After checking weather station readings serveral times against GPS on site today, it appears to be reading about 20 degrees further East than what is actually occurring.
I may be wrong, but it would seem a bit silly to have the weather station set to magnetic north, as you point out this changes over time.
It seems more logical to set it to True North as this doesn't change and is what GPS and paper maps use as datum.
20 degrees is roughly one point of the compass (22.5), ie. SSE instead of S or SSW instead of S.
Now did Les mean that when the wind is actually S the station is reporting it as SSE, it has its N set East of Datum North, or did he mean when the wind is actually S the station is reporting it as SSW, and has its N set West of Datum.
If it is the first, that means if Daron waits for a SW it is actually going to be coming from WSW. The latter case would mean Daron would find a SSW.
According to the site guide, yes. Purely from looking at Google Earth, I've always assumed that SSW was straight on at Moirs and S or SW was OK. Works for me, YMMV.
I would have thought that a S was better for XC, more island in that direction, no?
Just kidding. If SE wasn't such a crappy direction at Moirs it would be ideal as you travel along the landmass. I regulalry fly there on SW and W as my inlaws have a house at Snells beach and land in front. Recently flew there on a WNW and landed at Wenderholm.
Submitted by Dave Austin on Tue, 30/03/2010 - 20:07.
At the moment the weather station is reading east of actual wind direction. (that's the wind direction as you might see on a forecast chart, not magnetic) The tip of the north island lies in an approximate SE -NW line. The ideal wind direction for flying north being sou-east. Unfortunately a sou-easter is almost over the back which may not stop paragliding pilots from walking in but my nice performance wing weights in at the David Tua end of the scale. And before you all start giving me reasons to turn to the dark side, I'm very comfortable flying my heavy weight, thank you. The upshot of it all is, on Sunday, if we put our faith solely in the weather station reading we would have gone home as it was reading a steady SE. The actual direction was a more use-able southerly with the cycles straightening up the face for "twitchy" launch conditions.
If anyone is interested in knowing - I wasted the best looking XC day I've seen at Moirs this season. Yes, I need a good thrashing.
I have no idea how the Weather Station works, but when I ring it up I get a voice (not in my head) saying something like "blah blah blah for the last ten minutes".
I have always assumed that this was some sort of "average" calculated over the last ten minutes.
So when it says "SW 215 degrees" it actually meant "a-round-about 215 degrees give or take whatever the wind is swinging left and right over the last ten minutes (not right now)". I assumed steady, meant steady "around a direction".
How did you measure the wind direction manually? Could the wind at the top of the mast be the true wind direction above launch as opposed to wind coming up or across the face which has been interfered with by the terrain.
Certainly if we are to have the aide of the Weather Station it needs to be accurate both in direction and speed.
Just one more item in the "tool box", not the only item (albeit an important one).
It sounds like you didn't put your faith in the Weather Station anyway, so how far did you get?
For the Irish, wind over the back is a blessing.
"May the roads rise to meet you. May the wind be at your back. May the sun shine warm upon your face; The rain fall soft upon your fields and, until we meet again, may God hold you in the palm of His hand."
1stly; I posted this as an aid to pilots, not as a criticism.
2ndly; I was not flying so had plenty of time to evaluate the conditions.
The weather station does average over 10 minutes.
I was not measuring the wind direction across the face but walked several tracks in line with the anemometer (wind vane) and made calls to the weather station between these tracks several times. (20 degrees is my conservative estimate. Could easily be 25 degrees).
Therefore the assessment was made on these observations over about 20-30 minutes. Plenty of time to compare with the 10 minute average.
The decision to go into Moirs was based on analysis if several readings and forecasts, not just Moirs weather station. The object of this post was to inform that if you based your decision not to go solely on Moirs reading, you could miss out by thinking the wind was too far east.
1stly; I posted my comments not as a criticism, but as a discussion of what Les had found.
2ndly; I am never flying (cause I rely on the Moirs Weather Station) so have plenty of time to stuff around on the WWW, making up inane comments.
Talking about Weather Stations.
Finding a weather station on Weather Underground, situated near Dark Summit, I thought I could use this as backup/confirmation for Moirs. Unfortunately on one of my tiki tours I saw where the station was situated - on a house roof (about a metre from the roof ridge), the house is partly sheltered by surrounding trees, and is located well below the summit itself. Generally the wind speed reads between 25 - 50 % less than actual and certain directions are compromised by the trees.
This is obviously an amateur setup, but it serves the owners very well, but not really accurate or scientific, or much use to me.
On the other hand, I would expect the Moirs Station to be fit for purpose. Any discrepancies such as Les has found should be minimized, or failing that maybe an entry in the Site Guide would be of benefit.
The club members who lugged all the stuff in and set it up are legends and I thank them wholeheartedly, certainly its better than no Station and has apparently saved me on numerous times from flying on epic cross-country days.
I've never called the Moirs weather station, preferring instead to rely on free weather data . I've flown at Moirs many times in brilliant conditions (including on weekends) and been amazed that nobody else showed up. I wonder if they have been put off by the weather station.
I've been up at Moirs, no-one else in sight, conditions perfect.
But feeling loyalty to my flying "mates" have decided not to fly.
Well not quite.
Generally I use the wind velocity info more than direction, I hope it's accurate.
Next time (weekends preferred) if you are up there (or are about to go) and its on give us a "tweet", I can be at site and ready to launch in < 3/4 of an hour.
Of course if I had nothing else to do but fly I would hit Moirs a lot more times when it is a goer, "c'est la vie".
That would explain why Daron
That would explain why Daron is now so commited to flying it in a SW...
Moirs Hill Weather staion accuracy
Hi,
Hmm, never rely on the latest technology :-) Always carry a good old fashioned compass!
(One of those thingeemejingees with a floating needle...)
I reckon the weather station is actually correct in its reading. Which is probably in Magnetic North.
Your GPS is most likely set to True North or Map North.
Check the settings in your GPS, and possibly reset to Magnetic North, and do the test again.
Or do it with a compass.
The magnetic variation for this area of New Zealand is roughly 20 degrees East (it changes yearly by a fraction).
For a small explanation of this concept, have a look at:
http://www.mapworld.co.nz/declination.html
Or do a Google search for a full scientific explanation.
Cheers,
Stefan
Nice find, Checked on my
Nice find, Checked on my Iphone with both true north and magnetic north, perfect 20 degrees difference. Spot No.....
Where East Meets West
I may be wrong, but it would seem a bit silly to have the weather station set to magnetic north, as you point out this changes over time.
It seems more logical to set it to True North as this doesn't change and is what GPS and paper maps use as datum.
20 degrees is roughly one point of the compass (22.5), ie. SSE instead of S or SSW instead of S.
Now did Les mean that when the wind is actually S the station is reporting it as SSE, it has its N set East of Datum North, or did he mean when the wind is actually S the station is reporting it as SSW, and has its N set West of Datum.
If it is the first, that means if Daron waits for a SW it is actually going to be coming from WSW. The latter case would mean Daron would find a SSW.
Either way Daron launches, well picked Daron.
It reads SSE when it's S
It was reading @ 160 degrees when it was actually @ 180 degrees.
and
There is only one North and it's True.
Weather forecast winds are not given relative to magnetic north!
Does Moirs take S ? !
Does Moirs take S ? !
According to the site guide,
According to the site guide, yes. Purely from looking at Google Earth, I've always assumed that SSW was straight on at Moirs and S or SW was OK. Works for me, YMMV.
I would have thought that a S was better for XC, more island in that direction, no?
Just kidding. If SE wasn't
Just kidding. If SE wasn't such a crappy direction at Moirs it would be ideal as you travel along the landmass. I regulalry fly there on SW and W as my inlaws have a house at Snells beach and land in front. Recently flew there on a WNW and landed at Wenderholm.
The lay of the land
At the moment the weather station is reading east of actual wind direction. (that's the wind direction as you might see on a forecast chart, not magnetic) The tip of the north island lies in an approximate SE -NW line. The ideal wind direction for flying north being sou-east. Unfortunately a sou-easter is almost over the back which may not stop paragliding pilots from walking in but my nice performance wing weights in at the David Tua end of the scale. And before you all start giving me reasons to turn to the dark side, I'm very comfortable flying my heavy weight, thank you. The upshot of it all is, on Sunday, if we put our faith solely in the weather station reading we would have gone home as it was reading a steady SE. The actual direction was a more use-able southerly with the cycles straightening up the face for "twitchy" launch conditions.
If anyone is interested in knowing - I wasted the best looking XC day I've seen at Moirs this season. Yes, I need a good thrashing.
Every day I don't fly looks like a good flying day!
I have no idea how the Weather Station works, but when I ring it up I get a voice (not in my head) saying something like "blah blah blah for the last ten minutes".
I have always assumed that this was some sort of "average" calculated over the last ten minutes.
So when it says "SW 215 degrees" it actually meant "a-round-about 215 degrees give or take whatever the wind is swinging left and right over the last ten minutes (not right now)". I assumed steady, meant steady "around a direction".
How did you measure the wind direction manually? Could the wind at the top of the mast be the true wind direction above launch as opposed to wind coming up or across the face which has been interfered with by the terrain.
Certainly if we are to have the aide of the Weather Station it needs to be accurate both in direction and speed.
Just one more item in the "tool box", not the only item (albeit an important one).
It sounds like you didn't put your faith in the Weather Station anyway, so how far did you get?
For the Irish, wind over the back is a blessing.
"May the roads rise to meet you. May the wind be at your back. May the sun shine warm upon your face; The rain fall soft upon your fields and, until we meet again, may God hold you in the palm of His hand."
To the cynics out there
1stly; I posted this as an aid to pilots, not as a criticism.
2ndly; I was not flying so had plenty of time to evaluate the conditions.
The weather station does average over 10 minutes.
I was not measuring the wind direction across the face but walked several tracks in line with the anemometer (wind vane) and made calls to the weather station between these tracks several times. (20 degrees is my conservative estimate. Could easily be 25 degrees).
Therefore the assessment was made on these observations over about 20-30 minutes. Plenty of time to compare with the 10 minute average.
The decision to go into Moirs was based on analysis if several readings and forecasts, not just Moirs weather station. The object of this post was to inform that if you based your decision not to go solely on Moirs reading, you could miss out by thinking the wind was too far east.
I hope this is useful.
Cynics are motivated purely by self-interest.
Thanks Les for pointing that out.
1stly; I posted my comments not as a criticism, but as a discussion of what Les had found.
2ndly; I am never flying (cause I rely on the Moirs Weather Station) so have plenty of time to stuff around on the WWW, making up inane comments.
Talking about Weather Stations.
Finding a weather station on Weather Underground, situated near Dark Summit, I thought I could use this as backup/confirmation for Moirs. Unfortunately on one of my tiki tours I saw where the station was situated - on a house roof (about a metre from the roof ridge), the house is partly sheltered by surrounding trees, and is located well below the summit itself. Generally the wind speed reads between 25 - 50 % less than actual and certain directions are compromised by the trees.
This is obviously an amateur setup, but it serves the owners very well, but not really accurate or scientific, or much use to me.
On the other hand, I would expect the Moirs Station to be fit for purpose. Any discrepancies such as Les has found should be minimized, or failing that maybe an entry in the Site Guide would be of benefit.
The club members who lugged all the stuff in and set it up are legends and I thank them wholeheartedly, certainly its better than no Station and has apparently saved me on numerous times from flying on epic cross-country days.
lol, gee you are up late.
Interesting.....
I've never called the Moirs weather station, preferring instead to rely on free weather data
. I've flown at Moirs many times in brilliant conditions (including on weekends) and been amazed that nobody else showed up. I wonder if they have been put off by the weather station.
Likewise
I've been up at Moirs, no-one else in sight, conditions perfect.
But feeling loyalty to my flying "mates" have decided not to fly.
Well not quite.
Generally I use the wind velocity info more than direction, I hope it's accurate.
Next time (weekends preferred) if you are up there (or are about to go) and its on give us a "tweet", I can be at site and ready to launch in < 3/4 of an hour.
Of course if I had nothing else to do but fly I would hit Moirs a lot more times when it is a goer, "c'est la vie".