forecast wind at 2000/3000 feet?
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forecast wind at 2000/3000 feet?
I should know how to find this but don't. A current metar gives me
EGLF 290650Z 25005KT CAVOK 10/09 Q1021
Where do I find/how do I calculate the wind strength and direction aloft?
EGLF 290650Z 25005KT CAVOK 10/09 Q1021
Where do I find/how do I calculate the wind strength and direction aloft?
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I agree. You should primarily use metform 214 (or the European equipvalent 414) for that.
But in a pinch you can apply the principle that over land, due to surface friction, as you go down the last 1000-2000' the wind will "back" about 20-30 degrees and lose a few knots. (Northern Hemisphere of course)
So if the surface wind is 250/5 the wind at 2000 feet will be along the lines of 270/8 or something like that.
And to be honest, I think that's the sort of answer you were actually looking for, not?
But in a pinch you can apply the principle that over land, due to surface friction, as you go down the last 1000-2000' the wind will "back" about 20-30 degrees and lose a few knots. (Northern Hemisphere of course)
So if the surface wind is 250/5 the wind at 2000 feet will be along the lines of 270/8 or something like that.
And to be honest, I think that's the sort of answer you were actually looking for, not?
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I seem to remember it the other way round. Wind will veer & increase with height. Rather like unscrewing a left handed bolt. the increases were 20deg/20% per 1000ft I think.
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CrashOne, its not "the other way round" at all. BackPacker said that as you go down, the wind backs and lessens while you said that as you go up the wind veers and increases. That's the easy bit.
If you maintain the same height the wind, completely ignoring Coriolis and surface roughness, can have the temerity to change both direction AND speed
If you maintain the same height the wind, completely ignoring Coriolis and surface roughness, can have the temerity to change both direction AND speed
During daylight hours the surface wind is about two thirds of the 1000' wind due to turbulent mixing caused by heat from the sun, at night it is nearer to one third of the 1000' foot wind. As the wind increases with altitude it will tend to veer.
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Originally Posted by Suraci
CrashOne, its not "the other way round" at all. BackPacker said that as you go down, the wind backs and lessens while you said that as you go up the wind veers and increases. That's the easy bit.
If this, like a lot of other threads lately is going to develop into a bloody nitpicking grammar lesson then get on with it!!
You may also like to re-read the original question. Which amounts to: Ground speed is known, how do you look up or calculate wind speed at 2000/3000ft?
Last edited by Crash one; 29th Aug 2009 at 15:08.
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Easy really know the temp dewpoint work the cloudbase from that.
Hopefully it will be between 2000 to 3000 feet if less you shouldnt be flying.
Now visually work out the direction the clouds are going.
Time the cloud movement over a set distance and hey presto an accurate answer. We really do get into chest beating in these forums
Pace
Hopefully it will be between 2000 to 3000 feet if less you shouldnt be flying.
Now visually work out the direction the clouds are going.
Time the cloud movement over a set distance and hey presto an accurate answer. We really do get into chest beating in these forums
Pace
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Very good, Pace.
And if there's no cloud or medium to high level cloud? If you don't know the dewpoint? (which you won't if you don't have a met observer's station at your airfield). And then you guess at the lapse rate? Go get the compass out of an aircraft to check the cloud movement direction? Eyeball the speed of cloud whose altitude you've only guessed at and end up with parallax errors? Or run after a cloud to time it over a known distance?
Gordon Bennet.
I think it might me just a little easier to start from known wind on the ground, use a recognised rule of thumb (as already posted) and work out the 2000' wind from there.
And if there's no cloud or medium to high level cloud? If you don't know the dewpoint? (which you won't if you don't have a met observer's station at your airfield). And then you guess at the lapse rate? Go get the compass out of an aircraft to check the cloud movement direction? Eyeball the speed of cloud whose altitude you've only guessed at and end up with parallax errors? Or run after a cloud to time it over a known distance?
Gordon Bennet.
I think it might me just a little easier to start from known wind on the ground, use a recognised rule of thumb (as already posted) and work out the 2000' wind from there.
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Captain Stable
My addition to this thread was a joke and not really very serious just added some humour as everyone seemed to be getting their knickers in a twist
Pace
My addition to this thread was a joke and not really very serious just added some humour as everyone seemed to be getting their knickers in a twist
Pace
Avoid imitations
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What? Met forecasting, a joke? You should apply to the met office for a job, that combination seems to fit the requirements. 
Seriously though, it's best to use the F214, the theory of wind variation with altitude is a theory and doesn't always work out. The last few days I've flown, the wind structure certainly hasn't obeyed "the quoted rules".
Seriously though, it's best to use the F214, the theory of wind variation with altitude is a theory and doesn't always work out. The last few days I've flown, the wind structure certainly hasn't obeyed "the quoted rules".
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Airmets
The upper winds at 1,3 and 6 are also available in the Airmets section of the Met Office website and there is a separate airmet for the 10, 18 and 24(?) upper winds.
The actual difference between surface and upper winds varies by day, time of day and location. To really get the answer you can look at the forecast or actual tephigrams (soundings) at the URL below. Click on a sounding for e.g. Nottingham and on the right of the resulting graph is a set of arrows at each altitude showing wind strength and direction. There is also a graph in green showing the wind strength with altitude.
You will need to zoom in to see the detail. Put the mouse pointer over the tephigram and the mouse wheel will zoom the graph in/out. Hold the left mouse button down to move the graph around so you can see what you want.
The best approximation is my earlier post - daytime surface wind is 2/3rds upper wind and at night 1/3rd.
Have fun!
RASPtable
You will need to zoom in to see the detail. Put the mouse pointer over the tephigram and the mouse wheel will zoom the graph in/out. Hold the left mouse button down to move the graph around so you can see what you want.
The best approximation is my earlier post - daytime surface wind is 2/3rds upper wind and at night 1/3rd.
Have fun!
RASPtable
