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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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#11
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On Nov 14, 1:42*pm, Neo wrote:
On Nov 14, 12:19*pm, Dave Cornwell wrote: Neo wrote: * A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. ------------------- Winter? ;-) No, positioning of upper air features/jet trajectories, changes in stability, cloud distribution, proximity/arrival of drier air, modifying of slow moving air, origins of air masses.....of course winter makes it cooler, but with respect to average winter temperatures, air cools differently if it has a strong SSW Tropical origin than it would with a slow or moderate Polar or Polar Continental origin. Go and read basic meteorology texts about airmass theory and modification of airmasses in different seasons. Then read up about upper air theory and the broad scale distribution and propagation of jet streams and upper atmospheric thermodynamics. It is all very interesting, we are talking real weather here, not climate. Neo ---------------------------------------------------------------------------------------------------- It is all about the total (substantial) derivative in the model equations. Total cooling = that advected + the in situ cooling. The advected cooling is the dominant term. It's chilly up north. Cloudiness is rather important. Solar warming is small in winter, but longwave cooling at the surface important for land surface temps. Models are not especially good with the cloud radiative properties having to cope with horizontal inhomogeneity, multiple layers, cloud overlap... One could say that it's the flipping clouds that make the models flip. :-) Len Wood Wembury, SW Devon, 83m asl |
#12
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On Nov 14, 1:42*pm, Neo wrote:
On Nov 14, 12:19*pm, Dave Cornwell wrote: Neo wrote: * A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. ------------------- Winter? ;-) No, positioning of upper air features/jet trajectories, changes in stability, cloud distribution, proximity/arrival of drier air, modifying of slow moving air, origins of air masses.....of course winter makes it cooler, but with respect to average winter temperatures, air cools differently if it has a strong SSW Tropical origin than it would with a slow or moderate Polar or Polar Continental origin. Go and read basic meteorology texts about airmass theory and modification of airmasses in different seasons. Then read up about upper air theory and the broad scale distribution and propagation of jet streams and upper atmospheric thermodynamics. It is all very interesting, we are talking real weather here, not climate. Neo Nothing showing yet...... |
#13
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On 14/11/11 21:05, Dawlish wrote:
On Nov 14, 1:42 pm, wrote: On Nov 14, 12:19 pm, Dave wrote: Neo wrote: A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. ------------------- Winter? ;-) No, positioning of upper air features/jet trajectories, changes in stability, cloud distribution, proximity/arrival of drier air, modifying of slow moving air, origins of air masses.....of course winter makes it cooler, but with respect to average winter temperatures, air cools differently if it has a strong SSW Tropical origin than it would with a slow or moderate Polar or Polar Continental origin. Go and read basic meteorology texts about airmass theory and modification of airmasses in different seasons. Then read up about upper air theory and the broad scale distribution and propagation of jet streams and upper atmospheric thermodynamics. It is all very interesting, we are talking real weather here, not climate. Neo Nothing showing yet...... I will be interested to see just how long this mild weather continues for, the temperatures are bound to drop significantly at some point, aren't they? I'm hoping when they do, it will put an end to the ongoing caterpillar infestation on my brocolli. |
#14
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On Nov 14, 11:42*pm, Adam Lea wrote:
On 14/11/11 21:05, Dawlish wrote: On Nov 14, 1:42 pm, *wrote: On Nov 14, 12:19 pm, Dave *wrote: Neo wrote: * *A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. ------------------- Winter? ;-) No, positioning of upper air features/jet trajectories, changes in stability, cloud distribution, proximity/arrival of drier air, modifying of slow moving air, origins of air masses.....of course winter makes it cooler, but with respect to average winter temperatures, air cools differently if it has a strong SSW Tropical origin than it would with a slow or moderate Polar or Polar Continental origin. Go and read basic meteorology texts about airmass theory and modification of airmasses in different seasons. Then read up about upper air theory and the broad scale distribution and propagation of jet streams and upper atmospheric thermodynamics. It is all very interesting, we are talking real weather here, not climate. Neo Nothing showing yet...... I will be interested to see just how long this mild weather continues for, the temperatures are bound to drop significantly at some point, aren't they? I'm hoping when they do, it will put an end to the ongoing caterpillar infestation on my brocolli.- Hide quoted text - - Show quoted text - Certain to. They are at close to record levels for Nov. That could explain why now is a good time to forecast UK cooling to start, because of whichever factor one decides is the reason, apart from the fact that winter is coming and emperatures won't stay as high as they have been! PS You're still harvesting Broccoli Adam? |
#15
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On 15/11/11 06:53, Dawlish wrote:
On Nov 14, 11:42 pm, Adam wrote: On 14/11/11 21:05, Dawlish wrote: On Nov 14, 1:42 pm, wrote: On Nov 14, 12:19 pm, Dave wrote: Neo wrote: A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. ------------------- Winter? ;-) No, positioning of upper air features/jet trajectories, changes in stability, cloud distribution, proximity/arrival of drier air, modifying of slow moving air, origins of air masses.....of course winter makes it cooler, but with respect to average winter temperatures, air cools differently if it has a strong SSW Tropical origin than it would with a slow or moderate Polar or Polar Continental origin. Go and read basic meteorology texts about airmass theory and modification of airmasses in different seasons. Then read up about upper air theory and the broad scale distribution and propagation of jet streams and upper atmospheric thermodynamics. It is all very interesting, we are talking real weather here, not climate. Neo Nothing showing yet...... I will be interested to see just how long this mild weather continues for, the temperatures are bound to drop significantly at some point, aren't they? I'm hoping when they do, it will put an end to the ongoing caterpillar infestation on my brocolli.- Hide quoted text - - Show quoted text - Certain to. They are at close to record levels for Nov. That could explain why now is a good time to forecast UK cooling to start, because of whichever factor one decides is the reason, apart from the fact that winter is coming and emperatures won't stay as high as they have been! PS You're still harvesting Broccoli Adam? I started growing Broccoli this year so it has been producing copious amounts of leaves this season but no florets. I have been informed that they will produce a crop next year, however it is more a case of whether they will survive that long, as some of them look like a plague of locusts has gone through. rant Every single time I try to grow my own food it either gets destroyed by unusual weather conditions or a major pest infestation. /rant |
#16
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On Nov 13, 4:20*pm, Neo wrote:
Keep an eye on them. The intrinsic probabilistic data have recently shown signs of being flipped from the current solution (ie not cold), just as they were tilted towards a milder outlook a few days ago...Now thay are looking as if they could re-flip in the 6 to 15 day period outlook. A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. The models are such that this sort of situation becomes mathematically unstable with just the slightest change to just 1 or 2 aspects of the variable dataset. The deterministic output will consequently flip-flop for a while (ie now), before the true scope of the forecast becomes clearer mathematically (more constant model output/outcomes). This time span seems to be in the next 6 to 15 day period. Neo I kept an eye on them. Nothing extra-specially cold 3 days on, Neo; just the possibility of the high pressure that looked like it might settle to our S/SE, now looking like it may settle over the UK. Just looks like a slow and steady descent into early winter, with a little cooler temperatures, but with them staying pretty average really and the possibility of some frog and fost if the skies clear. 8)) See if the model agreement about the position of the high pressure lasts to tonight. |
#17
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On Nov 16, 8:30*am, Dawlish wrote:
On Nov 13, 4:20*pm, Neo wrote: Keep an eye on them. The intrinsic probabilistic data have recently shown signs of being flipped from the current solution (ie not cold), just as they were tilted towards a milder outlook a few days ago...Now thay are looking as if they could re-flip in the 6 to 15 day period outlook. A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. The models are such that this sort of situation becomes mathematically unstable with just the slightest change to just 1 or 2 aspects of the variable dataset. The deterministic output will consequently flip-flop for a while (ie now), before the true scope of the forecast becomes clearer mathematically (more constant model output/outcomes). This time span seems to be in the next 6 to 15 day period. Neo I kept an eye on them. Nothing extra-specially cold 3 days on, Neo; just the possibility of the high pressure that looked like it might settle to our S/SE, now looking like it may settle over the UK. Just looks like a slow and steady descent into early winter, with a little cooler temperatures, but with them staying pretty average really and the possibility of some frog and fost if the skies clear. 8)) See if the model agreement about the position of the high pressure lasts to tonight. Just as an addition to the last comment; neither the gfs 00z. nor the ECM 12z from yesterday back the establishment of a static high pressure over the UK at 10 days and we may well see the models change back to a more zonal outlook during today. There's nothing particularly cold about the ensemble means of either model. |
#18
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On Nov 16, 8:37*am, Dawlish wrote:
On Nov 16, 8:30*am, Dawlish wrote: On Nov 13, 4:20*pm, Neo wrote: Keep an eye on them. The intrinsic probabilistic data have recently shown signs of being flipped from the current solution (ie not cold), just as they were tilted towards a milder outlook a few days ago...Now thay are looking as if they could re-flip in the 6 to 15 day period outlook. A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. The models are such that this sort of situation becomes mathematically unstable with just the slightest change to just 1 or 2 aspects of the variable dataset. The deterministic output will consequently flip-flop for a while (ie now), before the true scope of the forecast becomes clearer mathematically (more constant model output/outcomes). This time span seems to be in the next 6 to 15 day period. Neo I kept an eye on them. Nothing extra-specially cold 3 days on, Neo; just the possibility of the high pressure that looked like it might settle to our S/SE, now looking like it may settle over the UK. Just looks like a slow and steady descent into early winter, with a little cooler temperatures, but with them staying pretty average really and the possibility of some frog and fost if the skies clear. 8)) See if the model agreement about the position of the high pressure lasts to tonight. Just as an addition to the last comment; neither the gfs 00z. nor the ECM 12z from yesterday back the establishment of a static high pressure over the UK at 10 days and we may well see the models change back to a more zonal outlook during today. There's nothing particularly cold about the ensemble means of either model.- Hide quoted text - - Show quoted text - And, as if on cue, the 06z does exactly that and the operational shows up as a big spikey, dry outlier! The jet is forcast to lie to the north of the UK at 10 days and not to the south. http://www.wetterzentrale.de/pics/Rtavn24014.png I don't see anything in the mnodel output that suggests a major change to below average temperature conditions - yet. Neo? |
#19
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On Nov 16, 8:37*am, Dawlish wrote:
On Nov 16, 8:30*am, Dawlish wrote: On Nov 13, 4:20*pm, Neo wrote: Keep an eye on them. The intrinsic probabilistic data have recently shown signs of being flipped from the current solution (ie not cold), just as they were tilted towards a milder outlook a few days ago...Now thay are looking as if they could re-flip in the 6 to 15 day period outlook. A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. The models are such that this sort of situation becomes mathematically unstable with just the slightest change to just 1 or 2 aspects of the variable dataset. The deterministic output will consequently flip-flop for a while (ie now), before the true scope of the forecast becomes clearer mathematically (more constant model output/outcomes). This time span seems to be in the next 6 to 15 day period. Neo I kept an eye on them. Nothing extra-specially cold 3 days on, Neo; just the possibility of the high pressure that looked like it might settle to our S/SE, now looking like it may settle over the UK. Just looks like a slow and steady descent into early winter, with a little cooler temperatures, but with them staying pretty average really and the possibility of some frog and fost if the skies clear. 8)) See if the model agreement about the position of the high pressure lasts to tonight. Just as an addition to the last comment; neither the gfs 00z. nor the ECM 12z from yesterday back the establishment of a static high pressure over the UK at 10 days and we may well see the models change back to a more zonal outlook during today. There's nothing particularly cold about the ensemble means of either model. Hi Dawlish, What is your source of the interpreted information? Or do you derive that from looking at some of the publicly available output? Do you work at a large glass building in Devon, hence your screen name? Something I have seen in the model outputs (Might have been be an outlier a few days ago, but a few more than one now suggest this) suggests something changing on or around the end of Nov/early Dec. It suggests a cold NNW incursion as low pressure/cold front sinks SE from a temporary mobile W scenario. This followed by rising pressure across the far N of the UK, giving some N, then NE winds. The high then becomes slow moving just to the N of the UK, and may even link with the high over towards Finland eventually. The info would suggest normal temps just ahead of this event, with any rainfall reverting to snow on scottish mountains, followed by a cold regime, especially for the N and E of the UK. Low pressure begins to affect the Med area/S Europe, with unsettled conditions for many down there. Looks like maybe we will see the changes take effect as December draws in. Can't be any worse that last year, whatever happens. I also wonder if the upper atmospheric cooling might be behind some models hinting at this...as not all models incorporate anything too much above the Jet levels in their longer term variables...it is still early days in that area of research even now, Just a thought. Cheers Neo |
#20
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On Nov 16, 1:01*pm, Neo wrote:
On Nov 16, 8:37*am, Dawlish wrote: On Nov 16, 8:30*am, Dawlish wrote: On Nov 13, 4:20*pm, Neo wrote: Keep an eye on them. The intrinsic probabilistic data have recently shown signs of being flipped from the current solution (ie not cold), just as they were tilted towards a milder outlook a few days ago...Now thay are looking as if they could re-flip in the 6 to 15 day period outlook. A few things are coming together now that will seem to aid the cooling process in W Europe over the coming days/weeks. The models are such that this sort of situation becomes mathematically unstable with just the slightest change to just 1 or 2 aspects of the variable dataset. The deterministic output will consequently flip-flop for a while (ie now), before the true scope of the forecast becomes clearer mathematically (more constant model output/outcomes). This time span seems to be in the next 6 to 15 day period. Neo I kept an eye on them. Nothing extra-specially cold 3 days on, Neo; just the possibility of the high pressure that looked like it might settle to our S/SE, now looking like it may settle over the UK. Just looks like a slow and steady descent into early winter, with a little cooler temperatures, but with them staying pretty average really and the possibility of some frog and fost if the skies clear. 8)) See if the model agreement about the position of the high pressure lasts to tonight. Just as an addition to the last comment; neither the gfs 00z. nor the ECM 12z from yesterday back the establishment of a static high pressure over the UK at 10 days and we may well see the models change back to a more zonal outlook during today. There's nothing particularly cold about the ensemble means of either model. Hi Dawlish, What is your source of the interpreted information? Or do you derive that from looking at some of the publicly available output? Do you work at a large glass building in Devon, hence your screen name? Something I have seen in the model outputs (Might have been be an outlier a few days ago, but a few more than one now suggest this) suggests something changing on or around the end of Nov/early Dec. It suggests a cold NNW incursion as low pressure/cold front sinks SE from a temporary mobile W scenario. This followed by rising pressure across the far N of the UK, giving some N, then NE winds. The high then becomes slow moving just to the N of the UK, and may even link with the high over towards Finland eventually. The info would suggest normal temps just ahead of this event, with any rainfall reverting to snow on scottish mountains, followed by a cold regime, especially for the N and E of the UK. Low pressure begins to affect the Med area/S Europe, with unsettled conditions for many down there. Looks like maybe we will see the changes take effect as December draws in. Can't be any worse that last year, whatever happens. I also wonder if the upper atmospheric cooling might be behind some models hinting at this...as not all models incorporate anything too much above the Jet levels in their longer term variables...it is still early days in that area of research even now, Just a thought. Cheers Neo- Hide quoted text - - Show quoted text - I agree the models could always change. Indeed, at 2 weeks, the odds are they probably will. Nothing showing at present however, that I can see and it certainly didn't change in yout initial 3/4 day suggested period. I see you are now suggesting the end of November. Are you trying to look in the 10-16 day period here on the gfs, or do have access to some non-publically avainlable data. If so. What is it? There appears to be nothing unusual happening in the stratosphere. http://wekuw.met.fu-berlin.de/~Aktue...w/wdiag/ts.php Recent research suggests that SSW events may influence NH weather. I'm not aware of reearch that shows that stratospheric cooling causes any changes at surface levels, but I'd be interested to see a link. |
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