Average wind speeds

I'd imagine that model would be of limited usefulness for a feature such as the Dart valley, particularly in conditions where the valley is tending to funnel the wind.

"There is no allowance for the effect of local thermally driven winds such as sea breezes or mountain/valley breezes.The model was applied with 1km square resolution and takes no account of topography on a small scale "
 
macd said:
I'd imagine that model would be of limited usefulness for a feature such as the Dart valley, particularly in conditions where the valley is tending to funnel the wind.

"There is no allowance for the effect of local thermally driven winds such as sea breezes or mountain/valley breezes.The model was applied with 1km square resolution and takes no account of topography on a small scale "
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Point taken - but bear in mind that the OP asked for average speeds. Whilst these will of course reflect local topography to some degree, averaging may also hide the sort of local variation you describe. If he needs more local detail, he could perhaps contact Plymouth University or the Brixham Environmental Laboratory to see if they know of any more local measurements or modelling?
 
macd said:
The average of erroneous speeds which fail to take account of micro conditions is...well, erroneous. His best hope, as you suggest, is probably a local data gatherer. There must be one or two fixed anemometers in the Dart valley.
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I'm not sure I'd use "erroneous" in this context, though I quite agree that a model's estimates may not be suitable for a specific requirement (which in this case we don't know). Yes, one might hope so - and even if not, PU or BEL (or the local EA) might know of temporary ones or local models (e.g. for research or an EIA).
 
I think I'd want to know the Standard Deviation as well as the mean. Then you can get an idea of how much of the time the windspeed is substantially different from the average, which might be more useful. Basically, the wind-speed will be the mean plus or minus one standard deviation about 65% of the time, the mean plus or minus two standard deviations 95% of the time and the mean plus or minus three standard deviations 99% of the time (percentages approximate and from memory, but they're about right). But note that for 1% of the time the wind-speed will be even more extreme - that's three days a year (on average!)

There are other things that affect the nature of the measurement; the integrating period of the measuring instrument, local effects and so on.

In the UK, "average" meteorological values are not really of much use, as the weather is so variable and subject to local effects.

Of course, places like Mawson in Antarctica have very reliable "average" windspeeds - gale-force or above for most of the year!
 
KellysEye said:
Bear in mind the gusts can be up to 40% higher than the average wind speed.
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There's nothing in atmospheric dynamics that imposes such a limit: it's merely a typical figure which one often encounters attached to forecasts of one kind or another. There's no intrinsic reason gusts can't be 100% or more higher than the forecast mean strength, although this is obviously a relative rarity.
 
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