On Monday, 8 February 2016 10:07:41 UTC, Graham Easterling wrote:
On Monday, February 8, 2016 at 9:47:33 AM UTC, JohnD wrote:
"Graham Easterling" wrote in message
...

It's here http://www.landsendweather.info/met/mainframe.htm . It's actually
the Porthgwarra side of Land's End, near Gwennap Head. It's run by John
Chappell

I also see Terry Perkin's VP2 on St Martins hit 97kn @ 0716. Maybe I'll hear
from him later in the day to confirm.

103kt gust here http://www.weatherlink.com/user/tape...mary&headers=1 is that the same site!

Just had a particularly strong gust which brought 2 large branches down just opposite my garden. I'm beginning to doubt if I'll make it to Sennen this afternoon, there are branches down everywhere. The conditions (windwise) are now arguably worse that at anytime in 2014, when it was the sea, not wind, that caused the issues.

Graham
Penzance

Graham

The AWS that the Met Office has on the Scilly Isles (St Mary) at 0950 UTC reported 260° 40/60 kts. I know that it's not St Martins, and showers can cause extreme gusts, but 103 knots does look a bit excessive in comparison.

Bruce.

Yes, fair enough, but the exposure of the 2 sites is very different, Trebehor is extremely exposed, complete open to the Atlantic across open ground.

Graham

On Monday, 8 February 2016 11:21:15 UTC, Graham Easterling wrote:
Yes, fair enough, but the exposure of the 2 sites is very different, Trebehor is extremely exposed, complete open to the Atlantic across open ground.

Graham

If John has a bit of land free, It might be an idea for him to approach the Met Office and see if they would be interested in siting an AWS their,
They could always reuse the old WMO number for Gwennap Head #03806 which stopped reporting years ago just to the south.

"JohnD" wrote in
:



"Graham Easterling" wrote in message
...

It's here http://www.landsendweather.info/met/mainframe.htm . It's
actually the Porthgwarra side of Land's End, near Gwennap Head. It's
run by John Chappell

I also see Terry Perkin's VP2 on St Martins hit 97kn @ 0716. Maybe
I'll hear from him later in the day to confirm.




The VP station at Prawle Point is giving a 10 minute avearge of 63kn at the
moment, the highest recorded gust was 87kn at 03:29.

Alan

On Mon, 8 Feb 2016 02:24:07 -0800 (PST), xmetman wrote:

On Monday, 8 February 2016 09:21:57 UTC, Graham Easterling wrote:
On Monday, February 8, 2016 at 8:51:24 AM UTC, xmetman wrote:
On Monday, 8 February 2016 08:41:23 UTC, Graham Easterling wrote:
Gust of 86mph at Land's End. Mean speed reached 67mph!

Wind WNW offshore here, but still a gust of 59mph, the strongest in a W-NW wind since November 2009.

Given the time of high tides, I think 6pm is a strange time to remove the warning. Significant (not maximum!) swell height now 30' at Sevenstones. Easily the biggest since 2014.

Graham
Penzance

Graham

Where do you get that observation for Lands End from?

Bruce.

It's here http://www.landsendweather.info/met/mainframe.htm . It's actually the Porthgwarra side of Land's End, near Gwennap Head. It's run by John Chappell

I see from your list Culdrose reached 79mph. I think most of the the west Penwith peninsula has seen gust well 70mph (ways from sheltered Newlyn/Penzance). 76mph gust at St Ives.

Under these conditions the webcams are useless, covered in salt http://magicseaweed.com/Live-Sennen-Webcam/65/ vut I hope to get to Sennen this afternoon and hopefully post some pics lately.

I think the real flooding issues will be on this afternoons high tide, the swell was smaller on the last one, and the period is getting longer now.

Graham
Penzance

Graham

I can see the site and the anemometer and vane using Google street view. Mean speeds as high as 67 and gust to 86 mph will cause damage and look a tad high to me.

It got me to thinking about cup size of my Vantage Pro. I've just checked mine and realised that I've had it on 'small' cups for many years (oops!), I had thought it would default to 'large' (wrong!). I don't know how much difference that will make to the speed, probably not a lot.

The upper air station at Camborne (81 M amsl) was meaning (at 09 UTC) 44 mph with gusts to 65 mph, that still can't match the latest live mean wind speeds from Trebehor (270' ASL).

I suppose the Vantage Pro just collects 1 minute mean speeds and graphs those values in its own LCD display, and it's down to the display software on the PC to take the average of 10 of those one-minute values to produce a 10 minute mean. A one minute mean of 67 mph would be significantly higher than a 10 minute mean (~x1.2 or more higher). The length of that mean should be a user setting I would have thought and I bet it's not 10.

Bruce.


Bruce,

The Vantage Pro console receives a wind measurement from the anemometer
sensorevery 2.5 seconds. That is the ever-changing figure that is displayed on
the console. It calculates a rolling 10-min mean from those figures which can be
displayed in the text bar on the bottom of the console screen. There are other
options for that text bar.

A random 1-min mean wind speed may be higher or lower than a corresponding
10-min mean within which it is embedded.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

On Monday, 8 February 2016 10:07:41 UTC, Graham Easterling wrote:

103kt gust here http://www.weatherlink.com/user/tape...mary&headers=1 is that the same site!

Yes, that's Terry. If you look at the map on the wl.com site (eg just click the map menu option that same page) then you'll see a number of other sites in the area. Regrettably the only other one on Scilly seems to have a very low or otherwise sheltered anemometer.

On Mon, 8 Feb 2016 03:08:31 -0800 (PST), xmetman wrote:

On Monday, 8 February 2016 10:39:50 UTC, Graham Easterling wrote:
On Monday, February 8, 2016 at 10:24:08 AM UTC, xmetman wrote:
On Monday, 8 February 2016 09:21:57 UTC, Graham Easterling wrote:
On Monday, February 8, 2016 at 8:51:24 AM UTC, xmetman wrote:
On Monday, 8 February 2016 08:41:23 UTC, Graham Easterling wrote:
Gust of 86mph at Land's End. Mean speed reached 67mph!

Wind WNW offshore here, but still a gust of 59mph, the strongest in a W-NW wind since November 2009.

Given the time of high tides, I think 6pm is a strange time to remove the warning. Significant (not maximum!) swell height now 30' at Sevenstones. Easily the biggest since 2014.

Graham
Penzance

Graham

Where do you get that observation for Lands End from?

Bruce.

It's here http://www.landsendweather.info/met/mainframe.htm . It's actually the Porthgwarra side of Land's End, near Gwennap Head. It's run by John Chappell

I see from your list Culdrose reached 79mph. I think most of the the west Penwith peninsula has seen gust well 70mph (ways from sheltered Newlyn/Penzance). 76mph gust at St Ives.

Under these conditions the webcams are useless, covered in salt http://magicseaweed.com/Live-Sennen-Webcam/65/ vut I hope to get to Sennen this afternoon and hopefully post some pics lately.

I think the real flooding issues will be on this afternoons high tide, the swell was smaller on the last one, and the period is getting longer now.

Graham
Penzance

Graham

I can see the site and the anemometer and vane using Google street view. Mean speeds as high as 67 and gust to 86 mph will cause damage and look a tad high to me.

It got me to thinking about cup size of my Vantage Pro. I've just checked mine and realised that I've had it on 'small' cups for many years (oops!), I had thought it would default to 'large' (wrong!). I don't know how much difference that will make to the speed, probably not a lot.

The upper air station at Camborne (81 M amsl) was meaning (at 09 UTC) 44 mph with gusts to 65 mph, that still can't match the latest live mean wind speeds from Trebehor (270' ASL).

I suppose the Vantage Pro just collects 1 minute mean speeds and graphs those values in its own LCD display, and it's down to the display software on the PC to take the average of 10 of those one-minute values to produce a 10 minute mean. A one minute mean of 67 mph would be significantly higher than a 10 minute mean (~x1.2 or more higher). The length of that mean should be a user setting I would have thought and I bet it's not 10.

Bruce.

You can't really compare Camborne with Land's End, it's like comparing the centre of Torquay with Berry Head. John is quite careful with his setup, I suspect he's following this thread.

Remember, the area near Land's End is used to gusts in the 80-90mph range, (I think Gwennap Head holds the record for a lowland site on mainland England & Wales, 106mph?). There are no real trees or wooden fences etc, mainly granite buildings and stone walls (Cornish hedges) so the damage is far less than in an area not susceptible to severe gales.

Graham
Penzance

Graham

I just commented that it looked a tad high. And the reason that I compared it to Camborne is that it's the nearest land station, and we are not exactly comparing it to Lands End, but Trebehor which is 1.5 miles inland. All I was saying is that if the software is pushing out a 1 or 2 minute mean, this is not the same as a 10 minute mean, and the mean speed will be much higher.

I notice that the weather buoy 62107 is reporting 280° 48/82 (55/94 mph) at 10 UTC but that's ~30km offshore.

Bruce.

This really can be a bit of a minefield. Reported mean wind speeds are
'snapshot' winds. They are not the maximum that occurs. The convention in the UK
is that reported mean wind speeds reported in SYNOPs are the 10-min means
between HH-20 and HH-10. Almost certainly, in any hour there will be a 10-min
mean speed that is higher than any that is reported in the hourly SYNOPs. If any
10-min mean is assumed to be made up of 10 consecutive 1-min means then
approximately half of those 1-min means will be higher than the 10-min mean and
half will be lower than the 10-min mean. This means, for example, that the mean
speed during the last minute of a 10-minute period has an equal chance of being
higher or lower than the 10-minute mean. The highest 1-minute mean within a
10-min period will always be higher than the 10-min mean but that is not what is
reported by stations that report 1-min means. It is the figure that is used in
hurricane forecasts, for example, but the conventions used in forecasting are
different to those used in observing. As I said, it's a bit of a minefield.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

On Monday, 8 February 2016 11:35:50 UTC, Norman Lynagh wrote:
On Mon, 8 Feb 2016 02:24:07 -0800 (PST), xmetman wrote:

On Monday, 8 February 2016 09:21:57 UTC, Graham Easterling wrote:
On Monday, February 8, 2016 at 8:51:24 AM UTC, xmetman wrote:
On Monday, 8 February 2016 08:41:23 UTC, Graham Easterling wrote:
Gust of 86mph at Land's End. Mean speed reached 67mph!

Wind WNW offshore here, but still a gust of 59mph, the strongest in a W-NW wind since November 2009.

Given the time of high tides, I think 6pm is a strange time to remove the warning. Significant (not maximum!) swell height now 30' at Sevenstones. Easily the biggest since 2014.

Graham
Penzance

Graham

Where do you get that observation for Lands End from?

Bruce.

It's here http://www.landsendweather.info/met/mainframe.htm . It's actually the Porthgwarra side of Land's End, near Gwennap Head. It's run by John Chappell

I see from your list Culdrose reached 79mph. I think most of the the west Penwith peninsula has seen gust well 70mph (ways from sheltered Newlyn/Penzance). 76mph gust at St Ives.

Under these conditions the webcams are useless, covered in salt http://magicseaweed.com/Live-Sennen-Webcam/65/ vut I hope to get to Sennen this afternoon and hopefully post some pics lately.

I think the real flooding issues will be on this afternoons high tide, the swell was smaller on the last one, and the period is getting longer now.

Graham
Penzance

Graham

I can see the site and the anemometer and vane using Google street view. Mean speeds as high as 67 and gust to 86 mph will cause damage and look a tad high to me.

It got me to thinking about cup size of my Vantage Pro. I've just checked mine and realised that I've had it on 'small' cups for many years (oops!), I had thought it would default to 'large' (wrong!). I don't know how much difference that will make to the speed, probably not a lot.

The upper air station at Camborne (81 M amsl) was meaning (at 09 UTC) 44 mph with gusts to 65 mph, that still can't match the latest live mean wind speeds from Trebehor (270' ASL).

I suppose the Vantage Pro just collects 1 minute mean speeds and graphs those values in its own LCD display, and it's down to the display software on the PC to take the average of 10 of those one-minute values to produce a 10 minute mean. A one minute mean of 67 mph would be significantly higher than a 10 minute mean (~x1.2 or more higher). The length of that mean should be a user setting I would have thought and I bet it's not 10.

Bruce.


Bruce,

The Vantage Pro console receives a wind measurement from the anemometer
sensorevery 2.5 seconds. That is the ever-changing figure that is displayed on
the console. It calculates a rolling 10-min mean from those figures which can be
displayed in the text bar on the bottom of the console screen. There are other
options for that text bar.

A random 1-min mean wind speed may be higher or lower than a corresponding
10-min mean within which it is embedded.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

Norman

Yes, of course you're right it could be. But what if the PC software people use in conjunction with their AWS (to publish it on a website) has been coded to select the highest 1 minute speed rather than the mean of the last 10 minutes?

All I'm trying to do is to compare like for like, i.e. mean wind speed reported by people's AWS with those in UK SYNOPs, and it's not that easy!

Bruce.

"xmetman" wrote in message
...
On Monday, 8 February 2016 11:35:50 UTC, Norman Lynagh wrote:
On Mon, 8 Feb 2016 02:24:07 -0800 (PST), xmetman
wrote:

On Monday, 8 February 2016 09:21:57 UTC, Graham Easterling wrote:
On Monday, February 8, 2016 at 8:51:24 AM UTC, xmetman wrote:
On Monday, 8 February 2016 08:41:23 UTC, Graham Easterling wrote:
Gust of 86mph at Land's End. Mean speed reached 67mph!

Wind WNW offshore here, but still a gust of 59mph, the strongest in
a W-NW wind since November 2009.

Given the time of high tides, I think 6pm is a strange time to
remove the warning. Significant (not maximum!) swell height now
30' at Sevenstones. Easily the biggest since 2014.

Graham
Penzance

Graham

Where do you get that observation for Lands End from?

Bruce.

It's here http://www.landsendweather.info/met/mainframe.htm . It's
actually the Porthgwarra side of Land's End, near Gwennap Head. It's
run by John Chappell

I see from your list Culdrose reached 79mph. I think most of the the
west Penwith peninsula has seen gust well 70mph (ways from sheltered
Newlyn/Penzance). 76mph gust at St Ives.

Under these conditions the webcams are useless, covered in salt
http://magicseaweed.com/Live-Sennen-Webcam/65/ vut I hope to get to
Sennen this afternoon and hopefully post some pics lately.

I think the real flooding issues will be on this afternoons high tide,
the swell was smaller on the last one, and the period is getting longer
now.

Graham
Penzance

Graham

I can see the site and the anemometer and vane using Google street view.
Mean speeds as high as 67 and gust to 86 mph will cause damage and look a
tad high to me.

It got me to thinking about cup size of my Vantage Pro. I've just checked
mine and realised that I've had it on 'small' cups for many years
(oops!), I had thought it would default to 'large' (wrong!). I don't know
how much difference that will make to the speed, probably not a lot.

The upper air station at Camborne (81 M amsl) was meaning (at 09 UTC) 44
mph with gusts to 65 mph, that still can't match the latest live mean
wind speeds from Trebehor (270' ASL).

I suppose the Vantage Pro just collects 1 minute mean speeds and graphs
those values in its own LCD display, and it's down to the display
software on the PC to take the average of 10 of those one-minute values
to produce a 10 minute mean. A one minute mean of 67 mph would be
significantly higher than a 10 minute mean (~x1.2 or more higher). The
length of that mean should be a user setting I would have thought and I
bet it's not 10.

Bruce.


Bruce,

The Vantage Pro console receives a wind measurement from the anemometer
sensorevery 2.5 seconds. That is the ever-changing figure that is
displayed on
the console. It calculates a rolling 10-min mean from those figures which
can be
displayed in the text bar on the bottom of the console screen. There are
other
options for that text bar.

A random 1-min mean wind speed may be higher or lower than a corresponding
10-min mean within which it is embedded.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

Norman

Yes, of course you're right it could be. But what if the PC software people
use in conjunction with their AWS (to publish it on a website) has been
coded to select the highest 1 minute speed rather than the mean of the last
10 minutes?

All I'm trying to do is to compare like for like, i.e. mean wind speed
reported by people's AWS with those in UK SYNOPs, and it's not that easy!

Bruce.
========

In the real world it's gusts that do damage. And gusts can last for less
than a minute, so I'd say that peak 1 minute gusts will be most
representative of real life. Another issue is that we measure wind speeds at
10 metres above ground, so means speeds experienced by Joe Public will be
lower but 1 minute gusts will not be very different of course.

Will
--
" Some sects believe that the world was created 5000 years ago. Another sect
believes that it was created in 1910 "
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
---------------------------------------------

On Mon, 8 Feb 2016 12:09:28 -0000, "Eskimo Will"
wrote:




Graham

I can see the site and the anemometer and vane using Google street view.
Mean speeds as high as 67 and gust to 86 mph will cause damage and look a
tad high to me.

It got me to thinking about cup size of my Vantage Pro. I've just checked
mine and realised that I've had it on 'small' cups for many years
(oops!), I had thought it would default to 'large' (wrong!). I don't know
how much difference that will make to the speed, probably not a lot.

The upper air station at Camborne (81 M amsl) was meaning (at 09 UTC) 44
mph with gusts to 65 mph, that still can't match the latest live mean
wind speeds from Trebehor (270' ASL).

I suppose the Vantage Pro just collects 1 minute mean speeds and graphs
those values in its own LCD display, and it's down to the display
software on the PC to take the average of 10 of those one-minute values
to produce a 10 minute mean. A one minute mean of 67 mph would be
significantly higher than a 10 minute mean (~x1.2 or more higher). The
length of that mean should be a user setting I would have thought and I
bet it's not 10.

Bruce.


Bruce,

The Vantage Pro console receives a wind measurement from the anemometer
sensorevery 2.5 seconds. That is the ever-changing figure that is
displayed on
the console. It calculates a rolling 10-min mean from those figures which
can be
displayed in the text bar on the bottom of the console screen. There are
other
options for that text bar.

A random 1-min mean wind speed may be higher or lower than a corresponding
10-min mean within which it is embedded.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

Norman

Yes, of course you're right it could be. But what if the PC software people
use in conjunction with their AWS (to publish it on a website) has been
coded to select the highest 1 minute speed rather than the mean of the last
10 minutes?

All I'm trying to do is to compare like for like, i.e. mean wind speed
reported by people's AWS with those in UK SYNOPs, and it's not that easy!

Bruce.
========

In the real world it's gusts that do damage. And gusts can last for less
than a minute, so I'd say that peak 1 minute gusts will be most
representative of real life. Another issue is that we measure wind speeds at
10 metres above ground, so means speeds experienced by Joe Public will be
lower but 1 minute gusts will not be very different of course.

Will

It all depends on response time. Stuff around the house like chimney pots,
roofs, fence panels etc respond to very short duration events. For them, a
single very strong gust is what does the damage. The max gusts reported in the
SYNOPs are representative in this context. Traditionally, with the old Munro
anemometers, they were generally taken to be of about 3 sec duration. With more
modern equipment I suspect that it is possible to get much finer resolution,
perhaps down to 1 sec. This means, of course, that the same gust would probably
register a lower speed on a Munro anemometer than it would on more sensitive
instrumentation.

At the other end of the spectrum, the mooring system of a super-tanker moored
alongside a terminal responds to mean winds of 1 to 5 minutes duration. Single
very strong gusts have very little impact.

The reason why single very strong gusts can do so much damage to property is
that the force exerted by the wind is proportional to the square of the wind
speed. Therefore, for example, an 80-knot gust exerts about 30% more force than
a 70-knot gust

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org