the skies stay clear. Mind you, I'm not sure you can describe the average British summer as containing "stifling heat" very often! Maybe on occasions in an average summer and in exceptional years! *)) I think hot September weather can occasionally be worse than earlier in the year because of the higher humidity. Sea temperatures are at their highest and the air has absorbed more moisture. -- Graham P Davis, Bracknell, Berks., UK. E-mail: newsman not newsboy "I wear the cheese. It does not wear me." |
High pressure and settled conditions 2nd week in September?
On Fri, 4 Sep 2009 at 10:18:28, Dawlish wrote in
uk.sci.weather : At least it shouldn't be the stifling heat of mid-summer, and the rapidly lengthening nights may get on the cool side. True Paul. I've deliberately referred to daytime temperatures all along. The nights are likely to be fairly cool if the skies stay clear. Mind you, I'm not sure you can describe the average British summer as containing "stifling heat" very often! Maybe on occasions in an average summer and in exceptional years! *)) Depends on your tolerance for muggy nights - anything above the low 20's at night in my bedroom, and I find sleep very difficult. -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) |
High pressure and settled conditions 2nd week in September?
On Sep 5, 10:31*am, Paul Hyett wrote:
On Fri, 4 Sep 2009 at 10:18:28, Dawlish wrote in uk.sci.weather : At least it shouldn't be the stifling heat of mid-summer, and the rapidly lengthening nights may get on the cool side. True Paul. I've deliberately referred to daytime temperatures all along. The nights are likely to be fairly cool if the skies stay clear. Mind you, I'm not sure you can describe the average British summer as containing "stifling heat" very often! Maybe on occasions in an average summer and in exceptional years! *)) Depends on your tolerance for muggy nights - anything above the low 20's at night in my bedroom, and I find sleep very difficult. -- Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me) The change to settled weather next week is likely to be pretty stunning. After the strength of the winds on Tuesday, especially in NW Scotland, where the gales could be severe, but also further south too, the change in the weather and the charts that is forecast for 48 hours later is nothing short of incredible. |
High pressure and settled conditions 2nd week in September?
SNIP
The change to settled weather next week is likely to be pretty stunning. After the strength of the winds on Tuesday, especially in NW Scotland, where the gales could be severe, but also further south too, the change in the weather and the charts that is forecast for 48 hours later is nothing short of incredible It's this rapid change, if it comes off, which could give some superb surfing conditions in Cornwall on Wednesday. Magic Seaweed now shows the potential for a 10' & clean swell Wednesday afternoon. I'm sure there are many keeping an eye on this, and planning a morning belting down the M5. Graham Penzance |
High pressure and settled conditions 2nd week in September?
On Sep 5, 8:31*pm, Graham Easterling
wrote: SNIP The change to settled weather next week is likely to be pretty stunning. After the strength of the winds on Tuesday, especially in NW Scotland, where the gales could be severe, but also further south too, the change in the weather and the charts that is forecast for 48 hours later is nothing short of incredible It's this rapid change, if it comes off, which could give some superb surfing conditions in Cornwall on Wednesday. Magic Seaweed now shows the potential for a 10' & clean swell Wednesday afternoon. I'm sure there are many keeping an eye on this, and planning a morning belting down the M5. Graham Penzance Hadn't thought of that, but sunshine and surf would be a terrific combination! |
High pressure and settled conditions 2nd week in September?
"Graham Easterling" wrote in message ... SNIP The change to settled weather next week is likely to be pretty stunning. After the strength of the winds on Tuesday, especially in NW Scotland, where the gales could be severe, but also further south too, the change in the weather and the charts that is forecast for 48 hours later is nothing short of incredible It's this rapid change, if it comes off, which could give some superb surfing conditions in Cornwall on Wednesday. Magic Seaweed now shows the potential for a 10' & clean swell Wednesday afternoon. I'm sure there are many keeping an eye on this, and planning a morning belting down the M5. England play Croatia on Weds. Pubs could be busy after the surfin safari :-) Will -- |
High pressure and settled conditions 2nd week in September?
On Sep 5, 8:51*pm, "Will Hand" wrote:
"Graham Easterling" wrote in message ... SNIP The change to settled weather next week is likely to be pretty stunning. After the strength of the winds on Tuesday, especially in NW Scotland, where the gales could be severe, but also further south too, the change in the weather and the charts that is forecast for 48 hours later is nothing short of incredible It's this rapid change, if it comes off, which could give some superb surfing conditions in Cornwall on Wednesday. Magic Seaweed now shows the potential for a 10' & clean swell Wednesday afternoon. I'm sure there are many keeping an eye on this, and planning a morning belting down the M5. England play Croatia on Weds. Pubs could be busy after the surfin safari :-) Will -- Looks as if it will be settled and dry at Wemberley on Wednesday. It will establish itself quickly and will be domination our weather by Thursday 10th and my forecast for then looks good. I'm looking for the change now (not that I want a change!). There's not enough consistency on the gfs to forecast that the UK, or even England will be under an anticyclone in 10 days time, but the ECM says otherwise and the high could hang around longer. |
High pressure and settled conditions 2nd week in September?
On Aug 31, 9:19*am, Dawlish wrote:
On Aug 30, 9:58*am, Nick wrote: There's enough consistency in the gfs and enough agreement with the ECM, for me to forecast, with 75% confidence, dry and settled conditions over the south of the UK in 10 days time, at T240. Temps will be above the September daytime average. The NW won't be faring as well and will be plagued by fronts, giving much more unsettled conditions. You've just got to ask yourself; "Why couldn't this have happened in July/August"! However I'll take this in September too. Just my kind of weather. Dry settled and warm in the daytime sunshine. The gfs spotted this pattern change first and the ECM followed soon after. The consistency the gfs showed about the change and the agreement from the ECM prompted the forecast and it was a good one. There are some fronts around the NW limb of the high and there is some light rain over the far NW of Scotland, but the rest of the country should enjoy a fine and a dry day, after some early mist and fog in a few areas. There's NE flow across the South producing breezy weather and Will did correctly mention that would happen, but the overall picture is dry and settled. Overall, that's 72 forecasts at 10 days and 54 correct; an outcome percentage success rate of 76%. The fine weather should last for a while too, as I've implied with my similar forecast for 3 days time, but a change may be a-coming for 10 days time - the ECM is leading that possibility but the gfs has not shown enough consistency yet; some runs having dallied with a continuance of the anticyclonic weather whilst others have shown a return to Atlantic weather over the last 48 hours. Another couple of gfs runs showing windy and wet weather at T240 and I'd be convinced this blocking pattern won't last to the end of the third week of September. Time to enjoy some quintessential Autumnal weather. 8)) |
High pressure and settled conditions 2nd week in September?
On Sep 10, 7:50*am, Dawlish wrote:
On Aug 31, 9:19*am, Dawlish wrote: On Aug 30, 9:58*am, Nick wrote: Overall, that's 72 forecasts at 10 days and 54 correct; an outcome percentage success rate of 76%. Sorry guys and gals, that's a mistake. I'd not added on this one! 55/72 and 76%. |
High pressure and settled conditions 2nd week in September?
On 10 Sep, 08:17, Dawlish wrote:
On Sep 10, 7:50*am, Dawlish wrote: On Aug 31, 9:19*am, Dawlish wrote: On Aug 30, 9:58*am, Nick wrote: Overall, that's 72 forecasts at 10 days and 54 correct; an outcome percentage success rate of 76%. Sorry guys and gals, that's a mistake. I'd not added on this one! 55/72 and 76%. Interesting - is this 55 times out of 72 consecutive days' forecasts? Richard |
High pressure and settled conditions 2nd week in September?
On Sep 10, 9:38*am, Richard Dixon wrote:
On 10 Sep, 08:17, Dawlish wrote: On Sep 10, 7:50*am, Dawlish wrote: On Aug 31, 9:19*am, Dawlish wrote: On Aug 30, 9:58*am, Nick wrote: Overall, that's 72 forecasts at 10 days and 54 correct; an outcome percentage success rate of 76%. Sorry guys and gals, that's a mistake. I'd not added on this one! 55/72 and 76%. Interesting - is this 55 times out of 72 consecutive days' forecasts? Richard No Richard. The technique does not allow that and never has. If it did, it would point to significant and consistent model accuracy at 10 days and we'd have consistently accurate forecasts from the MetO at 10 days and we don't. |
High pressure and settled conditions 2nd week in September?
On 10 Sep, 10:28, Dawlish wrote:
No Richard. The technique does not allow that and never has. If it did, it would point to significant and consistent model accuracy at 10 days and we'd have consistently accurate forecasts from the MetO at 10 days and we don't. Ahh right. Interesting, but doesn't this mean you're just picking and choosing when you make a forecast? A bit like betting on the favourite of a horse race when the odds are less than evens? Yes, I'm playing devil's advocate here !! Richard |
High pressure and settled conditions 2nd week in September?
On Sep 10, 11:02*am, Richard Dixon wrote:
On 10 Sep, 10:28, Dawlish wrote: No Richard. The technique does not allow that and never has. If it did, it would point to significant and consistent model accuracy at 10 days and we'd have consistently accurate forecasts from the MetO at 10 days and we don't. Ahh right. Interesting, but doesn't this mean you're just picking and choosing when you make a forecast? A bit like betting on the favourite of a horse race when the odds are less than evens? Yes, I'm playing devil's advocate here !! Richard No. I'm determining when a forecast is 75% likely to achieve outcome at 10 days. Most times, it most certainly isn't; as I'm sure you and any other forecasters would agree. Will did say that forecasting anticyclones at this time of year is not easy and the chances of this one developing (at 10 days out, back on Aug 31st) were no better than 50%. I didn't think that, or I wouldn't have forecast. This was one of those instances where it was possible to have forecast this accurately, from 10 days out. I don't mind you playing devil's advocate. Anyone who issues any kind of forecast should be prepared to defend both the accuracy and the methodology. I note you aren't doubting the accuracy! *)) If you follow the earlier posts on this thread, then back on Aug 31st., the MetO were not clearly forecasting the development of such a dominant high pressure having developed by today. So how could I have done it? I don't have access to any tools not available to the MetO. |
High pressure and settled conditions 2nd week in September?
In article bfcb244c-b717-4ea1-bd53-
, says... If you follow the earlier posts on this thread, then back on Aug 31st., the MetO were not clearly forecasting the development of such a dominant high pressure having developed by today. So how could I have done it? I don't have access to any tools not available to the MetO. What did the MetO predict? -- Alan LeHun |
High pressure and settled conditions 2nd week in September?
On Sep 10, 2:08*pm, Alan LeHun wrote:
In article bfcb244c-b717-4ea1-bd53- , says... If you follow the earlier posts on this thread, then back on Aug 31st., the MetO were not clearly forecasting the development of such a dominant high pressure having developed by today. So how could I have done it? I don't have access to any tools not available to the MetO. What did the MetO predict? -- Alan LeHun Post back on Aug 31st Alan. |
High pressure and settled conditions 2nd week in September?
On 10 Sep, 12:50, Dawlish wrote:
If you follow the earlier posts on this thread, then back on Aug 31st., the MetO were not clearly forecasting the development of such a dominant high pressure having developed by today. So how could I have done it? I don't have access to any tools not available to the MetO. I don't know how you did it. I just hope unlike the Piers Corbyns and Jon Wittys (posted on here many moons ago) of this world you'd be open enough to publish the methodology, or further than that, work with the MO to improve things unlike Piers was prepared to do. Getting the work peer-reviewed in a scientific journal is a good starting point. In terms of a 10-day forecast, it could have been that the Met Office had access to other forecast tools that you don't have - the ECMWF ensembles, the Arpege forecasts from France, Deutsche Wetterdienst etc. that could easily have displayed a bias against an anticyclone forming. In that sense, having the extra information could be distracting to the forecast. I don't know, I don't work there ! Richard |
High pressure and settled conditions 2nd week in September?
On Sep 10, 2:39*pm, Richard Dixon wrote:
On 10 Sep, 12:50, Dawlish wrote: If you follow the earlier posts on this thread, then back on Aug 31st., the MetO were not clearly forecasting the development of such a dominant high pressure having developed by today. So how could I have done it? I don't have access to any tools not available to the MetO. I don't know how you did it. I just hope unlike the Piers Corbyns and Jon Wittys (posted on here many moons ago) of this world you'd be open enough to publish the methodology, or further than that, work with the MO to improve things unlike Piers was prepared to do. Getting the work peer-reviewed in a scientific journal is a good starting point. In terms of a 10-day forecast, it could have been that the Met Office had access to other forecast tools that you don't have - the ECMWF ensembles, the Arpege forecasts from France, Deutsche Wetterdienst etc. that could easily have displayed a bias against an anticyclone forming. In that sense, having the extra information could be distracting to the forecast. I don't know, I don't work there ! Richard Unlike dear Piers, I've always been completely open about my methodology and it is simple. If I see 5 consecutive runs of the gfs showing a very similar set up (consistency) and if the ECM agrees with what the gfs is showing, there is a 75% likelihood of an event occurring. Without either of those two criteria being reached, I would not forecast. In doing what I have done, I know that the knack is knowing when NOT to forecast. Try it; simple methodology, pretty accurate outcomes. Then it just takes a nerdy kind of nature to watch almost every single gfs and ECM run for nearly 4 years to test it over time and a very thick skin to deal with the criticism when a forecast goes very wrong from the same people that wouldn't dream of giving praise when a forecast turns out correct. I can assure you that Internet vultures are a far more discerning panel of judges than any peer-reviewed journal!! Their silence is approbation enough. *)) |
High pressure and settled conditions 2nd week in September?
On 10 Sep, 16:53, Dawlish wrote:
Unlike dear Piers, I've always been completely open about my methodology and it is simple. Well fair play. If I see 5 consecutive runs of the gfs showing a very similar set up (consistency) and if the ECM agrees with what the gfs is showing, there is a 75% likelihood of an event occurring. Without either of those two criteria being reached, I would not forecast. In doing what I have done, I know that the knack is knowing when NOT to forecast. Is this specific weather types - i.e. a cold easterly or a high pressure or does this include very short-wave features? Have you had any luck prediction, for example, a day with a severe gale 10 days ahead? It would be interesting to see what sort of weather type the 75% of the successes are, and what weather types the 25% of failures are and whether the two populations are specifically different. Now I'm assuming that Hurricane Bill in the mid-Atlantic was classed as a failure? The GFS and the EC had a tight-cored low for several runs and that didn't come off in the end. Try it; simple methodology, pretty accurate outcomes. Then it just takes a nerdy kind of nature to watch almost every single gfs and ECM run for nearly 4 years to test it over time and a very thick skin to deal with the criticism when a forecast goes very wrong from the same people that wouldn't dream of giving praise when a forecast turns out correct. That should only really happen if you crow too much when it is right (see P. Corbyn, 1990-2009) and people want to put you in your place! If I had the chance to change your method I'd be looking for ECMWF first and then GFS second (third...fourth?) ! I can assure you that Internet vultures are a far more discerning panel of judges than any peer-reviewed journal!! Their silence is approbation enough. Judges should be fair unless you've upset them !! Richard |
High pressure and settled conditions 2nd week in September?
On Sep 10, 5:07*pm, Richard Dixon wrote:
On 10 Sep, 16:53, Dawlish wrote: Unlike dear Piers, I've always been completely open about my methodology and it is simple. Well fair play. If I see 5 consecutive runs of the gfs showing a very similar set up (consistency) and if the ECM agrees with what the gfs is showing, there is a 75% likelihood of an event occurring. Without either of those two criteria being reached, I would not forecast. In doing what I have done, I know that the knack is knowing when NOT to forecast. Is this specific weather types - i.e. a cold easterly or a high pressure or does this include very short-wave features? Have you had any luck prediction, for example, a day with a severe gale 10 days ahead? It would be interesting to see what sort of weather type the 75% of the successes are, and what weather types the 25% of failures are and whether the two populations are specifically different. Now I'm assuming that Hurricane Bill in the mid-Atlantic was classed as a failure? The GFS and the EC had a tight-cored low for several runs and that didn't come off in the end. Try it; simple methodology, pretty accurate outcomes. Then it just takes a nerdy kind of nature to watch almost every single gfs and ECM run for nearly 4 years to test it over time and a very thick skin to deal with the criticism when a forecast goes very wrong from the same people that wouldn't dream of giving praise when a forecast turns out correct. That should only really happen if you crow too much when it is right (see P. Corbyn, 1990-2009) and people want to put you in your place! If I had the chance to change your method I'd be looking for ECMWF first and then GFS second (third...fourth?) ! I can assure you that Internet vultures are a far more discerning panel of judges than any peer-reviewed journal!! Their silence is approbation enough. Judges should be fair unless you've upset them !! Richard Heh! LOL! I didn't forecast anything about ex-Hurricane Bill. There was nothing like enough agreement at 10 days - remember Bill was still tropical 10 days before and its path was by no means predictable, though the models did a fair job at that range, with a hurricane whose movements are often notoriously difficult to predict, even at 24-72 hours. The last time I issued a 10 day forecast using this methodology was on the 6th June for the 16th, saying that high pressure would be in charge. It was wrong. Over the summer, there have been no occasions that I have seen where agreement and consistency have occurred, Hence; no forecasts - mind you, like I said, I've been mainly looking for changes of pattern and what changes there have been came under my 10- day radar and were not showing at T240. |
High pressure and settled conditions 2nd week in September?
On Sep 10, 7:50*am, Dawlish wrote:
The fine weather should last for a while too, as I've implied with my similar forecast for 3 days time, but a change may be a-coming for 10 days time - the ECM is leading that possibility but the gfs has not shown enough consistency yet; some runs having dallied with a continuance of the anticyclonic weather whilst others have shown a return to Atlantic weather over the last 48 hours. Another couple of gfs runs showing windy and wet weather at T240 and I'd be convinced this blocking pattern won't last to the end of the third week of September. This illustrates perfectly the difficulties of forecasting at 10 days and the need for both gfs consistency and ECM agreement for me to be able to forecast with any degree of accuracy at that distance. After writing the above, yesterday, The 00z gfs and the runs last night, have shown a continuance of the higher pressure out to T240, at least for England. The 00z ECM shows an Atlantic low stalling. What do you forecast? Well the Meto is hedging its bets, but this forecast was issued at lunch yesterday and, as usual in the morning, is a day out of date. "UK Outlook for Tuesday 15 Sep 2009 to Thursday 24 Sep 2009: Much of the country will remain dry through the middle of next week and over next weekend, but with variable amounts of cloud. Some sunny spells are likely, more especially in the southwest of England and Southwest Wales at first. The far Northwest of Scotland could see a little little rain at times, with also a small risk of showers extending into far south and southeast of England. Temperatures in all parts should be near normal, and feeling pleasant in sunshine. **Southern and Central parts should start mainly dry and fine in the longer outlook, but there is a low risk of it turning more unsettled with time. The Northwest is expected to turn more unsettled with occasional showers or rain.**" Updated: 1201 on Thu 10 Sep 2009 That's also an interesting comment in the 6-15 day forecast because that phrase gives an insight into the forecaster's thinking - more likely to continue settled over England, but a chance of it not doing so. It also reflects my thinking that an actual forecast would have less than a 75% chance of being correct. Therein lies the current problems of forecasting at 10 days. It really is very difficult. Still super weather for most. Cool nights and mornings and a scintillating September day on the south coast yesterday. Hopefully another one to come. 20C and sunshine is just marvellous weather and the September light, especially on a morning is quite superb. |
High pressure and settled conditions 2nd week in September?
On Sep 11, 8:34*am, Dawlish wrote:
Well the Meto is hedging its bets, but this forecast was issued at lunch yesterday and, as usual in the morning, is a day out of date. "UK Outlook for Tuesday 15 Sep 2009 to Thursday 24 Sep 2009: Much of the country will remain dry through the middle of next week and over next weekend, but with variable amounts of cloud. Some sunny spells are likely, more especially in the southwest of England and Southwest Wales at first. The far Northwest of Scotland could see a little little rain at times, with also a small risk of showers extending into far south and southeast of England. Temperatures in all parts should be near normal, and feeling pleasant in sunshine. **Southern and Central parts should start mainly dry and fine in the longer outlook, but there is a low risk of it turning more unsettled with time. The Northwest is expected to turn more unsettled with occasional showers or rain.**" Updated: 1201 on Thu 10 Sep 2009 That's also an interesting comment in the 6-15 day forecast because that phrase gives an insight into the forecaster's thinking - more likely to continue settled over England, but a chance of it not doing so. It also reflects my thinking that an actual forecast would have less than a 75% chance of being correct. Therein lies the current problems of forecasting at 10 days. It really is very difficult. Really very interesting.... The high pressure will still be in charge tomorrow Sunday, with a front skirting around the northern limb of the high, then slipping down the North Sea to introduce cloud into some Eastern areas - but then look at how the forecast has changed next week. A strengthening north-easterly flow in the south is likely to bring cloud (and speak it in a whisper) a little rain to the SE (!) as southern areas come under more of an influence from a large area of low pressure over the Med. It is likely to be a change which I don't think was possible to forecast with accuracy, even 6 days ago, never mind 10. On Sept 11 (see above), the MetO had "Southern and Central parts should start mainly dry and fine in the longer outlook" i.e. high pressure would still be in charge in those areas on 17th to (say) 19 Sept (at 6-8 days from the forecast date). That's now unlikely and the "low risk" of it turning unsettled with time looks like it will happen well before that 6-15-day forecast was implying, ruining any outcome accuracy for that forecast. Even at 6 days, the forecast is now much more likely to be proved incorrect, than correct. That's why I didn't forecast the high pressure dominance continuing further than Sunday, but I admit I couldn't see this change next week at 10 days. All I could see was that there was not enough model agreement for anticyclonic, settled and fine weather, continuing to be 75% likely. The actual situation in mid-week next week was one that I feel was not possible to forecast with any current capability, except by guesswork and the change came well below my 10-day radar. Out at T240, the gfs has unsettled and the ECM has higher pressure with an anticyclone again building. You pays your money and you takes your chance on that one. |
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